Criticise my Retrofit - What Should and Shouldn't I Do?

BenIrishHome · 02-03-2025 12:09PM #1

Hello great people of the C&P Board. I've been lurking for a while and honestly this place is the best repository of info on upgrades and construction in have found online. I'm about to launch into a major retrofit of our house and while i think I know what I'm doing, I'd appreciate first hand experience from people here.

Context: 2001 built dormer bungalow, c. 220sqm. 4 bedrooms, 2 upstairs 2 downstairs. Currently a BER C1 but honestly it doesnt feel like it. Absolutely freezing in winter and costs me a fortune in gas (approx 16,000 kwh pa) with a 7 year old combi boiler. 6 of us living here, home a lot during the day, so we'd like it warm and plenty of hot water on demand.

We've been in the house 11 years, have only had the chance to do some modest changes so far. But due to an inheritance we have a once-in-a-lifetime chance to upgrade the house. We love this house and could live here for the next 30-40 years so i'm happy to invest in the future. We will have about €100k, we have no mortgage, but i'd also not get much in the way of loans. I'd hope to get €75k loan from SCBI Green Loan scheme, bit of credit union if necessary.

We just got an EV so we want to get as much solar as possible. We have very large East-West facing roofs, so something like a 22 panel, 10kw system, and hopefully 10-15kw battery.

A MUST HAVE is underfloor heating on the ground floor (135sqm). Our large kitchen has freezing tiled floors and we need to feel this warmth coming up into the house. Also our kitchen and living room are very high ceilings so UFH would heat it better. We don't want to dig up the whole ground floor concrete floor so we've found this floor milling system that will cut tracks for the UFH piping into existing slab (being a 2001 build we are going to assume there is SOME insulation under there, even if it's not the 150-300mm they would do these days). With this plan, we aim to use cheap night rates and solar/battery to run an Air-to-Water Heating system 'low and slow' throughout the day so that GF slab becomes our heatsump and just keeps the house warm all day.

Obviously for this to work and for the A2W not to cost us a fortune, we need to well insulate the house. Cavity Walls are to be pumped, new windows and doors throughout, replace attic insulation incl. knee walls. Better air-tightness measures throughout. I'm open to installing MVHR so i can seal off all airvents (I can feel the heat seeping out of them).

I've has a One Stop Shop out to quote for it all. The total energy upgrades bill with them came to nearly €100k, less €24k in grants. Bringing me from a C1 up to probably a A2 (I care less about that, just want it to be warm and cheaper).

A brief run down of that bill as follows:

Measure	full value incl VAT €	SEAI grant €	value after grants €
Pump cavity wall	4,100.56	1,700.00	2,400.56
Attic Insulation	12,327.07	1,500.00	10,827.07
Upgrade sloped ceilings	16,193.29	-	16,193.29
Triple glazed windows	18,352.51	4,000.00	14,352.51
Doors	9,340.17	1,600.00	7,740.17
Heat Pump	25,030.48	8,500.00	16,530.48
Radiators for heat pump	1,873.43	1,000.00	873.43
Stove or Block fires	406.8	-	406.8
Vents and Extract Fans	1,335.48	-	1,335.48
Solar PV	10,855.06	1,800.00	9,055.06
BER Consultancy and certification	650.88	-	650.88
Project Management	2,400.00	2,000.00	400
Subtotal	102,865.73	22,100.00	80,765.73

Of these, the glaring expenses are the Attic insulation (seems high), the sloped ceilings upgrades (basically taking down all plasterboard upstairs and replacing with thicker warmboard - seems not worth the effort), the Heatpump (although that includes some additional plumbing so overall it probably fair if they are going to fine tune and perfectly setup the whole system). I can cut approx €15-20k from this overall bill I think.

I have been shopping around for individual contractors myself, but honestly these OSS shop guys seems pretty competent and would project manage the whole thing. (I just don't like to see a company with a fleet of brand new vans, feels like I'm going to be paying for them!). Also only the OSS can get a grant for windows and doors so I'm thinking it might be worth it.

On top of this (call it €70k with the OSS), I'm also having to include €20k for the UFH milling and system. Another €10-15k on wood effect tile flooring to go with it. Another €20-30k on a new kitchen. We might do some new velux dormer windows upstairs in the bedrooms to get more space for our growing kids. Redo 2 whole bathrooms + a WC. Overall spending around €160k-175k on the total job. Hopefully the €75k SCBI loan will make up for the difference from the cash we will have.

House we bought for €265k 11 years ago and is now worth €550k, so we're not overspending what it would be worth. Not that that matters. As i said we will be here for the next 20-30 years and this will future proof the house.

