Phaedrus Posted February 16, 2021 Share Posted February 16, 2021 My planning permission contains commitments for installation of solar PV, air-source heat pump and rainwater harvesting. I'm not wanting to go through another round of planning variations so I will install them. However, I suspect if I'd done a full cost benefit analysis then it would be difficult to justify the rainwater harvesting in particular. The solar PV hardware appears to be getting much cheaper (haven't looked at install yet) but the Smart Export Guarantee tariffs don't look particularly attractive (5.6p/kWh). ASHP makes sense I feel as there is no gas supply available to site although some of the installed prices appear astronomically high (e.g. £11-12k). Does anyone have any evidence that these eco features more than pay for themselves in purchase premium on a house sale making them "no brainer" territory? Link to comment Share on other sites More sharing options...
Thorfun Posted February 16, 2021 Share Posted February 16, 2021 the question of whether something pays for themselves has been done on here a lot and you'll get answers from both camps. personally, we plan to have all 3 of those you've listed. RWH will never pay itself back in 100s of years, but that's not why we're doing it. For solar PV the payback period could be quite a long time but, again, we're not doing it to save money or for any payback period, we want to reduce our reliance on the grid. ASHP for us just makes sense regardless of the dwindling RHI payments and requirement for MCS installation to get them as we don't have mains gas and I don't want to use tank gas or oil so electricity/ASHP is the only really viable alternative. ultimately, it's up to you and what's important to you. some on here (like me) don't do these 'eco bling' products for financial benefit, others won't do them if the sums don't add up. as I said, there are plenty of threads on this subject in each of the respective sub-forums. take a read and see what conclusions you come up with. 1 Link to comment Share on other sites More sharing options...
nod Posted February 16, 2021 Share Posted February 16, 2021 They certainly don’t pay for themselves Solar in particular a couple of hundred quid per year saving A long time to recoup the cost Link to comment Share on other sites More sharing options...
Temp Posted February 16, 2021 Share Posted February 16, 2021 Welcome to the forum. Can I recommend you beef up the insulation and pay attention to how its installed. If there is one issue with ASHP that comes up regularly it appears to be undersizing - specifically the heat loss being greater than expected. 1 Link to comment Share on other sites More sharing options...
SteamyTea Posted February 16, 2021 Share Posted February 16, 2021 Does a kitchen or bathroom 'pay for itself'? You are where you are, so just start costing them out yourself and don't look at any MCS registered fitters. You will find that without registration, and even allowing for half the PV being exported for free, it is still viable as you will not be importing at 16p/kWh. Norfolk is a pretty good county for PV production. Just make sure the angles are optimum (look at PVGIS) and there is no shading. Look on eBay for ASHPs. Check out roof integrated PV, it is better looking than red tiles. The rainwater harvesting is interesting, can that be used instead of SUDs if that applies. 1 Link to comment Share on other sites More sharing options...
Phaedrus Posted February 16, 2021 Author Share Posted February 16, 2021 Many thanks for the responses and for challenging my perspective re: looking for a payback v doing the right thing and enjoying the broader benefits that these technologies provide. My parents who were early self-build adopters in the 1960s were also quick to fit solar pv and get a very nice boost to their retirement income from the legacy FIT. The solar pv/ASHP combination is therefore an easy sell for them. The only one that rankles is the rainwater harvesting which offers next to no storm water attenuation; has appalling economics; and the ongoing use of the system to flush toilets and feed the washing machine was strongly questioned in another thread I followed. Link to comment Share on other sites More sharing options...
SteamyTea Posted February 16, 2021 Share Posted February 16, 2021 2 minutes ago, Phaedrus said: The only one that rankles is the rainwater harvesting which offers next to no storm water attenuation; has appalling economics; and the ongoing use of the system to flush toilets and feed the washing machine was strongly questioned in another thread I followed. Basic swimming pool sand filter and a UV steriliser, or ozone injection should be pretty cheap. Make it large enough and it should help with the storm overflow. If you are digging holes, probably not that expensive to fit in a few tones of storage. 1 Link to comment Share on other sites More sharing options...
