Zero Energy Buildings


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These slides use concepts from my (Jeff Funk) course entitled analyzing hi-tech opportunities to look at how improvements are occurring in zero energy buildings. Improvements in the energy efficiency of appliances, in aerogels for insulation, in solar cells for electricity generation, and in passive solar design are helping us reduce energy usage. The goal is zero energy usage of external electricity and fossil fuels.

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Zero Energy Buildings

  1. 1. Zero Energy Buildings:Building a Sustainable FutureChen Jia, Shubham Duttagupta, Martin Heinrich, Ankit Khanna,Yeo Boon KheeMT 5009 Analyzing Hi-Technology OpportunitiesClass project
  2. 2. The definition of a Zero Energy Building 2010 US end-use emissions  Def: ZEBs generate equal or from fossil fuel combustion more energy than they consume annuallyEmission in Tg (CO2 eq. )  ZEB is a 3 fold concept:  Local use of green energy sources (our focus: BIPV)  Energy efficiency: passive design and efficient technologies  Optimal grid connections Adapted from: U.S. Greenhouse Gas Inventory Report (US Environmental Protection Agency), 2012
  3. 3. A qualitative look at ZEB costs ZEB’s advantage over the lifecycle Regular buildings ZEBs High construction cost offset Future ZEBs by low operating costs Construction cost ZEBs higher thanCumulative costs conventional buildings Conventional Lowering initial and operating cost by improvements in ZEB technologies Years (Cumulative cost = construction cost + operation costs)
  4. 4. ZEBs are energy efficientTechnologies and design to reduce energy usage  Reduction of energy demand is central to the ZEB concept  Energy efficiency is attained through:  High efficiency HVAC  Energy-efficient artificial lighting BCA Academy building, Singapore  Passive solar design  Maximizing day lighting
  5. 5. Photovoltaics: Technology and Integration
  6. 6. World cumulative PV installation Rapid growth in PV market, average annual growth rate of 40%Sources: International Energy Agency (IEA) 2008
  7. 7. Grid parity in Singaporea scenario under the assumption of net metering 0.40 +5%/a 0.35Electricity costs/prices in [S$/kWh] PV cost 0.30 0.25 0%/a Utility price -7%/a 0.20 0.15 -13%/a 0.10 0.05 0.00 2011 2012 2013 2014 2015 2016 2017 2018 2019 2020 Calendar year Source: Luther et. al., ICMAT, 2011
  8. 8. Market shares of PV technologies Other100% a-Si ClS80% CdTe Ribbon c-Si60%  Currently, silicon Multi c-Si dominates the PV market40%  Thin film materials (CIS, CdTe, etc.)20% growing slowly Mono c-Si 0% Source: S. Glunz, Fraunhofer ISE; Data Photon Magazine 2011
  9. 9. PV Technologies Thin film Dye-Sensitized Organic Best efficient in lab using different technology Source:Multi-Junction Solar Cells, ICMAT Yamaguchi 2011
  10. 10. Building Integrated Photovoltaics (BIPV)Concept, key aspects  PV materials replace conventional building materials  Integration  Addition to existing building (e.g. roof-top PV installation)  Replacing building envelopes (e.g. PV façade or window)  Aesthetically pleasing  Connecting to utility/grid
  11. 11. BIPV installationSplit by application (worldwide estimation) roofing facades transparent windows Source: Lux research, BIPV, 2010
  12. 12. Vertical scaling for ZEBsFaçade and window integration becomes more prominent  Modern ZEBs need to be several stories high  This would improve natural ventilation and allow more daylight  Trade-off: roof PV no longer sufficient for energy demand  Façade and window integration become more prominent An artistic impression of the Pearl River Tower in China
  13. 13. Learning curve of BIPVExperience for 20 yearsDrivers: Decrease in BIPV cost driven by reduced PV cost and increased efficiency Special BIPV feed-in-tariffs Architects and BIPV R&D Source: International Energy Agency, PV report, 2004 Source: K.Sopian et al , ISESCO Science and Technology Vision - Volume 1, 2005
  14. 14. The need for grid connected ZEBsPV electricity output varies with time Daytime surplus energy can be fed back to the grid Grid connections are necessary Daily electricity supply (PV) and demand, averaged over one year Source: Data from the BCA academy building, Singapore’s first ZEB
  15. 15. Energy efficient technologies for buildings
  16. 16. Energy consumption in Singapore By end-use Commercial sector Residential sector Others Air- Office Air- Washing 8% Equipment & conditioner conditioning 6% Others Kitchen 30% 52% 25% Appliance 6% Video Trans- Equipment portation 10% Fans 7% 4% Water VentilationLighting Heater Lighting Refrigerator 4% 12% 9% 10% 17% Major usage: 1. Air conditioning/ Refrigerator 2. LightingSource: Office Building Energy Saving Potential in Singapore, Cui Qi, 2006; E2 Singapore, NEA, 2010
  17. 17. Air-conditioning /RefrigeratorWorking principle Compressor Condenser 1. Compressor: Gas compression and heating 2. Condenser: Condensation of hot outside gas to liquid inside 3. Valve: sudden expansion of liquid => partly evaporation and cooling 4. Evaporator: Full evaporation of mist and cooling Evaporator Valve
  18. 18. Possible improvements for ACIdentified, selected technologies for AC with high potential Air conditioning Source: Energy Savings Potential and R&D Opportunities for Commercial Building HVAC Systems, U.S. Department of Energy 2011
