Too Hot to Ignore

Across Western Canada, extreme heat events are becoming more frequent and severe. For condominium boards, this creates a growing challenge: maintaining resident comfort and safety in buildings that were not designed for prolonged hot weather.

Many older residential buildings were constructed without air conditioning and with limited consideration for summer overheating. During heat waves, indoor temperatures can climb well beyond comfortable levels and, in some cases, exceed thresholds associated with health risks. Because residential buildings last for decades, and heat events are expected to increase further, it is increasingly important for condo corporations to consider overheating as part of their long‑term planning.

Cooling audits are emerging as a first step in addressing this challenge. They apply risk‑management principles to building thermal comfort, helping boards understand overheating risks and identify feasible responses within their financial and operational constraints. They are not a single standardized type of study, but rather a range of assessment approaches – from high level screening reviews to detailed modelling or monitoring – that can be scaled to a building’s needs, risks, and available budget.

As air temperatures rise, the human body’s ability to shed heat slows. At very high temperatures, especially during physical activity, the body must work harder to cool itself through sweating. Once indoor temperatures approach body temperature, passive heat loss becomes ineffective, and the risk of heat stress increases rapidly.

Buildings behave in a similar way. Heat is constantly generated inside homes from sunlight through windows, cooking, lighting, electronics, appliances, and even occupants themselves. Under mild outdoor conditions, this internal heat naturally escapes through walls, windows, and ventilation. During a heat wave, however, outdoor air is already hot. Instead of shedding heat, buildings begin to absorb it while internal heat gains continue. Put simply, overheating occurs when a building cannot effectively release the heat it generates.

In the case of prolonged heat waves, indoor temperatures will typically rise to match or exceed outdoor conditions unless there is some form of active cooling. Even buildings with cooling systems can experience overheating if they were not designed for the higher or prolonged temperatures that are becoming increasingly common.

In Alberta, rising summer temperatures and more frequent heat waves are no longer theoretical risks — they are already being experienced. The Pembina Institute’s Preparing Alberta’s Buildings for Severe Weather notes that owners should be preparing for increasing regularity of extreme heat events, wildfires, and smoke exposure related to climate change (among other hazards). The report notes that existing multi-unit residential buildings often lack resilience against these hazards and will require retrofits to protect their occupants.¹

As temperatures rise and heat waves become more frequent, the risk of sustained exposure to high in-suite temperatures also increases, putting occupant thermal safety at risk. Thermal safety refers to indoor temperature conditions where occupants will not

experience negative health impacts associated with elevated indoor temperatures. Recent guidance released by Metro Vancouver suggests thermal risks increase at sustained interior temperatures of 26°C and above, especially for vulnerable populations such as elderly or those with preexisting health conditions.² At a sustained interior temperature of 31°C, serious thermal safety risks are posed even to otherwise-healthy people. The Pembina Institute’s Healthy Buildings in a Changing Climate identifies over 12 health conditions and diseases exacerbated by extreme heat.3

Many of today’s residential buildings performed well under historical climate conditions. However, as outdoor temperatures rise, the same buildings are increasingly unable to release excess heat, leading to uncomfortable, and potentially unsafe, indoor conditions.

There is no single solution that works for every building. Adapting for heat waves could include one or a mix of different measures:

• Passive measures: Interventions that support thermal safety are inherently part of the building design such building insulation levels, windows, landscape design etc. Examples of passive measures could include providing shading over key areas of its façade, a roof that stays cool in the sun, windows which reduce solar heat gain, reflective blinds, and reduced indoor heat gain via efficient lighting or other electric loads.

• Active measures: Interventions that are typically engineered solutions that require energy to operate. Examples of active measures could include air conditioning equipment (serving resident suites, common areas, or both) or ventilation strategies.

• Monitoring measures: Interventions that allow for monitoring of thermal safety so that corrective actions can be taken as necessary. Examples include temperature sensors that enable an understanding of where and when any overheating occurs, or proactively coordinating a neighbour check-in program to be used during heat waves.

Appropriate measures for the building will depend on a variety of factors, including the goals for the building (e.g., improving comfort throughout the season vs increasing safety during heat waves), whether they align with the building’s existing capital plans (e.g., implementing low heat gain windows at the time that they are already being considered for replacement), and various other building-specific details (whether windows are conducive for shading, type of existing ventilation system, etc.).

Because the causes and effects of overheating can vary significantly between buildings, and even between facades of the same building, conducting a building-specific investigation is crucial to effectively manage the climate resilience of residential buildings with respect to overheating. Such an investigation can broadly be referred to as a cooling audit.

Cooling audits bear some similarities with other building specialist consultations such as energy audits or building condition assessments, but with a focus on thermal comfort and safety. An effective cooling audit will vary in depth and scale according to a building’s needs, and will be designed to help a condo corporation understand:

• When and where does overheating occur?
• What building systems or characteristics contribute to this overheating?
• Which areas or resident groups are most impacted?
• What options or interim measures are available?

