Before starting design, we needed to understand my existing bungalow. How is it currently performing in terms of energy efficiency? How draughty is it? Where is heat being lost? Are there specific parts of the building that should be targeted in the retrofit to make the building perform better?
We called in Diane Hubbard of Green Footsteps. Diane's a local expert in auditing buildings to understand their air tightness and - using thermal imaging - working out where heat is being lost.
Having heated my bungalow continuously for 24 hours, Diane turned up on a cold, clear day with a van full of equipment. She taped up obvious sources of ventilation (the fireplace, bathroom fan etc), installed a large fan in the doorway and depressurised the house. It was no surprise to see the carpets lifting as cold air flooded in from the unheated and uninsulated undercroft beneath the entire bungalow. More surprising (to me at least) were the significant drafts that whistled through the kitchen cupboards from the various holes in the external walls.
The thermal imaging was impressive. It revealed cold spots where the internal walls met the external walls, and showed that the cavity wall insulation installed in the 1980s was patchy at best.
Diane calculated the current air change rate per hour as 11.75. So a very long way from the EnerPHit target of 1.0 Air Changes per Hour (ACH) and the AECB Retrofit target of 2.0.
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