fan

Surface condensation and mould affect about 15% of the UK housing stock. This paper reports BRE work undertaken in occupied dwellings to identify the effectiveness of a range of remedial measures in various situations. The remedies investigated include the improvements to insulation levels, andheating systems, the provision of extract fans and dehumidifiers. The studies were undertaken in both flats and 2-storey houses, all of traditional construction with brick walls and pitched roofs.

This report examines three devices (exhaust fan, air-to-air heat exchanger and exhaust air heat recovery heat pump) which could be used to increase the ventilation rate of a tightly constructed house to a level sufficient to keep indoor air pollutants and moisture to acceptable concentrations.

The problems associated with the measurement of ventilation rates and air movement patterns in large single cell buildings which were unoccupied and unheated were investigated using the tracer gases nitrous oxide and sulphur hexafluoride. 

Describes a calibration technique to relate the air flow rate through a blower door to the fan speed and pressure difference across the door. To obtain an accurate and well-documented calibration of pressurization devices, a facility was designed and constructed at the US National Bureau of Standards. This accurately determines the flow rate through the fan as a function of fan speed, air density and pressure difference across the fan.

A major pathway for loss of conditioned air in east Tennessee homes with externally located HVAC systems is leakage in the ductwork. The effect on infiltration rates, as measured by Freon-12 tracer gas dilution, becomes marked if the central duct fan is operating. Duct fan on and duct fan off measurements of the rate of air exchange gave mean values of 0.41 and 0.78 ach respectively in a total of 31 homes.

Describes pressurization tests conducted by the National Testing Institute on 3 large industrial buildings. Sets out equipment and methods used including atracer gas method to calculate air flow through the fan rather than the usual measuring duct. Gives construction and volume details of buildings measured.

Outlines a method for measuring the air leakage through the surface exteriors of an apartment, by adjusting the pressure of the adjoining apartments to that of the test apartment, so that no air leakage occurs through adjoining walls.

Measures air infiltration and tightness of Swedish houses using the tracer gas technique and the fan pressurisation technique. Uses a previously developed model correlating air tightness and infiltration to evaluate the performance of Swedish homes. Shows that it is difficult to achieve the recommended minimum ventilation rate according to the Swedish Building Code by relying on natural air infiltration. Most new homes do, however meet the Code's stringent air tightness requirements. A comparison with American houses show that Swedish homes are very tight.

Describes detailed experimental analysis of the low energy Plainevaux House with regard to:< 1. Air infiltration, measured by the decay rate of CO2 tracer gas< 2. Air tightness, measured by the fan pressurization technique< 3. The evolution of inside temperature in a period of no-heating< 4. The corresponding air contamination.

This practice represents a standardized technique for measuring air leakage rates through a building envelope under controlled pressurization or evacuation, and is applicable to small temperature differentials and low-wind pressure conditions. It is primarily intended for use in one- story buildings.