RESEARCH REPORT. Potential impact of wood building on GHG emissions. Antti Ruuska, Tarja Häkkinen

Transcription

1 RESEARCH REPORT Potential impact of wood building on GHG emissions Authors: Antti Ruuska, Tarja Häkkinen

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3 1 (99) Report s title Potential impact of wood building on GHG emissions Customer TEM Author(s) Antti Ruuska, Tarja Häkkinen Keywords GHG potential, wood building, LCA Summary This report presents a review of literature and assessment results about the greenhouse gas saving potential of wood building. The assessment was done on the basis of a case study which assesses the effects of increased volumes of wood building on the greenhouse gases of building in Finland. The study uses alternative scenarios for the assessment of the potential volumes of wood to be used. The baseline scenario assumes that construction of new buildings will stay at a constant level between years 2010 and 2030 and that the relative share of concrete and wooden buildings will stay unchanged. This means that the share of concrete buildings will be 98 % and the share of wood buildings will be 2 %. The alternative scenarios assume that the share of wood construction will rise to 22%, 52%, or 82% by Increased use of wood in new construction results in lower annual greenhouse gas (GHG) emissions. According to the baseline scenario, the total annual GHG emissions are estimated to be 201 thousand tonnes in 2030 for new construction. On the basis of the calculation results, the potential saving is 13 % (25.6 thousand tonnes), 32 % (64 thousand tonne) or 52 % (102 thousand tonne) with regard to scenarios 2, 3 and 4, when compared to scenario 1. When the carbon stored in timber products is taken into account (and dealt with as negative emissions), this results in significantly decreased values for scenarios 2 4. The net GHGemissions of the baseline scenario are 197 thousand tonnes. On the bases of calculations, the decrease in net GHG-emissions is 62 thousand tonnes for scenario 2 (31%), 156 thousand tonnes for scenario 3 (79%) and 249 thousand tonnes (126%) for scenario 4. This leads to a negative emission value for scenario 4. When the mineral wool insulation is changed to cellulose insulation, the amount of calculated GHGs emitted is decreased by 2 10% (3 10 thousand tonnes) and the amount of calculated stored carbon is increased by 14% (0 21 thousand tonnes). The study also assesses the change in GHG emissions when an increased share of external wall refurbishments would be done with help of increased use of wood. The baseline scenario assumes that the most important group of buildings, with regard to external wall refurbishments, is the group of multi-storey residential buildings, built between 1950 and 2000 and that the volume of refurbishments stay constant between the years 2010 and Two alternative levels of refurbishments are used: 50% of the buildings built between 1950 and 2000 are refurbished by 2030 or 75% of those buildings are refurbished by The refurbishment studies are based on the assumption that external walls are mostly refurbished with additional thermal insulation and a rendered façade. The share of this refurbishment is assumed to be 98 % of all the façade refurbishments and the share of wooden façades with additional thermal insulation is estimated to be at 2 %. The alternative scenarios 2, 3 and 4 assume that the share of new wooden façade refurbishments will increase to 22%,

4 2 (99) 52%, or 82% by 2030, while the share of rendered façades decreases respectively. When 75% of the buildings built between 1950 and 2000 are renovated, the baseline scenario shows that the total GHG emissions from refurbishments als to 19 thousand tonnes. The savings were estimated to be 2, 5 and 9 tonnes for scenarios 2, 3 and 4 respectively. The additional estimated stored carbon is 11, 28 and 44 thousand tonnes for scenarios 2, 3 and 4 respectively. The total amount of potential savings is relatively high, the calculated maximum saving being 102 thousand tons or 333 thousand tonnes if also carbon uptake is considered. However, the relative share of savings, in relation to the GHG emissions of Finland ( thousand tonnes in 2009 according to OECD statistics) remains quite low; it is roughly 0.2 % or 0.5 % when absorbed carbon is taken into account. The use of the name of the VTT Technical Research Centre of Finland (VTT) in advertising or publication in part of this report is only permissible with written authorisation from the VTT Technical Research Centre of Finland.

5 3 (99) Preface This report presents a review of literature and assessment results about the greenhouse gas saving potential of wood building. The assessment was done on the basis of a case study which assesses the effects of increased volumes of wood building on the greenhouse gases of building in Finland. The study was performed for the Ministry of employment and the economy. The purpose of the study was to collect research results and make preliminary calculations in order to find out the need to establish an international project and deepen the understanding about the potential of wood building in saving GHG emissions. The study was carried out at VTT. The members of the project s steering group were as follows: - Reima Sutinen, Ministry of employment and the economy - Mikko Viljakainen, Puuinfo Oy - Harri Hakaste, Ministry of environment - Seppo Kangaspunta, Ministry of employment and the economy - Riku Patokoski, Skanska Oy - Kaisa Pirkola, Ministry of agriculture and forestry - Jukka Noponen, Sitra Authors

6 4 (99) Contents Preface Introduction Life cycle assessment and carbon footprint assessment LCI and LCA results of wood and other building products Cradle-to-gate inventories and attributional LCAs Life cycle assessments that cover consential impacts Significance of building materials Calculation scenarios, new construction Model building for calculation and amount of annually built residential multistorey buildings Relative share of concrete and wooden buildings Relative share of timber-framed and CLT-based buildings Emissions of new construction Mass of structures, new construction Annually built mass, in 2030, effects of timber-framed and CLT-based building Greenhouse gas emissions of new construction Annual GHG emissions Effects of timber-framed and CLT-based building Consideration of carbon uptake for new construction Stored carbon in Effects of timber-framed and CLT-based building Comparison of GHG emissions and carbon uptake of new construction GHS emissions and CO2 uptake Effects of timber-framed and CLT-based building Effects of use of cellulose insulation, new construction Effect of cellulose insulation on GHG emissions Effect of cellulose insulation on stored carbon Effect of cellulose insulation, comparison of GHGs and CO2 uptake Wood use of new construction Calculation scenarios for refurbishments Model building for calculation Scenarios - Relative share of rendered and wooden façade refurbishments Relative share of replacing and additional refurbishment methods in external wall refurbishments Building-level emissions for refurbishments Assessed mass of annual external wall refurbishments Annually built mass, in 2030, effects of a light wooden façade Greenhouse gas emissions... 56

7 5 (99) 11.8 Annual greenhouse gas emissions, in 2030, effects of a light wooden façade61 12 Consideration of carbon uptake, refurbishments Annually stored carbon Effect of a light wooden façade Stored carbon and emissions Effects of light wooden façades Wood use in refurbishments Comparison of wood use of refurbishments Effect of light wooden façades Summary and conclusions APPENDIX APPENDIX APPENDIX APPENDIX

8 6 (99) 1 Introduction In European Union, buildings account for 42% of energy consumption and 35% of GHG emissions 1. In order to reduce the environmental impact of buildings European policies have focussed on energy consumption. EPBD stipulates that all new buildings should be nearly zero energy by the end of The construction of new highly energy efficient or zero energy buildings will make it possible to reach the current targets because the payback times for climate mitigation are long (e.g. 30 to 50 years). In addition, the operational energy is only one part of buildings environmental impacts. When the whole life cycle of building is considered, also the energy consumption and greenhouse gas (GHG) emissions due to construction products and materials are taken into account. This is called here embodied energy. It consists of energy used during the manufacture of the building materials and components, in transporting these to site, and during the construction processes. Embodied energy can further include the energy needed for refurbishment and replacement of components during the lifetime of the building and that used in the demolition, waste and reprocessing at the end of life stage. For the same processes GHG emissions can be calculated, their sum being called embodied GHG emissions. The current EU policies do not address the problem of embodied energy and GHGs. However, when buildings tend to be zero energy, the share of embodied part may become significant. There are significant differences in the environmental impacts of alternative building materials both when looking the results on the mass bases and when comparing the results on the bases of functional units (see Chapter 3). The latter approach should naturally be always used when making comparisons between alternatives (see Chapter 2). This study assesses the potential of wood in saving GHGs in Finland when an estimated increased share of new residential buildings and building refurbishments would be done with help of increased use of wood. The report consists of a literature study and assessment results. The study of literature presents recent results about the environmental impact of wood and wood building. The assessment uses alternative scenarios for the potential volumes of wood to be used. The assessment also uses existing generic Finnish information about the environmental impact of building materials. The information about the current building stock was based on the results of the Nordic MECOREN 3 project. The building volumes during the coming years were assumed to be on the same level as in average during the past 10 years. The assessed effect of the use of wood products was finally based on the life cycle inventory results of buildings. 1 European Commission A Lead Market Initiative for Europe, Annex I: Action Plan for Sustainable Construction. 2 European Parliament and the Council of the European Union, Directive 2010/ 31/EU of the European parliament and of the council of 19 th May 2010 on the Energy performance of buildings (recast). Official Journal of the European Union 3 Methods and concepts for sustainable refurbishment of buildings. Nordic research project coordinated by VTT.

9 7 (99) 2 Life cycle assessment and carbon footprint assessment The general principles on life cycle assessment (LCA) of products and services have been agreed upon and introduced with help of standardisation 4 5. In addition, there are international standards available on the formats, contents and processes of environmental assessment and declarations of products 6 7. LCA is a technique for assessing the environmental aspects and potential impacts with a product by: - compiling an inventory of relevant inputs and outputs of a product system; - evaluating the potential environmental impacts associated with those inputs and outputs; - interpreting the results of the inventory analysis and impact assessment phases in relation to the objectives of the study. LCA addresses the environmental aspects and potential environmental impacts throughout a product's life cycle from raw material acquisition through production, use, end-of-life treatment, recycling and final disposal (i.e. cradle-tograve). Carbon footprint (CF) is a sub-set of the data covered by a more complete Life Cycle Assessment. Carbon footprint is the overall amount of carbon dioxide (CO2) and other greenhouse gas (GHG) emissions (e.g. methane (CH4), nitrous oxide (N2O)) associated with a product along its supply-chain, use and end-of-life recovery and disposal 8. These emissions are caused, among others, by electricity production in power plants, heating with fossil fuels, transport operations, and other industrial and agricultural processes. Carbon footprint is quantified using indicators such as the Global Warming Potential (GWP). The Intergovernmental Panel on Climate Change (IPCC) 9 defines the GWP as an indicator that reflects the potential relative climate change effect per kg of a greenhouse gas over a fixed time period, such as e.g. 100 years (GWP100). With regard to wood products the absorption of CO2 from the atmosphere during growth is an important issue in addition to the GHG emissions caused by fuels and caused by the possible decomposition of organic materials in the end of life. The European standard 10 defines that the product stage includes the following stages: - raw material extraction and processing, processing of secondary material input (e.g. recycling processes) (A1), 4 ISO Environmental management. Life cycle assessment. Principles and framework. 5 ISO Environmental management. Life cycle assessment. Rirements and guidelines. 6 ISO Environmental labels and declarations General principles. 7 ISO Environmental labels and declarations Type III environmental declarations Principles and procedures 8 Carbon footprint - what it is and how to measure it. JRC leaflet. European platform on LCA EN Sustainability of construction works - Environmental product declarations - Core rules for the product category of construction products. 2011

10 8 (99) - transport to the manufacturer (A2), and - manufacturing including provision of all materials, products and energy, as well as waste processing up to the end-of waste state or disposal of final residues during the product stage (A3). The current draft for product category rules for sawn timber 11 defines that with regard to wood products, stage A1 includes the formation of wood in the forest. This is based on the absorption of CO2 from the atmosphere; therefore, the amount of biogenic carbon contained in the wood product is counted as a removal of CO2. Correspondingly, all other natural processes related to the forest are outside the system boundary of the LCA. However, all technical processes related to forestry operations (e.g. stand establishment, tending, thinning(s), harvesting, establishment and maintenance of forest roads, etc.) are considered within the system boundary and are subject to co-product allocations. Wood - entering the product system - accounts for the feedstock energy and the biogenic carbon content as material inherent properties. Appendix 1 gives definitions for carbon footprint on the bases of relevant standards. 11 TC 175 WI Round and sawn timber - Environmental Product Declarations - Product category rules for wood and wood based products

11 9 (99) 3 LCI and LCA results of wood and other building products 3.1 Cradle-to-gate inventories and attributional LCAs Results of LCIs of wooden products in comparison with alternative products have been published by a number of researchers. For example Petersen and Solberg (2005) 12 have summarised Swedish and Norwegian studies which compared wooden building products to alternative products on functional ivalence basis. They analysed manufacturing processes in both countries and concluded on the basis of analyses that wood is a more beneficial alternative with regard to total GHG emissions during manufacture. The ELCD data base gives process data sets for spruce and pine log (with bark) and wood 13. The carbon dioxide incorporation is considered (assumed to be 1.85 kg/ kg wood; absolute dry) and the figure is given as an input value (Table 1). The results are calculated by PE International, which uses the same approach also in the formulation of environmental declarations for wooden products (for example 14 and 15 ). The LCI data sets can be used for LCA studies of products where timber is needed in production processes. The release of incorporated carbon in the end of life may then be allocated either to the wood product itself or possibly to other products if for example the energy content is recovered at the same time and made use of in other production processes. 12 Petersen, A.K. and Solberg, B Environmental and economic impacts of substitution between wood products and alternative materials: a review of micro-level analyses from Norway and Sweden. Forest policy and economics 7(2005). p ELCD database, data sets, category materials production, subcategory wood. =Wood The data represents the average data in Germany. 14 EPD-EHW E. Raw and Melamine faced medium and high density fibreboard. Institut Bauen und Umwelt e.v. 15 EPD-EHW E. Raw chipboard. Melamine faced chipboard. Institut Bauen und Umwelt e.v.

