The Accidental Smallholder Forum
Smallholding => Renewables => Topic started by: Pebbles on June 20, 2014, 12:37:46 am
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We're in the process of building our new build house on our farm. Despite some factors regarding our 'renewable' choices have been approved by Building Control, having looked more carefully in to all the options open to us I am none the wiser on what our best options would be. Of course I have spoken to the experts but as they would happily sell us 'anything' they are far from independent. So looking at our circumstances below and based on your own experience, if you could choose any combination of renewables what would you choose???
- Our house will be airtight and being a SIP build it will have 8"+ of insulation within all walls floor and roof and extremely efficient doors and windows...we thought (and still think) you could heat it with a candle!
- As it will be airtight we now have to install a 'mechanical heat recovery system' which I'm told will recirculate 90% of our generated heat???
- We will have two wood burning stoves and have a ready supply of wood at the farm
- We have a gas supply which will run underfloor heating throughout the entire ground floor.
- Building Control have insisted we must plumb the first floor for radiator points for "future owners" :rant: but we will have no heating upstairs.
- There is no water tank
- We have been advised to get a solar package for hot water which will be backed up by gas when needed
- We want to generate our own electricity and sell back to the grid any excess...with the rates all dropping is this still a good option? :fc:
- We sit on bedrock so a ground source heat pump is not an option and my OH doesn't like the look of the air source heat pumps
- Wind turbines (much as I'd love a big one) are out of the question. Being in the greenbelt has cost us 7 years of fighting to get to this stage I just don't have the energy to try and get approval for one
- The wood burners which burn pellets is an area I've never grasped the benefits of but friends of ours have been raving about them after a demonstration at the recent Home Building Show!! Anyone?
- Oh and we have had a single and three phase of electricity supply installed....can we then utilise a larger solar system???
We've received quotes for some of these items...two wood burning stoves £10,000 :rant: , Underfloor Heating £6,500. Hot water solar pack and cylinder £4,000. Solar for electricity £7,000....Is being eco-friendly supposed to be so costly??? Do you ever recoup your investment???Are any of them simply useless and not worth the effort??? :-\
So what would you do....and who would you recommend to install it?? Our project manager reckons some of these systems can just be bought as kits for less than half the cost of the quotes and installed by some of his team...really??? :thinking:
Any experiences and recommendations would be so welcome.
Thank you!
Gillian
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The Energy Saving Trust give impartial advice. I don't envy you - well, I envy you the house but not all the techy decisions ::)
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Hi Gillian,
On one specific point, I am not sure that wood-burning stoves are compatible with the airtight house system. When we had our woodburning stoves put in, possibly by the same bunch your quote is from as I know they are not far from you, discussions indicated that the function of the stoves depended on the leakiness of our house to air as the stove needs to draw air to burn the fuel, and if the house had not been so leaky ventilation holes would have needed to be put in. At least the draw of air from the house helps to prevent damp to some extent in this old house. I do not know if there are ways to draw outside air direct to the woodburner to avoid this problem, there may well be.
Simon
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We moved into our new build last year and had to make some of the same decisions. Our house is built with Scotframes Valutherm panels and is pretty well insulated although we do not have MVHR. We have UFH downstairs and no CH upstairs (although our small sitting room is upstairs and had a very small woodburner in it (mostly just for decoration!).
All of our CH and hot water comes from a gasifying log boiler (with a 2000 l thermal store) and we are on course for burning about 3 tons of wood in a year. As a result hot water solar panels would have saved us about £40 in wood a year which made the payback time over 100 years - so we decided against. Our neighbours on the other hand have electric water heating and consider their thermal solar panels to be a brilliant investment.
