ASHRAE’s exterior lighting density table lists exterior spaces under two categories. Tradable surfaces are those where the average LPD of all those surfaces are within the total LPD limits. For example, in LZ4, both sales canopy lighting and stairway ligh

ASHRAE’s exterior lighting density table lists exterior spaces under two categories. Tradable surfaces are those where the average LPD of all those surfaces are within the total LPD limits. For example, in LZ4, both sales canopy lighting and stairway lighting have a maximum of 1.0 Watts/ft². The project may decide to increase sales canopy lighting to 1.1 Watts/ft² as long as the stairways compensate with a decreased LPD of 0.9 Watts/ft² (given that the surfaces are the same area) so that the average of the two is 1.0 Watts/ft². For non-tradable surfaces, such as bank ATMs, each space must individually comply with the ASHRAE requirements. Identify whether exterior surfaces are tradable in order to provide flexibility.