Presentation Objectives. Environmental Performance of CLT. Life Cycle Thinking. Overview

Transcription

1 Presentation Objectives Environmental Performance of CLT Preliminary Results of a Comparative Building Life Cycle Assessment in Quebec City Blane Grann, MSc Research Scientist Environment & Sustainability Group Advanced Building Systems Provide a basic understanding of life cycle assessment (LCA) Communicate results for a comparative building LCA from Quebec City Provide recommendations based on these particular results Demonstrate the utility of a life cycle approach Location: Seattle, WA Date: February 28th, Overview Life Cycle Thinking Intro to life cycle assessment Study overview LCA Results Implications for sustainable design Image Source: Building green with wood, BC Forestry Innovation Investment 3 4

2 Life Cycle Thinking Life Cycle Thinking Image Source: Building green with wood, BC Forestry Innovation Investment Image Source: Building green with wood, BC Forestry Innovation Investment 5 6 Selected Environmental Indicators TRACI 2.0, USEPA Other Life Cycle Considerations Not included in this presentation Global warming (GWP) Respiratory Effects (RE) Acidification (AP) Eutrophication (EP) Ozone depletion (ODP) Smog formation (SP) Image Source: NOAA Environmental Visualization Laboratory Excluded due to greater uncertainty: Human Health carcinogenic, non-carcinogenic Ecotoxicity Can environmental problems be boiled down to 1 score? Total Waste Freshwater Use Total Primary Energy Use: Fossil energy Hydro Bioenergy Other renewables Feedstock fossil energy Feedstock biomass energy 7 8

3 Study Overview Study Overview System Boundary Motivations Limited work investigating the life cycle performance of CLT building systems CLT has an opportunity in non-traditional timber markets: i.e. mid-rise building structures Goals Develop a bill-of-materials for: A 4060 m 2, 4-storey, CLT apartment building built in Chibougamau, Quebec An equivalently designed concrete structural system Conduct a life cycle assessment of each building Compare the results 9 *Heated floor area 10 Study Overview CLT building Study Overview Equivalent building design Cross-laminated timber (CLT) Floor separation, external wall juncture 4.1in 8.2in Concrete slab and column with light gauge steel stud walls (CSSW) CSSW building: floor separation, external wall juncture 2 x 2.5in 2 x 4in 11 12

4 Assumptions & Limitations Quantifying the carbon storage benefit Assemblies deemed to be equivalent between both buildings were excluded: Foundation slab and walls Windows and doors HVAC Plumbing & electrical Etc. Excluded operational phase of the building Electricity use Heating Etc. Methods for quantifying the carbon storage benefit of wood products are in their infancy and should be interpreted with caution 13 Image courtesy ORNL 14 Quantifying the carbon storage benefit Default Scenario End-of-Life Landfilling non-recycled materials ends up in landfill 47% landfill gas captured (ecoinvent v2.2) Landfill gas flared 23% of wood products decay in the landfill (Skog, 2008) 77% of wood products remain stored in the landfill Image courtesy ORNL 15 16

5 Disclaimers Results of this LCA are specific to Quebec City Study Assumes Sustainable Forest Management Forest regrows after harvesting i.e. excludes land use changes Excludes old-growth harvesting Results currently undergoing peer review Results: Default Scenario CLT Building: Environmental Impact Results by Life Cycle Stage for End-of-Life Landfilling Results: Default Scenario CLT Building: Environmental Impact Results by Material for Endof-Life Landfilling Results: Default Scenario CSSW Building: Environmental Impact Results by Life Cycle Stage for End-of-Life Landfilling 19 20

6 Results: Default Scenario CSSW Building: Environmental Impact Results by Material for Endof-Life Landfilling Comparative Results: Default Scenario Environmental Impacts with Landfilling (LF) Scenario Evaluation End-of-Life Incineration Non-recycled, combustible materials sent to incineration facility energy captured from wood incineration used to offset natural gas use CLT building made with 50% reused CLT panels Scenario Evaluation 23 LF= landfilling scenario; INC = incineration scenario 24

