Ferdinand

This is from the approved plans for the floor section in my house, passed in 2007. 85mm polyurethane insulation in the floor is a slight puzzle - it was technically a renovate not a rebuild. From 2007 Building Regs what would the minimum be for that situation? The u-value seems to be about 0.26. I decided to have a little look to respond to a debate on the other thread about how much floor insulation is necessary for ufh to be a practical proposition. I can see from the 75mm screed why my ufh response has a delay in it, but even with that spec I like it. Ferdinand

Piccie taken from a front upstairs window an hour ago. It looks Edwardian ... dusting of snow, rough stone wall, next door's somewhat trimmed trees, the lane, the old-fashioned streetlamp, the bicyclist .... The iPad lens which cannot quite catch the piccie unmottled. Warms yer heart and cools yer heating.

Welcome to the madhouse. And the learning curve.

@PeterW Thanks. Are there any particular issues with the thin layer and spreader plate approach? F

Has anyone experience or opinions of the type of Underfloor Heating which are put on top of a suspended wooden floor? eg This one from Polypipe says it sits in a 18mm depth, and a "housepack" for a 50 sqm heated area 5 zone area works out at about £2.5k. Though of course it needs insulation below and a floor base above. Are they: 1 - An excellent product. 2 - A good product but with compromises. 3 - The spawn of the devil. This is part of the gas free rental conversation, but I thought a separate thread was merited. For me, thoug this seems pricey, it may be a good way of getting rid of rads altogether, which can then potentially be connected to a wet ASHP. My need is to do it properly, and then more or less leave it alone for 15 years. Also, ufh does have kudos in the rental arena. Any views - especially @Nickfromwales. Cheers Ferdinand

Or, ideally, before buying it .

@pdf27 Thanks - useful comments. If I take an engineering approximation and say that your 230W peak saving saves an equivalent of 100w over the entire year for ufh (assuming I find a way of doing ufh :-), that would be say £0.1 per unit for 9000 hours = £90 per year. If we call it £30-50 per year as a buffer for my approximations, then that suggests that it might be worth spending £100-£200 for a marginal improvement to a u-value of 0.18 and £300-400 for an improvement to 0.12 (-ish), if extra material can be installed without consequences and extra labour when the floor is up. That would probably leave as realistic options: 1 - a little more insulation in the over-floor for 0.18. 2 - or complete removal of the ventilatd cavity via pumped insulation / sealing air bricks, which could also be costed against the labour of lifting the floor, and a chap with a staple gun and rolls of rockwool for a couple of days, and the insulation in the over-floor. Both might be viable options, depending on the circs. I'm not competely heartless, so I am usually willing to do a bit extra if it is the right thing for the sake of a few ££. Unfortunately, EWI will not be viable for me here without at least a 50-70% grant. I had quotes and they were coming in at £8.5-£11k, even with us doing some things. And a small bungalow is the easiest type of building to EWI. In the event I have settled for installing all my 2G with extended windowsills should the EWI be realistic in the future. It is still a payback of many decades, as it would be 130sqm of wall with a u-value reduction of 0.55 to 0.22 (ish). I make the calculation to be money saved per annum by transmission if the heating was on 24*365 approx = 130 sqm * 0.33 u-value reduction * 12 C ave. temperature difference * 0.001 to give kWh * 0.05 £/Kw * 8760 hours / yr = £225, without the air leakage, and ignoring all kinds of subsidiary effects. EPC says the heating bill may be £300 a year, and removing the whole thing would be a 20-30 year payback. Ergo not viable. But I need to improve my heat modelling skills. Ferdinand

Over the w/e. I'll try and draw up a list of everything I did, though there are various threads talking about it. It might be worth looking up all the other flats on the EPC Register (https://www.epcregister.com/reportSearchAddressByPostcode.html) for a start for ideas and hints, since that information is published and free. And remember that there will be exceptions to the rules where improvement does not give a 15 year simple payback etc. Lining your outside wall looks like one option that should give benefit, or perhaps an overfloor. That would not disturb neighbours. Or EWI the entire building :-). Then you are into improving internal systems. That shower heat exchanger suggestion sounds good, especially with an electric shower - no moving parts, I would also check the very basics ... eg does your ventilation fan in the bathroom have a backdraft shutter, are you OK for condensation, do you have background ventilation that is adequate now you have well-sealed new windows? I now fit a Lo Carbon Tempra trickle/boost fan in all properties, plus a PIV loft fan (which doesn't apply to you). None of these will make much difference to the EPC, but they may make for a happy tenant and a lack of niggling problems. One important point is photographic evidence of everything for the EPC man. There is a reason I have never bought a flat :-), though I wish I had found a way to afford the short lease one bed I was offered by my LL in EC2 in 2000 for 70k. Ferdinand

Aha. I read the photo of the gap visually as a raised profile with sloping sides ... a hump in the floor. Ignore most of my suggestions.

