Another great benefit of using acid-stained concrete flooring in a home or business is the resulting energy savings. This is due to a basic property of concrete called “thermal mass”, which means concrete has a high capacity to absorb, store, and slowly release heat and coolness. This "thermal mass" property of concrete serves to moderate greatly the indoor temperature swings in rooms, reducing the load on heating, ventilating and air-conditioning equipment. The benefits of thermal mass are greatest in northern, Midwestern climates, like Michigan, Indiana, and Illinois, where outdoor temperature fluctuations are among the highest in the United States. The reason this property of concrete becomes so important is that floors are the second highest source of thermal mass in a building, accounting for approximately 35-50% of the total.
Energy savings from thermal mass, however, go unrealized if the concrete is covered, or unexposed. Carpeting, tile, and hardwood, for example, have very low degrees of thermal mass, and for the most part reflect and dissipate warm heat and cool air. Acid-stained concrete flooring, on the other hand, uses the full potential of thermal mass. Monetary savings for acid-stained, and other types of decorative concrete flooring, are estimated at between 15% and 26% annually, depending on the amount of concrete flooring used in a building. These savings can be even higher in states like Michigan, where customers in 2017 paid the highest monthly cost for natural gas in the nation - and Illinois, where customers paid the 5th highest cost (see WalletHub).
Two ways of enhancing these savings even more are to use radiant heating in a concrete floor or to use decorative concrete overlays on wood sub-floors. This is because radiant heating systems heat objects in a room, such as furniture and persons, by emitting heat rather than elevating air temperature; as a result, air temperatures may usually be set 7 or 8 degrees lower than normal. Dual radiant systems are also available that provide cooling in addition to heating.