Building Thermal Mass
Research group: professor Andy Woods
The Problem
Buildings account for nearly one third of global energy consumption and carbon emissions, with a large share used for heating and cooling. As cooling demand continues to rise, driven by factors such as more frequent heatwaves and expanding digital infrastructure, passive and low-energy solutions are becoming increasingly needed.
Work Needed
A promising yet underexplored approach is to better exploit the thermal mass, or inertia, of buildings to moderate indoor temperatures, particularly by quantifying the optimum level of thermal mass required in different buildings.
Our Work
We have been developing mathematical models, grounded in the fundamental theories of heat transfer and fluid dynamics, to quantify and explain the potential benefits of thermal mass across different climates.
Background
The main objective of building thermal design is to maintain occupant comfort while minimising heating and cooling energy consumption. This is becoming increasingly difficult in a sector that already accounts for roughly 30–40% of global energy use and associated carbon emissions. Cooling demand is expected to grow further as the climate warms, with additional loads arising from the rapid expansion of digital infrastructure such as data centres.
Our Work
A promising passive strategy is to exploit building thermal mass, defined as any material within the building envelope that experiences temperature variations and can therefore store and later release heat. When used effectively, thermal mass can shift part of the heating or cooling load away from peak hours and help reduce strain on the electricity grid.
During the day, when outdoor temperatures and solar gains are high, energy is stored within the mass. Because heat diffuses gradually through the material, the indoor temperature response is delayed, reducing and shifting peak conditions. As outdoor temperatures fall, the stored energy is progressively released, with a larger fraction rejected when the outside air is cooler, particularly at night. In summer, this behaviour can be enhanced through night-time ventilation to reduce daytime cooling demand. In colder periods, previously stored heat can also contribute to meeting heating needs.
We have been investigating how thermal mass, combined with strategies such as night cooling, can reduce building energy consumption. Physics-based models derived from first principles are being examined through numerical simulations and laboratory experiments to quantify performance and identify optimal design parameters.