High Performance Building Design Strategies


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Tech Session 2 from the 2009 ASHRAE Region VI CRC in Des Moines, Iowa.
Presented by Paul Torcellini of NREL
May 8, 2009

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High Performance Building Design Strategies

  1. 1. Tech Session 2: High Performance Building Design Strategies ASHRAE Region VI CRC Paul A. Torcellini, Ph.D., PE May 8, 2009 www.highperformancebuildings.gov NREL is a national laboratory of the U.S. Department of Energy Office of Energy Efficiency and Renewable Energy operated by the Alliance for Sustainable Energy, LLC Procurement Creating the RFP Example: – Office Building – Datacenter – Library – Conference/Meeting Space – Fixed budget $64M (just building) – Design Build
  2. 2. Project Objectives 1. Mission Critical 2. Highly Desirable 3. If Possible Project Objectives 1. Mission Critical Safety LEED Platinum
  3. 3. Project Objectives 2. Highly Desirable 800 staff Capacity Flexible workspace 25kBTU/sf/year Support future technologies Architectural integrity “How to” manual Honor future staff needs Real-time PR” campaign Measurable ASHRAE 90.1 Secure collaboration with outsiders Support culture and amenities Building information modeling Expandable building Substantial Completion by 2010 Ergonomics Project Objectives 3. If Possible Net zero design approach Most energy efficient building in the world LEED Platinum Plus ASHRAE 90.1 + 50% Visual displays of current energy efficiency Support public tours National and global recognition and awards Support personnel turnover
  4. 4. Energy Consumption Goal 25,000 BTU/sqft – Includes everything, even the datacenter. Credit for additional space utilization Credit for additional datacenter capability (beyond the building) Penalty for using electric resistance Assumed condensing boilers and good chillers (to avoid calculation from our central plant) Methodology document done before RFP issued Substantiation Show that building as-built is consistent with energy models Will be shown at time of turn-over No commitment on the operation side—although we will monitor and understand actual performance
  5. 5. Risk and Reward (from the designer) Risk Design competition 50% of Phase 1 fee at risk Reward Energy performance requirement High profile project LEED Platinum requirement Design fees (within GMP) Guaranteed maximum price Award Incentive Fee Risk Management Design-Build partnership Share risks Ability to control decisions It is Really About the Details Combinations of lots of little things that cause buildings to use energy Conceptually, low-energy buildings can be done—fail on the details Difference between expectations and actual operation? National Renewable Energy Laboratory Innovation for Our Energy Future
  6. 6. Major Components Envelope Windows Lighting Systems (Including Daylighting) HVAC Systems Electrical Systems Plug Loads Photovoltaic Systems National Renewable Energy Laboratory Innovation for Our Energy Future Building Form Set the Energy Goals with the program of the building – Form will follow the function and the goals – Many times the form is really historical in context Typically want no more than 60 foot width Long East-West Access East and West windows a problem
  7. 7. Envelope • As building become low energy, the envelope becomes more important (percentage-wise) • Reduce the glass – Cannot engineer around it – Design for views and daylighting (more on that later) – Is low-e the answer (or high-performance glass) • Reduce Thermal Bridging – Detail books – Insulated panels – Spray foams – Ground losses Lighting Energy One of largest end uses – Up to 40% of total end uses One the top of the list for meeting energy savings – Inexpensive and offer rapid payback – Helps to reduce cooling loads
  8. 8. Lighting Systems • Separate daylighting fenestration from view glass • Design the daylighting system to provide enough, but not too much daylighting • Daylighting must be “superior” to electrical lighting – Provide lighting needs or 50% to 75% of occupied hours • Allow for reductions in A/C load because of overhangs and daylighting • Help design teams understand the integration of pieces • Get the controls right Toplighting Daylighting for top floor or single story North or South facing clerestories
  9. 9. Sidelighting Sidelighting with Toplighting
  10. 10. Tubular Daylighting Devices Daylighting Hints High ceiling heights – Greater than 10’ Eliminate direct beam penetration – Exterior shading – Light shelves – Diffusing films – Baffles High reflectance on ceiling surfaces Dimming controls High visible transmittance for daylighting fenestration – Greater than 60%
  11. 11. Daylighting Design Slight over design needed – Never as bright as predicted – Darker colors common issue – Occupant perception – Do not over glaze (especially lower windows) Screens on operable windows Frame areas Glass type—errors? Glare control NREL Pix 09226 Daylighting control Enable daylighting where ever possible – Default on some sensors is no daylighting Central controls easier to calibrate – Retrofit on some projects Minimize photocells Minimize occupancy sensors Manual control is not effective NREL PIX 05171 Overrides for special functions
