Natural ventilation: what our sensors measured over twelve months

For twelve months we installed 34 temperature, humidity and CO₂ sensors in three buildings: a compressed-earth-block villa, a double-skin office building, and — as a control — a glazed building with permanent air conditioning.

Finding 1: mass beats insulation

In a Sahelian climate, the comfort gap comes not from the wall's thermal resistance but from its mass. The 40 cm earth-block wall (low R, high mass) stayed consistently more comfortable than a lightweight insulated wall of the same R.

Finding 2: the night does all the work

In the naturally ventilated building, 78% of effective cooling happens between 10 pm and 6 am. In other words: a badly designed night-ventilation strategy cancels every effort made during the day.

Finding 3: perceived comfort beats calculated comfort

At equal temperature, occupants of the ventilated building report feeling more comfortable than those in the air-conditioned one. Air movement, even slight (0.3 m/s), changes everything. Adaptive comfort models predicted it; we measured it.

Limits

Three buildings is not a statistical sample. The raw data is available on request — we would rather it be discussed than believed.