Modern residential building energy codes provide a component tradeoff mechanism by which builders can trade reductions in the efficiency of some building components in trade for corresponding improvement in other components. One common tradeoff approach is based on maintaining a building "UA value," which represents the building envelope's overall thermal conductance. The building UA is the sum of individual component UA values, each of which is calculated as the product of the component's U-factor and area.
Heat recovery ventilators (HRVs) save energy by recovering heat that would otherwise be exhausted as part of energy code-mandated mechanical ventilation systems. Residential HRVs can be life cycle cost effective depending on equipment/installation costs and the severity of the climate. This brief evaluates HRV cost effectiveness in the context of building energy codes to identify the climate zones in which a code might reasonably require residential HRVs.