Renewable energy for heating a renovated house

[scotslad]

Alright folks

 

Just looking for a bit of info from the more informed on here about various Renewable engergies and wether they are as good as some try to make out.

I have been trawling the net for a while now and it just seems to make things worse and my heid is about bursting now.

 

Did a search on here too and most of the threads were a good few years old now, just wondering if much has changed.

 

To give u an idea it is an old whin stone house, going to have to rip all timber out, new roof etc so have a fairly blank canvas to start from. I am planning to concrete the floor instead of timber and lay underfloor heating and it will be insulated up to all the current building regs. It will be about 100m2 area wise if that makes a difference so not a massive bungalow.

I'm at the early planning stage the now so just trying to get my head round it all

 

I originally thought a wood burner in living room/kitchen attached to a decent sized accumulator tank, nice and simple.

But worried now with a modern well insulated house and underfloor heating really won't take a lot of heat to heat the building/room but i will still need to have log burner on to heat the water. Most log burners from wot i have seen tend to heat 80/20, 20% of heat heats water rest the room. So worried i'll end up with a sauna trying to get enough hot water

 

Would i be better to have a more industrial style boiler in a boiler room just doing the accumulator tank and just having a log burner purely for 'looks' not even connected to water system.

I should say got access to plenty of cheap/free timber +saws+ tickets (local estate struggling to find boys with relevant tickets to take windblown hardwoods), so keen to use a log burner for as much as possible

 

Wot other renewables would suit well, the roof ridge lines runs n/s so have either east or west facing roofs, have thought about solar water pannels as would mean wouldn't need to put log burner on as much in summer to get hot water.

Was speaking to a government charity advising on all this the other day and they were really pushing PV but i couldn't see the point as i don't use a lot of elleccy anyway and i will be away at work when its producing the most so not really geting the full benefit from it

With the roof facing the 'wrong' way would either system work?

 

Finally do/are heat pumps any good?

I could put a ground source in fairly easily, have the space and could do the digger/labouring myself for a looped system. Are they worth it? Have heard in older ground source systems can get a voltage drop in ur house as it takes so much power to start the pump initally to get all the water flowing.

As for air source, energy trust where really trying to push the air source over all other types of renewable. Is it a better system than ground source?

Must admit i really don't understand how an air source heat pump works? Just can't understand how u can take air at say -2 and convert that into heating water to a temp off 20 or 30c. The house is up in the hills a bit so will be a bit colder up there, about 250m so does tend to get more frosts/snow when other local areas don't.

 

Cheers in advance.

Hope that all makes sense. The more folk i ask/or read the more confused i get esp when some folk are really pushing certain energies when others just really rubbish the same ones.

Hopefully this won't make it worse Cheers

[Fisherman Mike]

If you have a blank canvas you should endeavour to optimise the insulation of the fabric of the building in all areas. Its no good having 300mm in the loft and 100mm under the floor if the external walls are solid for example...so how do you intend to insulate these...thermal board lining ?

 

The key to any efficient heating system is to maximise efficiency and minimise heat loss, in short retain the heat in the building for as long as possible. Renewables are very efficient in properties highly insulated and where special attention is given to air leakage measures but sadly they lack controllability and if as you say you are not at home most of the day you will find more benefit in a instantaneous heat source.

 

Don't forget that to run air or heat source you need and uninterrupted electrical supply to run the heat exchange and circulation pumps as you would do in any conventional wet system. In many of the code 5 and 6 houses we build, air and ground source are coupled with PV which guarantees a generally uninterrupted supply. We install very few solar water heating panels as these are generally inefficient. Heat source operates in a similar way to your refrigerator but in reverse.

 

Wood burners are ok particularly if you can, as you say, get a cheap source of fuel but this will invariably become more expensive as their popularity increases.

 

Personally I don't particularly like under floor as its not instantaneous but if you can leave it ticking over in a well insulated property it can be very efficient.

 

If it were me, considering all the accumulated knowledge of over thirty five years in the industry I would use a conventional wet radiator system allied to a modern high efficiency oil boiler, use the wood burner as a feature and supplement with a couple of PV panels just to run the central heating pumps in the event of power failure.

 

I assume you will be replacing external doors and windows also.? if so consider triple glazing if its practicable and within your budget.

 

Hope this helps.

[goodo123]

If it was me I'd use a ground source heat pump coupled with solar panels and maybe a turbine.

[millrace]

Unless your 20 yrs old forget renuables unless you have green aspirations they won't pay for themselves and in twenty yrs will be inefficient and need replaced not ideal if your approaching retirement....you have to go full hog on it ,turbine PV heat pump,,,make your power run the pumps and emersions then it all works......take your money and put it into insulation the old building roof between rafter thermal board with plasterboard below rafter thermal board the walls the thickest you can afford high efficient boiler and wood burner,,,Stop the heat leaving!!!!! This way works just done in on 350 yr old listed house,,, good windows if you have to use wood fit shutters on inside,,triple glazing has/yet to be proved to save the increase cost factor of glass and fittings for the heavier units so wdnt bother but great for sound reduction.......

