EFFECTIVE USE OF BUILDING MASS

Recent research by BRE under the DoE Construction Sponsorship Directorate's Energy-Related Environmental Issues (EnREI) Programme has clearly shown that the dominant factor in the successful design of low energy buildings is the minimisation or avoidance of air conditioning. That is not to say that it is not possible to design a very energy efficient air conditioned building; it simply reflects the fact that if, by judicial design, a naturally ventilated building can create a comfortable working environment, there will be a significant reduction in energy use compared to a solution based on active systems. The key to success in buildings that minimise or avoid air conditioning is the provision of acceptable summertime temperatures, i.e. the avoidance of uncomfortably high internal temperatures. Much is currently made of the value of utilising a building's fabric as a thermal buffer to reduce summertime temperature swings. However, the effects are often considered in a notional or ad hoc fashion because of the lack of authoritative design tools to ''measure'' or ''design in'' the impact of exposed building mass. This paper will address the use of building thermal mass. It will illustrate the potential (and the limitations) of simply exposing the building structure to the work space, and will consider two innovative alternatives to this conventional approach that offer significant potential for the future.