cooling and heating with thermal mass

Natural heating and cooling strategies based on high thermal mass walls have a very limited scope of application in cold climates or climates with low day/night differences of temperatures. Instead of using thermal mass in walls, using it in floors is often a better and cheaper strategy to get the benefits of... thermal mass strategies.

Cooling and Heating with High Thermal Mass

High thermal materials are materials capable of storing the heat during the sunny hours (preventing overheating), and of freeing it slowly, during the night, when temperatures are lower. These properties of some materials - cement, bricks or stone,for instance - can be used in suitable climates, for natural heating strategies.

To be both energy-efficient and comfortable, high thermal walls (double brick/masonry, brick veneer/weatherboard cladding, etc.) should be built with a proper combination of insulation (to slow heat flow) and thermal mass. And that's not easy to figure out. It depends on the exact zone climate and on engineering data.

Overhangs (and their length) and the amount of the glazing surface of the walls are also important elements in such cooling/heating strategies: too much glazing collides with energy-efficiency, due to thermal bridging during colder or hotter periods.

Concrete slabs and floors

Concrete is excellent in thermal mass cooling and heating strategies involving floors, due to its cheap price and the ease of implementation.

The image below shows how high-mass slabs can be used (in conjunction with overhangs and a proper sun-exposure) to get passive solar heating from winter sun…

Concrete floors and carpets

Ceramic tiles on a concrete slab floor and some other hard floor finishes will also increase the thermal mass of the floor and its ability to store heat, improving passive heating and cooling.

In the opposite side are materials like cork tiles, or even common carpets. Some types of flooring may diminish or alter the performance of high thermal mass materials...

Carpets over concrete slab floors will insulate the concrete from incoming heat, delaying its entry and slowing down its release. The result is a slightly temperature rise, which is good in winter and bad in summer.

Thermal mass and trombe walls

Trombe walls are another typical element of thermal mass strategies. Typically, a trombe wall is an high thermal mass masonry wall (8-16 inch-thick) developed to absorb heat in the sunny hours and to radiate it later into the house shell, heating the building when the heat is advantageous.

See: Trombe Walls