Green Building Forum - What would you spend my budget on?

What would you spend my budget on?

Renovationnoob — Thu, 30 Nov 2023 20:45:51 +0000

Hi all!

As per the name, I am a beginner when it comes to renovations. We have bought a 200sq metre victorian house with brick (uninsulated) walls, uninsulated floors, and some loft insulation. Currently there are two (relatively new) gas boilers. All the windows are relatively new uPvc double glazing.

We have around 40k (excluding VAT) to spend on improvements from an energy efficiency point of view. We are willing to do what we can ourselves (i.e. fit insulation between the joists etc.

We are considering the following steps:

1. external wall insulation - the current finish is a pebbledash (painted white) - does anyone have any view on insulated render? I have seen (some) good things about Diathonite, Cork etc. but has anyone had any success with these approaches? If we go for traditional EWI it seems as though it will eat up 20k of the budget.

2. Insulation between joists

3. Top-up of loft insulation

4. Solar PV with batteries

5. Potentially replacing one boiler with an air source heat pump?

Any tips (on any of the above) welcome.

What would you spend my budget on?

Jeff B — Thu, 30 Nov 2023 22:45:26 +0000

Insulation and yet more insulation would be my first priority.

I daresay EWI has gone up in price since I last looked (it was about £80 per sq.m. pre-COVID) so £100 per sq.m. is probably par for the course now. IWI would be a lot cheaper and more DIY-able, but the work involved is substantial. I'm sure most of the posters on here will recommend EWI.

When you say insulation between the joists, I presume you mean the floor joists as you list your intention to top up the loft insulation as a separate item.

I would wait to see what effect the extra insulation has had before considering an ASHP.

What would you spend my budget on?

cjard — Thu, 30 Nov 2023 22:57:36 +0000

You forgot air tightness detailing and an MVHR

What would you spend my budget on?

djh — Fri, 01 Dec 2023 10:48:26 +0000

Why are there two boilers? And what power/type are they? How many people live there?

Topping up loft insulation is probably a no brainer. Just do it unless there's any reason not to. 270 mm is the government target, I believe. 400 mm seems more reasonable on here.

What would you spend my budget on?

Doubting_Thomas — Fri, 01 Dec 2023 11:44:34 +0000

I'd echo the advice to prioritise EWI if you can do it (so much more flexibility and long term robustness than IWI), but first perhaps consider using a small portion of your budget to fund a Whole House Retrofit plan.

There are various organisations out there who offer this (and will probably vary in quality), but there's an example here of the output, which includes a good comparison table at the end of all the options, their capital cost and their payback periods and carbon impact.

This will let you start to think about what things to do first and in what order to do the rest so that you don't end up wishing you'd laid certain pipes under a newly insulated floor, or putting in supports for new windows in the insulated line, even before the old ones come out etc.

https://superhomes.org.uk/winchester/wp-content/uploads/2022/03/Example-of-Whole-House-Retrofit-Plan.pdf

I also heartily recommend the LETI retrofit guide, which includes case studies (including detail sections) of retrofit measures to Victorian properties.

https://www.leti.uk/_files/ugd/252d09_c71428bafc3d42fbac34f9ad0cd6262b.pdf

What would you spend my budget on?

Nick Parsons — Fri, 01 Dec 2023 17:09:18 +0000

I have never used Diathonite but I get the impression from some users that you have to sit down a long time once you know the price (esp. for spraying, which seems to be the way to do it.

EWI would be my first choice. JeffB, I think you were v lucky to find £80 pre-covid. Lots of contractors 'talk' £100, but once enabling works are added in the costs shoot up.The last EWI I supervised in about 2018 or 2019 was about £160 incl enabling works and scaff, for 100mm gEPS.

Agree with the retrofit plan. Plan for the Whole, even if you do it in parts.

What would you spend my budget on?

Renovationnoob — Fri, 01 Dec 2023 20:46:32 +0000

Thanks all - really helpful!

The retrofit plan sounds like a good idea. Does anyone have any recommendations of providers? There are so many options online and I assume more than half are cowboys...! We are based on the Surrey/London border.

@djh

Posted By: djhWhy are there two boilers? And what power/type are they? How many people live there?

