| Airtightness FAQs |
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What is airtightness?Airtightness is the control of airflow in a building. In an airtight building air leaks do not occur at ceiling or wall junctions, plaster board joints, doors, windows, service entry points etc. Leaks create discomfort and heat is lost. The result is that the heating system has to operate at a greater capacity to compensate for the losses. Airtightness is absolutely essential in maximising the effectiveness of thermal insulation, ensuring vast savings over a lifetime.Why should air tightness be looked at in the context of HRV installation and operation?Air tightness is a measure of the flow of air in and out of a building. Improving air tightness in a dwelling can reduce air leakage - the uncontrolled flow of air through gaps and cracks in the fabric of a building. The target must be "build tight, ventilate right". This means that there should be no breaks or gaps in the envelope of the building fabric. There is complete control over the ventilation system within the building when using a HRV system. Having an airtight house does not mean there is insufficient air flow, it means that the air flow can be controlled.Where are the most common air leakage paths?
How should the airtightness of an existing house be approached?Air tightness testing highlights areas of heat loss. Infiltration of cold air from the outside should be minimised by reducing unintentional air paths as far as is practicable by (i) Fitting draught stripping in the frames of the openable elements of windows, doors and roof lights, etc. (ii) Sealing around loft hatches (iii) Ensuring that boxing for concealed services is sealed at floor and ceiling levels (iv) Sealing piped services where they penetrate or project into hollow constructions, cavities, or voids. (v) Sealing around underfloor ventilator grilles, gaps in and around suspended timber floors, extractor fans, etc. Open chimneys are a major source of air leakage. What level of airtightness should be achieved so that a HRV system will be beneficial?The revised Building Regulations will require that houses will need to achieve a result of below 10 m³/hr/m². We suggest that all buildings should attempt to meet the best practice of 3 m³/hr/m². With a level of 5 m³/hr/m² the HRV system will add to comfort levels and reduce heating costs. What is the best time to install an air tightness membrane if one is being installed?It is best installed after all trades have completed first fix and just before slabbing is done. This greatly reduces the possibility of it being damaged and should ensure that its integrity is not compromised. |
Brochure
The ProAir brochure outlines the principles of operation of Heat Recovery Ventilation (HRV) and why you should choose a ProAir system. It contains a guide to product selection.
To download it click here.