LIFE CYCLE ASSESSMENT AND SUSTAINABLE CONSTRUCTIONS: ECO-DESIGN ISSUES RELEVANT TO THE SAN PAOLO TOWER IN TORINO

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1 LIFE CYCLE ASSESSMENT AND SUSTAINABLE CONSTRUCTIONS: ECO-DESIGN ISSUES RELEVANT TO THE SAN PAOLO TOWER IN TORINO Vanni BADINO Prof. Dr. Eng. 1 Gian Andrea BLENGINI Dr. Eng. Ph.D. 2 Giulio MONDINI Prof. Dr. Arch. 3 Katia ZAVAGLIA Dr. Eng. Ph.D. 4 Polytechnic of Turin, Turin, Italy 1 giovanni.badino@polito.it, 2 blengini@polito.it, 3 giulio.mondini@polito.it, 4 katia.zavaglia@polito.it Keywords: LCA, eco-design, sustainable constructions Summary If on one hand the building sector plays an important role in the economy of an industrialised country, on the other hand, it must be recognised that its environmental impacts are more and more perceived as topical by the civil society. However, the environmental impacts of buildings are usually analysed with reference to the use phase only, although the embodied energy and the environmental impacts associated to the construction materials should be considered, as well. Therefore, to really understand the overall impacts of a building, the whole life cycle must be inventoried. For these reasons, Life Cycle Assessment (LCA) is more and more used in order to quantify natural resources consumption and pollutant emissions of construction materials and building activities. With this in mind, the application of LCA to the building sector can address the design phase, in order to select the construction materials and the technical solutions, and it can promote the most environmentally friendly end-of-life management. The paper will deal with the application of LCA methodology to the preliminary design of the San Paolo Tower, civil building located in Torino, providing designers with energetic-environmental information, in order to address the selection of materials and technical solutions to the most environmentally friendly solutions. 1. Economic benefits and environmental impacts relevant to the construction industry The construction industry is well known to be a driving sector in most of modern economies, both in terms of produced wealth and general employment. Although its trend roughly follows the general economic situation, showing therefore variable performances, official data reveal a constant medium/long terms growth. In Italy, for instance, according to the national statistics (ISTAT 2005) the added value of the construction industry was 66 billion euros in the year 2004, representing a 5,2% contribution to the GDP. In the same year, the nominal annual growth of the sector was 5,0%, which corresponds to a 2,7% real growth. Positive are the employment statistics, as well. In fact, employment in the sector, accounting for a 8% share of total national employment, faced a overall growth by 30,4% in the period , while, in the same period, the general employment grew by 10,3% only. Moreover, as far as construction activities are concerned, it is worth noticing how the relationship between capital investment and employment is tighter than in other productive sectors because of the higher incidence of the labour factor. In fact, it is estimated that each 0,5 million euros invested in construction activities generate 14 job positions, of which 9 are directly employed in the sector and 5 in downstream linked activities. Among the induced benefits, it is worth considering also the economic effects which are generated by the use of building assets. In this case, particularly important are the building leases which accounts for 130 billion euros, in Italy, in the year 2003, corresponding to a 10,3% share of the GDP. Therefore, it is possible to state that the construction industry provides an overall economic benefit (direct and indirect) of at least 15% of the GDP. However, if on one hand the construction sector represents a core contribution to the national economy in most of world s countries, at the same time, it must be recognised that its environmental impacts are more and more perceived as topical by the civil society. Depletion of non renewable resources, both with and without energy content, air pollution, land use and land degradation are typical examples. On the side of negative environmental impacts, as far as Italy is concerned, according to the official figures supplied by the Ministry of Production Activities for the year 2004, use of energy for indoor civil purposes 17