Ignore the humbug about bathrooms. Do just enough to make this unusable then you will have extra motivation for the bathroom.

Floor Buildup for Little Brown Bungalow. U-value = 0.23 (ignoring joists). Thickness above old floor = 53mm. Service cavities run alongside some internal walls. Calculations look slightly off but it is under £10 per sqm.

Cheers, Jeremy. An ASHP (playing with Stroma) seems to give an increase in the EPC number of a few points - tested by simply replacing the Combi Boiler in the Model with an ASHP. Which is, however, a slightly crude test. @A_L a - thanks for the comment. Keen to hear more of your experience. c - I am not sure that I agree entirely with your "c" reply. My current floor renovations give me a floor U-value of just under 0.25, which I think is the basic requirement for renovated 'flooral' thermal elements (not that I had any formal inspections just a "what if" conversation with the department while considering, and they said 'some improvement is better than nothing'). The wall u-value is 0.55 (50mm filled cavity brick). The roof u-value is about 0.14 (270mm rockwool). The cost-effectiveness or not comes from 2 things ... energy saved and cost of installation , and can be judged-ish on a simple payback. The cost of my whole floor buildup (ignoring the floor finishes and labour as most are self-builders here) was well under £10 per sqm. I will post the detailed buildup next. Even if I include labour, it is probably a 5-7 year payback in energy terms (depending on tariff). (*) I think that perhaps leaves room for a bit more, which would mean either more insulation in the layer-cake or EPS beads pumped into the underfloor cavity. I am already quite close to my doors' 65mm trimming margins at 60mm incl. ventilation gap, so to put more insulation in would need some redesign of the build-up. I could fit 38-40mm of celotex plus Engineered Floor attached directly to battens, or click-laminate/vinyl on 6mm ply on celotex. Just. Putting 40mm in as I planned would have given a u-value of about 0.21, which is still imo not really good enough. I estimate that 300-350mm of EPS beads would give me a u-value of 0.10-0.12, which may be worth it if it put me in a position to use an ASHP not a Gas Boiler. f - Than 10000kWh/yr is all energy. It is a conservative guesstimate as I do not have my EPC back yet with their modelled Guesstimate. The previous EPC (will post) says 13.5k with a potential 50% saving, but includes solar panels as well. Ferdinand (*) There are issues around transferring part of that saving from the Ts energy bills onto a slightly increased rent - say sharing the benefit 50:50, but at least I am now in a position to see if a dramatically better EPC number can give say £595 /month not £575.

@Tennentslager I am not quite clear what your objective is here. You say the front room is now carpet with a 6mm drop to the vinyl (?) Or is that the proposal for this kitchen-area threshold? Wouldn't black tape just make it an invisible trip hazard? What does it do? How deep is it to the base of the wooden threshold - eg does it go through the thickness of the floor? Could you hoick it out and replace it with something thin / flush? I had a hole-in-an-internal-wall like that at the LBB, and we just put the wall back . But that would not be a relief to your coffee-drinkers, who need a sort of site-hut to make their drinks. Are you planning to replace the vinyl (£6-8 (?) per sqm). If so - or if just replacing the vinyl in the coffee area - I think I would just put a 6mm (?) ply later down rather than hardboard, and use that to level it up to the raised threshold? Or make it flush as suggested with a level threshold. F

I think they are not required for rooms opening directly onto a hall which leads straight to an external door. Which was a surprise when I looked it up - on the LBB I have one in every bedroom, and the installer fitted handles without keys. Not convinced that that was correct.

