Mechanical ventilation and fabric thermal storage.

Modern UK office buildings have a reputation of being energy profligate, largely due to the fan power requirements of commercial air conditioning. Most architects and HVAC designers only associate low-energy consumption with natural ventilation. However, the UK electricity utilities have peak maximum demands in winter, and buildings need to be designed for year-round lowenergy usage. Relatively few monitored studies of the total annual energy implications of natural and mechanical ventilation strategies operating in conjunction with fabric thermal storage have been published. This paper reviews independently published performance data of low-energy buildings and the impact of the various ventilation and fabric energy storage strategies now available. It demonstrates that low-energy mechanical ventilation systems incorporating efficient heat recovery and effective fabric energy storage have higher year-round comfort criteria, and significantly lower prime energy consumption, than natural ventilation strategies. Supplementary cooling and heating demands and consumption are shown to be minimal in such buildings for temperate maritime climates.