PowerSwitch

I am building a house. I have the fun of being able to design my house from scratch and do not have to compromise on any particular solution . However - therein lies the catch - there is so much to consider it can be overwhelming!

I was planning a very well insulated house which would have a Ground Source heat pump, but am now having second thoughts (very expensive, maybe OTT?). It was going to be supplemented by an open fire, and electric immersion for hot water. I was also going to have Mechanical Heat Recovery air circulation.

I now think I want to have a multi fuel (but normally wood) burning stove. I have read this http://www.powerswitch.org.uk/forum/vie ... ight=stove which seems to suggest that Clearview are very good - and it was seeing a Clearview at a friends house that convinced me to switch from open fire to stove. It is so efficient that they use a big one downstairs and a small one upstairs and nothing else to heat their house. It is also very pretty to look at.

My current hope is that I should combine a big stove with mechanical heat circulation, and that it should heat the whole house. A back boiler combined with solar panels could provide hot water in winter (I understand a back boiler could cause the stove windows to soot up a bit - is there a way to avoid this?). During the summer, solar panels could heat hot water on their own. Supplement this with an immersion, and hot water should be guaranteed.

My worry is heating. Would what I have described be enough? I could fit under floor heating and a backup oil boiler - but that would seem very wasteful if it is not required / but much cheaper to do from the outset if things did not work out with the stove.

Has anyone done this all before? What would you do?

House on 3 levels. 300 sq m. Rural.

I'd go for so much insulation that heating would hardly ever be needed -- eg 300mm rockwool for the walls etc.

I like the idea of PassivHaus, but I'm no expert, yet. No heating except a simple woodburner for the coldest days. Our resident building expert Kenneal must still be recovering from Christmas, and doesn't seem to be around at the moment, but no doubt will turn up.

Built into the south-facing side of a hill is ideal - though the chances of you being that lucky with your site are remote. Next down the list: the passive house, as I knew JohnB was going to mention.

GSHP = high electricity running costs (i.e. microgeneration won't help.) MHRV's are dubious in their efficacy - every case where I've heard of them being used has been disappointed. Clearview aren't the most efficient stove, despite what Clearview owners would have you believe.

First off, I'd design a house that needs minimal heating (aspect, materials U-value, insulation, etc...) Then I'd put in a solar DHW system and a woodburner. For selecting a woodburner, start off by looking at the efficacy figures from HETAS (available from their website.)

Just my opinion...

Regarding stoves, yes of course get a wood-burner and never an open fire, but in a new-build do consider a masonry stove. Not common in Britain but often found in colder lands such as Canada. Basically, there is lots of brickwork around the fire that acts as a heat store. Whether it's for you depends a bit on your lifestyle - how much you want constant heat or just quick heat of an evening.

If you do a google images for masonry stove you'll get a quick idea of what I mean.

You might find the Green Building Forum useful.

About the MVHR: they're very good for single rooms (for example a Kair 150 in the bathroom: we had one in our previous house) but not so brilliant in a whole-house set-up.

Clearview stoves are ace (we have one) however if you want to heat water too, you're probably better off with a Dunsley Yorkshire, the only stove plus backboiler combo to pass Smokeless Zone thingie. I realise you're rural, but low emissions imply high efficiency.

If you have a GSHP it's best used with under-floor heating, which doesn't need as high a temperature as rads do. The lower the temperature difference the higher the efficiency (CoP) but you know that anyway don't you ? Underfloor heating is great in bathrooms (no soggy floors!), kitchens, and conservatories (my folks have it). If you want carpets everywhere there are also b-i-g rads that cover 1/2 a wall and look trendy and don't need to run at very high temperature.

But really, really, uberalles (as they say), you want loads of insulation.

RenewableCandy wrote:About the MVHR: they're very good for single rooms (for example a Kair 150 in the bathroom: we had one in our previous house) but not so brilliant in a whole-house set-up.

