CRAC March 4, Windows Update Regional Technical Forum March 4, 2003

CRAC March 4, Mission Assess methods to estimate savings –Deemed savings –Deemed calculation –Calculation protocols Establish baseline windows Consider market factors: practice, price, availability, programs

CRAC March 4, Savings Compared to What Savings should be relative to code –Oregon: <30% glass U54 SC57 >30% glass U37 SC35 –Washington:Elec: U40, SHCG40 Other: U90, U75, U60, U50 >25% –Seattle: Elec: U40, SHCG 40 Other: U55, U45>30% g SHGC40 –Common practice U50 SHGC45

CRAC March 4, What’s a Premium Window? Don’t have a premium standard Commercial window market is in flux Energy Star Specs: Maybe NBI Advanced Building Guidelines –Draft guidelines less than Oregon and Washington Code Difficult to optimize in the general case

CRAC March 4, Costs Street Prices (lacking good database) –Low-e coatings to U29 incr. Allows whole product ratings of: U35 for vinyl frame U40-U42 for metal frame –SHGC is $0 incr. –Better metal frames >$2.50/sf-glass incr. –Complete window $15-25 per sf glass

CRAC March 4, Cost-Effectiveness (electric) Based on ProCost runs with new draft marginal cost estimate and incremental cost of $1 per sf glass –Positive B/C ratio needs: 1.0 kWh/sf glass for cooling-only savings 1.5 kWh/sf glass for elec heat-only savings –Are these achievable?

CRAC March 4, It Depends ……. Heating savings are largest Range 0 to 6.0 kWh/sf glass Cooling savings are small and sometimes negative Range -0.7 to +1.0 kWh/sf glass Many variables drive energy flows

CRAC March 4, Simultaneous & Dynamic 68 F 10 F 74 F 110 F 50 F 85 F

CRAC March 4, Selected DOE-2 Results: Savings in kWh/sf-glass

CRAC March 4, Selected DOE-2 Results: Savings in kWh/sf-glass

CRAC March 4, Selected DOE-2 Results: Savings in kWh/sf-glass

CRAC March 4, Optimizing Glazing is Complex Many tradeoffs –PNW building types heating dominated (perimeter) –Lower U value reduces heating energy –Lower U value can increase cooling energy –Lower SHGC reduces cooling energy & peak –Lower SHGC increases heating energy –SHGC impacts are sensitive to orientation, geometry and external shading factors –SHGC can reduce cooling capacity requirements but often at the expense of energy savings Tradeoffs are sensitive to specifics And we haven’t considered day lighting

CRAC March 4, Selected DOE-2 Results: Savings in kWh/sf-glass

CRAC March 4, Electric Savings Depend on HVAC HVAC configuration –Fuel source –Set points –Heating sources for perimeter zones –Economizer –Fan logic –System type (SZ, VAV, DD, HR …) –Cooling system efficiency (DX, Chiller, part-load curves)

CRAC March 4, Next Steps Test confounding variables Window to Wall Ratio Internal Loads HVAC system types Economizer Identify key variables Build calculator External shading Set Points Building types Orientation

CRAC March 4, How big is the DOE-2 Run set? –Five building types –Three space heat fuels –Three cooling systems –Four ventilation systems –Six code baselines –Nine climate zones –Three window/wall ratios –Three external shading factors –Three windows 262,400

CRAC March 4, Hmmm…… Sounds daunting and expensive for a vaguely approximate estimate of savings from a measure that may not be very high volume

CRAC March 4, Other Options Protocol simulation models –Established protocols, input ranges –Requires confidence in modelers –Tools available –Can be calibrated to billing data Limit credit to fraction or multiple of incremental cost over code –Blue sox measure