Edited April 9, 2014 by millrace

[scotslad]

Nowadays with modern building regs i thimk the house will have to be pressure tested for leaks/drafts.

 

At moment not entirely sure wot building control will state for build but imagine will either be putting a timber kit type inside the existing walls or just straping and lining, but still with the insulation. I think it is something like either 100-150 of kingspan think seems have to be taped too now

It will have to meet all the modern building regs so will be well insulated

 

Just don't want to have big oil bills, hear plenty of others constantly moan about their bills (granted old houses with no insulation)

 

MMike u mention PV but is that any good on a east/west facing roof? Wot happens if it's not a sunny day when the leccy fails? (Which would be more normal)

 

Just the whole thing seems very confusing. And to be fair even more confusing when exp boys who work in the trade are advising not to put renewables in, yet u read the net or speak to these energy advisers who are meant to be impartial and there meant to be the best thing since sliced bread

Not so bothered about my 'green credentials' just want it to be as cheap to run as possible and the wood is free/cheap apart from my time

[Fisherman Mike]

Like I said super efficient insulation is the key coupled with available modern technology...given optimum insulation values thus reducing heat loss and air leakage most heat sources will be efficient...on many of the super efficient houses we build gas and oil are still king and modern condensing boilers are incredibly efficient.

 

You have the opportunity to bring the property up to date and in line with the new Part L regulations ( Conservation of Heat and Power )and should possibly be looking to insulate to Passive House standards and perhaps introduce a heat recovery and ventilation system.

 

I beg to differ with respect to Millraces' opinion of triple glazing..The Scandinavians and Canadians have been using it for years, by its very nature its 50% more efficient than double glazing and only in large dimension windows and doors or curtain walling is the additional cost prohibitive.

 

I’m confident as the governments push towards zero Co2 in new home building by 2016 gathers pace it will soon become a mandatory requirement of the Building Regs. in all new properties. The heat loss through poorly fitting and insulated windows can be as much as 30 % of the total heat loss of a building and that can equate to 10 -20% additional fuel costs. If you can afford it and its suitable I would recommend you seriously consider it.

 

Special attention will need to be given to air leakage prevention which includes, sealing and caulking all wall and ceiling junctions, floor/wall junctions, external frames, roofing underlay, window frames and even plastered surfaces. I suggest you down load a copy of the current Building Regs. Part L from the Planning Portal and make yourself familiar with it. The downside as you can probabaly imagine of all this sealing and taping and airtightness is also introducing efficient ventilation ( so you can actually breathe ) that wont just dump your hard earned heat straight into the atmosphere. This is where a domestic heat recovery and ventilation system comes into play. Sounds daunting, but they need not be expensive in the scheme of things.

 

I have found the following a most informative and generally unbiased source of information, especially the useful links.

 

http://www.channel4.com/4homes/build-renovate/self-build-advice/how-to-build-a-passive-house

 

In short it costs a premium to be green but in the long term your domestic heating bills should be minimal.

 

With respect in order to fully comply current Building Regs. you will have to worry about your Green Credentials to some extent I'm afraid.

 

With your geographical orientation I would suggest that PV would be next to useless and any surplus would be minimal if not non-existent. Ground source would be worth considering but to reiterate super insulation, ventilation and recovery is the key.

 

Good luck.

Edited April 9, 2014 by Fisherman Mike

[kent]

firstly forget panels unless they face the direction of the suns arc return will be poor, if things change in the future (which I doubt) they are the easiest to retro fit. Air source heat pump is a waste of time in Scotland reasons being 1. when you need them most they are at their least efficient and you will be running on electric 2. most are air conditioning pumps running in reverse and air con pumps don't have the run time life required. you will be fixing and exchanging too much unless you spend mega bucks on the kit .

Heat pumps are very good but a long geo survey with probes needs completing first to get it right, this costs and you need the right guys doing it! Basically if you get it right you get on going heat recovery at a constant rate, if you don't you get diminishing returns till its no longer viable. The issue is you wont know what the cost will be till that survey is done and the company doing it will want paying for the survey. Were will you put a heat pump? Have you enough room in the bungalow? They are ideal for UFH as you run them 24 /7 just as required with an UFH system, very expensive to buy though if done well forget the electric its hardly relevant.