I did want PV solar but my supply of money was not limitless (although the cost of PV has about halfed since I was looking 3 years ago)
There is no requirement for plumbing for CH upstairs. The building regs say that you must be able to heat the house to 18C ( http://www.scotland.gov.uk/Topics/Built-Environment/Building/Building-standards/publications/pubtech/th2013domcomp (http://www.scotland.gov.uk/Topics/Built-Environment/Building/Building-standards/publications/pubtech/th2013domcomp) ). The SAP calculations will show the heat demand that you need to heat your house and as long as the heating system covers this then I don't see how they can force you to plumb upstairs. I am sure this could be argued although you may find that getting the plumber to run a couple of pipes inside a wall would only cost a few meters of pipe and an hour of labour - leave the pipes hidden in the wall so they can't be seen. This is what my plumber did (although it was not on the plans so building control had no knowledge it was there) for no extra cost.
As you have a modern airtight house make sure you get woodburning stoves with a direct air supply (a pipe that ducts straight outside so the stove draws air from outside and not the room. 1) this prevents drafts coming into the room when the stove is not on 2) this means you do not need a permanantly open vent from the room to outside (thus defeating all the efforts in making the house airtight) 3) reduces the risk of carbon monoxide poisoning. Only a minority (although increasing) number of manufacturers have this option for their stoves.
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I don't like the idea of a sealed house at all. The only one I've been in was hot, stuffy and airless. I love having the doors and windows open to let fresh air through (except on those days when there's just too much air :D) and I like to be able to hear what's going on outside. But that's irrelevant as you've already taken that decision.
I would certainly be aware of the possibilities of a build-up of carbon monoxide. moisture and carbon dioxide, although surely those things are already included in Building Regs?.
As for recouping the cost, when we looked into a simple wind turbine, or solar power collection, we realised that we would never recoup the initial cost, as we are now retired and simply wouldn't live long enough. We are going for better insulation and building wind-block porches front and back. When new technologies appear, they are likely to be more expensive than once they have become mainstream. Rather than looking at the broken down prices, how about looking at the overall cost difference between building your eco-house and a 'normal' house?
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I don't like the idea of a sealed house at all. The only one I've been in was hot, stuffy and airless. I love having the doors and windows open to let fresh air through (except on those days when there's just too much air :D) and I like to be able to hear what's going on outside. But that's irrelevant as you've already taken that decision.
Nor me, but I doubt if any house could be totally 'airless' - leave the doors open! :innocent: I can't see how a wood burner and sealed are compatible either. The whole point of an internal fire is it needs a draught to function.
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I don't like the idea of a sealed house at all. The only one I've been in was hot, stuffy and airless.
That's what the "mechanical heat recovery system" is for. Basically you extract moist stale air, usually from the kitchen / bathrooms and heat exchange it with incoming fresh air from outside. Because the house is then 'breathing' through a heat exchanger, rather than through thousands of little draughts like our old farmhouses do, it reduces the need for additional heating, so pebbles can just use her candles ;) .
Oor Wullie is right about ducting wood burners in from outside. Several manufacturers offer that option, and in your case it's going to be vital, or else Building Control will insist you knock a hole in the wall to give air to the stove, thus undoing all your hard work in keeping the place airtight. (They were going to insist on this for our old draughty place as it's just 'the rules', so that's why we went for outside ducted instead).
BTW, great as TAS is, have you tried asking these questions on the Green Building Forum (http://www.greenbuildingforum.co.uk/) or similar? You'll get much more expert answers than the well meaning drivel posted by me! ;)
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If you are having wood burning stoves why no water tank? The stoves will heat your water for you. In our house they didn't put a tank in and it really bugs me that whenever we have the stove on it is only heating that room.
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To update on our choices...
Our original plan:
- Underfloor heating (UFH) and heated towel rails (no radiators or heating of any kind upstairs) fuelled by...
- ...a gas boiler
- solar thermal panels for most of our domestic hot water
- a mechanical heat recovery ventilation (MHRV) system to recirculate warm air and then exchange for fresh air in this air-tight house
- two wood burning stoves only for seasonal use
- one thing we were sure of was that we didn't want a biomass boiler or ground or air source heat pumps (remember that point!!)
