What 1,200 retrofitted households told us about heat

The Build Better Eain retrofit kit is deliberately unglamorous: shading, cross-ventilation and a flood threshold, installed by builders who live on the same streets.

Across 1,200 households, peak indoor temperature fell by an average of 4.6°C. The largest gains came from shading on west-facing walls, cheaper than every other component in the kit.

Where results lagged, the cause was almost always blocked airflow from later informal extensions. The next revision of the kit addresses that directly.