2 accounts for 31% of the total final energy use all over the country, most of which comes from fossil fuels burning and consequently corresponds to 31% of national greenhouse emissions (ENEA 2005). However, such statistics are limited to the use phase of buildings only, which roughly corresponds to the energetic-environmental burdens ascribable to the day-to-day running of building assets. Moreover, in the past and for too long researchers, designers, public administrators and constructors paid a great interest on understanding energy use during the operational period of the home (use phase) only. With this approach, some important factors has been neglected for decades: the embodied energy and environmental interventions relevant to construction materials. For these reasons, a growing number of operators are beginning to use Life Cycle Assessment (LCA) methodology as a tool for quantifying natural resources consumption and pollutant emissions. In fact, to really understand the overall environmental impacts of a building, the whole life cycle must be inventoried (material production, manufacturing, use, end-of-life). Using such a Life Cycle approach, and making further reference to official statistics (ENEA 2005), if we include manufacturing of construction materials (cement, bricks, glass, ceramics, etc.) and building activities, the overall contribution of the construction sector (direct and embodied) rises up to 37% of the Italian final energy use in the year On the side of air pollution, according to an estimation based on the above mentioned statistics for the year 2004, the contribution of construction activities (materials manufacturing and building construction phase) was, for instance, about 10% in terms of greenhouse emissions, the contribution of residential and service sectors (building use phase) being 30,5%, in the same period (ENEA 2005). Therefore, it is possible to estimate an overall contribution of the construction sector to the Italian share of global warming phenomenon by 40,5%. Construction industry represents therefore both a resource and a threat to sustainability, and both these aspects must be well kept in mind. In any case, when dealing with the environmental sphere, as far as common buildings are concerned, in order to issue significant conclusions on subjects such as pollution and resource stocks depletion, the analysis must be carried out by considering all life cycle phases. 2. Life Cycle Assessment and constructions Life Cycle Assessment, standardised by UNI EN ISO 14040, is both an approach and an objective technique for assessing the environmental impacts associated with a process or activity from cradle to grave, that means in the case of construction sector, from raw material mining/quarrying, to materials production, building construction, use, demolition, recycling and disposal. This methodology, schematically represented in Figure 1, is based on objective criteria and supplies a measurement of the environmental performances of products/processes, through the identification of inputs (raw materials and energy consumption) and outputs (wastes and releases), during all the life cycle. The life cycle approach, that originated in the 1970s and that received a systematic definition in the early 1990s by SETAC (Society for Environmental Toxicology and Chemistry), is an innovative methodology conceived to jointly deal with energetic and environmental issues relevant to products or processes. Reuse LCA identifies and quantifies energy and materials used as well as releases to the environment and their potential impacts throughout the whole life cycle Figure 1 Study boundary The Life Cycle Assessment approach. 18

3 The cradle to grave analysis takes into account products or processes in a global perspective, as well as it considers proposals for environmental improvements. Therefore the evaluation includes: extraction and processing of raw materials, production and transportation, distribution, use, re-use, recycling and final disposal. According to the ISO standard, LCA methodology comprises four stages. The Inventory phase is the core stage, which must be supported by dedicated software in order to build a research model and outline the environmental inputs and outputs relevant to the system under the study. The system boundaries usually include the following phases: pre-use (consists in manufacturing and transportation of building materials and the construction stage), use (includes all activities related to the use of a building) and end-of-life (includes the demolition and rubble treatment