Anything I'm doing here that is crazy or I should be leaving out. Thanks in advance!

Biker1 · 02-03-2025 08:01PM

Properly insulating and making airtight the slopes, knee walls and crawl space is the only way to ensure the dormer type roof will hold the heat. 25k for a heat pump install seems crazy given the unit can be bought for around €4k

MicktheMan · 02-03-2025 08:10PM

@BenIrishHome your project looks so familiar to me. These are eye watering amounts of money. I've surveyed quite a few houses now after the money has been spent (similar amounts) going with the OSS outfits on deep retrofits all backed up with SEAI approval/grants. And the reason why I am contacted is because the people are still cold with sky high esb bills.

You have a dormer, notorious for air tightness issues and yet I can't see any of the measures you list above addressing this!!!! Don't get hood winked.

Busman Paddy Lasty · 02-03-2025 08:33PM

Do you have any fireplaces in the house?

If the floor is freezing it either has not enough insulation or none. I'd dig it all up rather than use the milling system. Insulate properly if you want to maintain a thermal store.

Wouldn't get a battery since feed in tariffs are here. Do you have land for a south facing solar ground mount?

BenIrishHome · 02-03-2025 08:43PM

https://www.boards.ie/discussion/comment/123225596#Comment_123225596

yeah I know. I guess that’s the external unit, another €2000 for the internal hot tank, same again for plumbing, and so on. I would have said €10-15k sounds reasonable - but actually looking at my quote that €25k did include a bunch of other stuff (below) so in the grand scheme of things started to see fair:

Decommission existing gas boiler and dispose

Panasonic 11KW Aquarea High Performance Mono‑bloc J Generation Air to water heat pump.

1nr New 200ltr high-efficiency Domestic hot water cylinder.

1nr Aquarea smart controller.

Builders works to accommodate heat pump outdoor unit.

New insulated primary pipework from heat pump to new cylinder

New cylinder connected to existing domestic hot water outlets using existing pipework

New system connected to existing central heating system using existing pipework

Earth rod and electrical bonding of pipe work.

1nr Electric shower removed from ensuite and replaced with pumped shower (Triton Novel SR or similar using existing cold water supply pipe and power supply cable)

Subject to detailed surveys and testing by heating engineer and electrician.

BenIrishHome · 02-03-2025 08:47PM

Yes that’s what I’m worried about. These guys I feel at least would take ownership of the project and come back to balance the system if I need them.

I’ve been watching slot of Heat Geek content and other Heat Pump YouTube stuff from the UK. Someone here told me there was one Heat Geek certified guy in Ireland, conveniently he’s just down the road in Wexford. I have him coming next week for a second opinion.

Yes you are right about the attic. There’s actually about €30k in that quote for the attic and sloped ceiling and about €2k of that was “airtightness measures” - seems to be seals on attic hatches etc. We are getting new windows and doors so assuming they are properly air tight proofed.

BenIrishHome · 02-03-2025 08:51PM

https://www.boards.ie/discussion/comment/123225723#Comment_123225723

yes have a fireplace. Blocking that up, rarely used away, useless small cassette fire in it.

the coldest part is the rear kitchen floor which we actually might do a small 1.2m x 4 m glass box extension (just under the eaves, to grab a little more space and some nice views) and in doing so will be pouring concrete for that and a seamless patio. In doing that we will claw away a few feet at the back of the house and lay new insulation under the new concrete plus a bit, plus around the new edge, so keeping the heat in at the most crucial part. Hoping that is enough.

Digging it up would be €40k, twice the price for the UFH. Never make that back. And so messy and disruptive. Not needed.

Busman Paddy Lasty · 02-03-2025 09:12PM

https://www.boards.ie/discussion/comment/123225778#Comment_123225778

Damn, €40k for digging up the floors, hopefully that includes new insulation and concrete. I'd still prioritise it over batteries, or even solar if you were in temporary budget pinch. *assuming no insulation in place.

Reason mentioned chimney was to have a backup for power outages but I guess that's recency bias at work.

BenIrishHome · 02-03-2025 09:16PM

that €40k did include all that and the labour and the screed and the UFH gear. Still…

funny enough I’ve been laughing at the PTSD all these rural types have had in the last few weeks since the storms. A panic to get changeover switches etc.. we’re in a medium town and have a huge substation about 1 up the road… we never get power cuts. About 3 in 10 years. Then 9pm last night the substation blew and we were in darkness. Only for an hour tho 😅

Busman Paddy Lasty · 02-03-2025 09:22PM

Ha! Sure you have a new substation now, or a reconditioned one at least.

I've still got PTSD from living with a suspended timber floor. Ripped out and a new insulated screed floor in. The difference is night and day. So again I'm biased here.