Topping up loft insulation is probably a no brainer. Just do it unless there's any reason not to. 270 mm is the government target, I believe. 400 mm seems more reasonable on here.

The property has been used (somewhat outside of the law) as two flats - we are reinstating it as a single house.

What would you spend my budget on?

Jeff B — Fri, 01 Dec 2023 23:41:00 +0000

Posted By: Nick ParsonsI have never used Diathonite but I get the impression from some users that you have to sit down a long time once you know the price (esp. for spraying, which seems to be the way to do it.

EWI would be my first choice. JeffB, I think you were v lucky to find £80 pre-covid. Lots of contractors 'talk' £100, but once enabling works are added in the costs shoot up.The last EWI I supervised in about 2018 or 2019 was about £160 incl enabling works and scaff, for 100mm gEPS.

Agree with the retrofit plan. Plan for the Whole, even if you do it in parts.

Wow, so I'm definitely out of touch then. Even at £80 it was out the question for our place (100 sq.m.), so at £160.....!!

What would you spend my budget on?

Artiglio — Sat, 02 Dec 2023 10:50:10 +0000

It’s been posted on here before , there’s a chap on youtube that goes under the name of Urban plumbers, has some interesting things to say and on the face of it certainly seems to know his stuff. He did a video on a property that had two boilers and he then modified the system and had it far more efficient, also does heatpumps, you might find he’s pretty close to you, look him up and see if you think it’s worth contacting him.

https://www.urbanplumbers.co.uk/

What would you spend my budget on?

GreenPaddy — Sat, 02 Dec 2023 15:29:24 +0000

Remember, much of the work/materials would be zero VAT rated, if you use VAT registered contractors (perhaps that's why you noted the budget ex VAT?

This HMRC link details the inclusions;

https://www.gov.uk/guidance/vat-on-energy-saving-materials-and-heating-equipment-notice-7086

As regards your list;
1. EWI - might be half your budget, but I wouldn't consider NOT doing it.

2. Insulation between joists - assume under your ground floors? various ways to do this, but I always use VPM to support the wool type insulation. This is a more DIYable task, esp is lifting floors, as can do one room at a time, at your own speed. Of course, you'll then have to pay standard VAT on the materials, but free labour.

3. Top-up of loft insulation - yes, after you've done any other rewiring etc, so it doesn't get trod over repeatedly. 3 layers, each perpendicular to the previous layer. Use 140mm, to give you 420mm, uValue of around 0.1 W/m2K.

4. Solar PV with batteries - likely £15k ish, so maybe not at this time?

5. Potentially replacing one boiler with an air source heat pump? - after insulation, you may find one is obsolete anyway. Would need to understand the reason for 2 boilers at the moment. Possibly due geographical pipe work, rather than total power output, but detail out how it runs right now, and then consider how to delete one. Also consider what additional minor changes may allow an ASHP to replace the remaining boiler in the future.

What would you spend my budget on?

Peter_in_Hungary — Sat, 02 Dec 2023 19:22:01 +0000

Posted By: GreenPaddyTop-up of loft insulation - yes, after you've done any other rewiring etc, so it doesn't get trod over repeatedly.

But any electrics should be above the insulation or against the plasterboard ceiling but not in the middle of the insulation i.e. between the new and the old. If the wiring is in the insulation or has insulation on one side then the cables need to be de-rated according to the tables.

Re heating - was the 2 boiler system installed as such of was it a 1 boiler system split to cater for 2 flats. It may be worth considering going to a 1 boiler system if not too much rework is involved.

What would you spend my budget on?

djh — Sat, 02 Dec 2023 20:15:18 +0000

Posted By: Peter_in_HungaryBut any electrics should be above the insulation or against the plasterboard ceiling but not in the middle of the insulation i.e. between the new and the old.

I think GreenPaddy's comment was about the likelihood of the insulation being compressed below feet if the wiring was done after the insulation was placed. Not about the wiring itself.

What would you spend my budget on?

Peter_in_Hungary — Sat, 02 Dec 2023 21:14:15 +0000

Posted By: djh
Posted By: Peter_in_HungaryBut any electrics should be above the insulation or against the plasterboard ceiling but not in the middle of the insulation i.e. between the new and the old.
I think GreenPaddy's comment was about the likelihood of the insulation being compressed below feet if the wiring was done after the insulation was placed. Not about the wiring itself.