In total we had meetings and quotes from FOURTEEN different renewable companies....my head was spinning after all of that ::) ( I even had to create one of my complex spreadsheets to organise all the options) but it proved to be worthwhile as it totally changed our minds on just about everything! Some companies were ruled out as they couldn't work within our time scale, others because they seemed 'a bit dodgy' and others due to their hugely inflated prices which I think they based on what they "thought" we could afford looking at the size of the house....they'd have done better to look at our torn clothes, muddy boots and lack of any beauty treatments or trips to the hairdresser in years (that's me, not David BTW ;D )
Our decision:
- Still having UFH on entire ground floor (12 circuits of pipework feeding 9 individually controlled zones/ rooms) plus towel rails but no upstairs heating
- No gas boiler!!! (see below)
- One small company INSISTED on trying to convince us that an "air to water" air-source heat pump (ASHP) was PERFECT for our requirements. We humoured him but after about half an hour he had us interested, so we got some more ASHP specialists in (just to check) and they all agreed it was the way to go. Now the first chap had done all the hard work and won us over and we really wanted to give him the contract, but he went on holiday and on his return despite many calls from me he was just way to slow in coming back to us with the figures so we went with someone else (shame!). What he had convinced us was that we could forget installing a gas boiler and solar thermal panels (at a cost of around £10,000) and install an ASHP along with an unvented tank and booster tank in it's place (at around £13,000). This system would meet all of our UFH and domestic hot water requirements, and as a bonus we would receive an annual RHI (Renewable Heat Incentive) payment of around £1400 for seven years and the majority of its power would come from...
- ...Solar PV! I wanted as many panels as possible as we have a 3 phase electricity supply and had we opted to site them on the ground this could have been huge. In the end the professionals urged me to stick to a 4kw system and possibly install more panels at a later date on one of our steel sheds. We could have had a 4kw system installed for £4500, but as it's a new house with a gorgeous slate roof we wanted it to look good so opted for an in-roof system where the super slim black panels sit in a tray on the roof with only felt below and flashings (similar to velux windows) around which can be slated over.... the panels are almost flush with the slates and they look amazing....and we also saved on the slate which would normally have gone underneath!!! We also requested individual micro inverters which cost a little more but unlike a stringed system where the panels all link together and relay back to a single inverter only generating the maximum amount of the lowest performing panel, with individual inverters (in our case N-Phase ones) you get a much higher return from this more efficient system where the full amount of generated power from each panel is included. It, you and the manufacturer can also monitor each panel and have any failure or lack of performance flagged. There is also an on-line interface allowing you to monitor the amount of power being generated in real time....I will be glued to that screen, I just know it! I'm keen to see how it compare against the other systems TAS users are posting monthly performance of each month. To complement the Solar PV we have opted for a unit called an Immersun....best to just google that as I can't quite get my head how it works other than to say it's a clever little devise which reroutes excess power generated to where we need it rather than back in to the grid...in our case probably to the immerser in our tank. In total the Solar PV cost just over £8000....and in the 36 hours since it was turned on we have generated....wait for it....27.59kw (approximately £3.72...I think someone must have switched them off!!!)
- The MHRV system is still an essential requirement for an air tight house and it was originally needed for asthetic reasons....my partner used to be an architect - he designed our house and he does like things pretty....banks of air vents in the roof and ridge and walls was just too much of an eyesore for him, so the house went airtight and we needed MHRV!!! We received some ridiculous quotes to supply and fit one (upwards of £8500) and in the end we simply bought the "kit" for less than £3000 from the same company supplying and fitting our UFH and ASHP and following a free tutorial our joiners are now installing it (it's 95% ducting!!! and the supplier will check it all at the end.
- Finally the two wood burning stoves. They'll probably only be used for a few weeks each year but our hearts were set on them. Thanks to all the comments above it was confirmed that we did indeed need to install seperate air intakes for both stoves. These cost an additional £150 each to have installed and go straight through the outside walls and in to the back of the stoves. They don't affect the air-tightness of the house in the slightest :relief: We did look in to using the heat to generate hot water but it would have involved having a third water tank as connecting stoves (with flames) to pressurised tanks was akin to building a bomb :o and as the stoves will only be used a little in winter we were advised against.....and by this point I wasn't going to argue with anyone as I had information overload!
