EPCs: Underfloor Insulation, and Solar Water Heating

RHemmings

Two questions about EPCs.

When listing the insulation and other factors that affect the energy efficiency of a house, most houses have suspended floors with no insulation (assumed). But, for the rating, they always seem to give that a 'N/A'. Why wouldn't that be a 'poor' or similar as it would be for loft insulation?

Also, when I see solar water heating listed as a potential improvement, the financial benefits appear very small. E.g. £4000-£6000 to install, but only £76 yearly saving. which means it will take 53 - 79 years to pay for itself. Why is the benefit so small? 

Netexporter

EPCs, in general, aren't worth the paper/pixels they're written on, IMO.

The main problem is that it is purely a visual inspection, so if they can't see they will either infer the construction from the building regs in force at the time of construction, for more modern houses, or will put N/A if there is no reasonable evidence.

However, if you are prepared to spend some money to create a really low energy home then a poor EPC can gift you a bargain, assuming you don't also need a mortgage.

RHemmings

Netexporter said:

EPCs, in general, aren't worth the paper/pixels they're written on, IMO.

The main problem is that it is purely a visual inspection, so if they can't see they will either infer the construction from the building regs in force at the time of construction, for more modern houses, or will put N/A if there is no reasonable evidence.

However, if you are prepared to spend some money to create a really low energy home then a poor EPC can gift you a bargain, assuming you don't also need a mortgage.

I do in the long term want to end up with an energy-efficient house. But, I need to buy one first. That's a very interesting point about an inaccurate EPC helping get me a bargain. Though, I must admit that I'm still biased towards houses with good EPCs. 

From some more searching, I found a more optimistic estimate of the benefits of solar water heating, here: https://energysavingtrust.org.uk/advice/solar-water-heating/ That estimates a £120 per year saving with solar water heating. Better than what I've seen even from 2023 EPCs. 

It still seems to me, possibly due to ignorance on my part, a better idea to fill unused roof space with solar (electricity) panels, however. Is there any reason why a mix of solar electricity and solar water heating would be better than simply ... more solar electricity? 

Netexporter

You'll be better off with all PV.

RHemmings

Netexporter said:

You'll be better off with all PV.

Thanks. That's what I was thinking. 

markin

Solar thermal is a waste of roof space, It heats the water very fast in summer then sits doing nothing all day and then is almost useless in winter.

Only useful for pool heating.

Netexporter

A "good" cause of a poor EPC is LPG central heating. Easily remedied with replacement by a heat pump. (Well not quite so easily in my case as it was a microbore system, but I'm putting in underfloor heating, instead, which will free up lots of wall-space. Mustn't grumble)

QrizB

RHemmings said:

When listing the insulation and other factors that affect the energy efficiency of a house, most houses have suspended floors with no insulation (assumed).

I'm no expert, but I would be quite surprised if most houses have suspended (ground) floors.

I would expect the vast majority of post-WWII house to have solid (ground) floors.

Netexporter

I would expect the vast majority of post-WWII house to have solid (ground) floors.

The tricky bit is working out if they also have insulation under the slab. They generally rely on the construction date/building regs in force, to determine that, in an EPC.

RHemmings

QrizB said:

I'm no expert, but I would be quite surprised if most houses have suspended (ground) floors.

I would expect the vast majority of post-WWII house to have solid (ground) floors.

I've only been looking at EPCs for houses that I'm interested in. In very specific areas and specific property types. And, I've seen a lot of suspended floors. I just looked at a random selection of houses in my city, and found about half were solid floors and half suspended. 

The rented house I live in has a suspended floor. If I owned the property I would have someone around insulating the damn thing tomorrow if I could. 

matt_drummer

I would prefer to look at the bills of the house and talk to the vendors about their heating habits.

It is a much better indication of how well the house works than an epc that is a bit of an unreliable guess.

Most of the items on the epc list you can check yourself.

But the real test is how much energy the house actually uses, not what some `surveyor' thinks it might use.