How to Thermal Mass Concrete Floor

Pour concrete slabs so that they directly touch the ground to take advantage of the massive thermal mass of the earth beneath it. During the daytime the concrete acts as a heat sink, absorbing heat from the air and keeping internal temperatures cooler. At night when the air temperature is cooler the concrete releases some of the stored heat back into internal air, keeping the inside of the building warmer than the outside.

Place any internal concrete, such as stone walls, so that they are insulated from outside walls. The thermal mass of internal materials works best when it is insulated from transient outdoor temperatures.

Orient rooms so that they are facing south, west or east. Install large windows to capture sunlight during the day. This takes advantage of the ability of concrete to absorb the heat of the sun, store it and release it at night into the inside of the building.

Use ceramic, slate or vinyl tiles to increase the thermal mass of interior floors over a concrete slab. The use of carpet insulates a floor from thermal mass, which increases the average room temperature by several degrees. This is useful in winter, but requires more energy to cool during the summer. Use a tiled floor on which you lay extensive rugs during the winter to maximize the energy savings to be gained by effective use of thermal mass.

Use darker, textured materials for inner walls. A dark stone or brick interior wall supported by concrete has more thermal mass than a smooth surface.