7 Conclusions Recommendations Improving the environmental performance of CLT construction Considerable GWP benefit for the CLT building compared to the CSSW building Especially when considering: the benefit from net biogenic GWP, and potential for avoided natural gas emissions when wood is incinerated EP was very high for the CLT building when landfilling of wood products was considered Material production was the most important life cycle stage considered end-of-life was significant in a few cases Key materials included: CLT building CLT, rockwool, gypsum board CSSW concrete, rockwool, gypsum board, rebar High impact materials Alternatives to rockwool in floor separations? Explore hybrid wood structures that take advantage of CLT s strengths while reducing wood use Transporting CLT by rail rather than truck can provide additional improvements e.g. GWP for rail transport is 25% of truck transport (NREL, 2012) Regulatory and policy measures promoting and enhancing landfill gas recovery and energy recovery from incinerating wood products enables considerable life cycle benefits for the CLT building Incineration of wood products with energy capture can avoid significant quantities of fossil fuels Q & A FPInnovations Blane Grann Blane.Grann@fpinnovations.ca 2013 FPInnovations. All rights reserved. Copying and redistribution prohibited. FPInnovations, its marks and logos are registered trademarks of FPInnovations

8 References Additional Slides Cherubini, F., Strømman, A. H., & Hertwich, E. (2011). Effects of boreal forest management practices on the climate impact of CO2 emissions from bioenergy. Ecological Modelling, 223(1), doi: / j.ecolmodel Guest, G., Cherubini, F., & Strømman, A. H. (2012). Global Warming Potential of Carbon Dioxide Emissions from Biomass Stored in the Anthroposphere and Used for Bioenergy at End of Life. Journal of Industrial Ecology, no no. doi: /j x NREL. (2012). US life cycle inventory database. Retrieved February 15, 2013, from Skog, K. (2008). Sequestration of carbon in harvested wood products for the United States. Forest Products Journal, 58(6), Swiss Centre for Life Cycle Inventories. (2012). Database. ecoinvent Centre. Retrieved October 5, 2012, from Sensitivity Thickness of continuous insulation on CSSW building Indirectly examine the assumption of equivalent operational energy consumption Sensitivity of impact factors adopts emissions factor for upstream biogenic carbon emissions based on Guest et al. (2012) inclusion of emission factors for sulfur oxides* Avoided Fuel Natural Gas Bituminous Coal Fuel Oil Sensitivity Insulation of CSSW building Change in total results due to: ~12% change in thermal resistance of exterior CSSW walls 80 mm XPS 70 mm XPS Change in Total Results Global Warming Potential (kg CO2 eq) 0.6% Acidification Potential (moles of H+ eq) 0.4% Respiratory Effects (kg PM10 eq) 0.0% Eutrophication Potential (kg N eq) 0.3% Ozone Depletion Potential (kg CFC-11 eq) 0.4% Smog Potential (kg O3 eq) 0.5% 31 32

9 Sensitivity TRACI characterization factors Sensitivity Avoided fuel 200% 150% 100% 288% 8887% 8504% 50% 0% Global warming Acidification Respiratory effects Eutrophication Ozone depletion Smog Bituminous coal, combusted in industrial boiler NREL /US Heat from nat. gas FAL Natural gas, combusted in industrial boiler NREL /US Heat from DFO FAL 33 DFO = distillate fuel oil 34 Putting Operational Energy into Context Operational energy is a significant driver for the life cycle performance of buildings (Ortiz et al. 2009; Sharma et al. 2011) Average annual energy consumption for Quebec apartments in 2010: 0.7 GJ/m 2 (NRCAN, Office of Energy Efficiency) Projected energy consumption of Le Clos St-Andre 0.4GJ/m 2 (CMHC) Le Clos St-André, Montreal Quebec CLT Building CSSW Building R-value Walls R28 / RSI 4.9 R26 / RSI 4.6 R25 / RSI 4.5 R-value Roof R30 / RSI 5.3 R51 / RSI 9 R51 / RSI 9 R-value Double glazed windows RSI 0.7 Energy Consumption Typical design 0.7 GJ/m2 Based on energy modelling 0.4 GJ/m2 Additional Slides Apartment Energy Use in Quebec Energy Use per floor area (GJ/m2) Entire Building stock Model building Electricity Natural Gas Heating Oil Other Wood Total other includes coal and propane Source: NRCAN Office of Energy Efficiency - Comprehensive Energy Use Data Tables 35 36

10 Putting Operational Energy into Context 37 LF= landfilling scenario; INC = incineration scenario *Assuming 0.4 MJ/m 2 Additional slides Total Primary Energy Use 39 LF = landfilling; INC = incineration Putting Operational Energy into Context: TRACI Sensitivity Adjustments 38 LF= landfilling scenario; INC = incineration scenario *Assuming 0.4 MJ/m 2 Additional slides Freshwater Use 40 LF = landfilling; INC = incineration

11 Additional Slides Additional Slides CLT waste from building site CSSW waste from building site Additional Slides Forest Growth (Atmospheric Carbon Removal) Model Adapted from Cherubini et al