12 10 (99) Table 1. Carbon dioxide, methane and nitrous oxide inputs and outputs of logs and timber according to the ELCD data base (kg/kg). Spruce log 44% water content (1 Pine log 44% water content (2 Spruce wood 40% water content (3 Pine wood 40% water content (4 inputs CO kg 1.03 kg 1.12 kg 1.12 kg outputs CO kg kg kg kg CH kg kg kg kg N2O kg kg kg kg 1) spruce log with bark; refostered managed forest; production mix entry to saw mill, at plant; 44% water content 2) pine log with bark; refostered managed forest; production mix entry to saw mill, at plant; 44% water content 3) spruce wood; timber; production mix, at saw mill; 40% water content 4) pine wood; timber; production mix, at saw mill; 40% water content Table 2 gives the corresponding values for concrete. The life cycle assessment of pre-cast concrete elements covers the production of concrete and reinforcing steel. Concrete C20/25 is used. The average raw density is assumed to be 2.4 t/m 3 with the 0.5% share of reinforcement. The assessment includes the life cycle from the energy generation and raw material supply to the finished product on the factory gate. Transports "gate to building site" are not part of the system and have to be considered afterwards. If higher load is necessary additional reinforcement and more load bearing concrete should be considered and calculated. Table 2. Carbon dioxide, methane and nitrous oxide of concrete according to the ELCD data base. outputs (kg/kg) CO CH N2O The Finnish environmental declarations 16 give cradle-to-gate data for building products. The declarations that presented environmental information for concrete and wood covered widely the production in Finland. The following table gives information for sawn timber and different kinds of concrete products. Also the Finnish information considers the CO2 uptake of wooden products. It is important to note that according to the principals of LCA, the comparison of materials never takes place on the basis of material quantities but on the basis of functional ivalences (ISO 14040)

13 11 (99) Table 3. Carbon dioxide, methane and nitrous oxide of steel, concrete and wooden building products and composite products according to the Finnish data base (RTS 2010). CO2 CO CH4 N2O g/kg g/kg g/kg g/kg Hot-dip galvanized steel products (Roofing sheets, facade claddings, purlins, framings and composite frame systems) Steel columns, beams and frameworks Hot-rolled frames and bridge structures Cold rolled steel sheet and coils Structural hollow sections, steel pipe piles and steel sections Ready mixed concrete, medium strength Reinforced concrete element Reinforces concrete column Reinforced concrete beam Prestressed concrete beam Prestressed concrete slab Concrete wall element (indoor) non-load bearing concrete sandwich element Glued laminated timber Sawn timber Plywood (birch wood, uncoated) Plywood (coniferous wood, uncoated) Soft fibre board Rivela et al. (2006 and 2007) have studied the life cycle inventories of wooden particle boards and fibre boards. As the first approach in their study, the CO2 emission from wood burning (the heat of which was made use of in the process) was considered al to the CO2 up-take necessary for photosynthesis. Sometimes, these are reported separately as an input value (carbon uptake during growth) and biogenic CO2 emissions. The carbon storage in products was not dealt with by Rivela et al. This is a typical choice that also other LCA studies of 17 Rivela B., Moreira T., Feijoo G Life cycle inventory of medium density fibreboard. Int J LCA 12(3) Rivela B., Hospido A., Moreira T., Feijoo G Life cycle inventory of particle-board: A case study in wood sector. Int J LCA 11(2)

14 12 (99) wooden products use (for example 19 ). On the other hand often also the significance of CO2 up-take is addressed from the view point of carbon balance. For example Bribián et al. (2011) 20 point out that the primary energy demand in wooden building products is basically from biomass, representing 69-83% of the total primary energy demand. The balance in ivalent carbon dioxide emissions is almost neutral, due to the low level of industrial processing and would be negative (net absorption of emissions) if product is recycled or reused instead of incinerated at the end of its life. In conclusion: - environmental databases of building products typically give cradle-to-gate information - carbon footprint of timber in terms of kg GHG/kg of product is typically significantly lower than the corresponding value for concrete, brick and metallic building materials - emissions from renewable bio-fuels are typically taken as net zero - carbon up-take is typically reported as a separate value - the moisture content of wood significantly affects the CF value and is normally given as necessary background information - other wood products than logs or sawn timber may have significantly higher CF because of manufacturing processes that may use fossil fuels or because of the content of inorganic polymers such as glues - assessment results (on the basis of attributional LCI, see definition in the following section) given on the basis of functional ivalences typically show significantly lower GHG emissions for wood buildings than for concrete buildings especially if carbon uptake is considered and calculated as a negative emission. 3.2 Life cycle assessments that cover consential impacts Attributional LCA is defined by its focus on describing the environmentally relevant physical flows to and from a life cycle and its subsystems. Consential LCA is defined by its aim to describe how environmentally relevant flows will change in response to possible decisions (Finnveden et al ). According to Curran et al. ( ) attributional and consential LCIs are modelling methods 19 Puettman, Maureen E. and Wilson, James B Life-cycle analysis of wood products: cradle to gate LCI of residential wood building materials. Wood and fibre science. 37 Corrim Special Issue. p Bribián, I. Z., Capilla, A.V. and Usón A.A. Life cycle assessment of building materials: Comparative analysis of energy and environmental impacts and evaluation of the eco-efficiency improvement potential. Building and Environment 46 (2011) ks reference edellä 22 Mary Ann Curran, Margaret Mann, Gregory Norris. The international workshop on electricity data for life cycle inventories. journal on cleaner production. 13 (2005) 853e862

15 13 (99) which respond to different questions: attributional LCIs attempt to answer how are things (pollutants, resources, and exchanges among processes) flowing within the chosen temporal window? while consential LCIs attempt to answer how will flows change in response to decisions? Werner et al. (2007) 23 address several issues that need specific attention in an LCA of wood products. These include the consistent handling of carbon uptake, embodied energy, co-products generated through-out the processing chain, and options of reuse, recycling and energy recovery. Several co-product allocation procedures are possible. The procedure that should be selected depends on material and market characteristics and the purpose of the study. There are also studies like Garcia et al. (2005) 24, which account the carbon balance by considering the both forests and forest products and fossil fuel substitution as carbon pools. The third considered carbon pool is associated with energy displacement and avoided emissions. They concluded that shorter cycles produced more wood products sooner, thereby reducing fossil fuel-intensive alternatives earlier in time. Forests managed under short rotations sestered less carbon that forests managed over longer rotations. Sathre and O Connor (2010) 25 have reviewed and summarised 66 life cycle studies about the net impacts of wood products on GHGs. They summarise that the main mechanisms with help of which the wood products affect GHGs are 1) the consumption of fossil fuels in production processes of wood products, 2) the possibility to avoid the production of cement by providing wood products for the use of construction, 3) carbon storage in products and forests, 4) the concurrent or subsent production of by-products or wastes which may replace fossil fuels, and 5) carbon dynamics of landfills. The significance of these issues is important to discuss and investigate. However, the functional ivalence approach should be followed. It is questionable to allocate avoided emissions from wider systems to narrower systems and examine results from a limited perspective. An LCI always supports the comparison of alternative systems and thus items 1 and 2 are general mechanisms with help of which more beneficial product systems contribute to the decrease of GHGs compared to less beneficial product systems. Sathre and O Connor speak of carbon storage but - as they also address by themselves - actually the dynamics of the system matters. The focus should be directed to the question what is the effect of the use - or even more, what is the effect of added use - of wood products on possible carbon sinks and sources. In the calculation the attention was paid not only to the differences between wood and concrete building but also to the added availability of biomass by-products. It was assumed that this is used as biofuel replacing coal. The benefit was allocated to wood building. This may be problematic when the environmental advantages 23 Werner, F. Althaus Hans-Jörg, Richeter, Klaus and Scholz, Roland W Post-Consumer Waste Wood in Attributive Product LCA. Int J LCA 12(3) Perez-Garcia, John, Lippke, Bruce, Comnick, Jeffrey and Manriquez, Carolina Assessment of carbon pools, storage and wood products market substitution using life cycle analysis results. Wood and Fiber Science 37. Corrim special Issue, Sathre, R. and O Connor, J A synthesis of research on wood products & greenhouse gas impacts. Technical report TR-19R. 2 nd edition. FPInnovations. 117 p.

16 14 (99) of these biomaterials are also wanted to be assessed. If one million additional flats were made annually with wood frames instead of concrete frames by 2030, the carbon emission during the year of construction would be reduced by 4.3 million tonne in Sweden; 24% of this derives from reduced fossil fuels used for material production, 27% comes from reduced cement process reaction emission, 32% comes from increased substitution of fossil fuels by biomass residues and 17% comes from increased carbon storage in building materials. Over the complete life cycle of the buildings produced each year, the carbon emission reduction would be 4.2 million tonne. Of this, 25% is from fossil fuels for material production, 25% is from cement process reactions and 50% is from fossil fuel substitution. Over the complete life cycle of the buildings, there is no permanent emission benefit due to carbon storage in building materials, but by 2030, this carbon stock will still remain in the buildings. In scenario Finland, the respective emission reduction would be 9.7 million tonne compared with the concrete. GORCAM (Graz / Oak Ridge Carbon Accounting Model) 26 is a spread sheet model that has been developed to calculate the net fluxes of carbon to and from the atmosphere. It is based on the idea that land management and biomass utilization strategies offer opportunities to mitigate the increase of the CO 2 concentration in the earth's atmosphere. For example, land can be used to sester carbon (afforestation, forest protection), to produce bioenergy as a substitute for fossil fuels, or to produce other renewable raw materials like timber. The model assesses the output of 160 tc/ha (tonne carbon per hectare) for a forest that is harvested at the time point 0 to produce wood products and biofuels and replanted. Due to the initial harvest there is a net loss of on-site carbon. The studied rotation period was 60 years. The model considers the net carbon (C) uptake in soil and litter, net C increase in trees, net C storage in long-lived products, net C storage in short-lived products, net C storage in landfills, C in fossil fuels not burned due to substitution of wood-based materials for more energy-intensive materials like steel, and C in fossil fuels displaced by biofuels. The authors concluded that when product substitution is considered, the forestry can lead to a significant reduction in atmospheric carbon by displacing more fossil-intensive products. The actual system studied is not a forest but certain services provided with help of alternative materials. However, the actual system remains unclear as the rired functions of the services are not described. Thus it also remains unclear whether the activities assessed positive are really able to bring a change or whether the system is already for example saturated with biofuels or other wooden products. This kind of approach is interesting on economy or system level when there is a need to improve understanding about the impacts of added use. At the same time the real potential of added use should be shown with help of correct market information (Häkkinen & Haapio ) The Model GORCAM (Graz / Oak Ridge Carbon Accounting Model). B. Schlamadinger, G. Marland, L. Canella. JOANNEUM RESEARCH, Institute of Energy Research, Elisabethstrasse 5, A-8010 Graz, AUSTRIA and Oak Ridge National Laboratory, Environmental Sciences Division, Oak Ridge, TN , USA 27 Häkkinen, T. and Haapio, A. Principles of CO2 assessment of wooden building products. Manuscript. 2011

17 15 (99) When assessing the long term life cycle impacts of wooden products we should - instead of looking only the gradual uptake and potential storage of carbon in long lived products - consider all relevant consences to forests and, when needed, also to other systems. Kilpeläinen et al. (2011) 28 suggest that the net carbon balance should be dealt in LCAs with help of the following parameters: - carbon uptake in growth, - emissions from management and harvesting, - decomposition of soil organic matter and emissions from combustion of bioenergy and - degradation of wood-based items manufactured from timber. Kilpeläinen et al. (2011) made life cycle assessments forest product systems and concluded that when the emissions were allocated for energy biomass and timber (pulpwood and saw logs), pulpwood and saw logs were found to net sestrate carbon during the calculated rotation period (80 years) (Alam 2011) 29. Häkkinen and Haapio (2012) 30 suggested that especially when studying the potential of increased use of timber, the consences both to forest systems and to building stock should be considered. They also emphasized that while the longterm and steady state assessment shows the beneficial impacts of the use of wood in building in terms of GHG emissions, this does not directly necessarily prove that advantageousness of added use when seeking relatively short term effects on mitigating climate change. 3.3 Significance of building materials Sartori and Hestnes (2007) have made a review of literature and analysed the significance of building materials or in other words the significance of embodied impacts in terms of greenhouse gases and energy. The review covers 60 environmental studies of different buildings 31 located in 9 countries (including Sweden, Germany, Australia, Canada and Japan). They concluded that the proportion of embodied energy in materials used and life cycle assessed varied between 9% and 46% of the overall energy used over the building s lifetime, when low-energy-consumption buildings (with good insulation, adate orientation, passive conditioning, etc.) were looked at, and between 2% and 38% in conventional buildings. The lifetime usually considered is 50 years. Other studies assert that in conventional buildings, located mainly in Northern and Central European countries, the embodied energy in materials is around 10-20%, while 80-90% corresponds to energy in the use stage, and less than 1% to energy for end-of-life treatments. The wide range in results is due to the variety of 28 Kilpeläinen, Antti, Ashraful Alam, Strandman, Harri and Kellomäki, Seppo. Life cycle assessment tool for estimating net CO2 exchange of forest production Global Change Biology Bioenergy, doi: /j x. Blackwell Publishing Ltd. 29 Alam, Ashraful Alam Effects of forest management and climate change on energy biomass and timber production with implications for carbon stocks and net CO2 exchange in boreal forest ecosystems. Dissertation. University of Eastern Finland 30 Häkkinen, T. and Haapio, A. PRINCIPLES OF CO2 ASSESSMENT OF WOODEN BUILDING PRODUCTS. Manuscript Sartori I, Hestnes AG. Energy use in the life-cycle of conventional and low-energy buildings: a review article. Energy and Buildings 2007;39,

18 16 (99) buildings, materials, the lifetime considered and the geographic and climatic conditions. The relative significance of building materials increases as more and more effective measures are done in order to reduce the operational energy consumption of buildings. Lebert et al. (2011) 32 focussed on energy efficient buildings (<50kWh/m2/y). They considered 74 French buildings of various types (20 houses, 19 residential, 21 offices/administrative buildings, 8 schools or research buildings, 6 of other type). Buildings were modelled and impacts calculated with French LCA-based assessment tool. For the impact estimation of building materials and products, the tool uses the French national database. The percentage of the embodied energy and GHG (of construction products and materials) with regard to the whole life cycle impacts were calculated for lifetimes of 50 and 100 years. The main results for average embodied energy and GHG were the following: Percentage of embodied energy 50y: for houses 30% and 20% for offices. 100y: for houses 25% and 16% for offices. Percentage of embodied GHG emissions on total 50y: houses and offices 60% 100y: houses 60%, offices 50%. 32 Lebert, Alexandra, Chevalier, Jacques, Escoffier, Faustine, Lasvaux Sébastien, Berthier, Eymeric, Nibel, Sylviane, Hans, Julien, Evaluation de la performance environnementale des bâtiments. Définition d ordres de grandeur. Traitement statistique. Rapport final. 166 pages.

