high performance building design strategies
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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
ASHRAE Region VI CRC
Paul A. Torcellini, Ph.D., PE
May 8, 2009
www.highperformancebuildings.gov
Tech Session 2: High Performance Building Design Strategies
Procurement
Creating the RFPExample:
– Office Building– Datacenter– Library– Conference/Meeting Space– Fixed budget $64M (just building)– Design Build
1. Mission Critical
Project Objectives
2. Highly Desirable
3. If Possible
Project Objectives
Safety
LEED Platinum
1. Mission Critical
Project Objectives
2. Highly Desirable800 staff Capacity
25kBTU/sf/year
Architectural integrity
Honor future staff needs
Measurable ASHRAE 90.1
Support culture and amenities
Expandable building
Ergonomics
Flexible workspace
Support future technologies
“How to” manual
Real-time PR” campaign
Secure collaboration with outsiders
Building information modeling
Substantial Completion by 2010
3. If PossibleNet 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
Project Objectives
Energy Consumption Goal
25,000 BTU/sqft– Includes everything, even the datacenter.
Credit for additional space utilizationCredit for additional datacenter capability (beyond the
building)Penalty for using electric resistanceAssumed 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-overNo commitment on the operation side—although we
will monitor and understand actual performance
Risk and Reward (from the designer)
RiskDesign competition50% of Phase 1 fee at riskEnergy performance requirementLEED Platinum requirementGuaranteed maximum price
RewardHigh profile projectDesign fees (within GMP)Award Incentive Fee
Risk ManagementDesign-Build partnershipShare risksAbility to control decisions
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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?
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Major Components
EnvelopeWindowsLighting Systems (Including Daylighting)HVAC Systems Electrical SystemsPlug LoadsPhotovoltaic Systems
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 widthLong East-West Access
East and West windows a problem
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
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 storyNorth or South facing clerestories
Sidelighting
Sidelighting with Toplighting
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 surfacesDimming controlsHigh visible transmittance for daylighting
fenestration– Greater than 60%
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
windowsFrame areasGlass 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 photocellsMinimize occupancy sensorsManual control is not effectiveOverrides for special functions
NREL PIX 05171
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
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 MHMaximum: 9.0Minimum: 0.9Max : Min: 10.0
Average: 2.8 218W LEDMaximum: 5.2Minimum: 1.2Max : Min: 4.3
Lighting Design
Put Lighting Power Densities on space plans by zoneSet goals for LPDs
0.6 W/sqft for offices0.8 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 strategiesMore limited than economizer
Energy Recovery Ventilators
Balance air flowsDesign exhaust through ERVAllow for bypass (or no recovery option)
– Don’t sacrifice economizer abilityOberlin analysis: effective below 60°FIntegrated control logic
0
20,000
40,000
60,000
80,000
100,000
120,000
140,000
10 20 30 40 50 60 70 80 90Outdoor Temperature (ºF)
Ener
gy R
ecov
ered
(Btu
/hr)
Before filter changeAfter filter change
Energy Required To Operate ERV-2
Ground Source Heat Pumps
Watch backup mechanism– Electric boiler backup– Controls
Well capacityWatch temperatures
– verify loop capacity
HVAC
Look at system efficiency and not just componentsuseful stuff divided by what you pay for
More water, less airSeparate ventilation air from heating and coolingGood zoning
Control Systems
Mixed feelings: Only as smart as the operatorFlexibility important to tune buildingProbably the biggest success factorWell thought out algorithmsDemand 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-statsPush button overridesInclude plug loads on same systemKeep it simpleOn-off control of lights or good diming controlManual on – Manual off – Auto off
Controls can only make the design (and the related equipment) work to its potential
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Plug Loads (Turn things OFF!)
Night Plug Power Density (W/ft2)D
ay P
lug
Pow
er D
ensi
ty (W
/ft2 )
Annual Plug Load Energy Use Intensity (kBtu/ft2)
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
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PV Systems
Work well for UPS systemsParasitic loads (isolation transformers)Roughly 1 kWh/watt installed capacityInverter tripsInverter programming
Techniques
Daylighting—minimize the lighting loadEfficient 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 glassOperable windows for natural ventilationPlug loads on timersAppropriate zoning of HVACHot water heatingShould have minimal cooling load—target 1000 sqft/ton
Techniques
Set specific/measurable goals earlyUse simulation to engineer the buildingEnvelope to provide HVAC&LUse daylighting within (15-ish feet) of exterior surfacesUse standardized metrics for reportingDon’t delete economizers (especially with heatpump
based systems)
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How to Achieve ZEB… SummaryEnvelope 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 daylightingPlug loads
• Design vs. owner loadsClimate specific HVAC designed for the remaining loadsCommissioning (making sure the building works)Metering and evaluationMake it Simple
Site Specific Renewable generation within footprint, site, off-site
Small amounts of RECs
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Questions?
www.highperformancebuildings.gov
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