The UK’s exceptionally hot summer has pushed building overheating from a future concern into an immediate commercial property issue.
By the middle of July 2026, we had already experienced three official heatwaves. The Met Office also confirmed that temperatures of at least 35°C had been recorded in May, June and July for the first time in the UK weather record.
During the most intense spell, England set a provisional new June temperature record of 37.7°C. More than 150 weather stations also recorded their highest June maximum temperature.
But this isn’t just one unusually hot summer.
The latest Met Office data shows that the decade from 2016 to 2025 was 1.33°C warmer than the period from 1961 to 1990. In Greater London, the number of days above 30°C and nights above 18°C has more than quadrupled over the same comparison period.
For commercial property owners, heat resilience is becoming part of everyday building management.
Extreme heat is now a commercial property risk
Most UK commercial buildings were designed for a heating-dominated climate. Preventing heat loss in winter has therefore been a major priority for decades.
The problem is that highly insulated and airtight buildings can also retain unwanted heat. Large areas of glazing allow solar energy into the building, while lighting, equipment and occupants add even more heat throughout the working day.
The Chartered Institution of Building Services Engineers (CIBSE) warns that high indoor temperatures can affect comfort, health, wellbeing and productivity. It recommends assessing building performance throughout the year rather than concentrating on winter efficiency alone.
An Office for National Statistics model estimated that days reaching 28°C or above may have caused an average annual loss of £1.2 billion in economic output between 1998 and 2021. That figure allowed for adaptations such as ventilation and air conditioning. In 2020, the estimated loss reached £5.3 billion.
The ONS describes these figures as official statistics in development rather than observed losses, so they need to be treated with some caution. Even so, they give a sense of the potential economic cost of more frequent extreme heat.
The Health and Safety Executive has also reminded employers that heat is a workplace hazard (the UK doesn’t have a legal maximum workplace temperature, but employers still need to assess the risks and take reasonable steps to protect staff).
Why the facade matters during a heatwave
A commercial facade is the main interface between the building and the outdoor environment.
Its glazing, cladding, walls, joints, coatings, shading systems and ventilation openings influence how much solar energy enters the building or is absorbed by its exterior. They also affect how easily unwanted heat can be limited or removed.
New facade technologies are taking this further. As we explored in our article on new facade technologies for a sustainable future, dynamic shading, responsive facade systems and other climate-aware designs can help buildings react more effectively to changing temperatures.
RICS has also highlighted the role of external surfaces in the urban heat island effect. Dark materials tend to absorb more solar radiation and release it later as heat, raising temperatures around buildings and across dense urban areas.
A well-designed facade should be able to cope with normal seasonal changes. Prolonged periods of extreme heat, however, can place extra strain on older or poorly maintained systems and expose weaknesses that were already developing.
Heat doesn’t affect every part of a facade equally
Facade materials naturally expand and contract as their temperature changes.
Metal panels, glass, stone, concrete, fixings and sealants all respond differently. Facade systems therefore depend on correctly designed joints, flexible seals and suitable fixing arrangements to accommodate movement safely.
The Centre for Window and Cladding Technology notes that each side of a building can experience a different temperature range. Orientation, colour, exposure and nearby shading all influence how hot an individual elevation becomes.
That means a south- or west-facing facade can experience very different conditions from a shaded north-facing elevation.
The result is uneven stress across the building envelope. Joints and seals on the hottest elevations might be working much harder than those elsewhere, particularly if they’re already ageing or have been repaired using incompatible materials.
Impact of the sun on cooling expenditure
Glass facades bring natural light into commercial buildings and remain an important part of modern architecture. During a heatwave, however, poorly controlled solar gain can make overheating significantly worse.
The level of risk depends on several factors:
- The amount and orientation of glazing
- The solar-control performance of the glass
- The presence and condition of external shading
- The effectiveness of ventilation
- Heat generated by occupants, lighting and equipment
- The ability of mechanical systems to remove excess heat
Facilities managers often respond by increasing air-conditioning use. That may provide immediate relief, but it also raises energy consumption and operating costs.