19 17 (99) 4 Calculation scenarios, new construction This study assesses the potential of wood in saving GHGs in Finland. The study assesses the changes in GHG emissions when an increased share of new residential buildings would be done with help of increased use of wood. The study uses alternative scenarios for the assessment of the potential volumes of wood to be used. The overall GHG emissions in Finland were thousand tonnes in 2009 according to OECD statistics Model building for calculation and amount of annually built residential multi-storey buildings The calculations are based on a model building, which is a five-storey residential building. The volume of the building is 6108 m3, with respective floor area of 1813 m3. The modelled building consists of external walls, roof, bottom floor slab and other floor slabs. The internal walls, windows or other building components are not assessed in this study. The structures are presented in Appendix 3. The environmental profiles of building products were based on so-called cradleto-gate information (part A1 as explained in EN ). The data did not cover the transportation to building site nor material wastage during construction phase. Because of this the results underestimate the total impact by roughly 5 10%. Information about the sources of information is presented in Appendix 2. The number of annually built residential multi-storey buildings was calculated based on statistical information on built floor area between years 2000 and 2008, and the floor area of the model building. The building volume of the years is assumed to stay at the same level as that between 2000 and The data from Statistics Finland show that the total gross floor area of the buildings built between 2000 and 2008 is about m2. When the total gross floor area is divided with the model building s floor area, (1813 m2) the total number of buildings built between 2000 and 2008 als to 5136 pcs. When a constant rate for new building between 2000 and 2008 is assumed, the number of annually built multi-storey buildings als to 571 pcs. 4.2 Relative share of concrete and wooden buildings The study uses alternative scenarios for the assessment of the potential volumes of wood to be used Sustainability of construction works - Environmental product declarations - Core rules for the product category of construction products. EN

20 18 (99) Scenario 1 is used as a baseline scenario for this study. The baseline scenario assumes that construction of new buildings will stay at a constant level between years 2010 and 2030 and that the relative share of concrete and wooden buildings will stay unchanged. This means that the share of concrete buildings will be 98 % and the share of wood buildings will be 2 %. The scenarios 2, 3 and 4 assume that the share of wood buildings will not be constant, but will increase either by 20%, 50 %, or 80 % by year The situation in year 2010 will be the same as in scenario 1, and the increase to new levels of wooden construction will occur as a steady change. The corresponding shares for concrete and wooden buildings in 2030, according to scenarios 2 4, are 78 % and 22 % / 48 % and 52 % / 18 % (concrete) and 82 % (wood). The following figures show the number of concrete buildings and wood buildings built each year. The wooden construction increases at a steady rate from 2010 to 2030, and causes an analogous decrease in the number of concrete buildings built. The total number of annually built buildings stays constant (571 pcs built annually). Annually built concrete residential multi-storey buildings, Number of buildings, pcs Scenario 1 Scenario 2 Scenario 3 Scenario Figure 1, Annually built wooden residential multi-storey buildings,

21 19 (99) Annually built wooden residential multi-storey buildings, Number of buildings, pcs Scenario Scenario Scenario 3 Scenario Figure 2, Annually built wooden residential multi-storey buildings, The following figure shows the cumulative amount of residential multi-storey buildings built by Number of buildings, pcs. Residential multi-storey buildings, cumulative amount of buildings built by Concrete Wood Scenario 1 Scenario 2 Scenario 3 Scenario 4 Figure 3, Residential multi-storey buildings, cumulative number of buildings built by Relative share of timber-framed and CLT-based buildings Wooden multi-storey buildings can be built with different structural systems. This study analyses a case where two different systems are used for the buildings. It is assumed that part of the buildings will be done with timber-frame structures and the other part with cross-laminated timber (CLT) structures.

22 20 (99) The baseline scenario assumes that the share of timber-framed buildings is 75% of the total number of annually built wooden buildings and CLT-based buildings account for the remaining 25%. This study also takes a closer look into the effects of both timber-framed and CLT-based construction. This is done for two alternative calculation cases, where only a single system is used for wooden buildings. This means that situations where all the new wooden buildings are either timber-framed, or CLT-based, are also analysed.

23 21 (99) 5 Emissions of new construction The calculations of this study are based on a set of specific structures for roofs, external walls and floors. The complete list of structures, used for the calculation of concrete buildings, timber-framed buildings and CLT-based buildings are presented in Appendix 3. Concrete buildings all structures are concrete-based with no wood used in construction. This results in zero wood use and embodied carbon for concrete buildings. Timber-framed buildings consist of timber-framed external wall, roof, base floor and other floors. The CLT-based building has CLT-based external wall, roof and floors. However, the base floor structure is the same as in timber-framed buildings. Building-level emissions for all building types are presented in the following table. The table also presents the emissions for an average wooden building. Table 1, Building level emissions of new construction for concrete, timber-framed, CLTbased, and average wooden buildings Building Weight tn/bld* CO 2 - tn/bld* RRM tn/bld* NRRM tn/bld* REN GJ/bld NREN GJ/bld CO 2 (emb)* tn/bld* Wood tn/bld* Concrete building Timber-framed building CLT-based building Average wooden building (75% tf, 25% CLT) * tn/bld = tonnes (1000 kg) per building, * emb = embodied * tf = timber framed * CLT = cross laminated timber

24 22 (99) 5.1 Mass of structures, new construction Increased wood use in new construction results in a decreased annual use of construction materials. The assessment of scenarios 2-3 show that mass of annually built buildings decreases, when the amount of wood use in construction is increased. Scenario 2 results in a total saving of 144 thousand tonnes, or 13%, in the total mass of structures, compared to baseline scenario. The figures for scenario 3 are 360 thousand tonnes, and 33%. Scenario 4 results in the biggest savings in mass, 576 thousand tonnes, or 53%, compared to the scenario 1. In other words, increasing the share of wood construction from 2% to 82% (scenario 4) will more than halve the mass of structures of new construction. If the amount of wooden construction increases from 2% to 52% (scenario 3) the mass of structures is reduced by one third. If the amount of wooden construction increases only slightly, from 2% to 22%, the total mass of structures is reduced by 13%. Annually 1200 built mass, ktn/a The mass of stuctures built annually, residential multi-storey buildings built , thousands of tonnes. 1093,0 1093,0 948,9 732,8 516,7 Scenario 1 Scenario 2 Scenario 3 Scenario Figure 4 Mass of structures of new construction, annually built mass, , thousands of tonnes. The following table gives key figures for the annually built mass in 2030 in terms of total mass of structures in all buildings, mass per single building, mass per floor area and mass per volume of buildings.

25 23 (99) Table 2, Mass of structures, new construction, annually built mass in ktn = 1000 tonnes - br = gross Mass of structures of new construction, annually built mass, in 2030 Mass Mass Mass Mass ktn/total tn/building kg/brm2 kg/brm3 Scenario Scenario Scenario Scenario The following figure shows the share of wooden and concrete buildings in the mass calculations for different scenarios. In scenario 2, the relative share of wooden construction increases by 20 %-units, from 2% to 22 %. However, the structures of wooden buildings still account only for less than 10% of total mass of structures. The scenario 3 shows that when the share of wooden buildings rises with 50 %-units, their relative share of the total mass still remains relatively low, accounting for 27% of the total mass. Only when the share of wooden buildings increases significantly, to 82% of total buildings, their share (61%) of the total mass of structures exceeds the mass of the concrete structures Mass of structures built in 2030, thousands of tonnes Mass of structures, in 2030, ktn Scenario 1 Scenario 2 Scenario 3 Scenario 4 Mass, wood Mass, concrete Figure 5. The mass of structures built in 2030, thousands of tonnes

26 24 (99) The following figure shows the cumulative masses of structures for different scenarios. The cumulative results sum up all buildings built during the studied 20 years. The share of wooden buildings gradually increases until it achieves the selected share of the scenario in question by the end of the period. Cumulative mass of structures, by 2030, Mtn Mass of structures built by 2030, cumulative masses, millions of tonnes 25,00 20,00 15,00 10,00 5,00 0,2 21,7 0,9 19,6 2,0 16,4 3,1 13,3 Mass, wood Mass, concrete 0,00 Scenario 1 Scenario 2 Scenario 3 Scenario 4 Figure 6, Mass of structures built by 2030, cumulative masses, millions of tonnes 5.2 Annually built mass, in 2030, effects of timber-framed and CLTbased building This section looks into the effects of timber-framed and CLT-based construction, in terms of annually built mass. The baseline scenario assumes that 75% of the wooden buildings are timber-framed and 25% are CLT-based. This section analyses the cases where all the wooden buildings are either timber-framed, or CLT-based. The first table presents the mass of structures for the baseline scenario, and the following tables corresponding values for timber-framed and CLT-based building. The tables show that the CLT-structures result in a higher mass than timberframed structures. When only CLT-based structures are used, the annual mass of structures will rise by 0 21% (3 107 thousand tonnes). Respectively, when only timber-framed structures are used, the annually built mass will decrease by 0 7% (1 36 thousand tonnes), compared to baseline scenario. The difference between CLT-based and timber-framed structures is 4 thousand tonnes for scenario 1, and it increases to 143 thousand tonnes in scenario 4. This means that the use of CLT-structures causes an increase of up to 30% in the total mass of annually built structures, compared to situation when only timber-framed structures are built.

27 25 (99) Table 3, Mass of structures, new construction, annually built mass in 2030 The baseline scenario assumes that 75% of the wooden buildings are timber-framed and 25% are CLT-based. Total weight of structures in 2030 Mass Mass Mass Mass ktn/total tn/building kg/brm3 kg/brm3 Scenario Scenario Scenario Scenario Table 4, Mass of structures, new construction, annually built mass in 2030, all wooden buildings are timber-framed Total weight of structures in 2030, all wooden buildings timber-framed Mass Mass Mass Mass ktn/total tn/building kg/brm3 kg/brm3 Scenario Scenario Scenario Scenario Table 5, Mass of structures, new construction, annually built mass in 2030, all wooden buildings are CLT-based Total weight of structures in 2030, all wooden buildings CLTbased Mass Mass Mass Mass ktn*/total tn/building kg/brm3 kg/brm3 Scenario Scenario Scenario Scenario ktn = 1000 tonnes br = gross

28 26 (99) 6 Greenhouse gas emissions of new construction 6.1 Annual GHG emissions Increased use of wood in new construction results in lower annual GHG emissions. The assessment of scenarios 2-4 with increased wood use shows that their GHG emissions (in terms of ) are lower than that of the baseline scenarios. The biggest decline in emissions is achieved with scenario 4, which results in savings of 51 %, or thousand tonnes, compared to scenario 1. In other words, increasing the share of wood construction from 2% to 82% would more than halve the annual emissions from new construction. For scenario 3, the amount of wood construction increases from 2%, to 52%, while the annual emissions drop by about a third (32% / 64 ktn). For scenario 2, the decrease is 13%, or 25.6 thousand tonnes. Emissions,, ktn/a Annual GHG-emissions from construction of new multi-storey residential buildings , thousands of tonnes 201,1 201,1 175,5 137,1 98,7 Scenario 1 Scenario 2 Scenario 3 Scenario Figure 7, Annual GHG-emissions from construction of new multi-storey residential buildings , thousands of tonnes. The following figure gives more detailed information of the source of emissions in The decrease of emissions from concrete construction is bigger than the increase of emissions from wooden construction, resulting in lower total emissions from construction.

