What are ‘Climate Zones’ for buildings?
Climate zones refer to a spatial or regional classification system based on certain climate characteristics. Building professionals use climate zones to specify the thermal performance requirements for their design based on the amount of heating, or sometimes cooling, required. This approach enables the development of buildings that are suited to perform adequately given the thermal environmental loads of the region while complying with the energy efficiency requirements of the Building Code.
How are Building Climate Zones classified in Canada?
Building codes require compliance to energy codes and standards, such as the National Energy Code of Canada for Buildings (NECB), to provide minimum energy performance requirements. These performance requirements are keyed to Building Climate Zones. The NECB’s Building Climate Zones are determined using six Heating Degree-Day (HDD) categories, shown in Table 1.
The HDD is the cumulative number of degrees Celsius that a day’s average temperature is below 18°C during an entire year. For example, if the daily average temperature is -10°C, the heating degree-days for that day is equal to 28. However, if the daily average temperature is above 18°C, the HDD value for that day is zero. HDDs are then added for every day of the entire year and averaged over a multi-year period.
The HDD metric describes the average annual heating demand for a building in a specific location. Higher HDD, or a higher Climate Zone number, corresponds to a greater heating energy requirement, which means that a higher level of enclosure thermal performance is required. For example, Climate Zone 8 is the coldest zone, so Zone 8 buildings typically require more insulation compared to buildings in Zone 4, the warmest zone.