CIBSE warns that a major increase in mechanical cooling could reverse some of the progress already made in reducing energy use across the built environment. Its guidance therefore prioritises passive measures like solar shading and natural ventilation wherever the building allows.
Hotter summers make facade contamination worse
Heat resilience isn’t only about what happens inside the building.
Commercial facades are exposed to traffic pollution, dust, organic growth and other contaminants throughout the year. During long periods of dry, sunny weather, these deposits can become increasingly stubborn on stone, glass, coated metal and other surfaces.
This follows the seasonal pattern we explored in Wetter Winters, Hotter Summers: Why UK Climate Shifts Are Accelerating Facade Damage.
Milder, wetter months encourage algae, moss and other biological growth. Hot, dry conditions then dehydrate that contamination and can harden deposits onto porous or textured materials.
Commercial maintenance plans now need to account for both sides of this cycle.
Planned facade cleaning and restoration can remove contamination, reveal defects that were previously hidden and protect existing materials before more extensive intervention becomes necessary.
Climate resilience involves more than emergency cooling
The UK Green Building Council’s Climate Resilience Roadmap identifies overheating as one of five major climate hazards facing the built environment, alongside flooding, drought, wildfires and storms.
Its modelling suggests that offices, schools, hospitals and homes are all becoming more exposed to these risks. The Climate Change Committee has reached a similarly direct conclusion: the UK was built for a climate that no longer exists.
A resilient commercial property plan therefore needs to consider both immediate heatwave measures and longer-term physical adaptation.
For the facade, that means looking closely at several areas.
- Assess every elevation on its own merits
Solar exposure changes according to orientation, surrounding buildings and local shading. A survey should consider the conditions faced by each elevation rather than treating the whole facade as one uniform system. - Review glazing and solar control
Building owners should check whether glazing, blinds, louvres, canopies and other shading systems are still performing as intended. External shading is usually more effective than internal blinds at stopping solar energy before it enters the building, although the right solution depends on the property. - Keep ventilation routes working
Windows, vents and louvres can’t support passive cooling if they’re damaged, obstructed or poorly maintained. Their operation should be included in routine facade and building-services inspections. - Schedule maintenance around extreme weather
Inspections after prolonged hot periods may reveal movement-related defects or coating deterioration. Cleaning and restoration work also needs to account for safe working temperatures, access restrictions and the effect of heat on operatives.
Where commercial facade restoration fits
Commercial facade restoration works best as part of a coordinated strategy involving facade specialists, building surveyors, engineers, facilities managers and building professionals.
Where the existing facade remains fundamentally sound, specialist cleaning and restoration can help keep its materials in service for longer.
This approach supports climate resilience while reducing the cost, disruption, waste and embodied carbon associated with premature replacement.
Nick Down, Director at See Brilliance, explains:
“Hot weather changes the pressures placed on a building and can expose existing weaknesses more quickly.
“Property owners should be looking closely at joints, sealants, coatings, glazing and ventilation components, particularly on elevations receiving the most direct sunlight. Planned inspection and restoration give them an opportunity to address deterioration before it becomes a larger and more expensive problem.
“Facade resilience is ultimately about getting more safe and effective life from the materials already on the building, while making sure the envelope remains suitable for the climate it now has to face.”
Planning for a hotter UK
The Met Office estimates that there’s now roughly a 50% chance of the UK recording 40°C again within the next 12 years.
Commercial property owners shouldn’t wait for the next record-breaking summer before asking how their buildings will cope. A sensible starting point is a review of facade condition to identify where routine maintenance is enough and where more substantial retrofit or design changes may be needed.
As hotter summers become more common, commercial facade maintenance will have a growing influence on occupant comfort, energy consumption, building performance and the long-term cost of keeping properties operational.
Is your commercial facade ready for hotter summers?
See Brilliance has more than 30 years of experience delivering commercial facade restoration, facade cleaning and restorative cleaning projects across the UK.
Our specialist operatives work with property owners, facilities managers, landlords, architects and contractors to restore and protect stone, glass, metal and modern cladding systems.
To discuss the condition of your building facade or arrange a site survey, contact us today.