29 27 (99) Table 6, Annual GHG-emissions from construction of new multi-storey residential buildings, in ktn = 1000 tonne, br = gross Annual GHG-emissions from construction of new multistorey residential buildings, in 2030 ktn/total tn/building kg/brm3 kg/brm3 Scenario Scenario Scenario Scenario The following figures show the annual GHG emissions in 2030 (Figure 8) and the cumulative emissions by 2030 (figure 9). Annual GHG-emissions from construction of new multi-storey residential buildings, in 2030, thousands of tonnes Emissions,, ktn/a Emissions, concrete Emissions, Wood Scenario 1 Scenario 2 Scenario 3 Scenario 4 Figure 8, Annual GHG-emissions from construction of new multi-storey residential buildings, in 2030, thousands of tonnes

30 28 (99) Emissions,, ktn/a Cumulative GHG-emissions from construction of new multi-storey residential buildings, by 2030, thousands of tonnes Emissions, concrete Emissions, Wood Scenario 1 Scenario 2 Scenario 3 Scenario 4 Figure 9, Cumulative GHG-emissions from construction of new multi-storey residential buildings, by 2030, thousands of tonnes 6.2 Effects of timber-framed and CLT-based building This section looks into the effects of timber-framed and CLT-based construction, in terms of annual GHG emissions. This section analyses the cases where all the wooden buildings are either timber-framed, or CLT-based. The first table presents the GHG emissions for the baseline scenario, and the next tables present the corresponding values for timber-framed and CLT-based building. The tables show that the CLT-structures result in higher annual GHG emissions than timber-framed structures. When only CLT-based structures are used, the annual GHG emissions will rise by 0 23% (1 23 thousand tonnes). Respectively, when only timber-framed structures are used, the GHG emissions will decrease by 0 8% (0 8 thousand tonnes), compared to baseline scenario. The difference between CLT and timber-framed structures is one tonne for scenario 1, and it increases to 31 thousand tonnes in scenario 4. This means that the use of CLT-structures causes up to 35% higher annual GHG-emissions than timber-framed structures.

31 29 (99) Table 7. Mass of structures, new construction, annually built mass in 2030 The baseline scenario assumes that 75% of the wooden buildings are timber-framed and 25% are CLT-based. Table 8, Annual GHG-emissions from construction of new multi-storey residential buildings in All wooden buildings are timber-framed Annual GHG-emissions from construction of new multistorey residential buildings, in 2030 ktn/total tn/building kg/brm3 kg/brm3 Scenario Scenario Scenario Scenario Total GHG emissions of new cosntruction in 2030, all wooden buildings timber-framed ktn tn/building kg/brm3 kg/brm3 Scenario Scenario Scenario Scenario Table 9, Annual GHG-emissions from construction of new multi-storey residential building in All wooden buildings are CLT-based Total GHG emissions of new cosntruction in 2030, all wooden buildings CLT-based ktn tn/building kg/brm3 kg/brm3 Scenario Scenario Scenario Scenario ktn = 1000 tonnes br = gross

32 30 (99) 7 Consideration of carbon uptake for new construction 7.1 Stored carbon in 2030 Increased use of wood in new construction results in an increased annual stored (carbon up-take because of growth). The increase in carbon uptake compared to baseline scenario is 36.7 thousand tonnes (10-fold for scenario 2 compared to baseline) and 92.1 thousand tonnes (25-fold for scenario 3 compared to baseline). The biggest increase in annual carbon uptake is achieved with scenario 4, which results in a thousand tonne (or a 40-fold compared to baseline) rise in carbon uptake. Results are shown in Figure 10. Annually stored carbon, residential multi-storey buildings built , thousands of tonnes Stored carbon,, ktn/a Scenario 1 Scenario 2 Scenario 3 Scenario Figure 10, Annually stored carbon, residential multi-storey buildings built , thousands of tonnes. The following table gives key figures for the annually stored carbon in 2030, in terms of total amount of stored carbon in all buildings, carbon stored per single building, per floor area and per volume of a building.

33 31 (99) Table 10, Annually stored carbon, residential multi-storey buildings built in 2030 Annually stored carbon, residential multi-storey buildings built in 2030 ktn/total tn/building kg/brm2 kg/brm3 Scenario Scenario Scenario Scenario The following figure gives more detailed information on the stored carbon in It should be noted that the concrete structures of this study do not store any carbon. Cumulative results are given in Figure 12. Amount of stored carbon, in 2030, ktn Residential blocks of flats, amount of annually stored carbon in new construction, as in 2030, thousands of tonnes 160,00 140,00 120,00 100,00 80,00 60,00 40, Stored carbon, wood structures Stored carbon, concrete structures 20,00 0, ,00 4 0,00 0,00 0,00 Scenario 1Scenario 2Scenario 3Scenario 4 Figure 11, Residential blocks of flats, amount of annually stored carbon in new construction, as in 2030, thousands of tonnes. Blue columns al to zero.

34 32 (99) Stored carbon,, Mtn Cumulative amount of stored carbon, residential multi-storey buildings, by 2030, thousands of tonnes 1,60 1,40 1,20 1,00 0,80 0,60 0,40 0,95 1,47 Stored carbon, wood structures Stored carbon, concrete structures 0,20 0,00 0,42 0,00 0,07 0,00 0,00 0,00 Scenario 1 Scenario 2 Scenario 3 Scenario 4 Figure 12, Cumulative amount of stored carbon, residential multi-storey buildings, by 2030, thousands of tonnes. Blue columns al to zero. 7.2 Effects of timber-framed and CLT-based building This section presents the calculation results of the effects of timber-framed and CLT-based construction in terms of annual carbon uptake. The section analyses the carbon uptake, when all the wooden buildings are either timber-framed, or CLT-based. The first table presents the carbon uptake of the baseline scenario, and Tables 12 and 13 give the corresponding values for timber-framed and CLT-based building. The tables show that the CLT-structures result in higher carbon uptake than timber-framed structures. When only CLT-based structures are built, the annual carbon uptake will rise by 79% (3 120 thousand tonnes). Respectively, when only timber-framed structures are used, the annual carbon uptake will decrease by 26% (1 40 thousand tonnes), compared to baseline scenario where both types are assumed to be used. The difference between CLT and timber-framed structures is 4 thousand tonnes for scenario 1, and it increases to 160 thousand tonnes in scenario 4. This means that the carbon uptake of CLT-structures is 1.4 times higher, than that of timberframed structures for all scenarios.

35 33 (99) Table 11, Annually stored carbon, residential multi-storey buildings built in 2030 The baseline scenario assumes that 75% of the wooden buildings are timber-framed and 25% are CLT-based. Annually stored carbon, residential multi-storey buildings built in 2030 ktn/total tn/building kg/brm2 kg/brm3 Scenario Scenario Scenario Scenario Table 12, Annually stored carbon, residential multi-storey buildings built in 2030, all wooden buildings are timber-framed Annually stored carbon, in 2030, when all wooden buildings are timber-framed ktn tn/building kg/brm2 kg/brm3 Scenario Scenario Scenario Scenario Table 13, Annually stored carbon, residential multi-storey buildings built in 2030, all wooden buildings are CLT-based Annually stored carbon, in 2030, when all wooden buildings are CLT-based ktn tn/building kg/brm2 kg/brm3 Scenario Scenario Scenario Scenario ktn = 1000 tonnes br = gross

36 34 (99) 8 Comparison of GHG emissions and carbon uptake of new construction 8.1 GHS emissions and CO2 uptake The manufacture of construction materials produces emissions, but at the same time, the structures also include carbon sestrated during growth (here called stored carbon). This section makes a simple comparison between the amount of emitted and stored carbon. The annual GHG uptake is subtracted from the annual GHG emissions, and a theoretic net GHG-emissions value is calculated. Increased use of wood in new construction results in decreased net GHG emissions. The following figure shows that the amount of greenhouse gases exceeds the amount of annually stored carbon in scenarios 1-3. However, when the share of wooden construction is significantly increased (scenario 4), the amount of stored carbon, exceeds the amount of GHG-emissions. The decrease in net GHG-emissions is 62 ktn for scenario 2 (31%), 156 ktn for scenario 3 (79%) and 249 ktn (126%) for scenario Residential multi-storey buildings, comparison of GHG emissoins and carbon uptake, in 2030 ktn/a Scenario 1 Scenario Scenario 3 Scenario 4-96 Stored carbon, total Emissions, total Figure 13, residential blocks of flats, emissions from construction and stored carbon, in 2030 The following table gives the net GHG-emission for the different scenarios. The annual carbon uptake has been deducted from the annual GHG emissions. The values of the table present net GHG emissions as positive values and net sorption as negative values.

37 35 (99) Table 14, Annual net GHG-emission, stored carbon deducted from emissions, in 2030 Annual net GHG-emissions, stored carbon deducted from emissions, in 2030 ktn tn/building kg/brm2 kg/brm3 Scenario Scenario Scenario Scenario Effects of timber-framed and CLT-based building This section looks into the effects of timber-framed and CLT-based construction, in terms of net GHG-emissions. This section analyses the relation of GHG emissions and carbon uptake, when all the wooden buildings are either timber-framed, or CLT-based. The first table presents the net GHG-emissions of the baseline scenario, and Table 16 and 17 show the corresponding values for timber-framed and CLTbased building. The following tables show that the CLT-structures result in lower net GHG emissions than timber-framed structures. When only CLT-based structures are built, the annual net GHG emissions will decrease by 1 185% (2 96 thousand tonnes). Respectively, when only timber-framed structures are used, the GHG emissions will increase by 2 62% (1 32 thousand tonnes), compared to baseline scenario. The tables show, that for baseline scenario and timber-framed structures, the GHG emissions exceed the stored carbon, for scenarios 1-3. However, for scenario 4, the carbon uptake exceeds the annual GHG emissions. When only CLT-based structures are built, the carbon uptake exceeds the annual GHG emissions, not only for scenario 4, but also for scenario 3.

38 36 (99) Table 15, Annual net GHG-emissions, stored carbon deducted from emissions, in 2030 The baseline scenario assumes that 75% of the wooden buildings are timber-framed and 25% are CLT-based. Table 16, Annual net GHG-emissions, stored carbon deducted from emissions, in 2030, all wooden buildings are timber-framed Table 17, Annual net GHG-emissions, stored carbon deducted from emissions, in 2030, all wooden buildings are CLT-based Annual net GHG-emissions, stored carbon deducted from emissions, in 2030 Mtn tn/building kg/brm2 kg/brm3 Scenario Scenario Scenario Scenario Annual emissions, stored carbon deducted from emissions. ktn tn/building kg/brm2 kg/brm3 Scenario Scenario Scenario Scenario Annual emissions, stored carbon deducted from emissions. Mass ktn tn/building kg/brm2 kg/brm3 Scenario Scenario Scenario Scenario ktn = 1000 tonnes br = gross

39 37 (99) 9 Effects of use of cellulose insulation, new construction The previous calculations are made with mineral wool insulation. This section analyses how the results of the baseline scenario will change, when mineral wool insulation is changed to cellulose insulation. The density of cellulose insulation is assumed to be the same as for mineral wool insulation, so the mass of structures is not affected. When the mineral wool insulation is changed to cellulose insulation, the amount of greenhouse gases emitted is cut by 2 10% (3 10 thousand tonnes) and the amount of stored carbon is increased by 14% (0 21 thousand tonnes) As a result, the annual net emissions are cut by 6 60%, or by 8 31 thousand tonnes, compared to mineral wool insulation. 9.1 Effect of cellulose insulation on GHG emissions The effect of changing insulation material from mineral wool to cellulose results in decreased GHG emissions. The decrease in annual greenhouse gas emissions for scenarios 2-4 is 3 10 thousand tonnes, or 2 10%, compared to baseline scenario. The following tables show the GHG emissions for different scenarios with mineral wool and cellulose insulation.

40 38 (99) Table 18, Annual GHG-emissions from construction of new multi-storey residential buildings, mineral wool insulation Table 19, Annual GHG-emissions from construction of new multi-storey residential buildings, cellulose insulation. Amount of annual green house gas emissions, in 2030, mineral wool insulation ktn tn/building kg/brm2 kg/brm3 Scenario Scenario Scenario Scenario Amount of annual green house gas emissions, in 2030, cellulose insulation ktn tn/building kg/brm2 kg/brm3 Scenario Scenario Scenario Scenario Effect of cellulose insulation on stored carbon The effect of changing insulation material from mineral wool to cellulose results in increased amount of stored carbon. The increase in annually stored carbon is 14% (0 21 thousand tonnes) The following tables show the stored carbon for different scenarios with mineral wool and cellulose insulation.

41 39 (99) Table 20, Annually stored carbon, new construction, baseline scenario with mineral wool insulation, in 2030 Table 21, Annually stored carbon, new construction, baseline scenario with cellulose insulation, in 2030 Amount of annually stored carbon, in 2030, mineral wool insulation ktn tn/building kg/brm2 kg/brm3 Scenario Scenario Scenario Scenario Amount of annually stored carbon, in 2030, cellulose insulation ktn tn/building kg/brm2 kg/brm3 Scenario Scenario Scenario Scenario Effect of cellulose insulation, comparison of GHGs and CO2 uptake As showed previously, changing insulation material from mineral wool to cellulose insulation results in increased amount of stored carbon and decreased emissions, compared to baseline scenario. The following figure shows that the amount of greenhouse gases exceeds the amount of annually stored carbon in scenarios 1-3. However, when the share of wooden construction is significantly increased (scenario 4), the amount of stored carbon, exceeds the amount of GHG-emissions, when both are calculated as.

42 40 (99) Mtn/a Residential blocks of flats, emissions and stored carbon with cellulose insulation, in Scenario 1 Scenario Scenario 3 Scenario Stored carbon, total Emissions, total Figure 14 emissions and stored carbon with cellulose insulation in 2030 The following table gives the net emission for the different scenarios with cellulose insulation. The annual CO2 uptake has been deducted from the annual GHG emissions. The values of the table present CO2 emissions (positive values) and CO2 net uptake (negative values). The tables show that the use of cellulose insulation decreases the net emissions by 6 60%, or by 8 31 thousand tonnes annually, compared to mineral wool insulation.

