Masonry absorbs heat, stores it, and then gradually releases it. Because masonry remains warm or cool long after the heat or air-conditioning has shut off, it reduces heating and cooling loads and therefore energy consumption.
A recent building energy simulation compared a high mass building (having high thermal mass, typical of masonry) with a low mass version of the same building in five cities across Canada.The results showed that 8-13% heating energy savings, as well as lower peak equipment loads, could be achieved by high mass construction. Because operating costs account for most building costs over the life cycle, the benefits of masonry go straight to the bottom line.
A computer simulation study compared equivalently sized and shaped masonry and timber-frame buildings (with a 30% higher insulation R-value). The overall seasonal heating loads for the heavy building were 12.3% less and the seasonal cooling loads were 17.4% less than the better-insulated frame comparator.
Thermal mass also can shift energy demand to off-peak periods when it costs less. As jurisdictions increasingly adopt off-peak pricing to reduce peak energy demand, masonry’s ability to shift energy demand to off-peak times will be of growing importance.