ABSTRACT
A well-designed building will provide conditions close to the indoor comfort zone for most or all of the year even when it is free running. In high-thermal-mass buildings, the highest indoor temperature will occur in the early hours of the morning, many hours after the highest outdoor temperature has been reached. Heavy buildings are therefore said to have a slow response time. This is also known as the ‘thermal flywheel effect’, and it relates to the patterns of use of buildings. After a day of absorbing heat, from the sun and from internal sources such as people and equipment, it is necessary to flush it away with cooler night-time air. Nocturnal ventilation requires openings, and these need to be designed with security and weather in mind. A heavyweight construction can have exactly the same insulation value as a lightweight construction, but the heavy construction will have many times the thermal mass.