43 41 (99) Table 22, Annual net emissions, new construction, baseline scenario with mineral wool insulation, in 2030 Table 23, Annual net emissions, new construction, baseline scenario with cellulose insulation, in 2030 Annual emissions, stored carbon deducted from emissions, mineral wool insulation, in 2030 ktn tn/building kg/brm2 kg/brm3 Scenario Scenario Scenario Scenario Annual emissions, stored carbon deducted from emissions, cellulose insulation, in 2030 ktn tn/building kg/brm2 kg/brm3 Scenario Scenario Scenario Scenario

44 42 (99) 10 Wood use of new construction Increasing the relative share of wood construction will increase the annual need of wood products in year 2030, compared to year The following figure shows that the wood use for baseline scenario is 5 thousand cubic metres. The increase in need of wood products is biggest for scenario 4, alling to an increase of 196 thousand cubic metres of wood products. The increase for scenario 3 is 122, and for scenario 2, 49 thousand cubic metres. The waste of materials during construction phase was not considered in the assessment. If the material wastage was taken into account, the following figures for wood product use would be roughly 5 10% higher. In terms of round wood need, the volumes are roughly two-fold, compared to the total volume of wood product need. It should also be noted, that not all the sawn timber is suitable to be used as structural timber. The share of material that is optimal for the use as structural timber is roughly 8 13 % from the output of sawn timber. Volume, tm3/a The volume of annually used wood products, new construction, , thousands of cubic metres 200,6 127,2 Scenario 1 Scenario 2 Scenario 3 Scenario ,8 0 4,9 4,9 Figure 15, The volume of annually used wood products, new construction, , thousands of cubic metres.

45 43 (99) 11 Calculation scenarios for refurbishments This Chapter assesses the potential of wood in saving GHGs in Finland when increased share of building refurbishments would be done with help of increased use of wood. The study uses alternative scenarios for the assessment of the potential volumes of wood to be used Model building for calculation The refurbishment scenarios analyse buildings, which are expected to need a façade refurbishment before year The buildings from are considered to be the most important group in refurbishment need, so it is selected as a basis for this study. The calculations are based on statistical information and a model building. The model building is a five-storey residential building. The volume of the building is 6108 m 3, with respective floor area of 1813 m 3. The refurbishments concern only the external walls of the building. The area of external walls of model building is 1113 m 2. The number of annually renovated residential multi-storey buildings is calculated, based on statistical information on built floor area between years 1950 and 2000, and the floor area of the model building. The data from Statistics Finland show that the total gross floor area of the buildings built between 1950 and 2000 is about m2. When the total gross floor area is divided with that of the model building s (1813m2), the total number of buildings built between 1950 and 2000 als to pcs. Two alternative refurbishment amounts are studied: Either 50% or 75% of the buildings built between 1950 and 2000 are renovated. When a constant rate for refurbishments is assumed, the number of annually renovated multi-storey buildings between 2010 and 2030 als to 877 (50% renovated) and 1376 (75% renovated) An average U-value for this age group is estimated, based on information about the level of building regulations at the time the buildings were built. The assumed U-value was 0.32 W/m2 K Scenarios - Relative share of rendered and wooden façade refurbishments Scenario 1 is based on the assumption that external walls are mostly renovated with additional thermal insulation and a rendered façade. The share of this kind of refurbishment is assumed to be 98 % of all the façade refurbishments and the share of wooden façades with additional thermal insulation is estimated to be at 2 %. This value was chosen as the starting value in order to follow the same approach as for new construction. In reality, the value is zero or close to zero.

46 44 (99) The scenarios 2, 3 and 4 assume that the share of wooden façade refurbishments will increase by 20% / 50 % / 80 % by year The corresponding share of rendered façades and wooden façades in 2030, according to scenarios 2 4 is thus 78 % and 22 % / 48 % and 52 % / 18 % (rendered) and 82 % (wooden). The following figures show the corresponding numbers of buildings renovated with wooden and rendered façade buildings each year. The figures are made for two alternative refurbishment scenarios: the first assuming 50% and the other assuming 75% of the buildings built between will be refurbished. When 50% of the buildings are renovated by 2030, the number of refurbishments with wooden façades will rise from 2010 s 18 buildings to 193 in scenario 2, 456 in scenario 3 and 719 in scenario 4. The number of rendered façade refurbishments will decrease, respectively to 684 in scenario 2, 421 in scenario 3 and 158 in scenario 4. Number of buildings, pcs Residential buildings, number of annually made wooden facade refurbishments, Scenario 1 Scenario 2 Scenario 3 Scenario Figure 16, Residential buildings, number of annually made wooden facade refurbishments, , 50% of the buildings ( ) renovated. Total number of refurbishments is 877.

47 45 (99) Number 1000 of 900 buildings, 800 pcs Residential buildings, number of annually made rendered facade refurbishments, Scenario 1 Scenario 2 Scenario 3 Figure 17, Residential buildings, number of annually made rendered facade refurbishments, , 50% of the buildings ( ) renovated. Total number of refurbishments is 877. When 75% of the buildings are renovated, the number of refurbishments with wooden façades will increase from 2010 s 26 buildings to 290 in scenario 2, 684 in scenario 3 and 1079 in scenario 4. The number of rendered façade refurbishments will decrease, respectively to 1027 in scenario 2, 632 in scenario 3 and 237 in scenario 4. Number of 1200 buildings, pcs Residential buildings, number of annually made wooden facade refurbishments, Scenario Scenario 2 Scenario 3 Scenario

48 46 (99) Figure 18, Residential buildings, number of annually made wooden facade refurbishments, , 75% of the buildings ( ) renovated. Total number of refurbishments is Number of buildings, pcs Residential buildings, number of annually made rendered facade refurbishments, Scenario 1 Scenario Scenario Scenario Figure 19, Residential buildings, number of annually made rendered facade refurbishments, , 75% of the buildings ( ) renovated. Total number of refurbishments is The following figures show the cumulative number of refurbishments for rendered and wooden façade refurbishments by 2030.

49 47 (99) Number of buildings, pcs. Residential blocks of flats, number of buildings with facade refurbishment, by 2030,.50% of buildings built between 1950 and 2000 to be renovated Scenario 1 Scenario 2 Scenario 3 Scenario 4 Rendered Wooden Figure 20, Residential blocks of flats, number of buildings with facade refurbishment, by % of buildings built between 1950 and 2000 to be renovated Residential blocks of flats, number of buildings with facade refurbishment, by 2030,.50% of buildings built between 1950 and 2000 to be renovated Number of buildings, pcs Rendered Wooden Scenario 1 Scenario 2 Scenario 3 Scenario 4 Figure 21 Residential blocks of flats, number of buildings with facade refurbishment, by % of buildings built between 1950 and 2000 to be renovated

50 48 (99) 11.3 Relative share of replacing and additional refurbishment methods in external wall refurbishments Two main categories of refurbishments are analysed, which are replacing refurbishment and additional thermal insulation. The replacing refurbishment means refurbishment, where the existing façade and thermal insulation is completely removed, and the new thermal insulation is installed on top of the existing load-bearing structure. The additional thermal insulation means refurbishment where the additional thermal insulation is added on top of the existing wall structure, without removal of existing structures. The ratio of replacing and additional thermal insulation is fixed to 1/5 in this study ( replacing refurbishment methods account for 20% of the total refurbishment need and additional thermal insulation for the remaining 80%). Three different refurbishment concepts are analysed for both of the refurbishment methods. These are: - refurbishment option 1: mineral wool insulation and 3-layer rendering - refurbishment option 2: mineral wool insulation and wooden façade - refurbishment option 3: mineral wool insulation and light wooden façade

51 49 (99) 11.4 Building-level emissions for refurbishments The refurbishment methods are presented in more detail in Appendix 4. Buildinglevel emissions are presented in the following table for all the building types. The baseline scenario assumes that the share of replacing refurbishments is 20% and the share of additional refurbishments is 80%. The average emissions for each of the refurbishment concepts are presented in the following table. Table 24, Average emissions for alternative refurbishment concepts Building Average rendered façade, (20% replacing, 80% additional refurbishment) Average wooden façade, (20% replacing, 80% additional refurbishment) Average light wooden façade, (20% replacing, 80% additional refurbishment) Weight tn/bld CO 2 - tn/bld RRM tn/bld NRRM tn/bld REN GJ/bld NREN GJ/bld CO 2 (emb) tn/bld Wood tn/bld RRM = renewable raw materials, NRRM = non-renewable raw materials REN = renewable energy, NREN = non-renewable energy bld = building emb = embodied 11.5 Assessed mass of annual external wall refurbishments The comparison of scenarios 2-4, in relation with baseline scenario (scenario 1) shows that increasing the share of wooden refurbishments results in decreased mass of structures of refurbishments. When 50% of the buildings built between 1950 and 2000 are renovated, scenario 2 results in a total saving of 6 thousand tonnes, or 10%, in the total mass of structures, compared to baseline scenario. The figures for scenario 3 are 15 thousand tonnes, and 26%. Scenario 4 results in the biggest mass savings, 23 thousand tonnes, or 41%, compared to the scenario 1.

52 50 (99) Annually built mass, Mtn/a The mass of stuctures of refurbishments, , thousands of tonnes ,7 56, ,9 42,2 33,5 Scenario 1 Scenario 2 Scenario 3 Scenario 4 Figure 22, The mass of structures of refurbishments, , thousands of tonnes. 50% of the buildings ( ) renovated When 75% of the buildings built between 1950 and 2000 are renovated, scenario 2 results in a total saving of 9 thousand tonnes, or 10%, in the total mass of structures, compared to baseline scenario. The figures for scenario 2 are 22 thousand tonnes, and 26%. Scenario 4 results in the biggest mass savings, 35 thousand tonnes, or 41%, compared to the scenario 1.

53 51 (99) Annually built mass, Mtn/a The mass of stuctures of refurbishments, , thousands of tonnes. 85,1 85,1 76,4 Scenario 1 63,3 Scenario 2 50,2 Scenario 3 Scenario 4 Figure 23, The mass of structures of refurbishments, , thousands of tonnes. 75% of the buildings ( ) renovated The following table gives key figures for the annual mass of refurbishments in 2030, in terms of total mass of structures in all buildings, mass per single building, mass per floor area and mass per volume of buildings. Table 25, Mass of structures, annual mass of refurbishment in % of the buildings ( ) renovated. br = gross Mass of structures, annual mass of refurbishments, in % of the buildings ( ) renovated. Total mass Mass Mass Mass Mtn tn/building kg/brm3 kg/brm3 Scenario Scenario Scenario Scenario Table 26, Mass of structures, annual mass of refurbishment in % of the buildings ( ) renovated. br= gross Mass of structures, annual mass of refurbishments, in % of the buildings ( ) renovated. Total Mass Mass Mass mass Mtn tn/building kg/brm3 kg/brm3 Scenario Scenario Scenario Scenario

54 52 (99) The following figure shows the share of wooden and concrete buildings in the mass calculations for different scenarios. In scenario 2, the relative share of wooden construction increases by 20 %-units, from 2% to 22 %. However, the structures of wooden buildings still account only for only about 12% of the total mass of structures. The scenario 3 shows that when the share of wooden buildings rises with 50 %- units, their relative share of the total mass raises to about 35% of the total mass. When the share of wooden buildings significantly increases, to 82% of total buildings, their share of the total mass of structures (70%) exceeds the mass of the concrete structures. Mass of structures of refurbishments, annual mass of refurbishments in 2030, 50% of buildings renovated., thousands of tonnes. 60 Mass of structures, in 2030, ktn Mass, wooden Mass, rendered 10 0 Scenario 1 Scenario 2 Scenario 3 Scenario Figure 24, Mass of structures of refurbishments, annual mass of refurbishments, in 2030, thousands of tonnes. 75% of buildings renovated.

55 53 (99) Mass of structures of new construction, annually built mass, in 2030, thousands of tonnes Mass of structures, in 2030, ktn Mass, wood Mass, Rendered Scenario 1 Scenario 2 Scenario 3 Scenario 4 15 Figure 25, Mass of structures of refurbishments, annual mass of refurbishments, in 2030, thousands of tonnes. 50% of buildings renovated. The following figure shows the cumulative masses of structures for different scenarios from 2010, until 2030.

56 54 (99) Cumulative mass of structures, by 2030, Mtn Mass of structures of new construction, cumulative mass, by 2030, millions of tonnes 1,20 1,00 0,0 0,1 0,1 0,80 0,2 0,60 0,40 1,1 1,0 0,9 0,7 Mass, wooden Mass, Rendered 0,20 0,00 Scenario 1 Scenario 2 Scenario 3 Scenario 4 Figure 26, Mass of structures of refurbishments, cumulative mass of refurbishments, by 2030, millions of tonnes. 50% of buildings renovated. Mass of structures of new construction, cumulative mass, by 2030, millions of tonnes Cumulative mass of structures, by 2030, Mtn 1,80 1,60 1,40 0,0 0,1 0,2 1,20 0,3 1,00 0,80 0,60 0,40 1,7 1,5 1,3 1,0 Mass, wood Mass, Rendered 0,20 0,00 Scenario 1 Scenario 2 Scenario 3 Scenario 4 Figure 27, Mass of structures of refurbishments, cumulative mass of refurbishments, by 2030, millions of tonnes. 75% of buildings renovated.

