Case Study : Evidence and Thermal separation
This Is a lovely house that has been upgraded to be more efficient including an air source heat pump and solar panels internal wall insulation but scored a D63 and 1 tonne of Co2 emission due to a uncoupled conservatory, evidence of wall insulation and solar panels.
To have a thermally separated conservatory there needs to be an exterior quality door from the main house to the conservatory, this property has which is normally a common issue but a designer radiator has been installed running off the main heating system which makes the conservatory not thermally separated and a habitable room. This single radiator reduces the EPC sore by a huge 9 points. With it removed the property would be a C72.
Other than the EPC rating radiator is also a concern for the heat pump efficiency. This is a designer radiator which do not have a lot of heat output and not sufficient for heating a conservatory. Also, a concern as it’s a DIY install that it’s been balanced correctly and is not inadvertently increasing return flow temperatures to the heat pump affecting the whole system performance.
The EPC needs visual or documentary evidence of retro fitted insulation for it to be included. Documentary evidence if DIY then receipts of the material bought and pictures of the insulation part fitted, if a contractor fitted then a completion certificate or guarantee that states what and where insulation was fitted. Visual evidence can be obtained in some scenarios like the picture, where the home owner removed a plug socket to reveal the internal wall insulation.
Other solutions are installing small access doors in discrete locations that allows inspection.
In this case if there was evidence of the 100mm wall insulation it would again make a huge 9 point improvement to a B81
On an EPC solar panels can be added by two methods, Percentage of roof area or by panel details. Without paperwork this property is estimated at 25% roof coverage for a B81. With the MCS installation certificate which estimate will state 250 watt panels and aligns to common panels being fitting at the time and the inverter size of 4Kw. Adding the panel details instead of the roof % increases the score by 5 points to a B86 and 0.3 tonnes of Co2 per year.
What this case study shows that evidence is critical in having an accurate EPC and a small effort in finding paperwork or gaining photographic evidence made a 14 point difference which is huge. Also ensuring a conservatory is thermally isolated is key.
To improve this house more, I would recommend adding more loft insulation to 300mm from 125mm and gives a B88, then another 2Kw on the roof makes takes an A97 0.1 tonnes of Co2 as the house is fully electric it will benefit the most from self consumption in spring and autumn.