A well-executed cooling audit may involve any of the following:

1. Temperature and comfort assessment: Understanding the building’s current thermal performance is a crucial first step. This may involve a review of any temperature readings currently being gathered, options to install temporary or permanent temperature sensors, and/or surveying residents or building operators.
2. Building envelope and shading review: The building envelope, windows, window blinds, glazing performance, and shading opportunities will be considered.
3. HVAC system evaluation: The building’s heating, ventilation, and any existing air conditioning systems will be assessed. Ventilation can play a crucial role in addressing mild overheating, and a misbehaving heating system may be a contributing factor to overheating.
4. Building energy modelling: Conducting detailed hourly modelling of a building takes significant effort but can provide detailed insight into areas of risk, scale of potential overheating, and the effectiveness or trade-offs of different retrofit measures.
5. Electrical infrastructure review: Assessing the building’s electrical capacity to assess whether or to what degree adding air conditioning is an option.
6. Retrofit or mitigation pathway development: One or more mitigation pathways should be prepared, developed to align with the building’s long-term capital plans, and outfitting with interim, low-cost, and investment-heavy measures that address the pathway’s thermal goals.

In many cases, useful insights can be obtained through relatively simple assessments, without requiring higher-effort methods like full-building modelling or long-term monitoring. These more comprehensive approaches can then be layered in where higher confidence or deeper analysis is needed, such as during conceptual design for a retrofit project or where a critical risk is already known to exist.

In addition to providing actionable insight into current overheating problems, a cooling audit can provide a platform for long-term planning on this issue. Most buildings standing today will still be operating in 2050, at which point there will be even further heightened heat, storm, and air quality risks. Cooling audits support this resilience planning in the following ways:

• Increase the clarity around thermal goal setting, including distinguishing comfort and safety considerations.
• Identify low-cost or interim measures that can be easily implemented.
• Provide clear and evidence-based information to be used in reserve fund management.
• Allow boards to communicate more proactively with residents about thermal risks, options, and next steps.
• Clarify the secondary impacts of potential measures, including changes in operating cost, air quality impacts, or liability exposure.
• While much of the governmental funding toward building retrofits is currently focused on climate mitigation (reducing energy use), it is plausible that funding will increasingly apply to climate resilience, and assessing the current landscape of any such funding opportunities is a valuable outcome of a cooling audit.

Despite the increasing relevance of residential building overheating in Alberta, uptake of cooling audits has been limited. This likely reflects a combination of technical challenges and factors affecting local demand.

More detailed cooling audits, particularly those involving extended monitoring or building energy modelling, can require significant time, cost, and technical effort. As a result, the level of rigour and confidence associated with a cooling audit will vary depending on the scope selected. At the same time, the lack of widely adopted methodologies means that approaches are still evolving. This makes it important to clearly align the scope of a cooling audit with the decisions it is intended to support.

Some jurisdictions in Canada, such as in British Columbia, appear to have greater demand for, and be further advanced in, addressing overheating risks. This is likely driven by a combination of more severe recent heat events, earlier policy attention, and a stronger integration of public health considerations into building performance.

Climate also plays a role. For example, Metro Vancouver’s mild conditions have historically limited the need for mechanical cooling, but when combined with higher humidity and less night-time cooling, can increase vulnerability during extreme heat events such as the 2021 heat dome. Alberta has likewise been understood as a heating-dominated climate. Prairie conditions are typically higher altitude and drier, which has reduced the perceived need for active cooling and made the building stock less exposed to overheating risks.

Given their difficulty in being correctly scoped and the relatively less thermally challenging climate, it is unsurprising that cooling audits remain a nascent field in Alberta. As the climate continues to change and heat events become more frequent and prolonged, however, the climate distinction is becoming less pronounced, and similar overheating challenges are already beginning to emerge in Alberta buildings. There is therefore an opportunity to build on lessons from jurisdictions such as British Columbia while developing approaches suited to Alberta’s building stock.

Cooling audits can provide a practical path for condo boards to pursue their obligations around resident comfort, safety, and asset stewardship. Key characteristics of a cooling audit include that they are:

• Customizable: These studies can be molded in scope and focus on meeting the goals of a particular building within the context of the board’s resources and existing state of planning.
• Transparent: By providing a data-based third-party analysis, the board can provide better rationale for the proposed measures, be they interim, small scale, or capital intensive.
• Forward-looking: Evaluating both the current and future state of overheating, and informing better reserve fund planning.

Buildings in Alberta are increasingly overheating due to climate conditions that they were not designed for. Recent research is increasingly making clear that overheating is both a pervasive comfort issue and a potentially serious safety concern. It will be increasingly important that condo boards assess the extent this issue affects their buildings, how it can be addressed in the short term, and how to effectively incorporate this issue into long-term capital and reserve fund planning. As summer temperatures rise and heat waves become more common, such proactive engagement with this issue will be invaluable. Cooling audits provide a clear, customizable first step forward.

Thomas Patrick is an Analyst, Building Performance and Sustainability, at WSP in Canada. Thomas’ experience and expertise are centered in energy audits, building energy modelling, performance analysis, and sustainability consulting – Thomas.Patrick@WSP.com

Joseph Der is a Team Lead, Building Performance and Sustainability, at WSP in Canada. Joseph has technical expertise in energy benchmarking, carbon analysis and investment planning for building portfolios – Joseph.Der@WSP.com

References:

• Rachel Sutton and Ceiliegh McAllister, Preparing Alberta’s Buildings for Severe Weather (Pembina Institute, March 2025), pembina.org
• Metro Vancouver, Thermal Safety in Existing Multi-Unit Residential Buildings: A Policy Toolkit for Local Governments in BC’s Lower Mainland (April 2025), metrovancouver.org.
• Betsy Agar and Raidin Blue, Healthy Buildings in a Changing Climate: Improving Health with Multi-Unit Residential Building Retrofits (Pembina Institute, July 2024), pembina.org