operations, in order to recycle the waste). Inputs and outputs arisen from the inventory analysis represent the basic knowledge in order to estimate the environmental consequences. For instance, gross energy requirement (GER) and environmental indicators are useful in order to summarise use of energy resources and pollutant emissions. Such indicators can be interpreted and used for process improvement purposes and also for the selection of environmental best practices and technologies. Therefore the LCA analysis, applied to the construction sector, integrates the engineering project and supplies objective data for the following issues: - building materials selection; - construction techniques selection; - fixtures and equipments selection; - end-of-life management. As far as the design phase is concerned, LCA allows identifying the building elements and components with a relevant environmental impact during the life cycle and supplies an objective contribution to the decision making process. Previous LCA studies by Politecnico di Torino (Badino et al., 2005) allowed identifying and estimating the contributions of each life cycle phase to the whole impact of a standard medium size building, pointing out weak points and opportunities of improvement. One important issue is that relevant to the potential benefits that might arise from demolition and waste recycling. Thus, starting from the design phase, a building must be carefully evaluated, by considering not only the use-phase, but also the whole life cycle. In case appropriate demolition and recycling operations are carried out, the life-cycle environmental burdens of buildings can be reduced, as it will be later on discussed. 3. Life Cycle Assessment of San Paolo Tower in Torino The application of Life Cycle Assessment methodology to the San Paolo Tower, presented in the paper, is a part of a larger study carried out by a work team which involved the authors, the designers (Estudio Lamela Arquitectos, Madrid) and several researchers in different fields (arch. Marta Bottero for the environmental strategies, arch. Nadia Ciocia for the analysis of the project, eng. Stefano Corgnati for the strategies related to energy efficiency and arch. Andrea Moro for the environmental performance evaluation). Life Cycle Assessment methodology was applied to the preliminary design of the San Paolo Tower in Torino in order to supply the designer with energetic-environmental information and therefore address the selection of materials and technical solutions towards objectives of environmental sustainability. With that in mind, it is worth considering that a relevant aspect of the LCA methodology is the possibility of comparing, within the preliminary design phase, different proposals and solutions, in order to point out their environmental impacts and to identify and evaluate possible improvements. A from-cradle-to-grave LCA was carried out by including all the life cycle phases as shown in Figure 2 and by paying particular attention to those processes relevant to basic materials manufacturing and building endof-life management. As far as shell embedded construction materials are concerned, all the necessary from-cradle-to-gate energetic and environmental information (ecoprofiles) were retrieved from previous LCA studies by DITAG/Politecnico di Torino or from the databases included in the LCA software application SimaPro. The LCA model was developed with reference to 1 building floor thought as a typical representative of the whole tower, therefore not considering the basement and the roof system. The adopted functional unit was 1 m 2 net floor area over 1 year building use, the total net usable floor area being 1500 m 2 and the building life span being 60 years. The building life cycle was divided in three main areas: pre-use, use and end-of-life (Figure 2). The pre-use phase consisted of the manufacturing and transportation of all employed building materials (Table 1), as well as the construction of the San Paolo Tower. The use phase encompassed all the direct energy used for the day-to-day running of the building over the 60 years life span, including heating, airconditioning and lighting (Table 2). 19

4 Raw materials mining/quarrying Building materials production Building materials transport PRE-USE PHASE Building shell construction USE PHASE (60 years) Building dismantling/demolition END-OF-LIFE PHASE Transport Transport Rubble recycling Residual waste disposal Figure 2 San Paolo Tower Life Cycle Assessment: phases included in the from-cradle-to-grave LCA model. As last step, end-of-life phase inventoried dismantling and selective demolishing of the building shell, transportation, construction and demolition waste (C&DW) recycling and landfill of residual waste, mainly based on past experience gathered at DITAG/Politecnico di Torino. Table 1 shows the relative contribution of inventoried construction materials to the total mass of the building shell. As it can be seen, concrete is the main constituent, representing 63% in mass, followed by steel (reinforcing bars, steel plate, stainless steel, etc.) 25%, Aluminium and Copper 3% each, glass 5% and plastics (Neoprene, Polystyrene, Polypropylene and Polyethylene) around 1%. The estimated total mass of 1 building floor (1500 m 2 ) was around 2200 t which roughly corresponds to 1,47 t/m 2 (24 kg/m 2 per year). Table 1 Composition of building shell of San Paolo Tower (1500 m 2 flor area) Element Material Database/source Quantity [t] Quantity [%] Structural element Steel Ecoinvent ,7% (life 60 years) Aluminium Ecoinvent 55 2,5% Copper IDEMAT 36 1,6% Glass fiber Ecoinvent 21 1,0% Textile filters IDEMAT 0,26 0,0% Neoprene Ecoinvent 6 0,3% Polystyrene Ecoinvent 2 0,1% Polypropylene Ecoinvent 13 0,6% Ceramics Ecoinvent 12 0,5% Concrete Politecnico TO ,8% Glass Ecoinvent 79 3,6% Equipments Steel Ecoinvent 177 8,0% (life 30 years) Aluminium Ecoinvent 10 0,5% Copper IDEMAT 32 1,5% Neoprene Ecoinvent 4 0,2% Polyethylene Ecoinvent 3 0,1% Total mass % Table 2 Direct energy relevant to the use phase of San Paolo Tower (data refers to 1 m 2 per year) Energy use Energy source Database/source Quantity [kwh/m 2,y] Cooling Thermal from gas co-generator Ecoinvent 65 Electricity from Italian mix Buwal Heating Thermal from gas co-generator Ecoinvent 65 Lighting Electricity from Italian mix Buwal

5 LCA of the building under study has been carried out according to ISO standards (ISO 1997). Main achieved results after analysing Inventory data from the LCA model are summarised in Table 3 which supplies a picture of life-cycle impacts, as well as the main life phase contributions to the selected impact indicators, with reference to the functional unit. Life Cycle Impact Assessment (LCIA) was carried out according to ISO standards, limited to the characterisation step and limited to the following category indicators, familiar amongst LCA practitioners: GER (Gross Energy Requirement) as parameter relevant to total energy use (direct + indirect + feedstock), NRER (Non Renewable Energy Requirement) as parameter representative for depletion of fossil fuel resources; GWP (Global Warming Potential) as parameter relevant to greenhouse effect; EP (Eutrophication Potential) as parameter relevant to surface water eutrophication; AP (Acidification Potential) as parameter relevant to acid rain phenomenon; POCP (Photochemical Ozone Creation Potential) as indicator of photosmog creation (Badino 1998). Table 3 LCA impact indicators relevant to San Paolo Tower (data referred to 1 m 2, per year) Life phase GER NRER GWP EP AP POCP [MJ] [MJ] [kg CO 2 eq] [g O2 eq] [mols H+] [g C 2 H 4 eq] Pre-use phase (shell + construction) ,8 1015,4 28,0 0,54 Use phase ,9 740,9 9,2 0,78 End-of-life phase ,4-435,1-21,6-0,12 Total Life ,2 1321,2 15,6 1,21 The analysis of Table 3 can be more effective by comparing achieved results relevant to San Paolo Tower to those relevant to a second building, as shown in Figure 3. For comparison, Figure 4 summarises some useful information relevant to the LCA of Via Garrone building, a residential block of flats located in Torino, built in 1965 and blast demolished in 2004 within a project of urban area re-design, with emphasis on the role of building materials (Badino et al. 2005, Di Carlo 2005) GER MJ/m 2,year Torre SanPaolo, Torino - Italy Via Garrone, Torino - Italy -400 Pre-use Use End-of-life Total life Torre SanPaolo, Italy Via GarroneTorino, Italy GWP kgco 2eq /m 2,year 80,0 70,0 60,0 50,0 40,0 30,0 20,0 10,0 0,0-10,0-20,0 Pre-use Use End-of-life Total life Torre SanPaolo, Italy 30,8 57,9-18,4 70,3 Via GarroneTorino, Italy 7,7 60,2-1,1 66,8 Figure 3 Comparison between San Paolo Tower and Via Garrone buildings in terms of life-cycle energy use (GER) and greenhouse emissions (GWP). 21

