Thermal Mass

A material with a high thermal mass has a high capacity for absorbing and storing heat energy. Examples include concrete and bricks. By understanding that heat always migrates toward the cooler material, including air, thermal mass can be used to drastically increase the comfort of a home. Here are some examples from a cool temperate climate:

• In summer, ventilation with cool night air will draw heat out of the thermal mass to cool it down. During the day, as the air heats up, the thermal mass will then draw heat out of the air to cool the room.

• In winter, during the day, sunlight entering the home warms the thermal mass directly and heats the air, allowing the thermal mass to draw the heat in to warm it up. During the evening as the room cools down, the air will then draw warmth from the thermal mass and warm the room.

NOTE: Don’t make the mistake of interchanging thermal mass with insulation. A material with a high thermal mass needs to be able to absorb and expel heat by nature, so it’s not effective as an insulating product. This is why double brick homes in cool climates are notoriously freezing in winter, whereas an insulated reverse brick veneer home will be much more comfortable.

Where to find more

The information above is extracted from my book, 101 Things I Didn't Learn in Architecture School; And wish I'd known before my first job.

While the book is written for students and graduates of architecture, it is also an excellent handbook for anyone embarking on their own project. We provide a free copy with every on-site briefing and feasibility meeting, or you can purchase your own copy here.

Another great resource on basic principles in Australia is the YourHome.gov website which is free to access.