07/10/2026
A house can get hot when you have 8 rowers staying! Before installing air conditioning, should we be thinking more about the building itself?
In the height of summer we had eight rowers staying in a relatively small house, all training for Henley Women’s Regatta and Henley Royal Regatta.
Lots of people, lots of cooking, mostly pasta, and an old, largely uninsulated house that seemed to get hotter every day.
Unsurprisingly, everyone is asking for air conditioning.
We are already planning to improve the thermal performance of the house and replace the roof, so we also focus on how we design our homes not just to keep heat in during winter, but to keep heat out during summer.
One consideration is something called decrement delay.
Put simply, it is the time taken for heat affecting the outside of a wall or roof to influence conditions on the inside.
Think of the difference between a lightweight metal shed and an old stone house on a hot summer's day.
The shed heats up rapidly and its internal temperature can closely follow the conditions outside. The stone house behaves very differently. Its heavier construction can absorb and store heat, slowing its passage into the interior.
This is why U-values don't necessarily tell us everything we need to know about how a construction will perform in summer.
Not all house are built of stone, so when choosing insulation and designing a roof build-up, we should consider not only how much heat passes through it, but how quickly that heat travels through it.
If we can delay the effect of the afternoon sun until later in the day, when external temperatures are falling and ventilation can help release accumulated heat, we have a better chance of maintaining comfortable internal conditions.
Air conditioning may still have a role to play. But before reaching for mechanical cooling, we should be asking:
What can the building fabric do first?
For Simon Mack Architecture, that's becoming an increasingly important question when designing and renovating homes.