6 bricks 4% mortar 2% AVERAGE MASS: 1.45 t/m 2 (36 kg/m 2, year) plaster 4% reinforcing bars 4% ceramics 2% others 1% concrete 83% values % GER GWP EP AP POCP Concrete Steel Mortar & plaster Brick & ceramic Others Figure 4 LCA of Via Garrone building. Average composition of the building shell and fixtures (left). Contributions of main building materials to the pre-use-phase impacts (right). As it can be noticed by analysing Table 3 and Figure 3, the use phase is responsible for the highest impacts, in comparison to rest of the life cycle. An exception is made when considering EP and AP indicators which, as far as San Paolo Tower is concerned, are mostly determined by the shell embedded building materials and construction operations. By analysing Figure 3, it clearly appears that San Paolo Tower is characterised by much higher impacts relevant to the pre-use phase. This can be ascribed to the composition of the building shell and building fixtures as it can easily be understood by comparing Figure 4 and Figure 5. In fact, San Paolo Tower is characterised by a heavy and systematic use of building materials which hold much higher from-cradle-to-gate environmental and energetic burdens (ecoprofiles) like steel (25% in mass) or aluminium and copper (3% each) or glass (5%), in comparison to the ones used for Via Garrone building. Thus, in the further design phases, it might be appropriate thinking about substituting some of the building materials to be employed with others less energetic expensive and less pollutants in a from-cradleto-gate perspective. But this issue should be further addressed. However, in case the end-of-life phase is properly managed by dismantling, separating and recycling building materials, a considerable share of environmental burdens ascribable to the building shell can be recovered and therefore deducted from the total life cycle impacts, as shown in Table 3 and Figure 3. Thus, in a modern building like San Paolo Tower, end-of-life management becomes strategic in order to control the life-cycle impacts. 100% values % 80% 60% 40% 20% 0% GER GWP EP AP POCP Concrete & ceramics 3,0% 6,1% 3,6% 0,7% 5,0% Plastics 5,3% 2,5% 2,2% 0,6% 1,2% Glass 4,7% 5,3% 4,7% 1,4% 6,3% Copper 19,7% 28,5% 17,5% 86,8% 1,4% Aluminium 31,5% 27,4% 20,6% 5,1% 35,3% Steel 35,8% 30,1% 51,5% 5,4% 50,9% Figure 5 LCA of Torre San Paolo building. Contributions of the main building shell and fixtures materials to the pre-use-phase impacts. 22

7 Negative impact contributions relevant to the end-of-life phase can be ascribed to the fact that achievable avoided impacts, corresponding to new secondary construction materials entering further life cycles, are higher than the impacts generated by the recycling process. Figure 6 supplies an overview on life-cycle phase contribution to greenhouse emissions with emphasis on net benefits than can be achieved by means of an appropriate end-of-life management. San Paolo Tower (m 2, per year) 70,2 kg CO 2 eq PRE-USE (m 2, per year) USE PHASE (m 2, per year) END-OF-LIFE (m 2, per year) 30,8 kg CO2eq 57,9 kg CO2eq -18,4 kg CO2eq 2,5732 MJ Electricity Italy B250 4,2896 MJ Heat diesel B250 6,75 kg steel 0,84793 kg aluminium 1,0515 kg copper 1,019 kg glass 0,28272 kg Mixed plastics 14,084 kg aggregates 1,3962 kg Landfill Residual B250 0,442 0,350-3,632-7,955-6,265-0,781-0,523-0,177 0,033 Figure 6 Contributions of main life phases to the overall Global Warming Potential (GWP) of San Paolo Tower, with emphasis on the end-of-life phase. However, it must be remarked that net achievable benefits from end-of-life management are not to be considered in any case, but they can be accounted only in case building materials will be separated and recycled after dismantling. Therefore building end-of-life management must be considered a meaningful issue within building eco-design. The same Figure 6 is helpful in order to understand which are the building materials that hold an intrinsic best recovery yield after recycling and therefore allow a better recovery of shell embedded energetic and environmental burdens. These last issues can be useful in order to address the debate relevant to the sustainability of building materials. In fact, the perspective of solving sustainability concerns by choosing building materials from a list of good and bad materials is charming, but, from a scientific point of view, is unlikely. What does it mean sustainable building material? Assessing the sustainability of construction materials is not an easy target. There are not universally recognized or accepted criteria and even the definition of ecological material is still controversial. There is even authoritative criticism moved against the opportunity of talking about sustainability of materials (Boustead 2000). In