DrPsychia · 02-03-2025 11:19PM

https://www.boards.ie/discussion/comment/123225834#Comment_123225834

If you want a heat source backup for temporary power outages, google bio-ethanol stoves. You don't need a flue, so you can seal the fireplace.

BenIrishHome · 02-03-2025 11:52PM

nah, I have a big portable butane stove that I use already, tank does the bbq in the summer and extra indoor heating in the winter

Yellow_Fern · 04-03-2025 04:24PM

Personally Id drop the heating pump, battery and triple glaze and add some high end heat recovery and add airtightness measures.

BenIrishHome · 11-03-2025 02:05PM

https://www.boards.ie/discussion/comment/123231143#Comment_123231143

I'm actually expanding the battery and solar. 22 panels and 16kw with Sigenstor. With the amount of elec i use for EV, the better i can do to load shift from cheap night rates through the day.

MVHR and airtightness yes, i almost think these are more important than crazy insulation.

What is it about heat pumps? I'm gonna be keeping the Ufh on a steady low warmth all day, I don't want boiler on and off or running all day. HP perfect for this, steady low temp. Its almost a non negotiable for me. Not because I'm principled about getting off fossil fuels, its just gonna be cheaper in the long run if i generate good solar or use my batteries efficiently.

youcancallmeal · 11-03-2025 05:56PM

Out of interest have you gone to any non OSS building contractors to see what they would quote? I'm looking to get something similar soon and initial quotes from OSS was around 120k and then 100k after grants. I'm currently in talks with a good builder who I know has done very good retrofit/renovation work in my area so will be interested to see what he quotes compared to the OSS.

BenIrishHome · 11-03-2025 05:59PM

yes I’m in the process of doing just that. I’ve had the solar priced separately (went from €10k to €15.5k because I want a bigger system and more battery than the OSS standard provided for).

I’ve been referred to a good Heat Pump guy in Wexford. Waiting to hear on that, that’s the other big cost.

the rest I feel we can do with individual contractors. Loads of attic insulation and pumped beading guys around.

Then a small builder locally for the other bits and pieces. We’re not doing major structural work.

however from my calculations, It might save me €10k on the whole. Not a huge amount.

Yellow_Fern · 12-03-2025 02:01PM

https://www.boards.ie/discussion/comment/123253685#Comment_123253685

There are a lot of great things to be said for heat pumps, but the best a heat pump can do it is reduce bills, not make your life more comfortable, so it is a question of pay back. How many years will it take to pay back the 16,000 planned outlay by switching to a heat pump taking into hidden pros and cons service costs, no gas standing charge etc? I haven't done the sums but this would be a key point to see if it is worth it. gas boilers done well should be ticking away at a low temperature, although, this is rarely the case in Ireland.

BenIrishHome · 12-03-2025 02:49PM

I actually think the total opposite. A lot of people arguing about the payback, but you don’t question the payback on a new boiler or a new floor, a new kitchen. I don’t care if it takes five or 10 years to pay back. I’m going to get the comfort and enjoyment of a steadily warm house, not a up and down boiler going on and off.

hesker · 12-03-2025 05:37PM

https://www.boards.ie/discussion/comment/123257552#Comment_123257552

Fully agree. Have just completed a retrofit with EWI, heat pump, MVHR, new windows and my own air-tightness measures.

Our house is transformed completely. Such a pleasure to live in and even though we’ll never recover the costs it was some of the best money we ever spent.

monseiur · 12-03-2025 09:52PM

Forget about milling trenches in the floor for under floor heating. More than likely the floor is just a screed over insulation, this will break up very easy so it will be more economical to replace floor and insulation. Fit 100mm Kingspan Thermafloor or similar under new screed.

Retro fitting air to water pumps is something I would not recommend, chances are that you'll end up with a cold house but astronomical electricity bill more so due to dormer roof which are known to leak heat like an outdoor fire! (your solar pv may help reduce bill but…… )

As the house is almost 25 years old consider gas or oil fired heating, with the upgraded insulation, triple glazed windows etc. annual oil/gas bill should drop 35% but unlike air to water you'll be guaranteed a warm cosy home. Also consider not closing off chimney - I know the ''green taliban'' will slaughter me for the above, but I live in the real world not in their fantasy land.

