Energy Performance Certificate

Mon 11 Oct 2021, 12:46

Phil. If you haven't got it sorted I can do an EPC calculation for you. Reg

Fri 8 Oct 2021, 13:39 (last edited on Mon 11 Oct 2021, 14:32)

That is so Andrew. I have in fact used the RdSAP software when asked so by my clients. But I use 30-40 w/m2 depending on the level of insulation and age of the building - something I have used for the 500 plus heat pumps I have sold across GB.

Fri 8 Oct 2021, 11:59

Just picking up Hans's point about box ticking: he's right, in that the EPC is based on the RdSAP software which is now woefully out of date (2012, with minor tweaks in 2017 I think) and is at best a blunt instrument. (In our case the software didn't have our unusual type of boiler at all and the rating is notably worse than it ought to be.) 

None of that changes Phil's point, of course, that EPCs are a requirement for sale or rental.

Thu 7 Oct 2021, 16:59

I would echo the point about loft insulation, except that it is not limited to the depth of the joists. I have 300mm loft insulation and it's over double the joist depth. I have insulation 3 times the joist depth. You might think that having 300mm insulation would prevent the loft being used for storage, but it is possible to buy plastic legs which allow a raised storage platform to be built with 300mm insulation underneath. Also, it's not necessary to remove existing insulation to do this; a further 200mm could be laid over 100mm insulation.

Even if a loft has been boarded out for structural reasons (and some trussed roofs are built that way), insulation can be placed over the top of that. Insulation is cumulative. If somebody already has insulation up to the top of the rafters. However, when super-insulating lofts, ventilation of the space is extremely important or damp condensation can be a massive issue.

It's only something like an narrow aisle that people walk on where you cannot achieve 300mm depth unless some sort of raised walkway was built. However, as the energy saving is proportional to the area covered, if it's only 10% of loft space, then you still get 90% of the benefit (and going from 100mm to 300mm doesn't cut energy wastage by a factor of 3 - there are always diminishing returns).

Thu 7 Oct 2021, 15:24

Thank you Liz and Hans and Jo.

As I said, I think I've done all I can to improve the energy efficiency of my house. 

Cavity wall insulation in 2011. Loft spray foam of rafters in 2015. 

I have a 4K solar panel display and a storage battery and use my washing machine and dishwasher overnight to take advantage of this.

I pay £57 per month for electricity and £81 per month for gas. I'm with British Gas.

I'm not trying to be smug about this. I just think that, over time, people can make small steps towards better efficiency.

I still think it is worth getting an Energy Performance Certificate for any house sale in the future.

Wed 6 Oct 2021, 19:08

Liz raises a good point. Your total energy consumption per year is something your energy provider should give you. Subtract about 20% for lights, TV, computer, cooking and hot water. As an example if your total then comes to 15,000 kWh and if your house is 120m2, you will have 125 w/m2 and year. That's not bad and doing more might be a point of diminishing returns. The best investment is loft insulation, 300mm is recommended. That might be difficult to achieve as the joists are never that high. An alternative is Celotex on top of the joists and plywood on top. With Celotex you only need 150mm or so. But tape the joins! 

Wed 6 Oct 2021, 18:24

Phil - if you know how big your homes is in m2 and how much you spend on electricity a year you will have a reasonable point of comparison.

Wed 6 Oct 2021, 09:02

Hi we used an EPC company in chippy. Their number is 07799 266543

Tue 5 Oct 2021, 19:02

Shouldn't cost you much, but they are of questionable value. It's a box ticking exercise without much consideration to how the building actually performs. As an example the one we had when we bought our house said we had an oil boiler. When in fact we have a gas boiler. Should be an easy thing to get right.

Tue 5 Oct 2021, 17:03

I want to get an EPC for my house. I think I have done all the things I can possibly do to the property. I'm not thinking of selling at the moment but I understand that an EPC is required by agents when that time comes.

Looking at my search engine, there are literally hundreds of offers. Does anyone have a recommendation for a local provider?