Poorly insulated house- how to heat

ece9600

Hello

We have a grade II listed Tudor house, currently heated by oil. We're not on mains gas.

We are doing some refurbishment and will obviously insulate as much as possible. However, a lot of options (such as double glazing) aren't available due to the listing.

We've been thinking about switching to a greener form of heating but I'm not sure what the options are. Heat pumps seem to need excellent insulation.

I wondered whether anyone had any experience?

lohr500

Our Yorkshire farmhouse in parts dates back to the late 1700's. It isn't listed so we do have more flexibility than you, but it still has challenges when it comes to insulation. We are also on oil heating due to lack of access to mains gas and have a 30kw/102k btu external boiler.

I looked at Air Source Heat Pumps earlier this year and had an installation survey carried out by one potential supplier. The calculations suggested that virtually all our radiators would need upgrading and we would also need a three phase electricity supply to the property to power a twin heat pump solution. In addition our loft insulation needed upgrading. The lack of cavity walls meant that the only way to improve the wall insulation would have been to apply insulation material to the inside.
Even with the RHI heat pump grant, the maths didn't work out over the 7 year RHI grant time window.

In the end we took the decision to replace the existing 35 year old oil boiler with a much more efficient and cleaner burning modern oil boiler. At the same time we made some changes to the hot water/central heating system to make it more efficient. We now have thermostatic radiator valves in most rooms and the hot water and central heating boiler circuits are now individually controlled through motorised valves. Previously the hot water relied on thermal circulation only with no pump to heat the coil in the immersion tank and the central heating loop was not isolated. So when we wanted hot water only, the upstairs radiators warmed up due to thermal circulation around the central heating circuit. 

We also put more insulation in the loft spaces.

The old boiler had a theoretical efficiency of 70%, the new one 92%. Since changing the boiler and through careful monitoring of our oil consumption using an in line oil flow gauge I calculate we are using 30% less oil.

So whilst oil may not be the greenest form of heating, I do feel that by reducing our oil consumption and running an A rated lower emissions boiler, I am at least doing something to help the planet.

What make is your existing oil boiler and how old is it?

Reed_Richards

It's a complete myth that heat pumps need excellent insulation but:

1. The price of a heat pump is much more sensitive to its output capacity than the price of an oil boiler.  So if you need a big heat pump for your poorly-insulated home it will cost you quite a lot more.
2. If your EPC indicates that your house needs more loft or cavity wall insulation you cannot get the RHI payments (until you address what is recommended).

You could consider a hybrid boiler, which is a bit more green.  
 

FreeBear

Reed_Richards said: If your EPC indicates that your house needs more loft or cavity wall insulation you cannot get the RHI payments (until you address what is recommended).

A listed building is exempt from requiring an EPC.

Depending on the opinions & views of the Conservation Officer, he/she may well refuse consent for wall insulation or any other thermal improvements.

If installing GSHP with a slinky, before any ground works can be undertaken, there may well be a requirement to do an archeological survey - That could add £XXX to the bill. A ASHP  would likely require listed building consent for the external box of tricks.

Reed_Richards

FreeBear said:
A listed building is exempt from requiring an EPC.

But see https://www.ofgem.gov.uk/sites/default/files/docs/2017/11/drhi_faqs_about_epcs_v2_0_29_nov_2017.pdf

14. I have a Grade I or II listed building and my EPC assessor said I’m exempt from getting an EPC; do I need one to apply for the Domestic RHI?
Yes, you still need to get a domestic EPC to be eligible for the Domestic RHI, even if your property is exempt for other reasons listed by the Government in the ‘Buying or selling your home’ section. 

FreeBear

Reed_Richards said:

FreeBear said:
A listed building is exempt from requiring an EPC.

But see https://www.ofgem.gov.uk/sites/default/files/docs/2017/11/drhi_faqs_about_epcs_v2_0_29_nov_2017.pdf

14. I have a Grade I or II listed building and my EPC assessor said I’m exempt from getting an EPC; do I need one to apply for the Domestic RHI?
Yes, you still need to get a domestic EPC to be eligible for the Domestic RHI, even if your property is exempt for other reasons listed by the Government in the ‘Buying or selling your home’ section. 

OK. I stand corrected. However, any improvements recommended in an EPC would still need to run past a conservation officer before any work is undertaken.

ece9600

Thank you, everyone- really helpful. Things like cavity wall insulation aren't posiible, unfortunately, although we will be improving our loft insulation.

We do have an older boiler so it may be that simply updating that will be our best option.

FreeBear

ece9600 said: We do have an older boiler so it may be that simply updating that will be our best option.

If the boiler is old, quite likely the plumbing is too. It may pay to have zone valves fitted along with TRVs and a smarter control system.

I have a glorified "smart" thermostat that allows me to set different temperatures throughout the course of the day/week. It has saved a little on fuel (can't say for certain how much).

gm0

Another legacy retrofit solution option which has come along (been revived recently) is the insulated vacuum flask of hot rocks heat store.  Somewhat like the phase change solar DHW heat stores (SunAmp) but in this case a lot bigger.  Around ~85kWh worth.  Very hot "rocks" in the flask, extraction via 2 step heat exchangers to water at boiler temperature water distribution (i.e. legacy rads or whatever).  Takes an chunky electric feed (from grid mostly and any local PV or other generation) to charge it up over night but can timeshift when that happens to suit a time of day tariff.  There are heat losses to at least circa 10% level and there aren't many about yet to explore real world applicability.  Easy to fit though.  No rad changes - save a few k or meet listing requirements there. It looks like a retrofit, non-disruptive solution for this type of building where access to the boiler distribution circuits can be made and there is utility space to fit it and power to charge it.  Oil can stay in circuit alongside if you like just set the thermostat so it doesn't start until it needs to.  Same operating temperature.  Turns some Oil kWh into Electric kWh. 

Unfortunately the economics of this form of electric heating are very suspect in a world where we are not investing in excess cheap to consumer electricity sufficiently.  My fag packet early this year said circa ~10p unit to hold running costs vs oil - that before the recent oil spikes.  In any event Dropping ~10k on a gadget then 1.5x to 2x your running costs with no fallback is unattractive.  Need to do a lot better than that.  No RHI either or not yet anyway.  Fossil prices and electricity prices are volatile looking forward.  Even the time shifting of when the energy is consumed is unlikely (over ten years) to work out given car charger uptake and the propensity of government to fiddle and use electricity levies to subsidise the various industrial capacity building responses.  And muck about with electric (via dual fuel tariffage) as part of addressing what are gas issues). 

I'd be happier buying one of these if there was greater stability in the forward electricity pricing regimen and the availability of time of day tariffs. The same 3ph issues arise if you have such a huge house that you need more than one or wish to charge it quite quickly to make use of the time of day variation in unit prices.  Which you would want to do I think even if the local DNO would rather you didn't. It's still on my shortlist though but waiting for more *clarity* on green energy transition from the government