Has the National Building Code Lost Its way?

The Canadian Board for Harmonized Construction Codes (CBHCC) released the 2025 National Model Codes on December 22, 2025, introducing significant regulatory updates amid a severe housing market downturn. Ontario’s preconstruction ground-oriented home sales have dropped 70% and multi-unit residential sales 90%, intensifying concerns that stricter regulations will further harm affordability and supply.

The National Model Codes, once adopted by provinces and territories, set minimum standards for health, safety, accessibility, building protection and environmental performance. The 2025 edition advances national harmonization, integrates forward-looking climatic data to prepare for future conditions and reduce construction-related emissions, and improves accessibility requirements. However, these priorities reflect the policy direction of former Prime Minister Justin Trudeau’s government, particularly the 2021 Ministerial Mandate Letter, which drove the introduction of a net-zero emissions building code aligned with national climate objectives.

With Prime Minister Mark Carney now pursuing a more moderate climate approach—such as cancelling the federal consumer carbon tax and pausing Canada’s Zero-Emission Vehicle mandate—the new code appears politically out of step. Although the National Building Code (NBC) does not directly regulate Ontario, the 2019 Reconciliation Agreement on Construction Codes commits provinces to harmonize with national codes within 18 months of publication, setting a summer 2027 deadline. This would require Ontario to update its Building Code (OBC) only two years after the latest version came into force in April 2025.

While the CBHCC describes the changes as consensus-based, they were directive-driven and lacked rigorous cost–benefit analysis, especially problematic during a housing affordability crisis.

Key 2025 updates include:

·         Mandatory passive vertical radon stacks in dwellings;

·         Expanded seismic bracing requirements;

·         Revised thermal performance standards for windows and doors;

·         Optional energy-use intensity compliance pathways;

·         Updated prescriptive paths and minimum point sums for higher energy performance tiers;

·         Operational greenhouse gas (GHG) emissions limits (performance and prescriptive);

·         Expanded accessibility requirements for all dwelling types;

·         Use of projected 50-year climate data in design.

The most transformative change is the introduction of operational GHG emissions as a compliance metric. Previously focused on energy efficiency and conservation, codes will now regulate emissions directly. The NBC provides provincial GHG emission factors for electricity and utility gas, meaning compliance stringency will vary by province depending on electricity generation emissions. For example, Quebec’s electricity factor is 0.38 g CO₂e/kWh, Ontario’s 57.90, and Alberta’s 181.86, while utility gas averages about 185 nationwide. In Ontario, this incentivizes electrification of heating and water systems or envelope upgrades to offset emissions.

Ontario’s current SB-12 standard sits between NBC Tier 2 and Tier 3. Given harmonization commitments, Ontario will likely align with Tier 3, whereas most other provinces mandate only Tier 1 to balance climate and affordability. However, Ontario builders have long experience with high-performance homes and are positioned to adapt. A modeled hybrid home—featuring a three-season air-source heat pump, improved energy recovery ventilator and higher-efficiency water heater—achieved 20% better energy conservation and 36% lower operational GHG emissions compared to baseline SB-12 Package A1.

While change is hard in any industry, especially one as complex as delivering new housing that consumers can afford, ultimately market force and sentiment will always prevail. Despite federal ambitions, homebuyers will decide whether enhanced environmental performance justifies higher costs. The CBHCC has identified housing supply and affordability as priorities for the 2030 NBC, offering cautious optimism for future reforms.