Canada’s climate is changing, and the way buildings are designed must evolve in response. Structures built today are expected to perform for 50 to 100 years, during a period when temperature, precipitation, wind, and extreme weather patterns will continue to shift.
For the first time, Canada’s 2025 National Model Building Code (NBC) incorporates future climatic design values. These values reflect projected conditions such as heat, cold, wind, snow, and rainfall, rather than relying solely on historical observations. This represents a significant step toward ensuring that new and retrofitted buildings remain safe, functional, and resilient throughout their service life—particularly given the scale and longevity of Canada’s ongoing investment in buildings and housing infrastructure.
This article highlights updates made to climate design values in the NBC 2025 and also points readers to additional building-focused tools and resources on the site. It outlines what has been updated and how ClimateData.ca helps professionals apply this information in practice.
Canada is the first country to embed future climate projections directly into its National Building Code. This update reflects more than a decade of collaboration among Housing, Infrastructure and Communities Canada (HICC), Environment and Climate Change Canada (ECCC), the National Research Council (NRC), and other partners.
The update also supports the objectives of Canada’s National Adaptation Strategy, including a commitment to integrate climate resilience into major national codes. Parallel efforts include recent updates to the Canadian Highway Bridge Design Code and the Canadian Electrical Code.
Together, these changes provide a consistent foundation for incorporating climate-informed design values into buildings and infrastructure decisions in Canada.
Traditionally, building codes and performance models have relied on historical weather records. These datasets assume that past climate conditions are representative of the future.
However, climate stationarity is no longer a safe assumption – the planet is warming, and patterns of extreme heat, heavy precipitation, drought, and wildfire smoke are changing. What’s more, Canada is warming at roughly twice the global average, with even faster warming in northern regions.
These climatic trends have practical implications for buildings, including:
For long-lived buildings and infrastructure, designing solely for past conditions increases the risk of underperformance, higher operating costs, and reduced occupant comfort and safety.
Like previous NBC publications, climatic design data is presented in Table C-2 for more than 680 locations. These data include variables used throughout the Code, such as temperature, precipitation, wind, and snow. What has changed is how certain values are determined: NBC 2025 incorporates information from climate projections to inform where future conditions are expected to increase design demands.
Where warming is projected to intensify design-relevant conditions, the corresponding values are adjusted to reflect future climate conditions. Where projected changes would reduce design demands, current (historical) values are retained to ensure buildings remain robust under present-day conditions throughout their service life.
For example, July design temperatures are adjusted to reflect projected increases in summer heat. In contrast, values such as heating degree-days (a value that can be used to compute heating requirements during winter) and January design temperatures remain based on historical data, as buildings must still perform reliably under today’s cold-season conditions.
The 2025 NBC integrates climate design values that represent conditions along a pathway toward a global warming level (GWL) of 2.5°C. A GWL is a measure of global average temperature change relative to a reference period (a baseline). In Appendix C of the NBC, the baseline used for the supporting projection work is 1986–2016.
Appendix C also notes that projections were developed for other warming levels, spanning 0.5°C to 3.5°C (in 0.5°C steps) relative to the same baseline. These additional warming levels provide a consistent way to examine how climatic design conditions may differ under lower or higher levels of global warming.
To support practical use of NBC 2025 climatic design data, ClimateData.ca provides Future Building Design Value Summaries for locations across Canada. These summaries present design-relevant climate information in the same format as Table C-2, with brief technical notes and plain-language guidance.
The summaries are based on the same underlying foundation as the Code’s climatic design approach but make the information easier to access and apply in practice, helping address a common challenge: translating climate projections into design decisions in a way that feels clear and defensible. Users can quickly retrieve a location-based summary that brings together commonly used design variables – such as hot- and cold-day design temperatures, design snow loads, wind pressures, and rainfall variables.
A key added value is that the summaries provide results for additional global warming levels. While NBC 2025 uses a GWL of 2.5°C as its primary reference level, ClimateData.ca also presents comparable design-value information for 1.5°C and 3.0°C warming (relative to the 1986–2016 baseline).
Future Weather Files
Building performance simulation is used to assess energy use, thermal comfort, and mechanical system performance under expected operating conditions. These simulations rely on weather files to represent outdoor conditions over a typical year. In addition to historical files based on past observations, future weather files are also available for Canada through the Pacific Climate Impacts Consortium and the National Research Council of Canada (NRC).
ClimateData.ca provides guidance articles that explain what weather files are, describe the future weather file products available in Canada, and summarize how they are developed and intended to be used. Using future weather files, building designers evaluate how performance may shift under warmer conditions. For example, data on changes in cooling demand, overheating risk, and seasonal energy use can support more informed design and retrofit decisions.
Future Building Climate Zones
The National Energy Code of Canada for Buildings uses climate zones based on heating degree days to guide energy efficiency requirements.
Historically, these zones were developed using past climate conditions. To reflect ongoing warming, the Canadian Centre for Climate Services and partners have developed future climate zone maps based on climate projections.
These maps show broad shifts in climate zones across Canada, particularly in regions historically characterized by long, cold winters. In many areas, reduced heating demand and increased cooling demand are expected over time.
Future climate zones provide an important signal of changing baseline conditions and can support long-term planning for envelopes, mechanical systems, and energy strategies.
Building sector learning content
In addition to providing raw datasets and design values, ClimateData.ca hosts dedicated learning content for the building sector that supports the practical application of climate information.
The Building Sector Learning Content brings together sector-specific datasets, technical guidance, and real-world case studies that illustrate how climate data can be integrated into planning, design, and risk assessment processes.
This content addresses topics such as:
Case studies highlight how engineers, architects, planners, and asset managers are already using climate data to inform building projects across Canada. These examples provide practical insight into challenges, solutions, and lessons learned.
The integration of future climate design values into NBC 2025 represents a major step in aligning building practices with Canada’s changing climate.
By combining code-aligned summaries with a broader suite of climate datasets, ClimateData.ca supports both compliance and longer-term resilience planning. Building professionals can use these tools to reduce risk, improve performance, and enhance occupant safety and comfort over the full design service life of their projects.
This project was undertaken with the support of:
