ASHRAE 90.1-2001

Section: 9.3.1.1 - Building Area Method

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Building Area Method of Calculating Interior Lighting Power Allowance.

Use the following steps to determine the interior lighting power allowance by the building area method:

1. Determine the appropriate building area type from Table 9.3.1.1 and the allowed lighting power density (watts per unit area) from the building area method column. For building area types not listed, selection of a reasonably equivalent type shall be permitted.
2. Determine the gross lighted floor area (square feet) of the building area type.
3. Multiply the gross lighted floor areas of the building area type(s) times the lighting power density.
4. The interior lighting power allowance for the building is the sum of the lighting power allowances of all building area types. Trade-offs among building area types are permitted provided that the total installed interior lighting power does not exceed the interior lighting power allowance.