aha. People keep telling me I should have got grand designs to film our barn conversion but I gather it's not sufficiently doomed to failure, with oversized egos, tantrums and outrageously expensive design finishes 
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Pre-made homes
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Posted 2 years ago #
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one of the architects I worked with was on GD with her piano house in London. I think because she was an idiot her house went half a million over budget.
Posted 2 years ago # -
That would make insulating them pointless as you're dumpign a houseful of heat each time. I have that problem now in a brick flat!
Not so - letting all the warm air out of the house doesn't remove ALL the heat from the house, as air doesn't actually hold that much. Most of the heat is in the furniture, walls etc.
Posted 2 years ago # -
I am very much a fan of the Scandinavian houses, there are a few manufacturers that bring them over and put them up for you (the basic shell - you supply the plot and pop the foundations/services down then they put up the basic structure). They will probably be at the show... ace buildings that are very, very efficient.
For plots - an alternative is to buy a complete gopping wreck of a place and bulldoze it. It may be a cheaper/easier option than getting a site with planning
Posted 2 years ago # -
Not so - letting all the warm air out of the house doesn't remove ALL the heat from the house, as air doesn't actually hold that much. Most of the heat is in the furniture, walls etc.
I'm aware of the thermal mass of the hard parts of the house, but they convey very little to the heating of the house - i.e. if you open the doors and flush out the cold air, the temp diff from table to air is minimal, so the heat transfer is slow and low, in order to re-heat the air you need the rads on, which needs burning of fuel. Though that doesn't mean you have to re-heat the hardware again (which saves obviously) it's still not ideal. It takes 35 minutes (I checked, last night) just to increase air temp in my flat from 19.5 to 21 degress. 35 minutes of the boiler on full whack and the rads at 65c. To go from ~5C outside temp it would take considerably longer, you can appreciate. To do that daily is nuts. I'll find the article if I can, but killing draughts and air-loss is meant to be just about the most effective method of improving home efficiency, as lost hot air and replaced cold air = comeplete loss.
For plots - an alternative is to buy a complete gopping wreck of a place and bulldoze it. It may be a cheaper/easier option than getting a site with planning
Still need planning, just not quite as difficult as dropping a new house in a previously open green field!
Posted 2 years ago # -
I have approx 310kg of air in my flat. Heat capacity of air is 1.05 KJ/kgK. So that's 1.05*310=~330 KJ/K. To take open my windows and take the air away I'm going from ~20C to ~5C, so 15C diff. So 15*330KJ ~=5MJ of energy binned. Seeing as 1J = 1w.s, that's take a 3KW electric heater half an hour to replace if it was 100% efficient.
Posted 2 years ago # -
out of interest, how much does it cost to build 'a house'
nothing fancy or outstanding, just a detatched, 3-4 bedroom, bricks and mortar house, cavity wall insulation, normal central heating and radiators, double garrage. Just an average suburban house, built to a reasnoble standard (so not david willson [st]homes[/st]sheds etc)
Posted 2 years ago # -
try western log group
they're near afan so a good excuse for a ride if ever i've heard.
we're thinking of one too.
Posted 2 years ago # -
The standard insurance rebuild cost for 3-4 bedroom house is ca £90,000 (depending upon various rating factors such as location, materials etc....)
Posted 2 years ago # -
tinas - meant to be around the £100 per square foot region IIRC.
Posted 2 years ago # -
Standard off the cuff response is £1,000.00 per square metre.
Posted 2 years ago # -
Though I've read about people managing it for ~50 and as high as 250 /sqft
Posted 2 years ago # -
Just always wondered how much more people on grand designs were paying compared to if they'd just settled for a more normal house on the same plot.
There were plots for sale on the outskirts of Reading for £17,000, no planning permission, but in a place you could reasnobly expect to get it in 5-10 years time (technicaly greenbelt, but over the road form a new housing estate).
Posted 2 years ago # -
Clearly letting all the air out of your house is not ideal, I'd have to be an idiot to think that and as well all know, I'm not
I was just pulling you up on a technical point 
And the more practical point that even if you left all the windows open for half an hour your house wouldn't be as cold as it woudl be when you say came back from holiday having left the heating off.What about calculating the rate of heat loss through the required ventilation compared to the rate of heat loss through walls/windows/roof etc? Would be interesting.
Posted 2 years ago # -
tinas - stay well clear of those unless your are v. well informed. most land bank resellers are scamming the ignorant.
as to construction cost, Build it and self build magazines cover it regularly.
Posted 2 years ago # -
What about calculating the rate of heat loss through the required ventilation compared to the rate of heat loss through walls/windows/roof etc? Would be interesting.
I've no idea what the required ventilation rates are at the moment TBH, but ventilation losses will always be in addition to loss through walls, so while it may be a small percentage, it's always there and always something to minimise. The heat exchanger systems may well be good for this.
Posted 2 years ago # -
If letting air out of the building isn't an issue why are we designing air tight buildings... Enhanced accredited details etc ? Mevhr system that mean you don't have to open a window for ventilation.
Coffeeking- with reference to your post at the top... That's enough!
Posted 2 years ago # -
If letting air out of the building isn't an issue
I never said it wasn't an issue.
Interesting how people don't read things properly, isn't it?
Posted 2 years ago # -
I'm nearing the end of a self build. I looked into SIPS and beco wallforms but eventually went with tried and tested timber frame and went over spec on insulation.
Easily the best VFM way to build a house imo.
I would still love to do a beco house one day but I found it hard to get a builder interested in it. They are very resistant to change generally I've found.
Most will take your plans and think, 'Hmm, never used this stuff before, best think of a healthy price then double it.'
I also looked at various 'green' things for heat power etc but they all seem to be eye wateringly expensive and just before they have paid for themselves, will implode and need replaced. Only one I'd consider would be solar hot water but I dont have a suitable south roof area due to dormers.
Throwing a few extra thousand pounds worth of insulation at it is easy and effective long term.Posted 2 years ago # -
I'm 'experimenting' with photovoltaics at the moment, a lot better when it comes to awkward roofs. You thought about geothermal or did you not have the room?
Posted 2 years ago # -
My Dad works for a company that manufactures insulation products that are used in 'kit' houses, timber kit ones are a bit of a muchness though the best prefab ones are reckoned to be German or Scandinavian.
Posted 2 years ago # -
I think greenwoood make a small version of their MVHR, or you could try vent axia.
as for MVHR causing draughts - cant see it unless the vents/ducts were incorrctly placed. the fans are Dc powered, continuously running type and the actual flow rate is way less than that in one of the light/fan combo's you get in most bathrooms. 80% heat recovery is possble so it a nobrainer in new build IMHO.
Posted 2 years ago #
Topic Closed
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