They're an essential part of a PassivHaus, so they must work for a whole house. I only know what I've read on the Green Building Forum, but a lot of people are happy with them, and I think they're compulsory in Canada.

JohnB wrote:

RenewableCandy wrote:About the MVHR: they're very good for single rooms (for example a Kair 150 in the bathroom: we had one in our previous house) but not so brilliant in a whole-house set-up.

They're an essential part of a PassivHaus, so they must work for a whole house. I only know what I've read on the Green Building Forum, but a lot of people are happy with them, and I think they're compulsory in Canada.

Yes I wonder how the said PassivHaus would function in a power cut? I suppose you can have battery backup because they don't use much power.

RenewableCandy wrote:Yes I wonder how the said PassivHaus would function in a power cut? I suppose you can have battery backup because they don't use much power.

Better than one with a heat pump I should think! You can light the wood stove and open a window.

I really don't like the idea of depending on external sources for more energy than is really necessary, and think all house designing should be based around minimising inputs that could be scarce or intermittent in the future. Gas, oil, electricity, and wood too.

I agree with a lot of what has been said and would summarise as follows :-

1. Insulate to the highest degree you can get an architect to design in - go for scandinavian levels - triple glazing, high level of cavity insulation, breeze blocks on all exterior walls of the highly insulated variety (warm to the touch compared to standard breeze blocks).

2. Underfloor heating downstairs and upstairs - requires water at a much lower temperature than conventional radiators.

3. Solar Hot water panels and a south facing house with loads of windows on the South side and few on the north side. Conservatory to be South facing if possible.

4. Some form of renewable energy for heating - pellet boiler with auger and good storage area, ground source heat pump, etc.

5. No open fires - 70% heat up the chimney. And when not lit a fantastic conduit for syphoning all your heat in the house up the chimney and out into the cold air! Go for stoves with back boiler into your heating system / domestic hot water - 70% heat out into your room and/or into heating water.

6. Don't build it too big! We really don't need a massive house with a massive hall and stairway, etc. Build a sensible size.

7. Plant an orchard - your own (desert) fruit trees will be a delight, year in, year out.

Read up all over the internet and pick up on all the good points and get an architect who is into sustainable living and renewable energy - he will be a big bonus.

Good Luck!

I'd go with not so large a house as well, unless you have a HUGE family.
1000-1200 sq ft (I guess about 110-120sq metres) should be plenty. If you need room for storage of "things/stuff" build outbuildings. If it needs to be stored, 9 times out of 10 you don't need it.

Get a wood/multi fuel cook stove as well. Can't cook when there's no electric/gas available.

Jerry

Couple of points

GSHP are a bit of a bust.
4kw of electricity into 12kw of heat is pointless if you dont have 4kw of electricity.
Unless you have not that micro hydro, you dont.

Back boilers are not without problems.
Cooking on them is not really possible and they need cleaning more often.
If you want wood fired hot water, get two fires, one for cooking, one for water.

I'm not sold on masonary stoves personaly.
My maths may be off, but a 250kg cast iron stove should "store" 6900kj of heat assuming a temperature differential of 60 degrees.
Oh, thats actualy only two kw/h
Still, in a properly insulated house.

Anyway, I digress.
If your building from scratch, under floor heating, whether you power it by gas, oil, solar, wood or hamster generated electricity.

The most important bit is insulation.
Insulate everything OTT.
400mm rockwool in the loft, two cavity walls, triple glazing.

Then, solar hot water and a big thermal store for it, with a woodburning stove/back boiler.
A second wood burning stove with an oven, presumably the first in the living room the second in the kitchen.

The boiler one will get "sootie" but you only need to use it when you need to top up your hot water, which will probably not be very often.

Regarding wood fired cookers, we have been running an Esse for nearly 12 months. Very pleased so far. The model we opted for also provides hot water.

Bit pricey but should last many many years.

http://www.esse.com/cookers/cookers/woodfired.html

Gosh, the iPod of woodburners ...