57 55 (99) 11.6 Annually built mass, in 2030, effects of a light wooden façade The baseline scenario assumes that the wooden façades are timber-framed. This section analyses the effect on annually built mass, when the wooden façades are made with a lighter structure, without the supporting timber-frame. The details of the structure are shown in appendix. The following tables show that the lighter wooden façades result in a lower annual mass of refurbishments. The weight savings with lightweight wooden façades are 0%, 3%, 9% and 19%, for scenarios 1, 2, 3 and 4, respectively. The weight saving when 50% of buildings are renovated is 0 6 thousand tonnes. Table 27, Mass of structures, annual mass of refurbishment, in % of the buildings ( ) renovated. Wooden façades timber-framed structures. Mass of structures, annual mass of refurbishments, in % of the buildings ( ) renovated. Total mass Mass Mass Mass ktn tn/building kg/brm3 kg/brm3 Scenario Scenario Scenario Scenario Table 28, Mass of structures, annual mass of refurbishment, in % of the buildings ( ) renovated. Wooden façades made with lightweight structures.br = gross, ktn = 1000 tonne. Mass of structures, annual mass of refurbishments, in % of the buildings ( ) renovated. Total mass Mass Mass Mass ktn tn/building kg/brm2 kg/brm3 Scenario Scenario Scenario Scenario

58 56 (99) The weight of saving when 50% of buildings are renovated is 0 9 thousand tonnes. Table 29, Mass of structures, annual mass of refurbishment, in % of the buildings ( ) renovated Mass of structures, annual mass of refurbishments, in % of the buildings ( ) renovated. Total Mass Mass Mass mass ktn tn/building kg/brm2 kg/brm3 Scenario Scenario Scenario Scenario Table 30, Mass of structures, annual mass of refurbishment, in % of the buildings ( ) renovated Mass of structures, annual mass of refurbishments, in % of the buildings ( ) renovated. Total Mass Mass Mass mass ktn tn/building kg/brm2 kg/brm3 Scenario Scenario Scenario Scenario Greenhouse gas emissions The calculated results for the emissions of scenarios 2-4 compared to baseline scenario show that increasing share of wood use in construction results in decreased annual of emissions. The case, where 50% of buildings built between 1950 and 2000 are renovated, is first studied. The biggest decline in emissions is achieved with scenario 4, which results in savings of 41 %, or 5 thousand tonnes, compared to scenario 1. In other words, increasing the share of wood construction from 2% to 82% will lower the annual emissions from refurbishments by 41%. When the amount of wood construction increases from 2%, to 52%, as in scenario 3, the annual emissions will decrease by 26% (3 ktn). For scenario 2, the decrease is 10%, or one thousand tonne. The following Figures show the annual CO2 emissions of refurbishments when 50 % or 75 % of buildings are renovated

59 57 (99) Annual emissions, ktn/a Annual -emissions from refurbishments, , 50% of buildings renovated. Thousands of tonnes. 12,4 12,4 11,1 9,2 7,3 Scenario 1 Scenario 2 Scenario 3 Scenario 4 Figure 28, Annual -emissions from refurbishments, % of buildings renovated. The following table gives key figures for GHG emissions, such as total emissions, emissions per building, emissions per brm2, and emissions per brm3. Table 31, Annual GHG-emissions from refurbishments, 50% of buildings renovated, in br = gross Amount of annual green house gas emissions, in 2030 Mass Mass Mass Mass ktn tn/building kg/brm2 kg/brm3 Scenario Scenario Scenario Scenario When 75% of the buildings are renovated, the actual savings range from 9 thousand tonnes, for scenario 4, to two tonnes of scenario 2.

60 58 (99) Annual emissions, ktn/a Annual -emissions from refurbishments, , 75% of buildings renovated. Thousands of tonnes. 18,6 18,6 16,7 13,8 10,9 Scenario 1 Scenario 2 Scenario 3 Scenario 4 Figure 29, Annual -emissions from refurbishments, % of buildings renovated. The following table gives key figures for GHG emissions, such as total emissions, emissions per building, emissions per brm2, and emissions per brm3. Table 32, Annual -emissions from refurbishments, , 75% of buildings renovated. Amount of annual green house gas emissions, in 2030 Mass Mass Mass Mass ktn tn/building kg/brm2 kg/brm3 Scenario Scenario Scenario Scenario The following figures show the share of wooden and rendered façades of the total emissions. The emissions from wooden façades become greater than those from rendered façades when 82% of the refurbishments are wood-based (scenario 4).

61 59 (99) Annual emissions, ktn/a Residential blocks of flats, annual emissions from construction, in Emissions, Rendered Emissions, Wooden Scenario 1 Scenario 2 Scenario 3 Scenario 4 Figure 30, Residential blocks of flats, emissions from refurbishments, when 50% of buildings are renovated, in Residential blocks of flats, emissions from construction, in Annual emissions, ktn/a Emissions, Rendered Emissions, Wood Scenario 1 Scenario 2 Scenario 3 Scenario 4 Figure 31, Residential blocks of flats, emissions from refurbishments, when 75% of buildings are renovated, in 2030.

62 60 (99) The following figures show the cumulative emissions. Cumulative emissions, by 2030, ktn Residential blocks of flats, cumulative emissions from construction, by Emissions, Rendered Emissions, Wooden Scenario 1 Scenario 2 Scenario 3 Scenario 4 Figure 32, Residential blocks of flats, emissions from construction, cumulative emissions until % of buildings renovated. Cumulative emissions, by 2030, ktn Residential blocks of flats, cumulative emissions from construction, by Scenario 1 Scenario 2 Scenario 3 Scenario 4 Emissions, Rendered Emissions, Wood Figure 33, Residential blocks of flats, emissions from construction, cumulative emissions until % of buildings renovated.

63 61 (99) 11.8 Annual greenhouse gas emissions, in 2030, effects of a light wooden façade The baseline scenario assumes that the wooden façades are timber-framed. This section analyses case, where the wooden façades are made with a lighter structure, without the supporting timber-frame. The details of the structure are shown in appendix. The following tables show that the lighter wooden façades result in lower annual greenhouse gas emissions. However, the savings are such small ones (0,1% and 0,8%) for scenarios 1 and 2, that it doesn t show in the following tables. The savings are bigger for scenarios 3 and 4 (2,3% and 4,6%), but even they show only in the tables, when 75% of the buildings are renovated. The results indicate that the role of light wooden façade, in terms of GHG emission savings, is only marginal, compared to timber-framed façade. Table 33, GHG emissions of structures, annual emissions of refurbishments, in % of the buildings ( ) renovated. Wooden façades with timber-framed structures. br = gross Table 34, GHG emissions of structures, annual emissions of refurbishments, in % of the buildings ( ) renovated. Wooden façades with lightweight structures. GHG emissions of structures, annual mass of emissions, in % of the buildings ( ) renovated. ktn tn/building kg/brm3 kg/brm3 Scenario Scenario Scenario Scenario GHG emissions of structures, annual mass of emissions, in % of the buildings ( ) renovated. ktn tn/building kg/brm2 kg/brm3 Scenario Scenario Scenario Scenario The weight saving when 50% of buildings are renovated is 0 9 thousand tonnes.

64 62 (99) Table 35, GHG emissions of structures, annual emissions of refurbishments, in % of the buildings ( ) renovated. Wooden façades with timber-framed structures. GHG emissions of structures, annual mass of emissions, in % of the buildings ( ) renovated. ktn tn/building kg/brm2 kg/brm3 Scenario Scenario Scenario Scenario Table 36, GHG emissions of structures, annual emissions of refurbishments, in % of the buildings ( ) renovated. Wooden façades with lightweight structures. GHG emissions of structures, annual mass of emissions, in % of the buildings ( ) renovated. ktn tn/building kg/brm2 kg/brm3 Scenario Scenario Scenario Scenario

65 63 (99) 12 Consideration of carbon uptake, refurbishments 12.1 Annually stored carbon The following figures show the assessed stored carbon in different refurbishment scenarios. When 50% of the buildings are renovated, the stored carbon ranges from 1 (scenario 1) to 30 (scenario 4) thousand tonnes of annually. The case with 75% renovated results in carbon uptake of 1 to 45 thousand tonnes. Annually stored carbon, refurbishments,, , thousands of tonnes. Annual emissions, ktn/a ,2 Scenario 1 Scenario ,2 Scenario 3 Scenario ,1 0,7 Figure 34, Annually stored carbon, refurbishments, % of buildings renovated. Annually stored carbon, refurbishments,, , thousands of tonnes. Annual emissions, ktn/a Scenario 1 Scenario 2 Scenario 3 Scenario Figure 35, Annual stored carbon, refurbishments, % of buildings renovated.

66 64 (99) Scenario 2 stores 10 times the carbon of scenario 1. For scenarios 3 and 4 the figures are 25 and 50 times that of scenario 1. The following table gives key figures for the annually stored carbon in 2030, in terms of total amount of stored carbon in all buildings, carbon stored per single building, per floor area and per volume of a building. Amount of annually stored carbon in 2030 Total ktn tn/building kg/brm2 kg/brm3 Scenario Scenario Scenario Scenario Table 37, Annually stored carbon, refurbishments, in % renovated. Amount of annually stored carbon in 2030 Total ktn tn/building kg/brm2 kg/brm3 Scenario Scenario Scenario Scenario Table 38, Annually stored carbon, refurbishments, in % renovated. The following figures give more detailed information on the stored carbon in It should be noted that the rendered structures of this study do not store any carbon.

67 65 (99) Amount of stored carbon, in 2030, ktn Residential blocks of flats, amount of annually stored carbon in refurbishments, as in 2030, thousands of tonnes. 50% of buildings renovated. 35,00 30,00 25,00 20,00 15,00 10, Stored carbon, wood structures Stored carbon, Rendered structures 5,00 0,00 8 0,00 1 0,00 0,00 0,00 Scenario 1Scenario 2Scenario 3Scenario 4 Figure 36, Residential blocks of flats, amount of annually stored carbon in refurbishments, as in 2030, thousands of tonnes. 50% of buildings renovated. Blue columns al to zero. Amount of stored carbon, in 2030, ktn Residential blocks of flats, amount of annually stored carbon in refurbishments, as in 2030, thousands of tonnes. 75% of buildings renovated. 50,00 45,00 40,00 35,00 30,00 25,00 20,00 15,00 10,00 5,00 0, ,00 1 0,00 0,00 0,00 Scenario 1Scenario 2Scenario 3Scenario 4 Figure 37, Residential blocks of flats, amount of annually stored carbon in refurbishments, as in 2030, thousands of tonnes. 50% of buildings renovated. Blue columns al to zero. 45 Stored carbon, wood structures Stored carbon, Rendered structures

68 66 (99) Amount of stored carbon, in 2030, Mtn Residential blocks of flats, cumulative amount of stored carbon in refurbishments, as, millions of tonnes, % of buildings renovated. 0,35 0,30 0,25 0,20 0,15 0,10 0,19 0,29 Stored carbon, wood structures Stored carbon, Rendered structures 0,05 0,00 0,08 0,01 0,00 0,00 0,00 0,00 Scenario 1 Scenario 2 Scenario 3 Scenario 4 Figure 38, Residential blocks of flats, cumulative amount of annually stored carbon in refurbishments, as in 2030, millions of tonnes. 50% of buildings renovated. Amount of stored carbon, in 2030, Mtn Residential blocks of flats, cumulative amount of stored carbon in refurbishments as, millions of tonnes, % of buildings renovated. 0,50 0,45 0,40 0,35 0,30 0,25 0,20 0,15 0,10 0,05 0,00 0,13 0,02 0,00 0,00 0,00 0,00 Scenario 1 Scenario 2 Scenario 3 Scenario 4 Figure 39, Residential blocks of flats, cumulative amount of annually stored carbon in refurbishments, as in 2030, millions of tonnes. 50% of buildings renovated. 0,28 0,44 Stored carbon, wood structures Stored carbon, Rendered structures 12.2 Effect of a light wooden façade The baseline scenario assumes that the wooden façades are timber-framed. This section analyses the effects on carbon uptake, when the wooden façades are made

69 67 (99) with a lighter structure, without the supporting timber-frame. The details of the structure are shown in appendix. The first tables of the table pairs present the cases, where all the wooden buildings are built with timber-framed structures, and the second one the case where only light wooden façade is used. The tables show that the lighter façades result in lower carbon uptake than timberframed structures. When 50% of the buildings are renovated, light structures result in 0 10 thousand tonnes (from scenario 1 to scenario 4) lower carbon uptake, compared to timber-framed structures. With 75% of the buildings are renovated, light structures result in 0 15 thousand tonnes (from scenario 1 to scenario 4) lower carbon uptake, compared to timber-framed structures. The relative decrease of carbon uptake is 32% for all the scenarios, when timberframed structures and light wooden structures are compared. This section shows that the light wooden façades result in lower carbon uptake, compared to timber-framed refurbishments.

70 68 (99) Table 39, Carbon uptake of structures, annual uptake of refurbishments, in % of the buildings ( ) renovated. Wooden façades with timber-framed structures.br = gross Table 40, Carbon uptake of structures, annual uptake of refurbishments, in % of the buildings ( ) renovated. Refurbishments with light wooden facades. br = gross Table 41, Carbon uptake of structures, annual uptake of refurbishments, in % of the buildings ( ) renovated. Wooden façades with timber-framed structures. br = gross Carbon uptake of structures, annual uptake of refurbishments, in % of the buildings ( ) renovated. ktn tn/building kg/brm3 kg/brm3 Scenario Scenario Scenario Scenario Carbon uptake of structures, annual uptake of refurbishments, in % of the buildings ( ) renovated ktn tn/building kg/brm2 kg/brm3 Scenario Scenario Scenario Scenario Carbon uptake of structures, annual uptake of refurbishments, in % of the buildings ( ) renovated ktn tn/building kg/brm3 kg/brm3 Scenario Scenario Scenario Scenario

71 69 (99) Table 42, Carbon uptake of structures, annual uptake of refurbishments, in % of the buildings ( ) renovated. Refurbishments with light wooden facades. br = gross Carbon uptake of structures, annual uptake of refurbishments, in % of the buildings ( ) renovated ktn tn/building kg/brm2 kg/brm3 Scenario Scenario Scenario Scenario Stored carbon and emissions This section makes a simple comparison between the amount of emitted and stored carbon in building refurbishments. The following figures show that the amount of greenhouse gases exceeds the amount of annually stored carbon in scenarios 1 and 2. However, when the share of wooden construction is increased (scenarios 3 and 4), the amount of stored carbon, exceeds the amount of GHG-emissions, when both are calculated as. Residential blocks of flats, emissions and stored carbon from refurbishments, in ktn/a Scenario 1 Scenario 2 Scenario 3 Scenario Stored carbon, total Emissions, total Figure 40, residential blocks of flats, emissions and stored carbon of refurbishments, in % of buildings renovated.

