Friday, 12 February 2010

Air-tight test on new build in France

For the past twelve months I have been helping an English couple with building their new house in Brittany, France.

Introduction, liaising with the builder, site meetings, etc until today, the final day! Indeed the very last test was done this morning to find out who energy-efficient the house really is. The test - see photo - showed how air-tight the house is. It measures the uncontrolled air leakage.

The diagnostic tool is called a "blower door". A fan blows air out of the house to create a slight pressure difference between inside and outside. This pressure difference forces air through all holes and penetrations in the exterior envelope.

By simultaneously measuring the air flow through the fan and its effect on the air pressure in the house, the blower door system measures the air tightness of the entire building envelope. The tighter the building (e.g. fewer holes), the less air you need from the blower door fan to create a change in house pressure.

The result was exceeding expectations. In order to say the house is meeting the BBC (Batiment Basse Consommation) criteria the result of the test had to be less or equal to 0,6 m3/h.m2. It was 0.53.

On the ground floor we could not feel any infiltration through the front door or the windows. We could see the difference between air-tight sockets on the ground floor and 'normal' sockets on the first floor. The infiltration was greater upstairs. The TV sockets were the worse, real 'hair-dryers'!

The house is tightly sealed. Fresh air will only come through some vents and will circulate constantly thanks to the VMC (ventilation Méanique Controlée). This will prevent the air to become humid and stale.

The fact the house is air-tight will save the owners energy but will also provide a healthier environment. No more sneezing, coughing and head-ache during the winter months.

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