Energy efficient design of buildings:
ASHRAE/IESNA Standard 90.1

• ASHRAE/IESNA Standard 90.1 institutes power density limits for lighting (W/ft2).
• This standard is used as a basis for state energy codes, and many states have adopted several versions.
• Applies to:
• New construction
• Existing nonresidential and high-rise residential
• If > 50% of existing luminaires are replaced
• If renovation increases lighting power
• Total building wattage limitations
• Building area method: allows the designer to use a simple approach of multiplying the building square footage times the total lighting watts per square foot specified for that building type
• Space-by-space method: allows the designer to build a total lighting wattage budget by considering each space (application/task specific) within the building
• Building Area Method - 1999/2001
• Hospital - 1.6 W/ft2
• Library - 1.5 W/ft2
• Manufacturing - 2.2 W/ft2
• Museum - 1.6 W/ft2
• Office - 1.3 W/ft2
• Parking Garage - 0.3 W/ft2
• Retail - 1.9 W/ft2
• School - 1.5 W/ft2
• Building Area Method - 2004/2007
• Hospital - 1.2 W/ft2
• Library - 1.3 W/ft2
• Manufacturing - 1.3 W/ft2
• Museum - 1.1 W/ft2
• Office - 1.0 W/ft2
• Parking Garage - 0.3 W/ft2
• Retail - 1.5 W/ft2
• School - 1.2 W/ft2