In total the ASHP, two tanks, Solar PV, MHRV including labour and two wood burning stoves with flues have eaten a whacking £32,000 in to our budget :'( ...although shopping around and getting multiple quotes has 'saved' us £17,000 on the most expensive company's prices. We will get the RHI over seven years totalling around £9800 along with the feed in tarrif for electricity produced.
The ASHP will very rarely have to rely on mains electricity, the MHRV system uses very little electricity, we have an abundance of free wood at the farm for the stoves and our gas connection which thank goodness it only cost a few hundred pounds(!!!) will now only be used by the range cooker.
So to summarise:
- Solar PV will give us power, provide most of the power to the ASHP and we'll get some feed in tarrif payments
- The ASHP will supply us with all our domestic and UFH requirements, will cost very little to run and reward us with an RHI payment of nearly £10,000 over seven years
- The mega efficient tanks will store our hot water at a constant temperature and only require small, infrequent boosts from the immerser inside to maintain this.
- Excess solar power will be cleverly rerouted via the Immersun unit
- Wood burning stoves will look gorgeous and give us additional 'free' heat in the winter
- MHRV will recycle 90% of the heat within the house and also exchange for fresh air (still not quite sure of how that works exactly)
- Towel rails in all of the bathrooms will be fed from one of the tanks and keep the bathrooms cosy
- The airtightness of this highly insulated house will mean it will maintain a regular, relatively low temperature with virtually no heat loss or wastage
- I am going to turn in to a loony who closely watches monitors to see when I should turn on the washing machine or dishwasher for the free power trying to recoup the £32,000 investment we've made!!!
Simples!!!
The 100mm floor insulation, UFH and 60mm screed went in over three days last week. The Solar PV took two days to install a couple of weeks ago and they returned this week to finish wiring it up. The ducting for the MHRV system is in place and just awaiting delivery of the 'machine'?? The flues and air inlets were installed in 6 hours a few weeks ago but it will be a few more weeks until the floor is ready for the hearths and stoves. Thank goodness we factored a utility room in to our plans - it now looks like a power station with the UFH pipes, manifold and control panel attached to one wall and two (one which is huge) tanks along another wall....think there may still be room for the freezer and my pulley...just!
Thanks for all of your comments they REALLY were helpful!
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You've obviously done a heck of a lot of research and I've not noticed this thread before. Exciting times.
I'll play a little devil's advocate here, though.
I had a hobby-shed built. A reasonable 25x12 feet (wish it was thee times the size!) with 4inches off celcon under the floor, walls and roof. I'm a phillistine when it comes to some rustic looks - preferring fucntion and practicalit over looks.. so it's upvc cladded as zero maintenance on a timber frame and thick ply lined so i can hang anything anywhere. And thoroughly double glazed with large windows and doors. I chicked a woodburner in too and had it professionally fitted with wall vents to make sure insurance companies couldn't wriggle out of pay-outs on my expensive hobby stuff.
< a pause here while I chased the neighbours sheep out of my cabbages>
The first cold night I lit a roaring fire.. whereupon shortly after the CO alarms went off and I tottered out into fresh air feeling dizzy and sick. I now light it with all four large windows cracked open and try to make the tiniest fire or the shed gets uncomfortably hot. this last summer it got so hot just from sunlight that I nailed sheets over the windows, had the door open and a large fan in there.
Woodburners: dirty, dusty, need lots of cleaning and sweeping and some repairs and maintennace. It's nice to sit by and the house has a huge one with back boiler. 20 tons of timber a winter? It takes me ages to cut, drag back to the barn, saw and split and stack. There's the cost of chainsaws and splitters, protective clothing, fuel for the saw and tractor. If I didnt have unlimited wood and have to deal with fallen trees and keeping the woodland tidy, I wouldn't bother. It makes the house dustier too.
