John Faulkner knows all about high thermal mass

What is the main benefit of high thermal mass?
Introducing thermal mass into a building reduces energy consumption and reduces carbon emissions. For many buildings, introducing thermal mass along with night purging avoids the need for energy intensive air conditioning. Even for buildings which require air conditioning (due to high internal heat gains) the introduction of thermal mass can reduce energy loads.
What are the draw backs?
The client needs to understand that the building will operate over a greater range of temperatures. For short periods during the summer, the internal building temperatures may be at the upper end of what most people consider acceptable.

For thermal mass to be effective in controlling the internal environment the concrete soffit needs to be exposed as a daytime heat absorber (the heat is then purged away at night via night time ventilation) and this creates challenges on the acoustic side.

How effective can it be?
We have BMS graphs which show school classrooms holding temperatures at approx 26°C when the external ambient temperature is 32°C. This is without any form of air conditioning. A 6°C temperature difference between inside and outside is proof that the theoretical principles can be very effective when applied correctly.
What feedback have you had from Clients?
Some don’t particularly like the exposed concrete soffit to be honest. This can be screened by ceiling rafts to some extent, which helps. Other clients buy in to the whole sustainable approach and like the honest approach to the building and the services.

Information correct at date of publish: September 2010