Better evidence for better building codes

Background

Canada’s National Building Code (NBC) is developed by the Canadian Board for Harmonized Building Codes (CCHBC), and provides a framework that provinces, territories, and municipalities use to regulate local building design, construction, alteration, and demolition. The NBC includes technical requirements to ensure that buildings meet criteria for safety, occupant health, accessibility, fire and structural protection, and for environmental performance. Since 2010, the NBC has also included minimum energy performance requirements for all new homes and buildings.

Supported by Codes Canada and the National Research Council (NRC), CBHCC continues to update the building code’s energy provisions to support emerging policy objectives of Canadian governments, and to respond to changing expectations of code users. These priorities require code committees to develop new and innovative requirements that can decrease energy use and carbon emissions associated with new construction. But if they are not carefully designed, these same changes can bring unintended consequences, including increased construction costs.

To help mitigate these risks, CanmetENERGY Ottawa’s Housing & Building (H&B) Team launched the “Better Evidence for Better Building Codes” project in 2018. The objective of the project is to develop new data, new modelling tools and new insights into energy and emission requirements of Canadian building codes, and to apply this capacity in support of CBHCC’s efforts to improve Canada’s NBC.

Project Activities & Outputs

• New housing and buildings archetypes: H&B researchers have developed new archetypes for low-rise housing and commercial buildings. These archetypes contain examples of both contemporary new construction, as well as the existing stock. NRCan and NRC researchers use these archetypes to examine how prospective code changes could affect the cost of new construction and retrofit, as well as the energy and emissions reductions that might be achieved.
• New research into code design: In alignment with CBHCC’s policy priorities and in consultation with other code stakeholders, H&B staff undertake original research to examine how new code requirements could affect Canadian housing. This work includes reviewing international practices, devising new requirements for consideration in Canada’s NBC, and assessing the cost, energy and emissions impact on Canadian construction. H&B’s research efforts have explored stepped and tiered energy targets, operational and embodied greenhouse gas emission impacts, and new ways to measure energy use in housing.
• Support for CBHCC code committees: H&B staff participate in code committees and task groups, lending knowledge and data to help codes staff and committee volunteers design new code requirements, H&B staff also contribute analysis and insights to help committees anticipate how new requirements would affect housing and buildings, and to identify refinements to make them more effective.

Outcomes

H&B’s efforts directly supported new code requirements in the 2020 NBC, and changes expected in the 2025 NBC.

• H&B staff directly supported the design and impact analysis of the tiered energy requirements for low rise residential housing that currently appear in the code. These changes give local authorities a regulatory framework to move new housing towards net-zero energy performance.
• H&B staff conducted novel research examining operational and embodied carbon emissions outcomes from low rise housing when built to different energy tiers. This research demonstrated that the modest increase in embodied carbon emissions associated with meeting energy tier 4 or 5 is more than offset by operating emission reductions, especially in homes heated with natural gas. These findings guided CHBCC efforts to develop carbon emissions for the 2025 NBC.
• H&B staff designed new a code compliance pathway for low rise housing, based on energy intensity metrics (kWh/m²). Homes using this compliance pathway can demonstrate energy savings using more efficient architectural forms in combination with energy conservation measures. When adopted in 2025 these changes are expected to reduce the cost and effort required for attached and stacked homes to meet the highest energy tiers of the NBC.