Phaedrus Posted February 16, 2021 Author Share Posted February 16, 2021 Thanks. The tanks I've seen from the likes of Rainwater Harvesting have a backflow filter and a submersible pump but none of these disinfection provisions. At >£2k + installation for the 3000l tank, I'm tempted to look at buried IBCs or concrete manholes which are suggested in the other thread. Link to comment Share on other sites More sharing options...
dnb Posted February 17, 2021 Share Posted February 17, 2021 I have to watch the costs of my build so there does have to be an economic aspect to everything. Things don't have to necessarily "pay for themselves" but they do need to have some intrinsic benefit over and above the eco aspect. Solar PV makes sense to me for instance because the house should self use most of the power and thus pay back in 3 years (no mains gas etc...). Installing the PV wasn't particularly expensive and allows other expenses to be saved from the build. E.g. I can trade 7000kWh per year of "free" electric against the cost of say fitting more efficient but expensive heating. Rainwater harvesting does indeed fail the cost benefit analysis if i were to buy a kit of parts, and I can see little way for it to displace any other build costs. I will still do it but the system will definitely be done on the cheap. Happy to share the maths behind my (somewhat crackpot) plans in a couple of days when I am less busy with windows and scaffolding. 1 Link to comment Share on other sites More sharing options...
Mugwanya Posted February 17, 2021 Share Posted February 17, 2021 How much will it cost to get your house connected to the grid? The quote I had was £24k, so spending anything less than that meant that the payback for solar was immediate. Also the panels plus mounts are £116 for about 2 sq.m. and slates were quoted at £40-60 per sq.m. so depending on the quality of the slate chosen installing solar panels cost no or little more. I'm installing rainwater harvesting for eco reasons and I agree that on straight cost terms it's not worth it. I also don't think my air to water heat pump cylinder, at just over £2k, can be cost justified over a standard cylinder which would be around a thousand or less, particularly since for over 6 months a year I won't be able to use half the solar energy that I could potentially produce so a standard immersion cylinder would be fine. But again it's a long term eco thing. Installing and air to air heat pump for heating and cooling, at around £1500, is for comfort so again there is no monetary payback from it. But what price do you put on being cool in the summer? 1 Link to comment Share on other sites More sharing options...
Triassic Posted February 17, 2021 Share Posted February 17, 2021 4 hours ago, Mugwanya said: air to air heat pump for heating and cooling, at around £1500 That’s not too bad a price! Make and supplier ? Link to comment Share on other sites More sharing options...
Mugwanya Posted February 17, 2021 Share Posted February 17, 2021 @Triassic https://www.aircondirect.co.uk/p/1488434/multi-split-4-way-wifi-ready-inverter-wall-air-conditioner-system-with-four-9000-btu-indoor-units-to-a-single-outdoor?wgu=272195_196673_16135521108755_5842930f28&wgexpiry=1621328110&utm_source=RedBrain Ltd&utm_medium=webgains&refsource=webgains I'm building a three bedroom house so I'm thinking a cassette in each bedroom plus one in the main living area which is open plan with the kitchen. I have no idea how well they work but it will be an extremely well insulated, air tight house so a little heating and cooling should go a long way. Link to comment Share on other sites More sharing options...
ProDave Posted February 17, 2021 Share Posted February 17, 2021 My thoughts, ASHP is a viable source of heating and works, and solar PV gives you free electricity to reduce your bills. Both are good modern building ideas not "bling" I am far less convinced about rainwater harvesting. Perhaps that's because I live in a sparsely populated area with plenty of rainfall not renowned for water shortages or droughts. Perhaps if i was still in the SE where hosepipe bans were common when you got more than a week of sunshine, it might start to make sense to prop up the failing infrastructure a bit. 2 Link to comment Share on other sites More sharing options...
Jilly Posted February 17, 2021 Share Posted February 17, 2021 I read that this was one of Kevin McCloud's biggest disappointments, that many of the projects seemed great with their ambitious eco credentials, but when the crunch came they were unaffordable and had to be called back and the houses lost their 'Grand Design' effectively. Link to comment Share on other sites More sharing options...
Phaedrus Posted February 17, 2021 Author Share Posted February 17, 2021 11 hours ago, Mugwanya said: How much will it cost to get your house connected to the grid? The quote I had was £24k, so spending anything less than that meant that the payback for solar was immediate. Also the panels plus mounts are £116 for about 2 sq.m. and slates were quoted at £40-60 per sq.m. so depending on the quality of the slate chosen installing solar panels cost no or little more. We're in discussions with the electricity company at the moment. Overhead LV line goes straight through the plots but the original quote for connection was £13k + our own work to supply and install 125mm ducting for undergrounding the cable. I hadn't considered a full off-grid approach, isn't there a lot more to it than comparing grid connection with solar pv (e.g. battery, back-up power)? Yes, as I've started to look at this I'm amazed how cheap the solar pv panels have become! I have seen some analysis that suggests solar pv inset into the roof is now a competitive roof covering but have yet to prove it with quotes. Link to comment Share on other sites More sharing options...