I believe that the 100 sqm exemption does not apply to new build, but as a self-builder you should be exempt anyway, surely? There are elephant traps (ie they will charge you notwthstanding you being a self-builder) if you do not have your confirmed CiL exemption in place, and written in tablets of stone ,before development starts. Putting up tree fences may or may not count as development - someone else might know or confirm that it is foggy. The documents will be on display with the other Council Plans: Ferdinand

I think there may be someone here with the correct answer to that in their head already. it is always the first bit of insulation that saves the most and is the most cost-effective (subject to overheads etc eg if you have to trim doors), and since you are already lifting the carpet etc it is just the extra cost of materials plus adjustments. F

Can you add 25mm or even 12.5mm of Celotex into the build up ? Even that would help a lot.

I notice that you do not contradict the last statement....

+1 to all bedrooms. Different systems are not worth the complexity. I made that mistake in a bungalow in 2010 to "save" money. Only do not install in the bedrooms if the alternative is nothing. Ferdinand

Ohno. Shower with a door. Breakdowns and rescues of trapped people approaching...

Venturing gently into the Boffins' Corner, I am after some help to try and come up with a heating / water / ventilation system for rentals which will: 1 - Not involve gas (trying to get rid of Annual Checks, and the plain worry of gas appliances going wrong). 2 - Will not slug the EPC figure. I am regulated to be D or better from 2025, and C from 2030, and not to comply will be a criminal offence - though there are exceptions. 3 - Will not be overtly expensive. 4 - WIll be essentially maintenance free, which ideally means minimal self-done maintenance once per year, and professional assistance once every 5 years. This will be a slow-burn, but as a starting case study, I want to work on the real world renovation of the Little Brown Bungalow. This has been easy to renovate so is a good example for a first try - and there another 49 identical properties in the street to do next time. I may get a copy of the Stoma data from my EPC an, but the project characteristics are: a - Floor area is 64sqm. 3 beds, reception, kitchen, bathroom. Suspended wodoen floor over a concrete raft foundation. b - EPC will be 76 or 77 in the C band. Previously was 47E. c - I have addressed all the low hanging fruit and a bit more. Underfloor insulation 100mm rockwool + 25mm PIR. 27mm loft inculation. Good double glazing. Modern boiler (Ideal Vogue) + rads. 50mm cavity wall insulation. Background ventilation is a PIV fan at the far end of the hall, one end and an HR Trickle Fan in the kitchen. d - Attention has been paid to airtightness and detailing. e - The obvious weakness is the 0.55-ish U-value of the walls. f - Realistically energy costs should be around £500 per year give or take, and demand could feasibly be under 10kWh per year - the previous EPC number was 13.4kWh predicted from the EPC. g - As a marker, the all new heating/water system and the ventilation kit added up to £4k installed. EWI would be prohibitive unless substantial grants are available - looking at 25-30 year payback on the £8-9k I was quoted. If I need to I can do more modelling; I think I probably need to do some proper thermal modelling eg the @JSHarris spreadsheet. If there was a way of using them effectively without complications, PV would be a good thought as it would also benefit the EPC (2.5hWp would put it up to nearly the A band). My initial questions: How close is this to being practical as a low cost electric only house? Does the thermal demand need to be mitigated further? How can that be done? Pump LECA or EPS beads into the subfloor, perhaps? What sort of technology mix would be suitable in this rental application? ASHP? Storage Heaters? Sunamp? Economy Seven? MHVR combined with warm air heating? What to do with any solar panel output? Are there any creative possibilities? If we can come up with a good ideas, I would be willing to try it out on another identical bungalow in future if one comes up for sale. Cheers Ferdinand

Depends how you have insulated it. A skirt would keep them warm, assuming no side draughts. /metaphor If you have cross flow then you probably have to suck it up. Gable walls into the attic may lose more heat by conduction, as the ground is warm.

Not sure about further tightening. I was just aiming to place my LBB refurb's value of about 76 on the current scale. F

Slander ! Libel ! It was only last week that I bought an 18mm sheet of MDF at B&Q for £19.50 (reduced to £19.36 by B&Q Trade Discount). (*) The nice man on the saw cut it into 11 slices of 3, 4 or 5 inches for me, to make radiator shelves (to prevent Tenants drying washing on radiators) and door liners. F * I shall treat myself to one two-finger KitKat with that.

A quick EPC question to which I cannot find an answer. What would be an EPC value for a typical "building regs minimum" newbuild property? I did however find numbers for how EPC values have changed over the last 20 years. Right direction, more still to do. Source: https://www.gov.uk/government/uploads/system/uploads/attachment_data/file/627688/Potential_stock_improvements_Report_2015-16.pdf