Our project team requests clarification of the applicability of ASHRAE 90.1-1999 section 9.3.1.2 Additional Interior Lighting Power (b) in determining the baseline space by space lighting power densities. In determining energy code compliance, the referenced section allows the values in Table 9.3.1.2 to be increased by up to 0.35 W/ft2 for those spaces where visual display terminals are the primary viewing task and fixtures are installed that meet the detailed luminance at angle criteria. Please confirm that for any space type where visual display terminals are the primary viewing task and the proposed fixtures meet the detailed luminance at angle criteria, the baseline lighting power density shall be the value from Table 9.3.1.2 plus an additional allowance of 0.35 W/ft2 from 9.3.1.2 Additional Interior Lighting Power (b), regardless of the proposed lighting power density.
Per ASHRAE 90.1-1999, section 9.3.1.2 Additional Interior Lighting Power (b), the budget lighting power density is the value from Table 9.3.1.2 plus 0.35 W/sf where visual display terminals are used. The additional 0.35 W/sf only applies to those areas with visual display terminals; spaces without the visual display terminals do not qualify for the additional wattage. The spaces with visual display terminals must also meet the maximum average luminance requirements of this section. Applicable Internationally.