Overheating cities: why building regulations alone won’t fix the crisis

Overheating in homes is no longer a seasonal inconvenience - it’s a growing public health risk, especially in dense urban areas. The climate hazards we face should be treated as a national emergency, according to the UKGBC, following their recent report that found many homes, schools, care homes and hospitals are not prepared for the worsening impacts of climate change.

As designers, developers, and planners, we’re now facing a new reality: how to create homes that remain liveable in an increasingly hot, urbanised world.

Part O of the Building Regulations, introduced in 2021 to address the growing issue of overheating in new residential buildings, marked a welcome shift in UK policy. For the first time, overheating is recognised explicitly in building standards, with clear requirements around solar gain, ventilation strategies, and glazing thresholds. It’s a critical step forward - but only part of the solution.

Because here’s the truth: Part O tackles symptoms at the building scale - not the systemic causes at the city scale.
In our cities, we’re designing homes that comply with Part O, while placing them in neighbourhoods where:

• Green space is sparse
• Night-time temperatures don’t drop
• Glass-heavy facades dominate
• Cooling strategies default to mechanical systems

We’re regulating buildings but not designing climates.

And as climate change accelerates, this gap is widening.

At Civic, we’re approaching overheating not as a technical compliance issue, but as a strategic design challenge. One that intersects with urban form, social equity, biodiversity, and long-term health outcomes. For us, that means:

• Bringing overheating risk to the table at RIBA Stage 1 - not as a checkbox at Stage 4. Understanding thermal risks early allows us to specify high-performance glazing; light-coloured, high-albedo external finishes to reflect solar radiation, and thermal strategies, as well as integrating shading solutions into architecture from the start
• Integrating thermal comfort, ventilation potential, and solar analysis into our BIM processes early
• Working with landscape and sustainability consultants to deliver nature-based cooling, not just shading devices - such as sustainable urban drainage systems, blue-green walls and roofs, and parks and wetlands
• Designing buildings that are future-ready for heatwaves we haven’t yet seen - not just today’s weather patterns. Buildings don’t sit in isolation - they contribute to and can mitigate the urban heat island effect. Better design would include more green-blue infrastructure like treen canopies, planted courtyards and water features to cool spaces; the use of materials with low thermal mass for public realm to reduce heat retention overnight; and site layouts that allow for wind corridors to break up stagnant, humid air pockets

We’ve seen first-hand how urban heat risk is unequal. The most vulnerable - those in small, south-facing flats with little access to green space - are often the least able to act. It’s a design justice issue as much as an engineering one.

The industry needs to move from reactive compliance to proactive resilience.

That means local authorities embedding overheating strategy into spatial plans. Developers prioritising passive design, where factors such as orientation, shading and natural ventilation all work together, over quick wins. And all of us rethinking what “good design” really means in a warming world.