The performance approach provides an alternative method to the prescriptive approach for establishing the allowed lighting power for the building.
Under the performance approach, the energy use of the building is modeled using a compliance software program approved by the Energy Commission. In this energy analysis, the standard lighting power density for the building is determined by the compliance software program based on occupancy type, in accordance with either the complete building, area category, or tailored rules described above. This standard lighting power density is used to determine the energy budget for the building.
When a lighting permit is sought under the performance approach, the applicant uses a proposed lighting power density to determine whether or not the building meets the energy budget. If it does, this proposed lighting power density is automatically translated into the allowed lighting power for the building (by multiplying by the area of the building).
If the building envelope or mechanical systems are included in the performance analysis (because they are part of the current permit application), then the performance approach allows energy trade-offs between systems that can let the allowed lighting power go higher than any other method. Alternatively, it allows lighting power to be traded away to other systems, which would result in a lower allowed lighting power. This flexibility in establishing allowed lighting power is one of the more attractive benefits of the performance approach.
General lighting power is the power used by installed electric lighting that provides a uniform level of illumination throughout an area, exclusive of any provision for special visual tasks or decorative effect, exclusive of daylighting, and also known as ambient lighting.
Trade-offs in general lighting power is allowed between spaces all using the Area Category Method, between spaces all using the Tailored Method and between spaces that use Area Category and Tailored Methods.
Also, with the Area Category Method and the Tailored Method, the Standards provide an additional lighting power allowance for special cases. Each of these lighting system cases is treated separately as “use-it-or-lose-it” lighting: the user receives no credit (standard design matches proposed), but there is a maximum power allowance for each item).
See the 2013 Nonresidential ACM Reference Manual for additional information.