Think long and hard before you go down the route you're now planning. Do your own independent research, talk to householders who did air to water retrofitting, don't listen to snake oil salesmen -they say a fool and his money are easily parted. Don't become one in your quest to drag your house kicking and screaming into the ultra modern, post fossil fuel age. It's not possible to turn a donkey into a race horse irrespective of how much money you spend - it has to born a horse and a house has to be originally designed & built to suit air to water

hesker · 12-03-2025 10:22PM

https://www.boards.ie/discussion/comment/123259058#Comment_123259058

Hasn’t been my experience with an air to water heat pump on a retrofit installed Oct last year so we’ve been through the coldest months already. Every case is different but they can work out fine. I don’t live in a dormer though
I still have some air tightness work to do but even with what I have now I’m projecting our heating bills will be lower than what we had with a modern condensing oil burner. We’ll never recover the outlay fully but I’m ok with that.

If I was to offer advice on it I would recommend upgrading the pipework diameter to improve flow rates but there wouldn’t be that many that can dig up floors.

BenIrishHome · 13-03-2025 12:52AM

I’m enjoying this argument lads! It’s helping me as I’m in two minds. If I cut back on the cost of A2W etc I can afford a better kitchen or bathrooms. But with the solar + battery strategy I’m going for, I want to go all electric and try to keep my overall running costs down below 10c per kWh throughout the day.

For what it’s worth, we’re a bungalow with rooms upstairs but not a dormer. We just have skylights and a couple gable end windows upstairs. I’ve heard how bad dormers are for airtighness/heat loss.
We going to expand our upstairs with a few of these triplex mini dormers from velux. Hopefully better insulated than a real dormer.

Is it possible to make a bungalow airtight and insulated enough?

Busman Paddy Lasty · 13-03-2025 07:49AM

Have you or a solar installer put your system details into a PV GIS calculator? To determine your annual output with a monthly breakdown.

Solar production and needing heat happen at opposite ends of the calendar year. It won't get you much at all in December and January. I'd recommend post your solar + battery strategy in the renewables forum. Some folk with heat pumps can use 30 or 40 kWh on a cold day. That would eat you battery fairly quickly.

BenIrishHome · 13-03-2025 08:24AM

I already use 30kw a day due to my EV !!

All at the 2-6am night rate.

The plan would be to pump up the heat during that time and let it diffuse out during the day, carried over by at least a 16kw battery to get me to the evening if needed.

Solar is a bonus if we get any sun but not relying on it. we have modelled it, apart from about 3 months of the winter it will be pretty decent top up to the battery

Buzwaldo · 14-03-2025 08:56AM

https://www.boards.ie/discussion/comment/123257552#Comment_123257552

Re the steady warm house thing, I live in a house which we built in 2003 with UFH and a heat pump (early adopter at that time ). It’s obviously an older system and without modern computerised controls. The heat is great and house is generally toasty. BUT it’s not that responsive to temp changes. If we get a sudden drop in external temps, eg from 10 degrees to around zero, it takes a while for house to respond. Similarly when weather goes the other way, we can be sweltering a bit for a day or 2. This is due I believe to the sump / inertia effect of a large concrete slab. (Also our windows are not as airtight as they should be, and needs addressing, which has a role here, and you shouldn’t have that).
In short, I would love the flexibility of being able to boost the rads or vice versa from a boiler going on or off.

Yellow_Fern · 14-03-2025 10:37AM

https://www.boards.ie/discussion/comment/123257552#Comment_123257552

I don't want to push too hard because heat pumps are great and it's good to electrify generally, but your impression is totally wrong. It's incorrect to think that a gas boiler can only provide stop-start heating. That's a misconception you probably have from living in a poorly insulated house. A good gas boiler can run at 35 c with just 3 kW which will provide a very mild steady heat to a home. What matters is your heating heat loss and designing the system for your heating heat loss.

You say no one considers pay back with gas boilers, that's that not true. It is just easier as a good one is only 2,600 euro, instead of 16,000euro and it's why I tell people to buy a boiler with efficiency measures like weather compensation. Heat pumps are great but do the sums if your goal is to save money as they are not intrinsically more comfortable.

BenIrishHome · 14-03-2025 11:21AM

https://www.boards.ie/discussion/comment/123263043#Comment_123263043

Good for you being so early. I think things have moved along rapidly, even in the last 2 years let alone twenty. All the HP experts I am watching on youtube from the UK are hammering the point about 'weather compensation', having a connected thermostat outside the house which will prepare the HP for weather changes. How much ahead it is responsive I don't know, even in 4-6 hours to ramp up or slow down your heating would make all the difference, instead of 2 days of uncomfortableness.

In the future, you'd hope they would use weather forecasts to roughly plan even further ahead. I know the solar batteries I am hoping to get (Sigenergy) uses ""AI"" to predict upcoming sunny days etc and manage the battery accordingly.

I can imagine HP tech getting that in the near future too, or after-market controls being available to link these systems.

Criticise my Retrofit - What Should and Shouldn't I Do?

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