  19. 19. Improvements for air-conditioningExample: Liquid desiccant  Singapore: Over cooling and reheating air to reduce humidity  Solution: Liquid desiccant (like silica gel, but liquid)  Liquid desiccant: High affinity for water, attracts moisture in conditioner  Regenerator heats liquid desiccant to release moisture Source: Energy Savings Potential and R&D Opportunities for Commercial Building HVAC Systems, U.S. Department of Energy 2011
  20. 20. Outlook AC efficiencyAC efficiency (Energy Efficiency Ratio, EER) projection Average efficiency of all AC unit for sale MEPS: minimum energy efficiency requirements, target set by Chinese government Source: Energy efficiency of air conditioners in developing countries …, OECD/IEA, 2007
  21. 21. Energy efficient lighting outlookCurrent and projected advances in lighting (section 8 by Prof. Funk) projection LED CFL Light bulb In summary: • Recent advances in CFLs Energy consumption of lighting will • Future advances in LEDs projected become less Source: Solid State Lighting, U.S. Department of Energy (2010)
  22. 22. Passive design
  23. 23. Thermal insulation Reducing overall HVAC usage  Insulation prevents heat transmission, therefore overall HVAC usage  Past 20 years: only incremental improvements in insulating material  Recently, aerogels explored as new insulatingInsulation prevents heat transmission into technologybuilding (summer) and from buildings (winter)  Aerogels consist of network of bubbles, with very thin cell walls
  24. 24. Aerogels cost and performanceCommercially available building insulation materials Insulating Material Thermal conductance Cost per ft3 (US$) [W/m²·K] Polystrene Foam 0.20 8.04 Rock Wool 0.36 1.64 Fiber Glass 0.32 1.63 Cellulose 0.29 1.81 Pure Silica Aerogel 0.05 2500 Clay Polymer Aerogel (Aeroclay) 0.05 8  Aerogels commercially available and used mainly in clothing and for scientific applications (because of higher costs)  New startup Aeroclay (2010) is commercializing cheap aerogels made of clay; scale up from R&D to manufacturing underway Source: Evacuated Panels Utilizing Clay-Polymer Aerogel Composites for Improved Housing Insulation, Dalton et. al., 2010
  25. 25. Aerogels cost and performanceImprovements in performance of building insulation materials  Thickness of insulation reduces while thermal conductivity falls Source: Vacuum promises a thinner future, A.Birch, 2009
  26. 26. Improvements in AerogelsUse of aerogels in many industries is driving improvements  Wide applications across various industries Source: J. Non-Crystalline Solids, Schmidt et al, 1998
  27. 27. Aerogels for Building InsulationPotential Aerogel usage for Window insulation Thermal Conductance, U value (W/m2K) Insulation glass unit: Clear AerogelThermal transmittance for different insulations types of windows Source: Aerogels Handbook, Springer, 2011
  28. 28. Maximizing day lightingUsing light ducts for lighting in offices Source: Solar Energy Vol. 73, No. 2, pp. 123–135, 2002)
  29. 29. Solar chimneySolar assisted stack ventilation Use of natural convection to supply fresh air:  Under PV panels on rooftop hot air accumulates  Hot air is rising in chimney (buoyance effect)  Rising air generates suction, removing old air in offices  New (fresh) air introduced from sidewalls Source: BCA academy building, Singapore’s first ZEB
  30. 30. ZEB: State of the art and outlook
  31. 31. Case Study: BCA Academy, SingaporeSingapore’s first ZEB (retrofitted to existing building) Insulation • Low-absorption glass (1,2,3) • Green walls/roofs 5 • Meets annual energy demand 4 3 BIPV • PV on roof, facade, (4,5,6) car park 1 7 • c-Si and thin film 2 6 • LEDs, motion sensors (6) Lighting • Light ducts, (7) reflecting panels (maximising day lighting)
  32. 32. PV, closer look Solar chimney Facade PV Roof PV Roof PV Thin film PV on car park shelter Source: BCA Academy ZEB website, virtual tour
  33. 33. Passive design, closer look Green Roof Insulation on glass Sun shades with PV Motion Green Walls sensors Light duct LED Reflecting panels Source: BCA Academy ZEB website, virtual tour
  34. 34. Case Study: BCA Academy, SingaporeEnergy production, consumption and cost saving (Oct 09 – Jan 12)Cumulative energy Typical office 879350 kWh consumption of similar layoutCumulative energy 424830 kWh consumption ZEB, BCA AcademyCumulative energy 454958 kWh production Cost saving due to energy efficiency S$ 118,410 Cost saving due to onsite energy generation S$ 112,237 Source: BCA Academy ZEB website, Energy Production and Consumption, 2012
  35. 35. Customer needsThe ZEB approach and drivers for improvement Economy Comfort • Approach: Upfront cost offset by • Approach: Energy efficient HVAC, low operating cost smart lighting etc • Drivers: Advances in energy • Drivers: reduction in cost, more generating/saving components widespread information ZEBs Functionality Aesthetics • Approach: Smart design • Approach: Alternative building • Drivers: Architectural expertise materials specific to ZEBs • Drivers: Architectural expertise specific to ZEBs
  36. 36. Market prediction for ZEBs Analysis of US construction market  Pike Research: ZEBs market $690 billion by 2020  Market share for:  Architecture, engineering and construction firms (“zero energy design”)  PV and other renewable energies  HVAC, lighting and others  Building materials Source: Pike Research Report on ZEBs, 2011 and Green outlook, McGraw-Hill Construction, 2011
  37. 37. Thank you for your attention