Measure Room Climate – and Include Air Quality

How to measure well

Place a thermometer with a hygrometer where you actually spend time: at your desk, in the bedroom, or in the living room. Do not measure directly beside a window, above a heat source, or in direct sunlight. Compare readings in the same place and under similar conditions – preferably immediately before and after an action instead of only three times at arbitrary moments.

Interpret temperature and relative humidity together. Relative humidity changes when air warms or cools, even if the amount of water vapour stays the same. If your device also shows dew point or absolute humidity, it can help you compare moisture trends more accurately.

What the readings show – and what they do not

A thermometer and hygrometer help assess heat and moisture, but they do not tell you whether a room has enough fresh air. In occupied rooms, a CO₂ monitor can additionally indicate when ventilation is too low for the number of people present. CO₂ does not represent every pollutant either: odours, smoke, cleaning products, and cooking emissions still matter.

One number therefore cannot prove that ventilation, shading, or an evaporation trick works. Compare several before-and-after readings and consider how the room is being used.

When to ventilate

Block direct sun early with external shutters, blinds, or awnings. Use cooler evening, night, and early-morning hours for longer cross-ventilation.

Do not postpone necessary air exchange simply because it is warmer outside. Briefly ventilate an occupied or airtight room when CO₂ is elevated, the air feels stale, humidity is high, or cooking, showering, odours, or infection risk call for fresh air. Keep mechanical ventilation running and use summer mode if available. During smoke, high ozone, or heavy traffic, choose a better time or the cleaner side of the building where possible.

During extreme heat

Measurements are decision aids, not a safety guarantee. Drink enough, reduce physical exertion, and move to a cooler place if the room remains stressful. Pay particular attention to older people and those with chronic illness or care needs. Confusion, fainting, severe weakness, or a very high body temperature require urgent medical help.