The Step Code defines the energy performance targets of a building based on the climate zone (CZ) where the building is located in. The BC climate zones are defined by the average heating degree days (HDD) below 18° C. The BC Building Code states that the authority having jurisdiction (AHJ) can establish climatic values to define climate zones, typically based on information from Environment Canada, and building designers must consult the AHJ before making any assumptions about a building's climate zone. Note that in some locations, there may be several climate zones due to variations in elevation.

British Columbia climate zone map based on BC Building Code Appendix C climatic design data.