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EON Retrofit Test House: Airtightness and Ventilation Improvements

Solid-wall, ‘hard to heat, hard to treat’.


This case study is part of the CALEBRE project, 'Consumer Appealing Low Energy technologies for Building REtrofitting', which focused on solid wall 'hard to heat, hard to treat' properties.

The project considered a range of current, medium and longer-term technologies for domestic energy efficiency refurbishment, with the perspective of the householder at the heart of all thinking and decision making.


The Eon test house is a replica 1930's semi-detached dwelling, with an as built air permeability of 15.57 m³/h.m² @50 Pa. The building in its original state had single glazed windows, no insulation and no draught proofing.

Five levels of draught proofing were undertaken, with an airtightness test carried out after each stage.

In addition, a MVHR (mechanical ventilation with heat recovery) system was installed and insulation was applied to walls and the loft space.


The airtightness testing was carried out using the blower door technique and was carried out to industry standards.


After the five stages of draught proofing work was complete, the air tightness testing  achieved an air permeability of 4.74 m³/h.m² @50 Pa, a great improvement from the initial figure of 15.57.


This case study identified that draught proofing, though perceived as relatively simple was, in reality, proven to be quite challenging due to the care and attention required by those carrying out the work.

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