On the use of the reference building approach in modern building energy codes

Abstract

For decarbonization of the building sector to happen at scale, net-zero energy levels of operational efficiency must be achieved. A global consensus is emerging around the Passive House energy performance level (15 kWh/m2/a thermal energy demand) as “net-zero energy ready”. Given the imperative to rapidly transform buildings and shortcomings of the traditional prescriptive approach, a growing number of building energy regulations are adopting the performance-based or outcome-based approach, seeking to mandate net-zero energy performance with ambitious timelines. Some such regulations are based on the Reference Building Approach (RBA) where the energy performance of a building is assessed based on a hypothetical building of the same design but meeting a set of minimum prescriptive requirements. More commonly, performance targets are defined in absolute terms, based on energy intensity metrics. Although the European version of the RBA reconciles the absolute and relative performance targets through mandatory statistical performance baselines, the RBA in North America is used as an independent alternative to absolute energy use/demand intensity metrics (kWh/m2/a). This paper examines the North American Reference Building Approach, focussing on its implementation in the British Columbia Energy Step Code as an instructive example. It is shown that the RBA has serious flaws. Most importantly, by creating a sliding scale, the RBA does not deliver net-zero energy performance, while incentivizing inefficient designs and poor energy modeling practices. Despite the regional focus of the data, the conclusions are applicable to the RBA in general. Based on the results, it is recommended that the use of the RBA in building energy codes and standards be discontinued.