Carbon Footprint: some definitions

Transcription

1 Topic #2: Sustainable Design Considerations Carbon footprint Energy, materials, site, water, air quality Human factors, economy CE 5515: Sustainable Design and Construction Dr. Andrea Schokker Carbon Footprint: some definitions Carbon footprint: the total CO 2 and other greenhouse gas emissions produced directly or indirectly from an item or process Carbon neutral / zero footprint: having a net zero carbon footprint (no overall CO 2 produced or reduced) Carbon negative: having a net negative carbon footprint (overall reduction in CO 2 ) Embodied energy: energy embodied in the physical buildingincluding including raw materials, transport, manufacture, and later demolition Operational energy: Energy needed for building functions including heating, cooling, and lighting 1

2 Life Cycle Assessment (LCA): the quantification of the full environmental impacts of a building (or product or service) over its lifetime, not to be confused with Life cycle cost (LCC) which includes only the monetary impact Cradle to grave: LCA considering manufacture or birth (cradle) through demolition (grave) Cradle to cradle: an extension of cradle to grave to include recycle/reuse of the materials to bring the cycle back to the cradle (birth) Ecocalculator: tool for LCA calculations to evaluate potential to contribute to global warming Carbon Footprint Measures the potential contribution humans have on climate change expressed in weight of CO 2 equivalent Emissions from manufacture of a product Extraction of resources Burning of fossil fuels to manufacture Transport of raw materials and final product Emissions from a product s continued use, operation, and maintenance 2

3 Carbon Footprint of a T Shirt Map of Carbon Emissions in millions of metric tons/year/100 sq km (courtesy of the Vulcan Project, 2002 data) 3

4 Greenhouse gas emissions by industrial sector plastic and rubber 2% alumina & aluminum 3% cement food & bev 4% mining 5% 5% iron & steel 5% textiles 2% lime 1% metal castings 1% oil & gas 31% semiconductors 1% forest products 5% construction 5% other sectors 14% chemicals 16% Embodied vs Operational CO 2 Courtesy of GGLO (based on Seattle districts): 4

5 Embodied Carbon renovation Courtesy of GGLO (based on Seattle districts): Carbon Labeling T shirt cement Cemex cement = 17 kg / 25 kg bag (or 068kg 0.68 / kg cement) Potato Chips (Walker s crisps) = 80 g / 34.5 g bag (or 2.31 kg / kg chips) 5

6 Fuel economy and CO2 information on car labels in the U.K. Emissions directly relate to level of taxes paid on the car Cement Second most used after water and by far the most used building material worldwide CO 2 emissions from cement manufacture Generally accepted as 4 5% of world total; 1.5% of US total About 50% from burning limestone and 50% from fuel needed to run the kiln Raw Materials Grinding & Blending Burning Milling Packaging / Distribution Quarrying and crushing of limestone, shale, clay, and other raw materials Grinding of raw materials Blending Materials may be preheated to reduce energy Primary burning in kiln Clinker exits kiln and cools Add gypsum Grinding clinker to form cement powder Stored in silos, bagged 6

7 Cement Manufacture Image from See PCA site for flash tour of how cement in manufactured Concrete vs Cement About 1/10 of concrete is cement even if no supplementary cementitious materials are used SCMs often replace 5 40% of the cement in a mixture (and sometimes more) 7

8 SCMs (Supplementary Cementitious Materials) Fly Ash By product of coal fired plants that generate electricity Silica Fume By product of silicon metal and ferrosilicon production Slag cement By product of iron production Others: volcanic ash, rice husk skash, metakaolin Ternary blends (2 SCMs per mixture) Key topics in design/construction for sustainability Energy Materials Site Social (Human Factors) Water Air Quality Economic 8

9 Materials Reduce Structural efficiency Material substitution (such as SCMs) to reduce use of natural resources or CO 2 emissions Reuse Repair/retrofit Structural components (panels, pavers, block, etc) Wash water for concrete Recycle Steel Concrete (recycled concrete aggregate) Packaging from construction site Waste products (tire, glass, fiber, etc) Reduce Structural efficiency comparison Traditional CIP parking garage PT parking garage (Indianapolis Airport) 9

10 Reuse AOL Creative Center after being adapted from a large maintenance and storage facility Reuse Repair: Towson, Maryland Parking structure 10

