Building and energy efficient house





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  1. #1
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    Default Building and energy efficient house

    So we are looking at building in the next few years and already started the divorce proceedings... jokes (but we did check the prenup).

    Realizing that energy efficiency is too often added on afterward or as an after thought I want to design the house around security and energy efficiency.

    The security bit is another thread alone.

    House is in Cape Town, on a west facing slope.

    I was first thinking of building materials and style. Most fancy designer houses have parapet walls and after my current house and the sealing nightmares... never again. So the house will be standard brick and roof with large overhangs (balcony/ patio all the way around the house). These will keep the sun out the house and with roll down siding to keep the rain off the patio in bad weather.

    Face-brick.

    Roof will have North facing facet at optimum angle for solar panels, pool heating and geyser panels.

    Skylights.

    Fully insulated ceiling.

    And that's as far as I have got.

    I was thinking that a clever wall design with a fan could harness the South Easter.
    Talk softly, carry a big stick.

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    Have you thought of a light steel structure? Building time halved and insulation capabilities good.
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    Your architect has a complete SABS code to GUIDE him with an energy efficient design.

    Some see this as a hurdle to overcome to build your dream home .... those that have been in Europe smile as these rules are not even half way where it should be !!


    we CAN build homes that are a LOT more energy efficient !!


    but rather spend 99% of the design time on esthetics .....



    The person to give you the BEST guidance is certainly MikeAG



    from an energy perspective - see how you can gel the following with your esthetics :
    - INSULATE the home.
    - STOP air leakage
    - PV is the way to go -
    * PV panels and 48V element to drive your geysers
    * PV panels, and a battery bank to drive a 12V light system for the whole house
    - Invest in modern fridges and freezers with inverter starters
    - Invest in a modern washing mashine


    one thing to bear in mind - in a "few years" the whole grid tied solar issue may have been clarified, and just maybe it might be worth it (NOT, if they stick to the current proposals)

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    Quote Originally Posted by Stone Accessories View Post
    Have you thought of a light steel structure? Building time halved and insulation capabilities good.
    There are a couple of methods to looked at. There is a new type of breeze block a friend is using to build his house from that is also much cheaper than brick.

    Of cource insurance is easier with brick.

    What roof material is the most efficient? I am talking about overall. No point in something being a super insulator that needs replacing every two years.
    Last edited by Biggles; 2015/01/15 at 02:39 PM.
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    I am also looking at rain water harvesting. As the house is on a slope I can then use it for irrigation/ pool water without a pump.

    I also like the idea of using grey water for irrigation.
    Talk softly, carry a big stick.

  6. #6
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    Quote Originally Posted by ChrisF View Post
    Your architect has a complete SABS code to GUIDE him with an energy efficient design.

    Some see this as a hurdle to overcome to build your dream home .... those that have been in Europe smile as these rules are not even half way where it should be !!


    we CAN build homes that are a LOT more energy efficient !!


    but rather spend 99% of the design time on esthetics .....



    The person to give you the BEST guidance is certainly MikeAG



    from an energy perspective - see how you can gel the following with your esthetics :
    - INSULATE the home.
    - STOP air leakage
    - PV is the way to go -
    * PV panels and 48V element to drive your geysers
    * PV panels, and a battery bank to drive a 12V light system for the whole house
    - Invest in modern fridges and freezers with inverter starters
    - Invest in a modern washing mashine


    one thing to bear in mind - in a "few years" the whole grid tied solar issue may have been clarified, and just maybe it might be worth it (NOT, if they stick to the current proposals)
    I have done some cursory research on this an applying my own logic, full PV or Solar and 12V DC means battery packs and and and while we still have a functioning grid I think batteries are a waste of money and essentially a very expensive consumable. By omitting batteries payback is a lot shorter.

    I am not sure how legal this is but a heard via a friend of a friends gardener that if you end up generating excess power from the panels, it actually runs the power meter backwards. So while eksdom is not buying it off you you are reducing your bill.
    Talk softly, carry a big stick.

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    Since 2 years ago, the energy efficiency of a house is prescribed in South Africa's Building Standards . . it is not optional anymore, and your plans have to show the energy efficiency before the city of Cape Town will allow you to build.