I also put an extension on here. All the glass in that and general decent insulation in this house and this valley is a suntrap.. so last 2 summers we've had some very uncomfortable nights. I've just had some air source air-con put in. My business had some 16 units. Brilliant for keeping staff comfortable and quite economic for heating and cooling. BUT as a business i had them professionally serviced ona contract every 56 mths. They always found 'extras' and often a unit would fail 3-4 weeks after a service. The service was only a check and clean the filters and check the drains. That and motherboards that failed after the warranty put me right off Mitsubishi. I had a daikin unit put in my last house - never serviced it and it wa sbuller-proof for the 10 years we lived there. You can guess we used daikin again.
Units have changed. The 6.5kw (output effect) that's just been istalled - well i got the guy totest it's current draw while running and the figure was unbelievable at 1.2amps. In fact i don't beieve it - there has to be an error. But either way they are economic.
My dad designed his own house and helped build it. This was in the 60's and central heating UK was rare. He elected to hide all the pipework underfloor. Which was fine for 15 years until there was a leak- typically under the expensive 12 thick parquet that was over the concrete floor.
I had undercage hot pipes installed in my kennel banks cos those SS kennels look and feel cold. After dad's experience I made the plumbers pressure-test the system to failure - as in several times more than a usual pressure test - and then replace the failed bit. Not that we'ld ever do that again 'cos a pipe cap ricochetting around a room like a rifle bullet is quite scary. Next tme we'll just go to 50% over usual test.
Oh, and double glazing is the norm UK.. why? Other countries have gone to triple or even quadruple glazing.
My next project will be solarPV.. but not because I thik it's environmnally friendly.. far from it. the pollution making the stuff and shipping it and the future problems of disposal... No simply because interest rates on capital are so lousy that I'm betting against future price increases. I do worry about the poor warranty on the anciliaries- inverters etc and the cost/need to get someone up on the roof to clean them in a few years. it's a scary roof.
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So what is your projected electricity usage for both appliances and heat pump? What is the projected usage for heating and hot water? i ask because -
1. The number of UFH circuits indicate a very big house - much bigger than the surplus from 4 kwh of solar will service!
2. The inclusion of 2 WBS for back ground heating seems like overkill.
3. Heat pumps are good but they are at their least efficient cost wise when they are needed most and the contribution from 4kw PV (assuming noral electricty usage) will be next to nothing between Nov and Feb.
Regen
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We are coming to the end of our build( touching wood quickly). Including the garage its 180m sq.
We looked at timber frame kits and before we had lived in a new house we would have probably gone for one but during the planning stage we lived in a 9 year old house which had some form of timber frame. It was very warm but very noisy, the wood creaks and although you could not hear voices you could hear sound through the floors and walls.
So we went for traditional construction with a block and beam floors with UFH, with a air source heat pump, very insulated, 9kw PV. At the moment no additional heating is planned as the one thing we learnt from the newer house was most of the time we were too warm and only used the CH when it was really cold. So over the winter I am just going to use electric convector heaters if it needs a boost and if we really need one a wall hung gas fire run on LPG that needs no vent.
When its completed the next stage is to go into the roof, we went over the m sq that was allowed at initial planning so they would not pass the upstairs although the roof is the same. Originally we were going to have UFH upstairs but have decided just to use the odd electric heater.
I grew up in a 1950's house and have lived most of my life in homes with only standard insulation so I am more worried about being too hot.
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Hi all
Woodburners: dirty, dusty, need lots of cleaning and sweeping and some repairs and maintennace. It's nice to sit by and the house has a huge one with back boiler. 20 tons of timber a winter? It takes me ages to cut, drag back to the barn, saw and split and stack. There's the cost of chainsaws and splitters, protective clothing, fuel for the saw and tractor. If I didnt have unlimited wood and have to deal with fallen trees and keeping the woodland tidy, I wouldn't bother. It makes the house dustier too.
We've gone for modern self-cleaning stoves with a fast burn(?) which creates minimal ash and keeps the glass clean too (housework and me do not get along so it seems ideal ;D ) I am though slightly worried about the house being too warm but I've been assured the UFH runs at a constant, reletively low, comfortable level and although we'll have control panels in each 'zone' once everything is pre-programmed it should run well...it's predominantly there as we're installing a stone floor on the ground floor and I didn't fancy having to retrofit UFH when we realised we couldn't walk around without 3 pairs of socks on. The Mechanical Heat Recovery Ventilation system should also keep things comfortable (I hope).