11 Reuse Repair: Reagan National Airport Terminal A Reuse Concrete wash water 11

12 Recycled Site Clean up of Brownfield sites Pollutants, chemicals, etc. contaminated site Location to services Near transportation and necessary shopping Green space Preserve prime farmland, wetlands, areasnear water bodies Minimize footprint of building 12

13 Brownfield Sites San Francisco Green space planned community Vickery Village (GA) 13

14 Green space downtown Water Stormwater management Runoff ff( (quality and quantity) Water use Minimize quantity Reuse greywater, capture rainwater On site water treatment 14

15 Stormwater management Cisterns Pervious pavement Raingardens & vegetated swales Green roofs Minimize building footprint and paved areas 15

16 Green Roofs Air Quality Ventilation Natural ventilation to outdoors Air exchange systems Low emitting materials Paints, stains, adhesives, carpets: low VOC Avoid extra finishes when possible 16

17 Energy Embodied Operational 17

18 Solar Wind Geothermal Biomass Hydrogen Hydropower Renewable Energy Solar 18

19 Wind Geothermal Heat Mining (geothermal potential) from MIT 19

20 Biomass Hydrogen 20

21 Hydropower Heat transfer Conduction Thermal Resistance Convection Thermal Radiation Insulating materials are used to provide thermal resistance 21

22 R values Used to aid engineers in design U value (or U factor) is the heat transfer coefficient and U=1/R High R (low U) is a good insulator Calculation for a wall/system depends on the materials and configuration Avoid idthermal bridges bid Note that some system claims of R values are questionable for actual in place use Thermal Properties of Common Building Materials 22

23 Calculating R values for walls No thermal bridging use direct summation R total = R layers (including air spaces) Thermal bridging use parallel series method No thermal bridging example Sandwich panel 6 concrete interior layer, 3 XPS, 3 outer concrete 23

24 Sandwich panel With thermal bridging 6 concrete interior layer, 3 XPS, 3 outer concrete #3 steel ties use series parallel method Thermal bridging (continued) 24

25 Types of wall assemblies Cavity wall CMU Precast sandwich panel ICF Wood/steel framing Thermal Resistance of Concrete Standard concrete generally does not have good insulating properties when used alone Lightweight concrete has lower conductivity Autoclaved Aerated Concrete (AAC) In conjunction with other materials CMUs, cavity walls, precast sandwich panels, ICFs (insulating concrete forms) From concrete.org (PCA) 25

26 Thermal Mass High heat capacity + low thermal diffusivity = good thermal mass potential Heat capacity The property of a body to store heat Thermal diffusivity Slow transfer of heat 26

27 Concrete, masonry, brick Good heat capacity, relatively low thermal diffusivity + HIGH MASS Reduce temperature spikes Delay temperature effects to inside of building Reduced energy demand Effective with passive solar External source Internal source 27

28 Outside temperature Inside (low thermal mass) Inside (high thermal mass) Temperature lag 1 lag 2 6am 12pm 6pm 12am 6am day night 28

29 29

30 Thermal Mass in conjunction with passive solar Hot/Dry Climate High potential for energy savings Thermal mass in building envelope retards high flow in during the day and radiates heat back out during the night Use with good ventilation to exchange inside air at night with cool outside air Cold Climate Medium potential for energy savings Follow passive solar strategies: good envelope insulation Interior surfaces (walls/framing and floors) with thermal mass exposed to direct sunlight Hot/Humid Climate Lower overall potential for energy savings Good insulation and thermal mass in the envelope will level out temperature spikes outside and minimize the HVAC load inside 30

31 Trombe Wall Passive Solar & Ventilation Passive Solar 31

32 Social (Human Factors) Social (community, humanitarian issues, etc) Acoustics Aesthetics Daylighting Heat island effect (Air Quality) Sound quality in a room/concert hall Noise reduction Transmitted Acoustics Use high mass materials Reflected Absorbing, textured materials 32

33 Absorption coefficients of common building materials 1=complete absorption 0=complete reflection Daylighting 33

34 Aesthetics Cubic Houses, Rotterdam Library, Kansas City Solar Furnace, France Habitat 67, Montreal 34

35 Decorative Concrete Economic Life cycle cost Up front cost Maintenance cost Use cost 35