Ecohouse not worth it.

The zero carbon building, developed by University of Cambridge architects as a prototype for future living, is based on a 600-year-old Medieval design that retains heat from the sun while cooling naturally in the summer.

Any extra energy needs are provided by solar panels on the roof and a woodchip boiler.

The unusual dome-like design is based on a Medieval technique, originating in Spain, known as "timbrel vaulting".

The four-bedroom "Eco-house", which will feature on the Channel 4 programme Grand Designs tonight (Wed), cost £445,000 to build.

A four bedroom house without all these fancy features is more like £100,000 (maybe £150,000) to build.

I\’m not sure that anyone thinks that the net present value of the energy usage of a house over its lifetime is £300,000, so this isn\’t in fact a sensible thing to build.

"Many of the costs come from the new technology it uses for energy storage and generation. If those become more widely available, making a similar house cheaply in much larger quantities may be possible."

Quite. The only problem with low cost green energy generation is that there isn\’t, as yet, any method of low cost green energy generation. I agree absolutely that all sorts of wonderful things would be possible (even will be possible when) if there were, but there ain\’t.

10 comments on “Ecohouse not worth it.

  1. I am sure that the kind of mediaeval Spanish buildings on which the design is based did not cost 4* the average. Surely, as Luis says, it is like the difference between a made-to-measure Saville Row suit and one off the rack at Suits You.

  2. Nice. It’s classed as zero-carbon just because it might not use any fossil fuels to heat, handily ignoring the emissions from construction.

    It’s a big Nissen hut made of tiles or bricks. The triple glazing might represent a substantial cost as there is a lot of it. Some of the excess could also be in the labour, which given the scarcity of this building technique probably came at a hefty premium.

    The cost of recycled paper insulation ought to have comes down…

    I wonder if the cost of designing it is included in that £445,000. A one off is going to cost a bob or two. A Wimpey/Barratt/Taylor Woodrow jobbie gets drawn once and copied many times.

  3. Given value is subjective, I’m sure there’s some people who feel its worth them paying for it, even if its just for bragging rights/feeling superior to the Jones’s.

    So long as no tax money is spent on it… (chances of that? so close to zero I can’t tell the difference).

  4. and, umm, Tim, shouldn’t somebody who frequently talks about the role of externalities in environmental economics, not be talking about something being ‘not worth it’ because the private costs exceed the private benefits?

    Tim adds: True….but I don’t think that anyone says that the externalities of a badly insulated house are worth £350,000 either. Nor those of the extra power such a house would require etc. UK emissions per capita are under 10 tonnes a year (but allow me to use that for the maths) and average household size is 2.4. 25 tonnes a year then, of which under 20% is from housing (made up number but around right). 5 tonnes a year saved by this house being entirely non CO2 emitting. That has a social value, according to the Stern type numbers, of well under a £100 a year.

    Payback period is 3,500 years. Not really worth it, is it?

  5. johnny. I can see where you’re coming from (really!) but most would not consider Nuclear ‘cheap’ and the vast majority of the ‘greenies’ would not consider it green either. (Although it patently is!)

  6. I don’t think you could build an equivalent non-green house for £150,000. Are you sure the land costs aren’t included in the £445,000.

    Even if they are not, it will have many features and a build quality not seen anywhere near a Wimpy or Taylor Woodrow home.

    The Grand Designs web-site is quite detailed for previous houses, so it will be interesting to see more details when they put this one up.

  7. Medieval builders didn’t make houses that shape because of heat losses (they generally had a fire inside, it wasn’t really an issue).

    They made them that shape because they could find treetrunks and branches that shape (therefore less labour in cutting and shaping) and because they hadn’t found any materials suitable for horizontal load-bearing members (except for inconveniently massive – therefore heavy and rare – tree trunks).

    No real need to emulate it now, therefore, unless you just like the look of it. It is, admittedly, a handsome building.

    Second Tim’s comments about the cost; build a cheaper house, pay for the energy out of the money you didn’t spend on gimmicks.

  8. Andrew – have you ever been to inland Spain in the month of August, where at 0900 the temperature is 30 degrees and it remains like that till about 0100 the next morning? thick walls, small windows and lots of air flow…

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