So what is your projected electricity usage for both appliances and heat pump? What is the projected usage for heating and hot water? i ask because -
1. The number of UFH circuits indicate a very big house - much bigger than the surplus from 4 kwh of solar will service!
2. The inclusion of 2 WBS for back ground heating seems like overkill.
3. Heat pumps are good but they are at their least efficient cost wise when they are needed most and the contribution from 4kw PV (assuming noral electricty usage) will be next to nothing between Nov and Feb.
Regen
[/size]We never imagined a 4kw system would meet all of our electricity demands, we've just gone on the advice of 'the experts' but it should perform really well in the summer, we'll get our feed-in tarrif payments and we'll just need to pay for it in the winter....it will still be a lot cheaper than our current, smaller home to run.
[/size]As for the projected electricity usage, let me get back to you as all the paperwork and the installers reams of calculations are at the farm/build but it's actually a LOT less than our current useage in a 50 year old city apartment where we eat through a whopping 16000kwh per year :o and we don't even have a TV lolOverall the house is 310m2 (175 of which is the ground floor/ UFH) but it actually doesn't seem like a large house....it only has 3 bedrooms :innocent:
Its an 11kw Panasonic ASHP we're having installed and I still can't quite get my head around how it works but I think I remember being told that for every 1kw it takes to run it produces 4kw of energy...that'll do me![/font]
The wood burning stoves are totally unecessary....but we really wanted them. It's Scotland, the winters are blooming miserable, cold, dark, grey....these will bring a little bit of 'sunshine' and warmth in to the house :)
We are coming to the end of our build( touching wood quickly). Including the garage its 180m sq.
We looked at timber frame kits and before we had lived in a new house we would have probably gone for one but during the planning stage we lived in a 9 year old house which had some form of timber frame. It was very warm but very noisy, the wood creaks and although you could not hear voices you could hear sound through the floors and walls.
So we went for traditional construction with a block and beam floors with UFH, with a air source heat pump, very insulated, 9kw PV. At the moment no additional heating is planned as the one thing we learnt from the newer house was most of the time we were too warm and only used the CH when it was really cold. So over the winter I am just going to use electric convector heaters if it needs a boost and if we really need one a wall hung gas fire run on LPG that needs no vent.
When its completed the next stage is to go into the roof, we went over the m sq that was allowed at initial planning so they would not pass the upstairs although the roof is the same. Originally we were going to have UFH upstairs but have decided just to use the odd electric heater.
I grew up in a 1950's house and have lived most of my life in homes with only standard insulation so I am more worried about being too hot.
Yes, as I said above I am a bit worried about it being too warm....I don't need that with my hot flushes!!! :-[ so perhaps we'll manage some of the time just with the wood burning stoves....and slippers!!! We were immediately sold on the idea of a house constructed using SIPs (structural insulated panels) - quick to erect and super insulated we would have happily had a go at having NO heating systems inside but thanks to building regulations we have had to install not one, but two...kind of defeats our initial plans >:( but what can you do, you just cannot win with building regs - god knows we tried!
How long have you been in completing your build honeyend?
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We've gone for modern self-cleaning stoves with a fast burn(?) which creates minimal ash and keeps the glass clean too (housework and me do not get along so it seems ideal (http://www.accidentalsmallholder.net/forum/Smileys/default/grin.gif) ) I am though slightly worried about the house being too warm
The new woodburner I had installed in my hobby shed is that type.. has an extra afterburner thingy in it too. To be fair it's door glass does stay pretty clean and if it's cranked up to max then it'll burn off any dirt. BUT it still creates a mess - you can't avoid having to open the front to toss more wood in. I should have bought a smaller capacity one 'cos cranked up it delivers some serious heat. Cue open windows..
I wish my OH didn't feel the cold as much. I usually abandon downstairs when she has heating on or end up sitting just in underwear.. which sadly stopped being an attractive sight 20 years ago :-[