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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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    • CommentAuthorgoodevans
    • CommentTimeFeb 2nd 2020
    The first full month of living in the house is complete and the results are better than I had expected.

    Headline numbers: Gross internal floor area of the house is 154m2, envelope area 371m2 (roof walls and floor). ASHP heating & DHW. No solar. No gas or oil, i.e. all electric.

    Total energy usage for Jan 2020: 575 kWh (18.5kWh per day on average) That's all the energy usage for the house for 2 people.

    Heating accounts for about 3.5kWh per day for this January (the mild night last night and the morning sun meant the heating didn't cut in today) so today's usage was down at 15kWh.

    I think I will use around 6000kWh per year (39kWh per m2 floor area). The strange thing is I have not yet completed the MVHR system and so have 2x150mm diameter holes in the roof 24 hours a day, left open for temporary ventilation - so heating demand may come down further but ventilation energy may replace that.

    I have an ageing pc that I run 24 hours a day that could/should be replaced and would save perhaps 1kWh per day or more. But the heating seems to be cheap - I know it has been a mild January but I am still pleased. and I think that when outside averages around 9degC no heating would be required

    By many standards on this forum the house isn't spectacular in insulation values which are...

    Roof: 127m2, U value 0.13 (300mm of Rockrool and 15mm T&G4 OSB)
    Walls 113m2, U value 0.17 (175mm graphite EPS, single skin block)
    Windows 27m2, U value 0.8 (Triple Glazed, Munster)
    Ground 100m2, U value .137 (Beam and block suspended floor, 225mm white eps)

    Thermal bridges are good with the exception of door threshold design which I made a complete mess of. However no internal wall (light aggregate block) penetrates the eps floor insulation.

    Redeeming features: Small envelope for floor area, blower test TBD but no drafts have been detected (I'm hoping for around 1m3/m2env). Window area not excessive so hopefully keeping cool in the summer is possible.

    I'm feeling smug about the heating but perhaps more needs to be done WRT the day to day usage of energy or am I being too hard on myself? Most of the appliances are new but we didn't go all out for high efficiency.
    • CommentAuthortony
    • CommentTimeFeb 2nd 2020
    Impressive, well done, once running the ventilation system is likely to have a consumption

    Donโ€™t buy an electric toothbrush ๐Ÿ™‚
    Well done. What temperature do you keep the interior at and is it the same all over the house. What form of electric heating do you use.
    • CommentAuthorgoodevans
    • CommentTimeFeb 2nd 2020
    Peter, I have one thermostat at the moment - however because of the response time I am manually turning on and off the heating - If by early evening the lounge has reached 20.0 degC without in there that seems to make the lounge comfortable for the evening wearing jumpers (with the two of us in there the temp increases by around 0.4 degC - it decreases quite fast one we leave the room). To automate the heating I may need to build my own thermostat integrating heat loss, solar gain and heating supply over 24 hours or so.

    Heating is from an 9kW output ASHP on minimum (draws around 200 to 300 watts).

    We have no heating upstairs at the moment (UFH pipes are located in the ceiling - primarily for the summer so I can pump the cooleth from the ground floor slab upstairs - or, in a heat wave, cool the house from the bedrooms down with the ASHP.

    Upstairs seems only a degree or so cooler than downstairs although we are keeping all the doors open upstairs.

    I had thought I would need to balance the UFH loops but the heat appears to balance around the house fairly fast with open doors and reasonably fast with them closed. So all the UFH loops are open to full flow - this way I can reduce the power to the circulation pump - which makes it cheaper to run but most importantly quiet.

    The UFH manifolds are directly connected to the flow and return of the ASHP - no blending valves, no buffer tank, no heat exchanger.
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