As you have an on-going supply of logs and the means to collect I suggest an external log furnace boiler batch burning and feeding to an appropriate sized accumulator tank. these tanks can take other hear sources as well so if you wanted to you could connect other secondary green or even non green sources of heat like an oil boiler or a space heating log stove etc. Fuel security long term is going to be no joke over the next twenty years and its as well to cover your bases! The issue is again this kit takes room though it need not be as high quality as the heat pump requires. Super insulated pipe can feed the heated water a good way and a lot of these furnaces have their own external housing. Consider also log drying and long term storage. consider though that furnace needs to be fed so its not ideal if you don't like getting up early before work and are away for 16hrs a day.

Just on the subject of UFH, when I was in the industry I found many owners just did not get the need to run 24/7 and often did not get their heads round suitable installation venues, its ideal for modern well insulated or passive homes but when your looking at an old stone bungalow its hard enough to bring it to modern stds of insulation let alone bring it up to a high enough std. If in doubt fit radiators! Chances are you have big windows and a high roof area to volume right and don't want to completely dig down and re-start that solid floor? Renovation costs can easy run away with you on these projects.

Above all do not trust the government they have a real history of lies, deception and changing their minds on funding in these areas. Any incentives are quickly being eaten up by raised cost of installations, inspections, certifications and hassle

[Nial]

triple glazing has/yet to be proved to save the increase cost factor of glass and fittings for the heavier units so wdnt bother but great for sound reduction.......

We're looking at an extension with a lot of glass. The increase from double to triple glazing was £20K to £22K with a U value improvement of 1.4 to 0.8.

 

It's a no brainier in my opinion.

 

Nial

[kent]

Just watch window stated U values theory and practice don't always come together that well. Triple glazing has two very big issues 1. increased weight on hardware 2. more than twice as likely to suffer premature breakdown of the seal. The best sound reduction is secondary glazing with acoustic tile btw. The fact remains windows no matter how good glass cannot compare with a well constructed and insulated wall in a 1930's-1970's bungalow the glazed area is likely to be a third of the outside walls at that's a big overall heat reduction.

If you want to see how poor windows are in relation to walls walk over and put your hand against the inner pane on any window without a rad under it warming the glass right now

[Brad93]

Air source heat pumps work because there is energy in any heat about absolute zero -273.15 degree Celsius. So as long as the temperature of the outside air is above absolute zero the refrigerant can take that energy and put it out as heat.

[Nial]

Air source heat pumps work because there is energy in any heat about absolute zero -273.15 degree Celsius. So as long as the temperature of the outside air is above absolute zero the refrigerant can take that energy and put it out as heat.

Aye but they're most efficient when the outside air isn't too cold.

 

They also supposedly make a bit of a racket. No probs in a commercial environment but not great in a residential back garden?

 

Nial

[kent]

Aye but they're most efficient when the outside air isn't too cold.

 

They also supposedly make a bit of a racket. No probs in a commercial environment but not great in a residential back garden?

 

Nial

 

In England you need planning consent to fit one, I have planning for one but didn't as the returns are terrible at the times its needed most and like I say most are air con pumps and wont give the required service life for payback.

[kent]

Air source heat pumps work because there is energy in any heat about absolute zero -273.15 degree Celsius. So as long as the temperature of the outside air is above absolute zero the refrigerant can take that energy and put it out as heat.

 

yes but its the rate of that return that's very poor when they have the longest run hours in winter. its likely cheaper to run on electric alone when you take plant and installation cost into account, great if you using it to keep an indoor pool heated in florida

[Brad93]

I know lots of people that heat their koi ponds on them. They have no problems with noise and it works out a lot cheaper than gas or electricity.

[Fisherman Mike]

I know lots of people that heat their koi ponds on them. They have no problems with noise and it works out a lot cheaper than gas or electricity.

yeah but Koi are happy living at 10 degrees c humans are not.

[kent]

I know lots of people that heat their koi ponds on them. They have no problems with noise and it works out a lot cheaper than gas or electricity.

I just have a little plug in job that keeps a small circle of ice free in mine for gasses to escape in winter and its quite a big deep pond and some of the koi are touching double figures. ASHP seems a bit over the top, not something I have seen personally, they aint tropical fish

[figgy]

Insullation and air leakage is the key to cheap bills.

 

You can insulate a house that well these days that your daily living and sunlight will generate more heat than you need.

 

Having just built a modern timber framed house that's full of Insullation and membranes to stop heat and air leaving, the underfloor heating can run at lower temperatures.

 

Modern anhydrate screeds with underfloor heating can heat up in about an hour from being set on frost, this makes it better in rooms you use less or if your out during the day.

 

As for taping the kingspan/cellotex type Insullation I used expanding foam to fill and seal all the joints in mine.

 

I never bothered with a heat recovery passive system due to too many joists running different ways stopping the duct runs, but people coming and going and dogs in and out will make more than enough air changes for me. If the structure had allowed I probably would have fitted it.

