As more and more is learned about energy conservation in buildings, one fact continues to stand out: Concrete and energy conservation go hand in hand. This article takes a look at some of the reasons why this is so. As an energy conserving material, the benefits of concrete are realized starting right at the production stage. Although cement is basically an energy intensive material, concrete is less energy intensive than most other construction materials based on production energy expended per unit weight of material. Concrete requires only about 3 percent as much production energy as steel or glass and only about 1 percent as much production energy as aluminum.
Concrete buildings use less energy in their day-to-day operation than buildings constructed of lighter weight materials. This is because of a phenomenon called thermal inertia, known more commonly as "mass effect." Basically, there is nothing profound about the way mass works. Concrete has the ability to absorb and store significant amounts of heat. Since heat stored in a concrete wall or roof is still within the building system, it is available to reenter the conditioned space. When this happens, heat that would otherwise be generated by heating equipment is supplied from storage, thus eliminating the need to pay for it again.
The absorbing and storing of heat benefits a concrete building in two ways. First, it reduces the peak heating and cooling loads in a building. This means that smaller heating and cooling units can be installed, resulting in a saving in first cost. It also means that operational savings will be increased because the smaller heating and cooling units will run at a level closer to capacity and therefore more efficiently. The second benefit results from the favorable effect mass has on annual heating and cooling loads.