The proposed “Energy Conservation Standards for New Federal Residential Buildings” are embodied in an interactive computer program which analyzes over 400 Energy Conservation Options (ECOs) for 9 housing types and 5 fuels across 1000 U.S. climate zones. The program uses Life-Cycle Cost (LCC) economic analyses in a two-step procedure to derive a result close to the “economic optimum”: (1) an initial Savings-to-Investment Ratio (SIR) ranking, followed by (2) a series of Net Benefit (NB) iterations. Consideration is given to the interaction between the set of envelope and the set of mechanical equipment ECOs.
The distinctive.feature of the LCC algorithm is that it simultaneously evaluates these two sets of ECO types, and in doing so it keeps active the entire list of energy conservation measures through-out the NB calculations. Envelope ECOs found to be ineffective at a certain combination of heating/cooling mechanical equipment efficiencies are re-examined every time equipment efficiencies change. In a new context of efficiencies, these envelope ECOs may become cost-effective. Similarly, envelope ECOs which were before cost-effective may lose this status. The same process applies to the LCC evaluation of equipment ECOs within a changing loads context.