Thermal comfort: More than just temperature

Green renovation by Roy Nandram

Energy efficiency is only effective when you are comfortable. When you’re not, you’ll probably seek alternative means of heating and cooling: electric space heaters and cooling fans, for instance. And that just increases energy use.

According to Standard 55-2013 of The American Society of Heating, Refrigerating and Air Conditioning Engineers, “thermal comfort” is the state of mind that expresses a person’s satisfaction with the thermal environment – or in other words, whether a person is too hot or too cold.

Temperature and relative humidity are not the only important factors in maintaining optimal environmental conditions for comfort in your home. There are also our metabolic rates (activity level), the insulation factor of our clothing, the air velocity (including drafts) and particularly the radiant temperatures of our surrounding surfaces. On a cold day, rooms with large window(s) will generally feel colder while the temperature of the room remains normal.

Although thermal comfort affects us all year round, it seems to be most important to us in Canada during the winter, especially when it is extremely cold.

We often use strategies to cope with our thermal environment. For example, we often turn up the heat when we get a chill, without understanding why we aren’t comfortable.

The reason we feel cold in our homes during the winter is because of the radiant temperature of our surroundings. Thermal radiation occurs when heat radiates from a warm object. When there is a difference in temperature, heat will always move from the higher temperature to the lower temperature. So when we are sitting in front of our fireplace, we are comfortable and warm because our bodies are gaining the radiant heat that it is emitting.

The opposite effect occurs when we are sitting or standing near a window, which can feel much cooler than the air temperature near the fireplace because our warm bodies are radiating heat to the cooler window.

There are large variations, both physiological and psychological, from person to person. It’s difficult to satisfy everyone in the same space, because the environmental conditions required for comfort are not the same for everyone. My wife and I can never agree on a comfortable temperature setting. She is always too hot.

You can maximize thermal comfort during the winter by reducing heat loss from your home. Here are some short-term or immediate solutions: caulk any cracks around doors and windows; keep blinds closed when the sun is not out; consider purchasing thermal blinds for the winter.

Some long-term solutions that can help drastically reduce heat loss and save money are installing storm doors, adding extra insulation, upgrading to triple-glazed or ENERGY STAR windows. Our homes primarily lose heat through windows and exterior doors and air leakage.

Why doesn’t raising the temperature help?

There is a common misconception that raising the temperature of the home when the outdoor temperature drops will quickly do away with the cold feeling you have during the winter months. However, this couldn’t be further from the truth. Not only is it an immense waste of energy, but it can also become costly over time. There are a number of small ways you can feel warmer without raising the temperature.

Move furniture such as beds and sofas away from doors, windows and exterior walls. because these are the coldest areas of the home. Close the blinds or curtains at night and when it is really cold outside, and open when the sun is out (in order to decrease the radiating cooler air from the windows). Put on a sweater and try wearing slippers. This is an inexpensive way to stay warm.

Relative humidity has a direct impact on your comfort level. Ideal indoor relative humidity levels are 35 per cent at 21 degrees Celsius in the winter and 50 per cent at 24 degrees Celsius in the summer.

Levels below 25 per cent
are associated with:
• Increased discomfort and drying of the
mucous membranes and skin
• Increased static electricity.
High humidity levels
are associated with:
• Condensation within the building
structure and on interior or exterior surfaces
• Subsequent development of moulds nd fungi.

Roy Nandram is a LEED® Accredited Professional,
President of RND Construction and a Green Builder / Renovator
You can reach him at roy@rndconstruction.ca
To subscribe to Roy’s Email Newsletter, visit www.rnd construction.ca or send him an email

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