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There is magic to the fabric: going all out with insulation

Posted by NEF Gabby on 13 September 2016 at 9:55 am

As summer fades into the distant past we all know that the cold months of the year will soon be upon us, but turning up the heating isn’t the only action you can take to keep warm at home this winter. In a recent interview with SuperHome owner Ian Mawditt, he told us how he took a fabric-first approach to improving home comfort and energy saving.

Getting cosy
It’s not new knowledge that insulation is a cost-effective and relatively simple way to upgrade any home. During the construction of an L-shaped extension to his home, Ian wanted to apply his building performance expertise to demonstrate the benefits of super- insulating a home.

Ian used a combination of internal and external wall insulation alongside the existing cavity wall, which was also insulated during the retrofit to eliminate existing thermal weak spots. Former cold bridges relating to the concrete gutters and original balcony were addressed by replacing them with thermal bridge-free structures, so warmth now has no choice but to stay indoors!

The added insulation delivered far superior U-values (measured in W/m2K) of between 0.1 and 0.17 for the walls, for the roofs of between 0.1 (loft) and 0.14 (extension flat roof), and 0.13 for the new floor. Note that the lower the U-value, the better a built form is at keeping warmth where it belongs – in your home. The new triple-glazed windows have a U-value of 0.9, compared with the original windows, which ranged from 2.4 to 3.2.

Photo: under refurbishment – showing the new external wall insulation shell.

Draughts are now a thing of the past as airtightness was improved by around 90% with the combination of insulation, air barriers and tape. By creating a super barrier to prevent heat loss, Ian says the work has dramatically reduced heat demand and draughts. The result is a more consistent comfortable feel all year round across the property, which means that during the cold winter months leaving the thermostat set at 19 degrees C turns out to be just fine.

Insulation measures alone have delivered an incredible 69% carbon saving, showing that there truly is magic to the fabric. But he didn’t stop there! Other investments included a mechanical ventilation heat recovery system to ensure good air quality without heat loss, and triple glazing for every window. The new windows which vary in shape and size do not only contribute to keeping the house warm in the winter and cool in the summer, have also, along with the new render insulated layer, added character to the original, utilitarian façade.

With an eye to what might be learned from the experience, Ian deployed a range of sensors and data loggers about the house, both before and after the build. Based on monitoring data, overall energy use in the house has been reduced by 73%, while the energy required for heating alone is down 90%. In the year before any works, the gas bill was £1200. In the first year after completion, gas costs for both space and water heating had plunged to just £225. Ian and his partner are very happy with the results.

Photo: The completed SuperHome in all its glory!

Ian does have an important lesson learned to share. He says he’d get the construction works covered by a waterproof ‘tent’ over scaffolding were he to do it all again. Moisture trapped will always find its way out and with non-breathable external wall insulation it can only have one eventual direction of travel – towards the interior. This has caused some extended drying out issues. Installation during dry weather, or at least better weather protection during the works, would have been a better choice.

Come and find out more!
Ian will be hosting a free open day at his Bristol home on Sat 17 Sep as part of SuperHome Open Days. A guided tour will allow you to quiz him and get honest and frank advice on what worked well and what didn’t. To receive full details including directions, register your place in advance at: www.superhomes.org.uk/190

Written by Matt Malcolm and Sam Tonge
 

More information about Insulation on YouGen.

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