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160   ENERGY CONSERVATION


                  allowances are determined room by room and task by task, with the area category
                  method used for other areas in the building.
                4 Performance approach. This method is applicable when the designer uses a CEC-
                  certified computer program to demonstrate that the proposed building’s energy
                  consumption, including lighting power, meets the energy budget. This approach
                  incorporates one of the three previous methods, which sets the appropriate allowed
                  lighting power density used in calculating the building’s custom energy budget. It
                  may only be used to model the performance of lighting systems that are covered
                  under the building permit application.
                5 Actual adjusted lighting power method. This method is based on the total design
                  wattage of lighting, less adjustments for any qualifying automatic lighting con-
                  trols, such as occupant-sensing devices or automatic daylight controls. The actual
                  adjusted lighting power must not exceed the allowed lighting power for the light-
                  ing system to comply.


                LIGHTING TRADEOFFS
                The intent of energy control measures is to essentially restrict the overall installed
                lighting power in the buildings, regardless of the compliance approach. Note that
                there is no general restriction regarding where or how general lighting power is used,
                which means that installed lighting could be greater in some areas and lower in oth-
                ers, provided that the total lighting energy wattage does not exceed the allowed light-
                ing power.
                  A second type of lighting tradeoff, which is also permitted under the standards, is a
                tradeoff of performance between the lighting system and the envelope or mechanical
                systems. Such a tradeoff can only be made when permit applications are sought for
                those systems filed under performance compliance where a building with an envelope
                or mechanical system has a more efficient performance than the prescriptive efficiency
                energy budget, in which case more lighting power may be allowed. Figure 6.11 is a
                residential energy use distribution.
                  When a lighting power allowance is calculated using the previously referenced per-
                formance approach, the allowance is treated as if it is determined using one of the
                other compliance methods. Note that no tradeoffs are allowed between indoor lighting
                and outdoor lighting or lighting located in non–air-conditioned spaces.



                MANDATORY MEASURES
                Mandatory measures are compliance notes that must be included in the building
                design and on the engineering or Title 24 forms stating whether compliance is of the
                prescriptive or performance method building occupancy type.
                  The main purpose of mandatory features is to set requirements for manufacturers of
                building products, who must certify the performance of their products to the CEC.
                However, it is the designer’s responsibility to specify products that meet these
                requirements.
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