Air tightness can be tested with a door blower fan to identify areas experiencing heat loss through leakage. A fan is put on the door and the house is pressurised and de-pressurised to 50kp to check for leakage. We have achieved good results by lining the inside of the roofs with 9mm OSB with the joints taped or a Vapour Control layer. Sealing around service pipes and windows/doors improves results. Chimneys can be stuffed with a bin bag filled with Rockwool or a special balloon.

A Thermal imaging camera identifies patterns of heat loss that are invisible to the naked eye. It is quite difficult to identify small air gaps using building air tightness testing alone. Air tightness testing and thermal imaging complement each other and their combined use quickly indicate air leaks within a property.

This Image shows a Dublin roof on a calm day

This image shows the same roof on a windy day. This clearly proves that we need to address Wind tightness in the next round of the building regulations. On windy nights the U-value is blown out of the insulation in most Irish roofs. Our calculations show that the U-value of this roof dropped from 0.25 to 0.65 when the wind started blowing which is every second day in Ireland. We usually line our roofs with Softboard to make them breathable and windthight.

Significant savings on annual heating bills can be realised by carrying out Airtightness work. Air infiltrates into and out of dwellings via many routes. The rate of infiltration depends upon the airtightness of the dwelling and the driving forces of wind and temperature. Excessive infiltration wastes heat and causes draughts, which can be a major source of discomfort. The ventilation required in a home is better provided by purpose-designed openings, over which occupants have some control, rather than by incidental leakage where there is no control. Full airtightening work should not be undertaken without providing controllable ventilation.