high performance building design strategies

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

National Renewable Energy Laboratory Innovation for Our Energy Future

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?


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


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


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)


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


Questions?

www.highperformancebuildings.gov