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World Bank Working Paper
Box 2.1. Categories of Compliance Approaches for BEECs A true prescriptive compliance approach provides specific details about materials to be used. For example, for the insulation of the building envelope or the insulation of pipes and ducts for HVAC systems required R-values are specified. A compliance approach that specifies a rating for an assembly of materials is not really a true prescriptive compliance option, but a component performance compliance option. For the building envelope, a maximum U-factor for a wall or roof assembly or a maximum U-factor or solar heat gain coefficient (SHGC) for a fenestration product (window, door, skylight) are examples of such a compliance option. Designers and manufacturers develop an assembly of materials that comply with the BEEC criteria. The next step up in complexity is the partial subsystem performance compliance approach. This option addresses more than one component of a building subsystem. For example, the overall thermal transfer value (OTTV) considers the heat gain through the opaque building envelope components as well as the glazed components, but it does not allow tradeoffs between maximum heat loss and maximum heat gain, nor does it consider the effects of air leakage on maximum heat gain and maximum heat loss. A further step up in complexity is the multiple subsystem performance compliance approach. It addresses more than one building subsystem, but not the entire energy consumption of the building. For the building envelope and the mechanical system, there are multiple subsystem performance compliance options that specify maximum energy consumption for space heating and/or space cooling. In this case, the designer has the flexibility to make a trade-off between the building envelope and the mechanical system. For example, higher mechanical equipment efficiency can be used to offset an otherwise noncomplying building envelope with excessive heat loss and excessive heat gain from a large window area. At the top end of the complexity range are the total building performance approaches that include all of the energy consumption for the overall building. The criteria are usually specified in terms of total energy consumption or total energy cost. Within these total building performance options, there are usually some constraints on assumptions that can be made so that the approach is not abused. In the fixed budget approach, some BEECs specify performance using a fixed energy consumption value, such as kWh/m2. In this case, in order to be fair for all projects, the BEEC must also specify all of the key calculation assumptions such as hours of operation, internal loads from people and equipment, temperature setpoints for space heating and space cooling, and so on. The downside to this approach is that these fixed assumptions necessary for compliance calculations may not correspond with the proposed building. In the custom budget approach, some BEECs specify that the proposed building is to be compared with a baseline reference building that is similar to the proposed building but that complies with the prescriptive and component performance criteria. A points system is a more-simplified version of a total building performance option. In this option, the developer of the BEEC has calculated the relative energy benefits of a variety of energyefficiency measures. Each of these measures is included in the BEEC and is given a certain number of points. The designer must then show compliance with the BEEC by selecting enough energy-efficiency measures to achieve a certain minimum number of points. Source: Authors.
More comprehensive and more sophisticated BEECs can also provide better direction to manufacturers to think about the big picture for building components in addressing heat energy savings as well as cooling energy savings and lighting energy savings. For windows, for example, this involved