Why Our Buildings Are Not Ready for a Hotter Future

Overheating is already here 

One of the first questions Sue asked the audience was straightforward: 

"How many of you have experienced overheating in your home during summer heatwaves?" 

Nearly every hand went up. 

This is not a distant future problem. It is happening now. 

The data is clear. Climate scientists such as Ed Hawkins show that we are moving towards a significantly hotter future, with more extreme weather. Yet our homes, offices, and public buildings are largely designed around historic climate assumptions. 

In other words, we are designing buildings for a climate that no longer exists.  

A lesson from history 

Sue took the audience back to the late 19th and early 20th centuries, when ideas about climate and comfort were shaped by colonial thinking. 

European engineers and architects often tried to export their buildings and lifestyles to warmer parts of the world. When that failed, technology stepped in. 

Air conditioning was the breakthrough. 

The first modern electrical air conditioning system was developed by Willis Carrier in 1902, initially to solve humidity problems in a printing factory. Over time, it became the dominant way of controlling indoor comfort across the world. 

Air conditioning was revolutionary. It allowed buildings to maintain stable temperatures even in extreme climates. 

But it also had unintended consequences. 

Instead of designing buildings that worked with the climate, we started designing buildings that relied on machines to fight it.  

The comfort myth 

Much of modern building design relies on assumptions about what makes people comfortable indoors. 

These assumptions often come from engineering tools such as the psychrometric chart, developed in the early 20th century to understand temperature, humidity, and air conditions. 

These tools helped standardise building systems, particularly mechanical heating and cooling. 

But Sue highlighted a fascinating point. 

Humans cannot actually sense humidity directly. 

Our bodies detect temperature, airflow, and sweat evaporation. These signals are processed by our nervous system to regulate our core temperature, which must remain around 37°C. 

Humidity only becomes noticeable when it affects how sweat evaporates from our skin. 

This means many of the assumptions built into mechanical comfort standards may not reflect how people actually experience comfort in real life.  

The thermoneutral zone 

Another insight from physiology is the concept of the thermoneutral zone. This is the temperature range where the human body does not need to work hard to stay comfortable. No shivering, no sweating. 

Many engineers assume this sits around 20°C, which is why so many heating systems are designed around that figure. 

But research into human physiology suggests something surprising. 

For someone relaxed, lightly clothed, and in shade, the thermoneutral temperature is closer to 30°C. 

That sounds high to many people, but context does matter. Air movement, clothing, and activity levels all influence comfort. 

In everyday life, humans adapt constantly. We change clothes adding more on or taking off, opening windows, move to cooler spaces, or increase airflow. 

Our buildings, however, often do not allow for that same flexibility.  

The problem with mechanically conditioned buildings 

Many modern buildings rely heavily on mechanical systems to maintain fixed internal temperatures. 

This creates several problems: 

• High energy demand 

• Buildings that fail during power outages 

• Limited adaptability to changing climates 

• Indoor environments disconnected from natural conditions 

When buildings are sealed and dependent on air conditioning, occupants lose the ability to adapt naturally. As temperatures rise globally, this approach becomes increasingly risky.  

Learning to design with climate again 

One of Sue Roaf’s key messages is that we need to return to adaptive comfort. 

Instead of forcing buildings to maintain a single temperature year round, we should design buildings that allow people to adapt. 

This includes: 

• Natural ventilation 

• Shading and solar control 

• Thermal mass 

• Air movement 

• Seasonal flexibility 

In other words, buildings that work with human behaviour and local climate, rather than trying to override them.  

What this means for housing 

For those of us working in housing, this conversation is incredibly important. The homes we build today will still be standing in 50 or 100 years. 

If they cannot cope with heat, they risk becoming unhealthy and even dangerous. 

We already know that poor housing conditions can drive respiratory illness, cardiovascular stress, and poor wellbeing. Overheating is now becoming another major housing health issue. 

Creating healthy homes means thinking beyond insulation and heating efficiency. It means designing homes that are resilient in both winter and summer.  

A future we need to design for 

Professor Roaf described herself as feeling like an “ambassador from the future”. 

That may sound dramatic, but the reality is that the climate changes we are seeing now will continue to accelerate. 

The question is not whether buildings will need to change. The question is how quickly we adapt our thinking. 

For housing providers, planners, and policymakers, the challenge is clear. 

We must move beyond designing homes for yesterday’s climate and start creating homes that remain healthy, safe, and comfortable in the climate of tomorrow. 

Because when it comes to our homes, comfort is not a luxury. 

It is a foundation for health.