- Project plans
- Project activities
- Legislation and standards
- Industry context
- Specialist wikis
Last edited 01 Apr 2022
Active thermal mass in buildings
To help develop this article, click ‘Edit this article’ above.
The term ‘thermal mass’ describes the ability of a material to absorb, store and release heat energy. Thermal mass can be used to even out variations in internal and external conditions, absorbing heat as temperatures rise and releasing it as they fall. In building design, this can useful for evening out and delaying extremes in thermal conditions, stabilising the internal environment and so reducing or eliminating the demand for building services systems. It can be beneficial both during the summer and the winter.
Thermal mass is often considered to be a passive component of environmental design, with heat transfer between the internal air of the building interior and the thermal mass by ‘natural’ convection. However, it can be difficult to achieve close temperature control with passive thermal mass, and large quantities of thermal mass can be required.
The term ‘active thermal mass’ refers to the controlled absorption and release of heat energy from thermal mass. This active control can be used to maximise heat transfer between thermal mass and internal spaces and to better tune the absorption and release of heat to heating and cooling demands.
- Air-based systems operate by drawing ventilation air past the thermal mass at low velocity, to maximise the heat transfer with the air. This can be achieved by using the hollow core in pre-cast concrete slabs as a ventilation duct, or using the void created by raised floors as a supply plenum. Air-based systems can be used to regulate the temperature of the thermal mass during occupied periods and for night-time purging.
- Fluid-based systems typically pump water through pipes embedded in the floor slab (similar to underfloor heating piping) to moderate the temperature of the thermal mass. Water has a greater cooling potential than air, however, in this case, ventilation must be provided separately. The water temperature is generally maintained at above 14°C to avoid condensation, and it can also be used to provide heating in the winter.
Building management systems can be used to control active thermal mass systems based on internal and external temperatures, the temperature of the mass, the occupancy pattern of the building and any heating, ventilation and air conditioning (HVAC) systems.
 Related articles on Designing Buildings Wiki
Featured articles and news
Review and comment on the revised draft before July 11.
Write about something you know, help us build and grow !
A blended event and triumphant return.
Mark Reynolds succeeds Andy Mitchell as Co-Chair of CLC
Designing Buildings is 10 years old.
From alteration to deconstruction on DB.
Refurbishment for Net Zero.
Understanding temperature in buildings on DB.
A call for home energy management to be modernised.
How many different types can you think of ?
Looking back and fourth to what still needs to be done.
Targets, impacts and action from ECA member.
Pioneering Indian environmental design Architect.
The greenest building is the one already built.
History of Temple Meads rewritten.
Currently standing at just 1%.
Find out more with BSRIA.
A cricket pitch is 1 chain long whilst 80 chains is a mile.
What is your pledge ?
Changes come into force for F,L,O and S.
CIAT member reasons on why it matters.
Nine in ten civil engineers think so.
IHBC Annual School, 15-18 June.
A trusted clip with a long history, worth celebrating.
The new wave of green architectural features in context.
For built environment professionals.