The Long Tail of the Heat Wave

Reading Time: 2 minutes
This morning it felt nice and cool so I spent as long as I could ventilating before the sun heated the Southern side of the building to a point where cooling was no longer effective. I went from 30°c down to 26°c very, very fast. The Outside Air Temperature (OAT) was 18-20°c so it’s a shame I didn’t capture more of that fresh air. The Long Tail of the heat wave comes as soon as you close the windows.

As soon as you close the windows the temperature climbs right back up to what it was before you blasted the apartment with fresh air. In a normal building, if you ventilate and get fresh air in, it cools down the building, and when you close windows and doors it sticks around.

With a minergie building, if you open windows for fresh air, when it’s cool outside then you get cool air into the building, but you face the impossible task of cooling the building itself because it was designed for cold winters, not warm summers. That’s why you face the Long Tail of the heat wave.

It might be comfortable and fresh outside, ideal for running, cycling and more, but it’s when you head home, to the oven, officially called Minergie, that you face the unpleasant radiant heat.

As I write this, it’s 23°c outdoors, and 29.5°c and rising where I am writing. The problem is that the balcony is a hot slab and reflector. In winter it amplifies and captures the heat, which is great in winter, but makes aeration much harder in summer.

We’re now in the heat inertia part of the heat wave, where the buildings in towns, cities, and villages are unable to get rid of their latent heat, thus keeping humans overheated.

The [heat wave itself might have killed 12,000 people across twelve countries](https://phys.org/news/2026-07-excess-deaths-europe-june.html) but with heat inertia we will see many more deaths, since it is impossible to cool modern buildings.

When the heat dome moves on, and freshness returns apartments won’t cool for days or weeks afterwards, but at least we are able to flee indoor heat for outdoor freshness. It also means that we can aerate for longer each day.

La Canicule Est Finie, Longue Vie à la Canicule

You’re familiar with the phrase. the king is dead, long live the king, except that I replaced king and canicule. The point is simple. The canicule is over, when the exterior temperatures drops but it lives on in apartments and various buildings that absorbed heat, but didn’t vent it. Now we’re in the long tail, hoping that enough heat is lost for buildings to feel fresher before the next heat wave hits.