 

 

Figgy

[Spoonbed]

I would go with a Mitsi' Ecodan air source heat pump.

Also the Renewable Heat Incentive (RHI) kicks in from the 9th April, giving the householder 7.3p for every kWh of renewable heat they use in their home, if generated by an air source heat pump such as Ecodan.

[Fisherman Mike]

I would go with a Mitsi' Ecodan air source heat pump.

Also the Renewable Heat Incentive (RHI) kicks in from the 9th April, giving the householder 7.3p for every kWh of renewable heat they use in their home, if generated by an air source heat pump such as Ecodan.

True and they are very good but rely on maximum levels of insulation over and above the Governments target U value reductions in order to operate with any real efficiency.

 

You will probably use more than 7.3 pence worth of electricity to produce 1 KWH of surplus heat energy.

[Mungler]

Very interesting topic chaps.

[scotslad]

As will be obvious i'm not a builder so not very familar with regs and from wot i gather they are constantly changing and getting more stringent with reguards to insulation.

 

Will have to wait and see wot planning/building control say but imagine i will be putting a timber kit up in side the existing walls, my mate has just built a house and i have been well warned by him about all this insulation and taping joints etc (he ended up buying silage bale wrap tape as a lot cheaper than the stuff he was meant to, but still air tight tape)

 

I have looked into this RHI payments but to be eligible u need to have it signed of by a reistered MGS fitter and from the quotes i have had make numbers up and then treble them. Pretty scary. ! company recconed 10k for the smallest boiler, b loody crazy money that and becuase it shouldn't take much heat to heat such a small house i won't be using/generating enough Kw to get a decent return. A lot of farmers in my area are putting biomass in for this reason, there loving it. Makes a mockery of green energy the way the RHI payments work, all wrong.

 

 

My brother built his house about 8ish years ago so fairly modern and fairly well insulated (althou nothing like the standards now) his heating/boiler has broke twice this year, first time was in Jan when we had a bit of a cold snap took about 4-5 days before u actually noticed the heaing wasnae on althou it did take 3-4 days to get the house warmed up again once it was fixed. The concrete holds so much heat

 

Never heard of this heat recovery before so i will give it a look later on when i get some time.

 

All the timber in the house is going to have to come out including floor joists and floor anyway so it won't be that much extra hassle to concrete the floor anyway when i'm going that far.

 

Cheers folks some really good info so far.

 

Just an add on while ur here. Do any of u know much about private wind turbines? Got a wee bit of land with the house which is only a couple of miles as the crow flies to about 200 odd big turbines, think it might be slightly in a lee of the hill thou, only had the site a month so still learning it a bit, althou i have been climbing a cutting a few trees and i am fairly getting bufted about at times.

Is it easy to stick up an anometer? on a mast to try and measure wind speed? Is there and easy way to tell if there is any turbulance? as i gather the turbines don't like turbulance much

[kent]

with a bungalow your always faced with ventilation issues and condensation. unfortunately good insulation can make things worse. Heat recovery ventilation is of most use in passive homes, you simply wont get to that std unless you knock the think down and start again.

So insulate as you can, use your windows to air the property out and try and not dry washing indoors as much as practical. Seriously consider a thermal store that can take secondary heat sources as time will change viability and certainly use the logs if you have daily free access to this fuel even if its just a big long burning range in the home. We run an ESSE Ironheart and it does about 70% of our winter time cooking and kettle boiling as well as wacking out a high level of space heating (reducing call on the boiler), its perhaps the best buy we made in a 200k renovation of this place.

Renewable install costs are crazy (especially in Scotland) and can run way higher than they are worth in terms of savings and service life

[Yellow Bear]

I would go with a Mitsi' Ecodan air source heat pump.

Also the Renewable Heat Incentive (RHI) kicks in from the 9th April, giving the householder 7.3p for every kWh of renewable heat they use in their home, if generated by an air source heat pump such as Ecodan.

Air source are far less efficient in colder area than ground source - " slinky" buried at about 1m but no less than 600mm is probably the best option for this climate - air source also tend to "ice" at times reducing efficiency further.

[goodo123]

If you wanted to be really imaginative build a game room outhouse thing. Rig up the heat pump to keep that cool too. Your in effect using the heat from your game room to heat your home.

[Mungler]

Interesting thing on the news about Russia suggesting a massive hike in gas prices....

 

I think that's 100% on the cards.

 

Is there a site or an idiots guide to heating solutions? I just don't know enough about the options and solutions to make a decision.

 

I'm moving in 2 weeks and it's going to be a start again job, and I could go solar, under floor, gas, multi fuel, oil or a combination thereof. We're getting (or rather digging an extension that will include) a basement and someone suggested a heat pump. It's all Greek to me and unless I get into it it's going to be gas.