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Green Building Bible, Fourth Edition
Green Building Bible, fourth edition (both books)
These two books are the perfect starting place to help you get to grips with one of the most vitally important aspects of our society - our homes and living environment.

PLEASE NOTE: A download link for Volume 1 will be sent to you by email and Volume 2 will be sent to you by post as a book.

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    • CommentAuthorMH
    • CommentTimeApr 15th 2007

    I was wondering what forms of current renewable energy technologies can actually provide energy for space heating. With natural gas used alot, a replacement will be needed soon but what realistic alternatives are there for natural gas?

    I've been trying to find energy consumption figures for an average home so I could compare the required figures with what the existing technologies 'say' they can provide. I though it'd be easy but its proven very difficult. Anyone have any tips. All I've found so far is this http://www.defra.gov.uk/environment/statistics/supp/spkf22.htm but it seems to only show our electrical needs. I think space heating is a key aspect to help reduce those carbon emissions!
    Biomass, GSHP (if you sign up to a renewable elec tariff (or have an enormous pv array, or a wind turbine). If V windy, speak to Jane Smith re storage htrs as dump-loads from a turbine. Solar (passive first, SWH 2nd).
    • CommentAuthorpatrick
    • CommentTimeApr 16th 2007
    I know that technology, turbines, pipes, valves etc is very interesting (I have a house full of interesting things to prove it, so I am not in a position to have a go at anyone) But if the object is to reduce carbon emissions we should not discuss alternative energy generation until we have reduces demand. The first consideration for space heating is the human body in a super insulated house. The carbon emission from building all of this unnecessary kit must be huge.
    I am probably as bad as any one, so don’t throw stoned as I am living in a bit of a “glass house” myself ….. I just think the interesting technology and pressure from client makes us tackle the problem from the wrong end.
    I totally agree with Patrick. Too much emphasis on changing heating systems for something eco-friendly and expensive when reducing consumption is the key to cutting emissions.

    When you look at space heating, you need to think about reducing the length of the heating season. Obvious way of doing this is to first insulate your body. I am happy, nay proud, to admit to wearing full thermals indoors (I have two sets so I can wash...) all through the heating season. It really does make a difference to the temperature that you can set your thermostat to to remain comfortable (2 degrees I think).

    I had a student tenant call me recently complaining she had received a mild burn to her upper arm from a pipe drop to a central heating radiator in her hallway. I expressed my disapproval that she was wearing a sleeveless top in the house with the heating on full bore, to wish she seems to take mind offence but people need to be taken to task over this. How many houses have you been in which are swelteringly hot but the occupants are walking round dressed like it is the middle of June?

    Next, address the thermal efficiency of the building envelope and draft proofing and efficient ventilation. Once you have done all that, you might find that the space heating load isn't that great. You might knock a month or two off either end of the heating season. You might then decide to keep the existing heating system until it is beyond economic repair (or fuel suppliee become unreliable or too expensive) then replace it with something simple and cheap, like a wood or multi-fuel stove, to see you through the coldest months.
    • CommentAuthorMH
    • CommentTimeApr 16th 2007
    Thats what I put forward in my research 1) reduce wastage therefore less consumption then 2) Retro fit Microgeneration tech. But the angle I was looking at was to achieve the 'zero' carbon home (if its actaully possible that is for the existing stock) which is why I wanted to know if microgen tech like Wind and PV (which aim to provide electricity first) can provide All the heating needs.

    I'm quite surprised the lack of data available that actually looks at the our energy consumption levels. The Government seems to like to show the carbon levels of sectors etc and how they meet their targets but when you try and narow down the actual data it proves to be very difficult. It seems they think electrical energy is ALL the energy a home consumes. I have to admit before I started my research, I also thought that electrical energy is more than our heating needs so and if thats what most of the public think aswell that's a major issue in my opinion. More awareness is needed!!!
    • CommentAuthorMH
    • CommentTimeApr 16th 2007
    Just incase there are others interested, I found this by the BRE: Domestic energy fact file 2003 which can be found at http://projects.bre.co.uk/factfile/BR457prtnew.pdf. Includes figures over the past 30 years of consumption levels by end-use.
    • CommentAuthorpatrick
    • CommentTimeApr 16th 2007
    Thanks for the BRE fact file link (very timely).
    In theory 'zero' carbon may be possible with some of the existing stock, but the economics (VAT, economy of scale) and public reluctance to spend on upgrading their own homes explains why government policy is towards large scale rebuilds, to increasingly high specs. (in over 50 loft conversions and extensions no client has ever asked about insulation other than to meet minimum building regs. as cheaply as possible)
    As to microgen tech like Wind and PV; the best theatrical option will be a balance between transmission costs and most effective scale in the generation plant.
    Take your choice; can people work together on "village" level CHP burning, waste, biofule, pets etc despite all of the legislative, political, NIMBY and social barriers.
    I think not until gas prices triple.
    Just writing this depresses me..... what was your question?
    • CommentAuthorMH
    • CommentTimeApr 16th 2007
    It does seem a bad situation, even if the domestic sector ever achieved zero the other sectors need to help big time.
    I think if there was a form of technology that could replace the heating of space and water demands in a home many people would go for it just like changing their boilers for efficiency ones. I'm surprised how much energy space and water heating consumes and wouldn't be surprised if many of the occupants in the UK actually know this themselves.
    • CommentAuthorGuest
    • CommentTimeApr 17th 2007
    Anybody tried or know of anyone who has tried the solar air heating panels such as SolarVenti? From their website it looks as if they could provide quite a substantial chunk of space heating for a domestic property for free.
    See http://www.solarventi.co.uk/index.pl?art=20
    • CommentAuthorGuest
    • CommentTimeApr 17th 2007
    I wouldn't put much hope on Solar Venti. The analysis on that web-page is technically flawed - their units are wrong for a start.
    • CommentAuthorGuest
    • CommentTimeApr 17th 2007
    Follow up question to my first post (1st Guest post above).
    Can you explain what you mean by "technically flawed"? And what do you mean by "their units are wrong"? Have you tried or used one, or can you point me to some technical evidence/discussion that suggests that they don't work?
    I came across their website by chance and thought maybe someone here might have tried/seen/knew of one in use anywhere because looking at the customer feedback that they have on their site, it looks as if they actually provide some pretty decent supplemental heat energy. One guy claims to have turned his heating controls down by 50% over last winter. If that's true, then it surely represents a substantial energy saving.
    • CommentAuthorGuest
    • CommentTimeApr 17th 2007
    The units of energy are kWh not kW/hr. And the simplification of the calculation they've used is pretty extreme. Describing that because the air temp. is increased by 30 deg.C it provides over half a kW for 1000 hours of free heat is dubious.

    Firstly, does the panel increase the heat of air by 30 deg.C - plausible but depends upon incident sunlight and surrounding air/surface temperatures - and does this allow for the poorly situated panel as shown in the picture (though granted this does depend on the latitude of the building).

    Secondly, is the heat usable? The hours of incident sunlight may not be during occupied hours or when the building is requiring heat. Thermal mass is also a factor. Air is a poor heat transfer medium and if anyone waas interested in this system I'd query whether a solar collector isn't a better use of the roof area.
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