Extension Sandford Road. Engineer: Antoin Conroy & Sheenagh Egan. Architect: Darmody Architecture. Photography: Enda Kavanagh

Did you know that concrete can store energy and that, later on, this energy is then released?

This effect, which is due to the high ‘thermal mass’ of concrete, makes buildings more energy efficient, lowers CO₂ emissions, and improves well-being and comfort. Thermal Mass is a word used to describe the ability of construction materials to store and release large quantities of thermal energy.  These materials are normally dense structural elements that form part of the building’s fabric.  Materials such as concrete and stone are particularly effective.

Thermal mass has two effects in a building. It moderates internal temperatures and it delays the time at which peak temperatures occur.  In effect, daytime temperatures in a heavyweight building, such as a concrete or masonry built building, will peak lower and later than in a lightweight building and temperatures will not drop as much over the course of the night. Behaving like a thermal flywheel, the walls and floors of a concrete building can store thermal energy during times of surplus and release it back to the building during times of scarcity.  By moderating internal temperatures, thermal mass can reduce the heating and cooling requirement of buildings, providing substantial energy savings while producing a comfortable living environment.

Thermal mass reduces winter heating requirements and in summer, it reduces the risk of overheating and the need for air-conditioning. The high level of thermal mass in concrete means that indoor temperatures remain stable irrespective of external fluctuations. As the energy use of buildings accounts for the largest part of their environmental impact, thermal mass in buildings offsets the impact resulting from the production of concrete itself.