fact, it does not make sense talking about sustainability of building materials, unless talking about sustainability of buildings. A lot depends on what use is made of the building material in order to accomplish a given function. In other terms, it is conceptually wrong to talk about sustainability of steel or concrete: it depends on what steel or concrete are used for, what will be the consequences on the use phase of the building, how they can affect the life span of the building itself and, finally, what will happen to those building materials after building dismantling. However, someone still makes confusion between sustainability of building materials and the concept of ecoprofile. Ecoprofiles of building materials represent the basic knowledge and the starting point for studying the life cycle of a building. Nevertheless, although they can tell us what are the cumulative energetic and environmental burdens that are embedded in the building shell, the full LCA of a building must not be confused with a cocktail of ecoprofiles. In fact, ecoprofiles are representative of the pre-use phase only, while use-phase and end-of-life are fundamental elements to be further considered. In particular, the end-of-life of building materials, whatever will happen to them: reuse, recycling or landfill, must be considered. In fact, further energy use or emissions, during end-of-life might increase their cumulative impacts or, in some cases of reuse or recycling, net benefits could lower the overall life cycle impacts. Therefore, in order to carry on with full LCA of buildings, ecoprofiles of recycled building materials are needed, as well. 23

8 4. Conclusions The first step in order to improve he sustainability of buildings is certainly the reduction of energy consumption during the use-phase. However, in case of a new and modern building like San Paolo Tower in Torino, presently under design phase, significant life-cycle improvements could be achieved through the choice of environmentally friendly materials, or by lowering building scraps during shell construction operations. Moreover, it must be noticed that a significant share of those burdens than can be ascribed to the building shell (embedded burdens) can be recovered at the end-of-life phase by appropriate dismantling and recycling operations (59% of gross energy and greenhouse emissions embedded in the San Paolo Tower shell), thus reducing the environmental impacts of the overall life cycle. Although ecoprofiles of building materials can be regarded as the scientific background for quantifying sustainability of construction activities, as well as instruments than can not be renounced when studying life cycle impacts of buildings, their role must not be misunderstood. In fact, ecoprofiles tell us what are cumulative energetic and environmental performances of building materials, allowing therefore to quantify from-cradle-to-gate burdens that are embedded in the building shell. However, sustainability of buildings is more concerned with energetic-environmental performances of a production system, which performs a defined function, rather than on from-cradle-to-gate performances of products. It is not therefore a cocktail of ecoprofiles that can quantify sustainability of buildings. Nor a list of bad or good materials can be really helpful. A full Life Cycle model must therefore be developed by including building use-phase and building end-of-life. Acknowledgements Authors would like to thank Estudio LAMELA Arquitectos (Madrid) for LCA input data supplied. References Badino V. & G. Baldo (1998). LCA, Istruzioni per l Uso, Progetto Leonardo, Esculapio Editore (BO). Badino V., Blengini G.A. & Zavaglia K., Demolition and rubble recycling as a new source of building materials, Proc. Conf. MPES, Banff, Canada. 1-3 November pp ISSN Boustead I., B.R. Yaros & S. Papasavva (2000). Eco-labels and Eco-Indices. Do they make sense? Paper Number: 00TLCC-49. Society of Automotive Engineers Inc.. Di Carlo, T., Applicazione della metodologia LCA alla vita di un edificio: analisi dell efficienza ambientale della fase di demolizione e smaltimento delle macerie, Master Degree thesis, Politecnico di Torino. ENEA, Rapporto Energia e Ambiente 2004, Rome. ISO International Standard 14040, Environmental management Life cycle assessment Principles and framework. International Organisation for Standardisation (ISO), Geneva. ISTAT Annuario statistico italiano 2005, Rome. UN-FCCC, United Nations Framework Convention on Climate Change, 24