EasierVentilation

The feeling of hot and cold – Humidex

Humidex –
The FEELING of being hot in the summer and cold in the winter.

We’ve all experienced the muggy summers day where it is 26 Deg C and yet it ‘feels’ much hotter. This ‘feeling’ is caused by the moisture in the air, not the actual temperature.

The very important words here is ‘how we feel’.

Why do we like 18 deg C in summer yet heat our home to 22 or 24 deg C in the winter, have you ever really thought about it?

To help us and them selves the Canadians have come up with a scale or chart and called it a Humidex chart. This is designed to show us the feeling of a temperature in different conditions (as the humidity changes) and why we ‘feel’ hot in the summer and helps explain why we ‘feel’ cold in the winter.

Generally we can’t ‘feel’ air but as the Humidity rises there is more moisture in the air which increases the ‘feel’ and the higher the temp and humidity the hotter it feels.

Look through the chart below, as an example take 28 Deg C when it is 50% humidity we feel about right, but as the humidity increases to say 90% (as often happens in Auckland) the feel of temperature increases to 33 Deg C

humidex-easierventilation

Click on the Humidex Chart to see a larger view

Now this is where it gets very interesting, as we now acknowledge moisture effects how a temperature ‘feels’ and we also know that water always ‘feels’ colder than air when they are at the same temperature, for example they may tell us the swimming pool is 20 Deg C but if ‘feels’ much colder.

So now we look at this chart in a different manner from 24 Deg C down it shows the ‘feeling’ temperature drops as the humidity increases, as an example 22 Deg C at 100% humidity we have a feeling of only 18 Deg C. Which when you want warmth it feels very cold. This chart also shows that by drying out the air, the temperature you feel is more correct and far more comfortable both in winter and summer.

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