If the wiring is done after the insulation then feet squash (destroy) the insulation. If the wiring is done first the insulation is OK but the wiring cooks.

The key is (whether the wiring is done first or second) to have tradespeople who know what they are doing and actually take care about what they do.

What would you spend my budget on?

Doubting_Thomas — Mon, 04 Dec 2023 09:50:37 +0000

Posted By: RenovationnoobThe retrofit plan sounds like a good idea. Does anyone have any recommendations of providers? There are so many options online and I assume more than half are cowboys...! We are based on the Surrey/London border.

Whilst I should be recommending my own profession (architect), I'd actually suggest you approach one of the charities that are likely to be a bit more impartial first.

https://retrofit.coop/

is probably a good place to start

What would you spend my budget on?

djh — Mon, 04 Dec 2023 12:41:29 +0000

Posted By: Doubting_ThomasWhilst I should be recommending my own profession (architect), I'd actually suggest you approach one of the charities that are likely to be a bit more impartial first.

https://retrofit.coop/

is probably a good place to start

I think it's a really good idea to talk to as many people as possible. It's a really good way to clarify your ideas, and it's important to make contact with somebody you can trust to help you.

retrofit.coop seems to be based in Manchester, but they might be able to suggest an equivalent in Michael's area. It might be worth talking to https://www.london.gov.uk/programmes-strategies/environment-and-climate-change/energy/low-carbon-accelerators/retrofit-accelerator-homes as well for example. And anybody else you can find. Most conversations won't lead anywhere, but hopefully the odd one will.

What would you spend my budget on?

GreenPaddy — Tue, 05 Dec 2023 08:26:42 +0000

Just to clarify, I always get the cabling fixed to the rafter undersides, about 500m above the ceiling ties, so it's not under the insulation. Drops then don't travel through much insulation. So you're both correct djh & PiH

What would you spend my budget on?

philedge — Tue, 05 Dec 2023 11:42:41 +0000

In a 2 storey house with modernish lighting/appliances there's likely a much lower load on the loft wiring circuits than they are designed for, so burying wiring in insulation is much less likely a problem than it was a decade or 2 ago.

Most lighting circuits have 6 amp protection for cabling that will carry twice that and with CFL/led lamps there's unlikely to be anything like 6 amp running in the cabling.

Bedroom/upstairs socket circuits again will likely be carrying a fraction of the current that they are capable of so well over sized for the likely load.

Given the cost and/or effort in rerouting cabling out of insulation its probably worth properly identifying cabling and considering its actual load before expending too much effort on blanket rerouting. There'll be some loft circuits that will have a considerable load such a showers/immersion heaters where they'll likely need specific consideration, but the bulk of what's in your average loft is likely fine under insulation, but get a spark to confirm if you're not sure.

What would you spend my budget on?

Peter_in_Hungary — Tue, 05 Dec 2023 16:11:48 +0000

Posted By: philedgeBedroom/upstairs socket circuits again will likely be carrying a fraction of the current that they are capable of so well over sized for the likely load.

The problem is when someone plugs in a fan heater, an electric kettle or an electric radiator etc. The usual way around the problem is to swap the MCB for one that suits the cable under the insulation.

If you are rewiring then not much extra in hanging the cabling on the rafters, although there are restriction on the drops and how much insulation the cable can go through before impacting the current carrying capacity.

What would you spend my budget on?

philedge — Tue, 05 Dec 2023 18:02:54 +0000

Even a fan heater or kettle is only drawing a fraction of the 32A that a typical socket circuit is rated for.

As you say downsizing the protection is the easiest way to leave most of the loft wiring in situ under insulation. All our socket circuits are on 20A MCBs and they've never tripped. I think we could easily go down to 16A on all but the kitchen sockets.

What would you spend my budget on?

Peter_in_Hungary — Tue, 05 Dec 2023 18:43:44 +0000

A 3000w fan heater is 13A
If more than 500mm of the cable is in insulation then the derating factor is 0.5. So your 32A ring main is down to 16A. You don't much else on the ring main to take it over the top.

What would you spend my budget on?

Renovationnoob — Thu, 07 Dec 2023 12:46:07 +0000

Thanks all - hope this forum gets ported somewhere when it closes