Our question pertains to a residential highrise project. It has been observed by our energy modeler that no baseline exists either within ASHRAE or the local energy code for residential lighting power density. In fact, in ASHRAE 90.1 Section 9.1 "General", lighting within living units is explicitly not included (Exception b.). The 1.0 w/sf allowance under 9.3.1.1 is for common areas only. These comprise a small percentage of a typical residential highrise building. Similarly, our state (Oregon) Energy Code Section 1316.1 Exception 4 provides 1.2 w/sf for apartment buildings, which would be the applicable code for the common areas of the building, including mechanical rooms, stairs, lobbies, and hallways, but excludes living areas. Because the residential lighting will comprise a relatively significant component of the total energy load of a residential highrise project, we propose that a baseline must be established against which energy efficient design strategies can be measured and rewarded. We retained Benya Lighting Design (BLD), a nationally-recognized consultant, to propose a baseline for us. James Benya, BLD Principal, is a member of the ASHRAE 90.1 committee. BLD
NOTE: this credit ruling was amended on 3/29/05, regarding maximum W/sf. Assumptions used as a baseline for residential lighting will need to be supported by specific study results if you propose to include residential lighting savings in the energy performance calculations. These studies will need to address both light density AND daily duty cycle. The maximum allowable baseline for such residential lighting is restricted to 2 W/sf. Also note the following in response to details in your inquiry: (1) Although residential lighting density is higher than offices, the duty cycle of these lights is much lower than in offices. Some studies suggest figures near 2 hours a day or less for hard-wired residential fixtures. This reduces the significance of residential lighting in the energy model. (2) Baseline lighting assumptions should not include \'portable\' light fixtures, nor should the baseline calculations assume use of hard-wired fixtures in rooms where the studies cited indicate portable lights are the norm. Therefore applying a factor of 3 w/sf to the entire residential floor area, even though only three rooms would be anticipated to have hard-wired fixtures, would be inappropriate. (3) In residential units which are heating-load driven, there is an energy offset penalty of approximately 40% (according to numerous Pacific Northwest studies) for reductions to residential lighting load. That is, 4 of every 10 watts saved by reduced lighting loads must be made up for by increased heating energy. This offset must be accounted by your model. (4) Use of residential lighting energy savings to achieve LEED credit represents an exceptional calculation methodology outside of the LEED modeling protocol. As such it will be carefully scrutinized with respect to baseline and performance claims, and clear and concise documentation will be expected.