72 70 (99) Residential blocks of flats, emissions and stored carbon from refurbishment, in ktn/a Scenario 1 Scenario 2 Scenario 3 Scenario Stored carbon, total Emissions, total Figure 41, residential blocks of flats, emissions and stored carbon of refurbishments, in % of buildings renovated. The following table gives the net emissions for the different scenarios. The annual CO2 uptake has been deducted from the annual GHG emissions. The values of the table present CO2 emissions (positive values) and CO2 uptake (negative values).

73 71 (99) Table 43, Annual "net emissions", in 2030, 50% renovated. br = gross Figure 42, Annual "net emissions", in 2030, 75% renovated. br = gross Annual emissions, stored carbon deducted from emissions, in 2030 ktn tn/building kg/brm2 kg/brm3 Scenario Scenario Scenario Scenario Annual emissions, stored carbon deducted from emissions, in 2030 ktn tn/building kg/brm2 kg/brm3 Scenario Scenario Scenario Scenario Effects of light wooden façades The following tables give the net emissions for the scenarios 1-4, when all the wooden façade refurbishments are either timber-framed or light structures. The annual CO2 uptake has been deducted from the annual GHG emissions. The values of the table present CO2 emissions (positive values) and CO2 uptake (negative values). The tables show that when lighter wooden façades are constructed, the net GHG emissions will rise.

74 72 (99) Table 44,Annual net emissions, in 2030, all wooden façade refurbishments are timberframed. 50% of buildings renovated. br = gross Annual emissions, stored carbon deducted from emissions. Total mass Mass Mass Mass ktn tn/building kg/brm2 kg/brm3 Scenario Scenario Scenario Scenario Table 45,Annual net emissions, in 2030, all wooden façade refurbishments are light structures. 50% of buildings renovated. Annual emissions, stored carbon deducted from emissions. Total mass Mass Mass Mass ktn tn/building kg/brm2 kg/brm3 Scenario Scenario Scenario Scenario Table 46,Annual net emissions, in 2030, all wooden façade refurbishments are timberframed. 75% of buildings renovated. Annual emissions, stored carbon deducted from emissions. Total mass Mass Mass Mass ktn tn/building kg/brm2 kg/brm3 Scenario Scenario Scenario Scenario

75 73 (99) Table 47,Annual net emissions, in 2030, all wooden façade refurbishments are light structures. 75% of buildings renovated. Annual emissions, stored carbon deducted from emissions. Total mass Mass Mass Mass ktn tn/building kg/brm2 kg/brm3 Scenario Scenario Scenario Scenario

76 74 (99) 13 Wood use in refurbishments 13.1 Comparison of wood use of refurbishments Increasing the relative share of wooden façade refurbishments will raise the annual need of wood products in year 2030, compared to year The waste of materials during construction phase was not considered in the assessment. If the material wastage was taken into account, the following figures for wood product use would be roughly 5 10% higher. In terms of round wood need, the annual volumes would be roughly two-fold, compared to the figures shown in the following. The following figure shows that when 50% of buildings are renovated, the rise in need of wood products is biggest for scenario 4, alling to an increase of 38 thousand cubic metres of wood products. The increase for scenario 3 is 24, and the increase is 9 thousand cubic metres for scenario 2. Annually used wood volume, tm3/a The volume of annually used wood products, refurbishments , thousands of cubic metres. 50% renovated. 1,0 39,4 25,0 10,6 1,0 Scenario 1 Scenario 2 Scenario 3 Scenario 4 Figure 43, the volume of annually used wood products, refurbishments between % renovated. When 75% of buildings are renovated, the rise in need of wood products is biggest for scenario 4, alling to an increase of 38 thousand cubic metres of wood products. The rise for scenario 3 is 24, and for scenario 2, 9 thousand cubic metres.

77 75 (99) Annually used wood volume, tm3/a The volume of annually used wood products, refurbishments , thousands of cubic metres. 75% renovated. 59,1 37,5 Scenario 1 Scenario 2 Scenario 3 Scenario ,4 15,8 1,4 Figure 44, the volume of annually used wood products, refurbishments between % renovated Effect of light wooden façades When 50% of buildings are renovated, the use of light wooden façades in refurbishments leads to a decrease of 0 12 thousand cubic metres of wood annually, compared to timber-framed refurbishments. If 75% of buildings are renovated, light wooden façades lead to a decrease of 0 19 thousand cubic metres of wood annually, compared to timber-framed refurbishments. The use of light wooden structures will lead to a decreased wood use. Table 48, Annual wood use of refurbishments, timber-framed structures, in % of buildings renovated. Amount of annual green house gas emissions, in 2030, mineral wool insulation Total ktn tn/building kg/brm2 kg/brm3 Scenario Scenario Scenario Scenario

78 76 (99) Table 49, Annual wood use of refurbishments, light wooden structures, in % of buildings renovated. Amount of annual green house gas emissions, in 2030, mineral wool insulation Total ktn tn/building kg/brm2 kg/brm3 Scenario Scenario Scenario Scenario Table 50, Annual wood use of refurbishments, timber-framed structures, in % of buildings renovated. Amount of annual green house gas emissions, in 2030, mineral wool insulation Total ktn tn/building kg/brm2 kg/brm3 Scenario Scenario Scenario Scenario Table 51, Annual wood use of refurbishments, light wooden structures, in % of buildings renovated. Amount of annual green house gas emissions, in 2030, mineral wool insulation Total ktn tn/building kg/brm2 kg/brm3 Scenario Scenario Scenario Scenario

79 77 (99) 14 Summary and conclusions New construction This study assesses the potential of wood in saving GHGs in Finland when increased share of new residential buildings would be done with help of increased use of wood. This can be done with help of two basic solutions; the wooden structures may either be timber-framed or CLT (cross laminated timber) structures. A baseline scenario is used for assessments of this study. The baseline scenario assumes that construction of new buildings will stay at a constant level between years 2010 and 2030 and that the relative share of concrete and wooden buildings will stay unchanged. This means that the share of concrete buildings will be 98 % and the share of wood buildings will be 2 %. The alternative scenarios assume that the share of wood construction will rise to 22%, 52%, or 82% by The results for new construction show that increased wood use in new construction results in a decreased annual use of construction materials, lower annual GHG emissions and increased annual carbon uptake. The study also calculated annual net GHG-emissions, which showed to decrease when wood use increased. Mass of structures, new construction Increased wood use in new construction results in a decreased annual use of construction materials. The baseline scenario shows a total weight of 1093 thousand tonnes for annually built new construction. If the amount of wooden construction increases slightly, from 2% to 22%, the total mass of structures is cut by 13%. When the amount of wooden construction increases from 2% to 52%, the mass of structures is cut by a third. Increasing the share of wood construction greatly, from 2% to 82% will more than halve the mass of structures of new construction. It should be noted that the masses were calculated based on the dimensions of structures. The actual masses for both concrete and wood buildings would be somewhat bigger than those estimated in this study, because the wastage of materials during construction is not taken into account in this study. GHG emissions, new construction Increased use of wood in new construction results in lower annual GHG emissions. The baseline scenario shows the total annual GHG emissions of 201 thousand tonnes in 2030 for new construction. The assessment of scenarios 2-4 with increased wood use shows that the biggest decline in GHG emissions is achieved with scenario 4, which results in savings of 51 % or thousand tonnes. In other words, increasing the share of wood construction from 2% to 82% would more than halve the annual GHG-emissions from new construction. When the amount of wood construction increases from 2% to 52%, as in scenario 3, the annual GHG-emissions will decrease by about a third (32% / 64 thousand tonnes) compared to scenario 1. For scenario 2, the decrease is 13%, or 25.6 thousand tonnes compared to scenario 1.

80 78 (99) Stored carbon, new construction Increased use of wood in new construction results in an increased amount of stored carbon in wooden constructions. The baseline scenario shows the total annual stored carbon uptake of 4 thousand tonnes for new construction in The carbon assessment of scenarios 2-4 shows an increase in stored carbon as follows: 36.7 thousand tonnes (or roughly 10-fold compared to scenario 1) for scenario 2 and 92.1 thousand tonnes (or roughly 25-fold compared to scenario 1) for scenario 3. The biggest increase in stored carbon is achieved with scenario 4, which results in a 147,4 thousand tonne (roughly 40-fold compared to scenario 1). Net GHG-emissions, new construction A simple comparison between the amount of emitted and stored carbon, with the annual GHG stored subtracted from annual GHG emissions, shows that net GHGemissions will decrease with increased wood construction. The net GHGemissions of baseline scenario are 197 thousand tonnes. When wood use is increased in new construction, it results in a decrease in net GHG-emissions by 62 thousand tonnes for scenario 2 (31%), by 156 thousand tonnes for scenario 3 (79%) and by 249 thousand tonnes (126%) for scenario 4. It should be noted that when the decrease of 100% or more is explained so that the result turns from positive (net emissions) to negative (net sorption ). The effects of timber-framed and CLT-based structures on new construction The effects of timber-framed and CLT-based structures were also analysed, with a scenario where all the wooden buildings were either timber-framed or CLTbased. The results show that CLT-structures result in a higher mass than timber-framed structures. When only CLT-based structures are used, the annual mass of structures will increase by 0 21% (3 107 thousand tonnes). Respectively, when only timber-framed structures are used, the annually built mass will decrease by 0 7% (1 36 thousand tonnes) compared to the scenario where both structures are used (80% and 20%). The use CLT-structures also results in higher annual GHG emissions than timberframed structures. When only CLT-based structures are used, the annual GHG emissions will increase by 0 23% (1 23 thousand tonnes). Respectively, when only timber-framed structures are used, the GHG emissions will decrease by 0 8% (0 8 thousand tonnes), compared to baseline scenario. In terms of carbon stored in timber, CLT-structures have a higher stored carbon than timber-framed structures because of bigger mass per functional unit. When only CLT-based structures are built, the annual stored carbon will increase by 79% (3 120 thousand tonnes). Respectively, when only timber-framed structures are used, the annual stored carbon will decrease by 26% (1 40 thousand tonnes), compared to baseline scenario. The relation between annual GHG emissions and stored carbon was also studied with help of a simple comparison between them. This was made by calculating net GHG-emissions, where the annual stored GHG was subtracted from the annual GHG emissions. The study finds that the CLT-structures result in lower net GHG emissions than timber-framed structures. When only CLT-based

81 79 (99) structures are built, the annual net GHG emissions will decrease by 1 185% (2 96 thousand tonnes). Respectively, when only timber-framed structures are used, the GHG emissions will increase by 2 62% (1 32 thousand tonnes), compared to baseline scenario. The effects of cellulose insulation, new construction When the mineral wool insulation is changed to cellulose insulation, the amount of greenhouse gases emitted is decreased by 2 10% (3 10 thousand tonnes) and the amount of stored carbon is increased by 14% (0 21 thousand tonnes). As a result, the annual net emissions are decreased by 6 60%, or by 8 31 thousand tonnes compared to mineral wool insulation. Wood use, new construction Increasing the relative share of wood construction will increase the annual need of wood products. The baseline scenario corresponds to the use of wood use of 5 thousand cubic metres. The increase for scenario 2 is 49 thousand cubic metres, and for scenario 3, 122 thousand cubic metres. The rise in the need of wood products is biggest for scenario 4, alling to an increase of 196 thousand cubic metres of wood products annually (2030 and onwards). Refurbishments This study also assesses the potential of wood in saving GHGs in Finland when increased share of external wall refurbishments would be done with help of increased use of wood. A baseline scenario is used for the assessment. It assumes that the most important group of buildings, concerning external wall refurbishments, is the group of multi-storey residential buildings, built between 1950 and 2000 and that volume of refurbishments stays constant between years 2010 and Two alternative levels of refurbishments are used: 1) 50% of the buildings built between 1950 and 2000 are renovated by 2030, 2) 75% of those buildings are renovated by The refurbishment studies are based on the assumption that external walls are mostly renovated with additional thermal insulation and a rendered façade. The share of this kind of refurbishment is assumed to be 98 % of all the façade refurbishments and the share of wooden façades with additional thermal insulation is estimated to be at 2 %. The alternative scenarios 2, 3 and 4 assume that the share of wooden façade refurbishments will increase to 22%, 52%, or 82% by 2030, while the share of rendered façades decreases respectively. The results for refurbishment scenarios show similar results, than those for new construction. The increased wood use in refurbishments results in a decreased annual use of construction materials, lower annual GHG emissions and increased annual carbon uptake. The calculated annual net GHG-emissions also decrease when wood use increases. Mass of structures, refurbishments When 50% of the buildings built between 1950 and 2000 are renovated, the baseline scenario shows that the total use of construction materials in structures is 57 thousand tonnes. The scenario 2 results in a total saving of 6 thousand tonnes, or 10%, in the total mass of structures. The results for scenario 3 are 15 thousand tonnes, and 26%. Scenario 4 results in the biggest mass savings, alling to 23 thousand tonnes, or 41%, compared to the baseline scenario.