    The simple rules are to keep the fenestration (glazed windows) under 10 or 15% of floor area. Minimal west-facing windows. Bedrooms and living-rooms with north-facing windows. (long rectangular floor-plan on an east-west axis). Roof overhang calculated to shade windows in summer but allow full sun in winter. (600mm wide eave, 400mm above window top works for Cape Town). 130mm "think-pink" on ceiling. Cape Town outer walls have to air-space cavity, which already does insulate somewhat.

    A 40 degree steep roof is great for solar panels. Also allows the tank to be neatly in the roof, without needing pumps for circulation.

    Hope your main sewer line is on the lower side of your sloping plot. Helps to drain sludge of grey water tank.

    Before designing for energy, consider designing for Cape Town's notorious wind from the south-east. A high pitched roof can be part of the anti-wind plan. If anywhere near the sea, consider corrosion-proof materials and avoid wooden window frames. (Quite different here to Windhoek)

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    Maybe investigate NewTec (SP) as well with the light steel frame building. The houses I have been in was very insulated and it made a big difference. While building maybe dig a large tank into the foundation in which you can store rainwater - no plastic tanks standing around the house...?!?!

    Enjoy the research and good luck!
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    Quote Originally Posted by Christob View Post
    Maybe investigate NewTec (SP) as well with the light steel frame building. The houses I have been in was very insulated and it made a big difference. While building maybe dig a large tank into the foundation in which you can store rainwater - no plastic tanks standing around the house...?!?!

    Enjoy the research and good luck!
    Sitting in a light steel frame building now... it just doesn't have the "safe as houses" feel to it. You knock the wall and if feels prefab. Looks great. I have aircon and a huge window so cannot comment on the insulation but just not sure about whether it will last like brick and mortar.
    Talk softly, carry a big stick.

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    Quote Originally Posted by Gerald_D View Post
    Since 2 years ago, the energy efficiency of a house is prescribed in South Africa's Building Standards . . it is not optional anymore, and your plans have to show the energy efficiency before the city of Cape Town will allow you to build.

    The simple rules are to keep the fenestration (glazed windows) under 10 or 15% of floor area. Minimal west-facing windows. Bedrooms and living-rooms with north-facing windows. (long rectangular floor-plan on an east-west axis). Roof overhang calculated to shade windows in summer but allow full sun in winter. (600mm wide eave, 400mm above window top works for Cape Town). 130mm "think-pink" on ceiling. Cape Town outer walls have to air-space cavity, which already does insulate somewhat.

    A 40 degree steep roof is great for solar panels. Also allows the tank to be neatly in the roof, without needing pumps for circulation.

    Hope your main sewer line is on the lower side of your sloping plot. Helps to drain sludge of grey water tank.

    Before designing for energy, consider designing for Cape Town's notorious wind from the south-east. A high pitched roof can be part of the anti-wind plan. If anywhere near the sea, consider corrosion-proof materials and avoid wooden window frames. (Quite different here to Windhoek)
    But the View is to the West!! Plattekloof is the target suburb. I have a house there now but looking at moving (I am in Windhoek temporarily).

    The wind is a large consideration. I am thinking of a large U shaped building with the pool in the U and sheltered. The u will have the southern side longer than the northern side. If you have all the doors opening into the U you should not have a wind tunnel like most CT house seem designed to have.

    Winter sun will be through skylights.
    Talk softly, carry a big stick.

  11. #11
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    Biggles, if you want send me a pm with you phone number, then we can chat. Over here in Germany we have unreal rules & regs concerning energy efficiency, insulation etc. I have looked into these as I contemplated building here.
    I currently plan a house to be build near Mosselbay, so there are a few similarities to your building plans, and I am concentrating on security and insulation.

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    There is a whole book to be written on the subject, rather than just a post on a forum, but as I have said many times on here, with your climate, it is child's play to design a building that requires zero space heating, zero cooling, and zero external inputs for hot water, yet remains at a constant comfortable temperature and has hot water whenever you want it.

    None...none......of your houses have enough insulation. No-one seems to be thinking about the huge differences in thermal performance between lightweight (ie framed) construction, and heavyweight construction. Insulation is a very long way from being the whole story with thermal performance: it has to be tied to thermal mass to get its full benefit.

