ID#6009 made on
EAp2 - Minimum energy performance
LEED BD+C: New Construction
We are currently designing the lighting systems for a new laboratory facility for the State of Iowa, Department of General Services. We are concerned about the ability to comply with the lighting po...
We are currently designing the lighting systems for a new laboratory facility for the State of Iowa, Department of General Services. We are concerned about the ability to comply with the lighting power allowances under the 1999 edition of ASHRAE 90.1, which appears to be the more stringent than the 1989 edition. The 1999 edition does not have an overall classification for professional laboratories such as this one. Therefore,to calculate the total lighting power allowance, we must use the space-by-space method, which does provide a sub-category for laboratory rooms under "office" building types. To comply, the space-by-space method permits only 1.8 W/sf for the lighting in laboratory rooms. This may work in an office or school application, however, it seems insufficient for professional labs where 100+ footcandles must be maintained (and HID technology is inappropriate). To provide 100 footcandles in the labs on this project, a design approach using energy-efficient fixtures/ballasts with high-performance T8 or T5 lamps requires 2.15 W/sf, which exceeds the 1999 ASHRAE 90.1 power allowance by 0.35W/sf. Unlike the 1999 edition, the 1989 edition of ASHRAE 90.1 takes into account factors such as the ceiling height and methods of lighting control. This facility has high ceilings that are sloped to optimize day-lighting. The 1999 edition eliminated adjustments to the lighting power allowance based on ceiling height and lighting controls. In other words, a large investment is being made for this facility to include day-lighting controls, sloped ceilings to optimize day-lighting, multi-level switching, occupancy sensor controls, and EMS low-voltage sweep controls, but the 1999 edition does not take any of this into account when figuring the overall lighting power allowance. For these reasons, including the ambiguous building classification under the 1999 edition, we request that it be acceptable to base the LEED credit on the 1989 edition of ASHRAE 90.1 (in lieu of the 1999 edition). Thank you
The benchmark for this prerequisite cannot be changed through the CIR process. However, in the space-by-space calculation method for ASHRAE 90.1-99, the interior lighting power allowance is the sum of lighting power allowances of all spaces. Per ASHRAE 90.1-99 page 51, "trade-offs among spaces are permitted provided that the total installed interior lighting power does not exceed the interior lighting power allowance." Therefore extra lighting power density required in one space, such as the laboratory, can be offset by using lower lighting power density in another space. Applicable internationally.
Related Addenda (Corrections & Interpretations)