Mr Punter Posted February 17, 2021 Share Posted February 17, 2021 Was the rainwater harvesting a planning condition, like "submit details of xxxxxx system"? If so, either do another application to discharge the condition, stating that the rainwater system was not viable. Alternatively just do not install it, as planning will not check. Link to comment Share on other sites More sharing options...
Phaedrus Posted February 17, 2021 Author Share Posted February 17, 2021 32 minutes ago, Mr Punter said: Was the rainwater harvesting a planning condition, like "submit details of xxxxxx system"? This is my planning condition - "The rainwater harvesting system as set out in dwg no. 02 G shall be implemented in full prior to the first occupation of the dwelling. The system shall then be maintained and managed by the occupants of the dwelling hereby approved as set out in the agents e-mail of the 9th November 2018. Reason for the condition: To minimise the possibilities of flooding in accordance with Policy 1 of the Joint Core Strategy." There is also the water use calculation aspect. I have a target of 105l/person/day and when I do the calculation I get 111l/person/day. Rainwater harvesting is calculated to give a reduction of 35l/person/day (i.e. 13l for WC, 17l for washing machine, 5l for outside use) taking the use down to 76l/person/day. 51 minutes ago, Mr Punter said: either do another application to discharge the condition, stating that the rainwater system was not viable. Alternatively just do not install it, as planning will not check. Tempting but do not think I'll go down that route. Maybe will install a "Heath Robinson" solution with potential to switch to outside use only if there are problems in operation. Link to comment Share on other sites More sharing options...
Thorfun Posted February 17, 2021 Share Posted February 17, 2021 3 minutes ago, Phaedrus said: There is also the water use calculation aspect. I have a target of 105l/person/day and when I do the calculation I get 111l/person/day. Rainwater harvesting is calculated to give a reduction of 35l/person/day (i.e. 13l for WC, 17l for washing machine, 5l for outside use) taking the use down to 76l/person/day. I also would've failed this if it wasn't for the RWH tank. the main thing for us for the RWH was (to quote @ProDave as I don't think I could've said it any better) "prop up the failing infrastructure a bit". basically to allow those who don't or can't get water in a drought period to get it from the mains as we won't have to (as much). 1 Link to comment Share on other sites More sharing options...
Mr Punter Posted February 17, 2021 Share Posted February 17, 2021 Just submit another scheme, with an attenuation tank. You can easily pass the water consumption and you will not need rainwater harvesting to do this. It is a waste of money. Link to comment Share on other sites More sharing options...
Mr Punter Posted February 17, 2021 Share Posted February 17, 2021 3 minutes ago, Thorfun said: I also would've failed this if it wasn't for the RWH tank. That is interesting. What would you fail? Was this an additional planning condition, on top of the standard building regs part g / Code level standards? Link to comment Share on other sites More sharing options...
Thorfun Posted February 17, 2021 Share Posted February 17, 2021 1 minute ago, Mr Punter said: That is interesting. What would you fail? Was this an additional planning condition, on top of the standard building regs part g / Code level standards? our water usage calculated to be more than the standard building regs but with the RWH being used for toilet flushing and garden it brought our water usage to below the BR. Link to comment Share on other sites More sharing options...
Mr Punter Posted February 17, 2021 Share Posted February 17, 2021 The requirement in part g is self cert. Just a note from you saying that the dwelling meets that standard. Done. 1 Link to comment Share on other sites More sharing options...
Thorfun Posted February 17, 2021 Share Posted February 17, 2021 22 minutes ago, Mr Punter said: The requirement in part g is self cert. Just a note from you saying that the dwelling meets that standard. Done. that may be, but we had an architect who required calculations to be done to ensure we complied with building regs which I then sent off to building control as they wanted to see the calculations. Link to comment Share on other sites More sharing options...
Bramco Posted February 17, 2021 Share Posted February 17, 2021 1 hour ago, Thorfun said: our water usage calculated to be more than the standard building regs Our M+E chap said just say you are putting pressure limiters on the showers etc. Obvs don't fit them ? Simon 1 Link to comment Share on other sites More sharing options...
Mr Punter Posted February 17, 2021 Share Posted February 17, 2021 59 minutes ago, Thorfun said: that may be, but we had an architect who required calculations to be done to ensure we complied with building regs which I then sent off to building control as they wanted to see the calculations. Waste of time and money. They used to do these when it first came out. Now it is self cert. Link to comment Share on other sites More sharing options...
Recommended Posts
Create an account or sign in to comment
You need to be a member in order to leave a comment
Create an account
Sign up for a new account in our community. It's easy!
Register a new accountSign in
Already have an account? Sign in here.
Sign In Now