82 80 (99) When 75% of the buildings built between 1950 and 2000 are renovated, the total mass of structures rises to 85 thousand tonnes for baseline scenario. Scenario 2 results in a total saving of 9 thousand tonnes, or 10%, in the total mass of structures, compared to baseline scenario. The figures for scenario 2 are 22 thousand tonnes, and 26%. Scenario 4 results in the biggest mass savings, alling to 35 thousand tonnes, or 41%, compared to baseline. It should be noted that the masses were calculated based on the dimensions of structures. The actual masses for both concrete and wood buildings would be somewhat bigger than those estimated in this study, because the wastage of materials during construction is not taken into account in this study. GHG emissions, refurbishments When 50% of the buildings built between 1950 and 2000 are renovated, the baseline scenario shows that the total GHG emissions from refurbishments als to 12 thousand tonnes. The biggest decline in GHG-emissions is achieved with scenario 4, which results in savings of 41 %, or 5 thousand tonnes. When the amount of wood construction increases from 2%, to 52% (scenario 3), the annual GHG-emissions decrease by 26% (3 ktn). For scenario 2, the decrease is 10%, or one thousand tonne. When 75% of the buildings built between 1950 and 2000 are renovated, the baseline scenario shows that the total GHG emissions from refurbishments als to 19 thousand tonnes. The savings for scenarios 2, 3 and 4 are, 2, 5 and 9 tonnes, while the relative savings remain the same as for the 50%-case. Stored carbon, refurbishments Increased use of wood in refurbishments results in an increased annual carbon uptake. The baseline scenario (when 50% of the buildings are renovated) shows total annual stored carbon in structures of 0.7 thousand tonnes. Scenario 2 results in additional 7 thousand tonne (10-fold) in stored carbon; scenario 3 in 18 thousand tonne (25-fold) increase; and scenario 4 29 thousand tonne (40-fold) increase. When 75% of the buildings are renovated the annual carbon uptake is one thousand tonne. The additional stored carbon in scenarios 2, 3, and 4 is, 11, 28 and 44 thousand tonnes. Net GHG-emissions, refurbishments A simple comparison between the amount of emitted and stored carbon, with the annual GHG uptake subtracted from annual GHG emissions, show that net GHG-emissions will decrease with increased use of wood in refurbishments. The net GHG-emissions for 50% refurbishment level are 12 thousand tonnes, and for 75% refurbishment level, 17 thousand tonnes. With regard to 50% refurbishment level, the decrease in net GHG-emissions is 9, 22, and 35 thousand tonnes for scenarios 2, 3 and 4. For 75% refurbishment level, the figures are 13, 32 and 51 thousand tonnes. The effects of light wooden façade, refurbishments

83 81 (99) The baseline scenario assumes that the wooden external wall refurbishments are made with a timber-framed structure. The light wooden façade is a concept, where no timber-frame is used, but the thermal insulation is attached straight to the external wall with an adhesive. The studies on light wooden façade show that the lighter wooden façades result in a lower annual mass of refurbishments, lower GHG emissions, lower annual carbon uptake and thus also to a rising amount of annual net GHG-emissions. Conclusions Increasing wood use in new construction and refurbishments is highly beneficial, taking into account all the factors analysed in this study. The amount of annually used construction materials falls significantly when wooden construction increases, for both new construction and for refurbishments. With a 22% share of wooden construction, the mass savings for new construction would al to 12%, and for refurbishments 10%. The annually emitted greenhouse gases fall with increased wood use. If wooden construction would have a 22% share, the savings in greenhouse gas emissions for new construction would be 13%, and for refurbishments, 10%. When the share of wooden construction increases to 22%, the increase in stored carbon is significant compared to baseline scenario, alling to a 10-fold increase in stored carbon for both new construction and refurbishments. Even though not analysed in detail in this study, it should be taken into account that the transfer to wooden construction materials also causes a shift from nonrenewable energy and material sources to renewable ones. The ratio of renewable energy and non-renewable energy for concrete based new buildings is, 1:214, whereas for wooden buildings it is 1:2. The ratios between renewable and nonrenewable raw materials are 1:28 for new concrete buildings and 1:3 for wooden buildings. (These can be seen from Table 1). It should also be noted that the mass of new construction in Finland is at the level of 1100 thousand tonnes annually, and the mass of refurbishments at the range of 60 to 90 thousand tonnes. In other words, the refurbishments contribute to about 5 8% of the annual mass of construction materials used. This underlines the importance of new construction, when promoting wood construction.

84 82 (99) APPENDIX 1 Definitions based on ISO CD Carbon footprint of products Part 1: Quantification (ISO/TC 207/SC ) carbon footprint, CF net 35 amount of greenhouse gas emissions and greenhouse gas removals, expressed in CO2 ivalents The CO2 ivalent is calculated using the mass of a given GHG multiplied by its global warming potential. greenhouse gas, GHG gaseous constituent of the atmosphere, both natural and anthropogenic, that absorbs and emits radiation at specific wavelengths within the spectrum of infrared radiation emitted by the earth's surface, the atmosphere, and clouds GHGs include among others carbon dioxide (CO2), methane (CH4), nitrous oxide (N2O), hydrofluorocarbons (HFCs), perfluorocarbons (PFCs) and sulphur hexafluoride (SF6). carbon dioxide ivalent, CO2 ivalent, CO2e unit for comparing the radiative forcing of a GHG to carbon dioxide The carbon dioxide ivalent is calculated using the mass of a given GHG multiplied by its global warming potential. global warming potential, GWP factor describing the radiative forcing impact of one mass-based unit of a given GHG relative to an ivalent unit of carbon dioxide over a given period of time climate change change of climate which is attributed directly or indirectly to human activity that alters the composition of the global atmosphere and which is in addition to natural climate variability observed over comparable time periods The greenhouse gases have been calculated by considering the carbon dioxide, methane and nitrogen oxide emissions and by using the IPCC weighting factors 36 as follows: CO2 1 CH4 25 N2O Including greenhouse gas emission (GHG emission ) total mass of a GHG released to the atmosphere over a specified period of time and greenhouse gas removal (GHG removal) total mass of a GHG removed from the atmosphere over a specified period of time 36

85 83 (99) APPENDIX 2 Product System and Life Cycle Carbon footprint is considered as one parameter of life cycle inventory. The environmental profile of a product is based on cradle-to-gate information (covering A1 according to EN ). Transportation to building site was not considered. Neither loss at building site was considered. Sources of information The carbon footprint information about the manufacture of products is based on RT environmental declarations 38. In those cases where this information was not available, the assessment is based on other publicly available good-quality data. In some cases also the specific assessment tools created at VTT for the use of manufacturers were made use of. Concrete and concrete products Source of information was data published as RT environmental declarations. Concrete walls In addition to RT environmental declarations also BERTTA 39 Reinforcement steel, see below. tool was made use of. Concrete slabs, columns and beams In addition to RT environmental declarations also BERTTA tool was made use of. Reinforcement steel bars The assessment was done at VTT. The basic sources of information were the environmental report of the Nordic manufacture (scrap metal based steel) and ELCD 40. The final result was calculated with help of weighting the result in accordance with the assessed market shares. Stainless steel bars The source of information was IISI 41 data about European steel. Assumed rate of recycling was 80%. 37 Sustainability of construction works - Environmental product declarations - Core rules for the product category of construction products. EN

86 84 (99) Sawn timber Source of information was data published as RT environmental declarations. Insulation material manufactured from recycled paper Source of information was data published as RT environmental declarations. Glass wool Source of information was data published as RT environmental declarations. Bitumen roofing The source of information was the environmental declaration published by the European Bitumen Association 42. The final assessment of roofing was done at VTT. Vapour barrier material The source of information was APME 43 data for low density polyethylene. Gypsum board Source of information was data published as RT environmental declarations. Rendering The assessment was done at VTT. The main background information included information about stainless steel and cement (see VTT Symposium ) and environmental reports of manufacturers. 42 Life cycle inventory: Bitumen Published by the European bitumen association. Brussels, Belgium

87 85 (99) APPENDIX 3 STRUCTURES, NEW CONSTRUCTION Floor slabs for new construction Floor structure, timber-framed Layer thickness Layer Materia l density (kg/m3) 50 mm Plaster * 0,2 mm Polypropene sheet 910 -* 18 mm Plywood sheet 490 -* 300 mm Wooden beams, 400 mm spacing 495 -* 100 mm Mineral wool 35 -* 0,2 mm Kraft paper 820 -* 48 mm Wooden battens, 300 mm spacing 495 -* 22 mm Wooden battens, 400 mm spacing 495 -* 30 mm Gypsum board, 2 x 15 mm 993 -* Thermal conductivity, (W/mK) *=thermal conductivity of internal floor slabs is not significant in terms of this research

88 86 (99) Floor structure, CLT-based Figure source: Puuinfo Layer thickness Layer Material density (kg/m3) 50 mm Plaster * 0,2 mm Polypropene sheet 910 -* 50 mm Acoustic mineral wool 120 -* 50 mm Crushed stone * 300 mm CLT 500 -* 48 mm Wooden battens, 400 mm spacing 495 -* 25 mm Acoustic spring steel * Thermal conductivity, (W/mK) 26 mm Gypsum board, 2 x 13 mm 728 -* *=thermal conductivity of internal floor slabs is not significant in terms of this research

89 87 (99) Floor structure, concrete Layer thickness Layer Material density (kg/m3) 60 mm Concrete finish * 265 mm Hollow core slab, concrete, 380 kg/m * *=thermal conductivity of internal floor slabs is not significant in terms of this research Thermal conductivit y, (W/mK)

90 88 (99) Roof structure, timber-framed U-value 0,071 W/m 2 K Figure source: Puuinfo Layer thickness Layer Material density (kg/m3) 20 mm Concrete tile roofing mm Wooden mounting layer for tile roofing mm Wooden battens for attachment of covering sheeting 0,25 mm Polypropene sheet mm Wooden beams 495 0, mm Wind shield wool mm Mineral wool 35 0,25 mm Kraft paper 820 0,330 3 mm Wood fibre board 265 0, mm Wooden battens, 400 mm spacing mm Wooden battens, 400 mm spacing mm Gypsum board, 2 x 15 mm Thermal conductivity, (W/mK)

91 89 (99) Roof structure, CLT-based U-value 0,071 W/m 2 K Figure source: Puuinfo* Layer thickness Layer Material density (kg/m3) Thermal conductivity, (W/mK) 20 mm Concrete tile roofing mm Wooden mounting layer for tile roofing mm Wooden battens for attachment of covering sheeting 0,25 mm Polypropene sheet mm Wooden roof truss 495 0, mm Wind shield wool mm Mineral wool mm CLT 500 0,12 48 mm Wooden battens, 400 mm spacing mm Gypsum board 728 -

92 90 (99) Roof structure, concrete U-value 0,071W/m 2 K Layer thickness Layer Material density (kg/m3) 12 mm Water insulation, bitumen mm Concrete slab, K , mm Lightweight aggregate 250 0, mm Polyurethane insulation 30 0, mm Hollow core slab, concrete, 380 kg/m ,20 40 mm Concrete finish ,20 Thermal conductivity, (W/mK)

93 91 (99) Base floor structure, wood U-value: 0,122 W/m 2 K Figure source: Puuinfo* Layer thickness Layer Material density (kg/m3) Thermal conductivity, (W/mK) 50 mm Plaster ,2 mm Polypropene sheet 910 0, mm Plywood sheet 490 0, mm Wooden beams, 400 mm spacing 495 0, mm Mineral wool mm Wood fibre board 265 0, mm Wooden battens, 400 mm spacing mm Wooden battens, 22x x150, mm spacing 50 mm Expanded polystyrene mm Drainage layer, gravel *The layers have been modified from those of the figure as follows: wooden beams and mineral wool layer are 300mm and 275mm in the original figure, and 325 mm and 300 mm in this figure, respectively.

94 92 (99) Base floor structure, concrete U-value: 0,122 W/m 2 K Layer thickness Layer Material density (kg/m3) 5 mm Finishing plaster mm Concrete slab, K , mm Expanded polystyrene 20 0, mm Drainage layer, gravel ,13 Thermal conductivity (W/mK)

95 93 (99) External wall structure, timber-framed U-value: 0,078 W/m 2 K Layer thickness Layer Figure source: Puuinfo* Material density (kg/m3) 28 mm Wooden cladding mm Ventilation gap with fire barriers (steel) mm Wooden battens, 600 mm spacing mm Fiber gypsum board 680 0, mm Wooden battens ( mm), ,037 mm spacing 471 mm Mineral wool 35 0,2 mm Kraft paper 820 0, mm Fiber gypsum plate 680 0, mm Wooden battens, 48x48, 600 mm 495 0,037 spacing 48 mm Stone wool mm Gypsum board 728 0,210 Thermal conductivity (W/mK) *The layers have been modified from those of the figure as follows: wooden battens and mineral wool layer are 446mm in the original figure, and 471mm in this structure. The original figure also has wood panel on internal surface, which is not included in this structure.

96 94 (99) External wall structure, CLT-based U-value: 0,078 W/m 2 K Figure source: Puuinfo* Layer thickness Layer Material density (kg/m3) Thermal conductivity (W/mK) 28 mm Wooden cladding mm Ventilation gap with fire barriers (steel) mm Wooden battens, 600 mm spacing mm Gypsum board 821 0, mm Wooden battens ( mm), ,037 mm spacing 478 mm Mineral wool mm CLT 500 0, mm Gypsum board 728 0,210 *The original figure has wood panel on internal surface, which is not included in this structure.