    I would start with an externally insulated masonry wall construction, and control the amount of direct sunlight which reached it. I would have north-facing external sun-spaces for passive solar gain in the winter (you all know how chilly it can get in SA in the winter) which can be folded away in the summer. Of course, it would be double glazed. Those of you following my renovation thread know that I will be installing triple glazing, and a mechanical ventilation system with a heat exchanger to control ventilation heat losses. The latter also handles ventilation "coolth" losses. I doubt such stuff is available in SA.

    Anyway, this subject is my daily bread, so my over-arching advice would be to select your architect very carefully. If they don't aspire to producing a zero-energy building, then don't employ them. If they think that 130mm of mineral wool is adequate......don't employ them.
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    Mike sadly very FEW architects in SA has the first clue of "energy efficiency" ....

    THAT is why we now have "Energy efficiency Regulations" ... which is LIGHT WEIGHT.



    were involved with two homes for a person with homes in various countries and continents .... was almost sad to see the client fighting the architect to implement European energy efficiency principles.

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    Quote Originally Posted by Biggles View Post
    But the View is to the West!!
    West facing windows grab hot sun in the afternoons, unless they are double-glazed and have special heat reflection. Overhanging eaves only work properly for north facing windows.

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    Here is a brief overview of Cape Towns energy efficiency requirements:
    https://www.capetown.gov.za/en/Energ..._01Mar2012.pdf

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    Quote Originally Posted by ChrisF View Post
    Mike sadly very FEW architects in SA has the first clue of "energy efficiency" ....

    THAT is why we now have "Energy efficiency Regulations" ... which is LIGHT WEIGHT.



    were involved with two homes for a person with homes in various countries and continents .... was almost sad to see the client fighting the architect to implement European energy efficiency principles.
    And my son has a Masters Degree in Architecture and he specializes in energy efficient homes. He designs some of the countries best.

    He designed mine which is in build and broke ground today. see other thread.

    Mike we have spoken one to one on this.

    I really nead to put you two in touch.
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    Quote Originally Posted by Gerald_D View Post
    Here is a brief overview of Cape Towns energy efficiency requirements:
    https://www.capetown.gov.za/en/Energ..._01Mar2012.pdf
    Awesome! That's so slack it looks like it was written in the 1950's.
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    Quote Originally Posted by MikeAG View Post
    Awesome! That's so slack it looks like it was written in the 1950's.
    yeah, which is a godsend actually!!!

    don't forget we don't suffer significant interior / exterior temperature differences in most areas (places like sutherland excepted)

    in winter I light fires on the days when I am in danger of having to close the door and possibly put on long trousers.

    on hot days, I stick my feet in the pool and open some windows.

    on very hot days I get in the pool.

    I have normal brick walls and a thatch roof.

    Where Fluffy lives they wear jackets in anything under 30degrees and 80% humidity as they feel a bit chilly.


    On the other hand, my office has zero roof insulation (tin roof, 80 year old building) and there is no breeze it's a sauna in there.

    but, it has doors and windows, I've never had to stop working, and there is a brewery 200m away for the really bad days.

    I suppose that, carbon consumption wise, a load of open fires isn't the best, but I heated my place last year with R3 000 worth (150 quid) of wood, and it was obscenely warm.

    that included braaiing a lot.

    In SA massive insulation is wasted - our issues centre around dependance on municipal services, and , sad to say, that isn't going to improve soon.

    it must also be borne in mind - our power costs are still CHEAP compared to UK - solar systems and so on don't amortise nearly as well here...

    and , despite the doom sayers , it's not going to go up - it will remain cheap to appease the majority (poor) population. the errors will be paid for in tax (wealthier population that vote for the wrong party)

    no matter how much you spend on household alternative energy supply , we'll still pay for electricity - though tax and commodity.

    these are things to consider when looking at energy efficient houses in warmer climates - I am sure the MEd countries look at them the same way!

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    Quote Originally Posted by MikeAG View Post
    Awesome! That's so slack it looks like it was written in the 1950's.
    EXACTLY !!!

    it is disgraceful !

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    Quote Originally Posted by Fluffy View Post
    And my son has a Masters Degree in Architecture and he specializes in energy efficient homes. He designs some of the countries best.

    He designed mine which is in build and broke ground today. see other thread.

    Mike we have spoken one to one on this.

    I really nead to put you two in touch.
    Fluffy GOOD to hear there are some that starting go this route.

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