“1: Insulate. 2: Insulate a bit more.”
At the heart of their energy-saving strategy, they specified Celotex polyisocyanurate (PIR) insulation on the ground floors and external walls for high thermal performance. This gave U values of 0.1 on the ground floor and 0.12 on the 600mm-thick external stone walls once they’d been lined internally with another 165mm of PIR foam. The roof spaces — one warm, the other cold under a natural and beautiful Cotswold-stone roof — are similarly highly specified.
Impressive Energy-saving Features
Add in no-less than 63 square metres of PV panels — giving a whopping 9.8kW at peak load — and you can fully understand the scope of this dream for an idyllic rural hideaway. This array produced well over ten thousand kWh in the most recent year-to-date: that’s four times the buildings’ yearly requirement. And there’s more…
Part the master plan was to install a MVHR (mechanical ventilation heat-recovery system). Nothing too radical there, except that the benefits of MVHRs are usually associated with ultra-airtight new builds – not conversions. But that did mean that very high levels of air-tightness needed to be achieved; and there was certainly no room for trickle vents.
A remarkable A94 EPC Rating
As our energy assessor Dawn Munn explains: ‘Tim and Paul were set on including MVHR with other energy-saving measures. At the time of writing, the project is part complete, with one of the two barns being inhabited. The whole building looks set to achieve an A94 EPC rating’.
‘A key part of our role in this attainment has been advising on which MVHR model and specification would help the buildings pass their SAP assessment with flying colours. Although the dwelling didn’t need to achieve overall compliance because it’s an existing — and listed — building, it had to do so to meet the long-term demand that the owners had placed on reducing energy waste. Specifically, the MVHR system had to meet the minimum requirements of the Domestic Building Services Compliance Guide 2010 for specific fan power and heat recovery efficiency. The originally-proposed system, designed to comply with the 2006 regulations, didn’t achieve this.’
As Tim and Paul look forward to completing their build, they can be rightly proud of the inspiration they’ll give to others who thought that barn conversions could only aspire to mediocre EPC ratings.
And we’re pleased that our modest contribution has helped make their (and our) world a little better.