  12. 12. Lighting Design Lower levels acceptable in most cases – Effective task lighting allowed lower ambient levels – Daylighting augmented spaces; allowed for lower levels at night – Circuiting NREL PIX 09217 Emergency Lighting Wall packs worked well for egress lighting—minimal parasitic load Integral battery ballasts are a parasitic “hog.” 24-hour lighting – can be large part of lighting loads – motion sensors – daylighting control NREL Pix 09229
  13. 13. LED Outdoor Area (Parking Lot) Lighting Why LEDs make sense for commercial parking lots – Save energy • Enhanced luminaire optical efficiency • Better total system efficacy (lumens per watt) • Control capability, e.g., dimming – Reduced maintenance costs – Improved uniformity Timing for common specifications – Retailer Energy Alliance working group established in April 2008 – Specifications completed in 2009 Metal Halide Parking Lot LED Parking Lot Average: 3.5 455W MH Average: 2.8 218W LED Maximum: 9.0 Maximum: 5.2 Minimum: 0.9 Minimum: 1.2 Max : Min: 10.0 Max : Min: 4.3
  14. 14. Lighting Design Put Lighting Power Densities on space plans by zone Set goals for LPDs 0.6 W/sqft for offices 0.8 W/sqft of retail Also look at kWh/sqft annually (or BTU/sqft) Watch lamp efficacy Spend the resources to do it correctly. HVAC Systems-Natural Ventilation Natural ventilation – Occupants don’t want to interact with building (somewhat different than residential)—should they? – Automatic windows worked well • Set-up issues • Interface with EMS • Open area (screens, window distance) • Hardware failures • May be better to use relief dampers Control strategies More limited than economizer
  15. 15. Energy Recovery Ventilators Balance air flows Design exhaust through ERV Allow for bypass (or no recovery option) – Don’t sacrifice economizer ability Oberlin analysis: effective below 60°F Integrated control logic 140,000 120,000 100,000 Energy Recovered (Btu/hr) Before filter change 80,000 After filter change 60,000 40,000 Energy Required To Operate ERV-2 20,000 0 10 20 30 40 50 60 70 80 90 Outdoor Temperature (ºF)
  16. 16. Ground Source Heat Pumps Watch backup mechanism – Electric boiler backup – Controls Well capacity Watch temperatures – verify loop capacity HVAC Look at system efficiency and not just components useful stuff divided by what you pay for More water, less air Separate ventilation air from heating and cooling Good zoning
  17. 17. Control Systems Mixed feelings: Only as smart as the operator Flexibility important to tune building Probably the biggest success factor Well thought out algorithms Demand management – Set points, setback, control to goals and comfort Staff to program – All systems from case studies were reprogrammed from original sequencing Controls Simple programmable T-stats Push button overrides Include plug loads on same system Keep it simple On-off control of lights or good diming control Manual on – Manual off – Auto off Controls can only make the design (and the related equipment) work to its potential
  18. 18. Plug Loads (Turn things OFF!) Night Plug Power Density (W/ft2) Day Plug Power Density (W/ft2) Annual Plug Load Energy Use Intensity (kBtu/ft2) National Renewable Energy Laboratory Innovation for Our Energy Future Minimize Plug Loads • Timers for all plug loads • Minimize water coolers • Energy Star equipment (computers/copiers, etc.) • Consolidated printing via network – Document processing equipment – Minimize (no?) fax machines National Renewable Energy Laboratory Innovation for Our Energy Future
  19. 19. PV Systems Work well for UPS systems Parasitic loads (isolation transformers) Roughly 1 kWh/watt installed capacity Inverter trips Inverter programming Techniques Daylighting—minimize the lighting load Efficient lighting (less than 0.7 W/sqft) – Minimize the type of lamps (T-8) – CFL’s are not a substitute for area lighting – Minimize decorative lighting – Wall pack egress lighting, no emergency ballasted fixtures More insulation (R-25 walls, R-40 ceilings, R-10 below grade, including slab) Appropriate amounts of glass Operable windows for natural ventilation Plug loads on timers Appropriate zoning of HVAC Hot water heating Should have minimal cooling load—target 1000 sqft/ton
  20. 20. Techniques Set specific/measurable goals early Use simulation to engineer the building Envelope to provide HVAC&L Use daylighting within (15-ish feet) of exterior surfaces Use standardized metrics for reporting Don’t delete economizers (especially with heatpump based systems) How to Achieve ZEB… Summary Envelope and Orientation to Reduce Loads • Well Insulated roofs, walls, floors, windows (with shading) Envelope and Orientation to Meet Loads • Daylighting • Passive Solar Heating, Trombe walls • Natural Ventilation Lighting design to match daylighting Plug loads • Design vs. owner loads Climate specific HVAC designed for the remaining loads Commissioning (making sure the building works) Metering and evaluation Make it Simple Site Specific Renewable generation within footprint, site, off-site Small amounts of RECs National Renewable Energy Laboratory Innovation for Our Energy Future
  21. 21. Questions? www.highperformancebuildings.gov National Renewable Energy Laboratory Innovation for Our Energy Future