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in-ground portions of the walls of the conditioned basement. Equation 9 shall be used to make this adjustment.

Equation 9:


= [(CFAbsmt

× SLAbsmt

) + (CFAa-g× SLAa-g)] / [CFAtotal










= = = =

ELA (ft2)/CFA (ft2) SLAstd (where subscript ‘a-g’ indicates above-grade or exposed) SLAstd × (above-grade basement wall area)/(total basement wall area) 0.00057

For single-family houses, this can be calculated by zone, applying SLAbsmt to the basement zone and SLAstd to the above-grade zone of the Benchmark and treating the energy balances

separately for each zone. It can also be done by applying SLAoverall Benchmark is modeled as a single zone.

to the combined spaces if the

Additional air exchange due to whole-house mechanical ventilation shall be calculated assuming a balanced ventilation system with the same ventilation rate used for the Prototype, up to a maximum value consistent with the rate recommended by ASHRAE Standard 62.2. Whole- house mechanical ventilation air shall be added to the natural infiltration rate assuming no interactive effects and no heat recovery. Ventilation fan energy use for the Benchmark shall be calculated using a fan efficiency of 0.5 W/cfm, where it is assumed only one fan is present in each house or housing unit.

In addition to whole-house ventilation, the Benchmark shall include a kitchen range hood and a spot ventilation fan in each bathroom. The flow rates of each fan shall be the same as the Prototype, and the efficiency for each fan shall be 0.50 W/cfm. The kitchen range hood is assumed to operate 30 minutes per day, and each bathroom fan (including those in central restrooms) is assumed to operate 60 minutes per day. Interactive effects between these spot exhaust ventilation fans and natural infiltration shall be included in the analysis.

For multi-family common spaces, the air ventilation rates required for the Benchmark are combinations of values suggested by ASHRAE 62.1 and NREL’s Commercial Building Benchmark for 2009. Values to be used are shown in Table 15.

Table 15. Multi-Family Common Space Ventilation Rates

Area Outdoor Air Rate Room Type (cfm/ft2)

Central Laundry Office Indoor Corridors Workout Room

0.12 0.08 0.05 0.06

Electrical Equipment Room Multi-Purpose Room Central Restroom

0.06 0.06 50 cfm per urinal/water closet

Lighting Equipment and Usage

Annual hard-wired indoor lighting, in kilowatt-hours, represents approximately 80% of all indoor lighting and is expressed as a linear function of finished house area relative to a constant base value. Garage and exterior lighting are treated in a similar manner. When combined with


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