The Variation of Heat Loss Through Suspended Floors with Ventilation Rate.

Increases in the levels of thermal insulation required in the walls and roofs of houses in the U.K. in recent years have meant that heat losses through floors now assume greater significance, as a proportion of the total heat loss from a dwelling. To effect further reductions in the energy consumption of houses, the thermal performance of floors needs to be examined to assess the most cost effective insulation strategy. Suspended floors present a more difficult problem than solid floors because they require under-floor ventilation to prevent build-up of moisture, and variations in wind speed lead to changes in the ventilation rate and consequent heat loss'. To assess the thermal performance of a suspended floor, a full-size experimental room- was built and tested in an environmental chamber. The magnitude and direction of the airflow under the floor were found to vary substantially over its area, and there were corresponding variations in the effective U-value of the floor, related to the overall ventilation rate- and the relative position of the air inlet and outlet vents.