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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.

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    • CommentAuthorRex
    • CommentTimeJun 20th 2020
    What ho one and all,

    This article from today's Telegraph: (https://www.telegraph.co.uk/news/2020/06/19/disturbed-sleep-growing-problem-warmth-energy-efficient-new/)

    Sleeping problems are on the rise because energy-efficient homes are too warm at night, a Government study has concluded.
    The Ministry of Housing, Communities and Local Government (MHCLG) reported that high temperatures are causing new homes to fail standards designed to tackle sleep deprivation.
    The problem will get worse over the next 30 years as properties designed to be energy-efficient become so hot at night that people will not be able to sleep properly in the warmest months.
    Experts have warned that highly insulated homes leave people "stewing in their beds".
    The study looked at new flats and houses in sites around England, including developments in Nottingham, Southampton and London, and concluded that none met the acceptable standard – the "compliance threshold" – for overheating set by the Chartered Institution of Building Services Engineers (CIBSE). CIBSE guidelines say bedroom temperature in new homes should be above 26C for a maximum of one per cent of hours from 10pm to 7am annually – an average of five minutes and 24 seconds per night. But in the worst-affected London homes analysed, the temperature was above 26C for an average of almost half an hour a night.
    Such overheating can cause disrupted sleep, a loss of productivity, domestic abuse and even death, according to the report.
    "Higher temperatures are linked to an increase in mortality rates, and this response is not just seen at extreme temperatures," it said, adding that the problem is likely to be exacerbated by climate change over the next 30 years.
    The report's conclusions follow a King's College London survey, published this month, which found that more than half the UK population has struggled with sleep during the coronavirus lockdown.
    New-build homes are particularly prone to overheating because they are designed to be more heavily insulated than older properties.

    I both understand and don't understand!

    My house is ten year old, t/f, 180mm Warmcel insulation, 3g, UFH, MVHR, designed to an air change requirement of only 9. I was pretty anal about sealing everything big time, and the actual test gave a reading of 1.7.

    South facing rooms get to around 24/25 during a sunny summer day (large windows); the master bedroom at the back, max at around 23 on very warm nights. Winter I keep the house around 21 and the master bedroom around 19/20.

    Given what I have seen of ‘developer built’ houses, I cannot fathom how they are of such airtight built quality that they overheat. In fact, the rate of winter snow melting from the roof indicates very poor insulation standards.

    But what do I know?

    Toodle pip
    • CommentAuthortony
    • CommentTimeJun 20th 2020
    Rubbish, I live in one of the lowest energy use homes in the country - warm in winter cool in summer

    Not too much glass, Good ventilation Design, solar gain shading by design.

    Insulation keeps the heat out during the summer

    It is complete nonsense to suggest that energy efficient homes ... ( like saying “he made me do it” )

    Good design Is all that is needed

    My number one priority is Energy Use Reduction — this should a government priority too
    • CommentAuthorgyrogear
    • CommentTimeJun 20th 2020
    Posted By: tonyMy number one priority is Energy Use Reduction


    • CommentAuthorEd Davies
    • CommentTimeJun 20th 2020
    The only ways I can see a house overheating in the UK, apart from the odd summer weeks of very high temperatures we can occasionally get, are incompetent design resulting in:

    1) too much window area facing the wrong way or

    2) rubbish heating or ventilation controls.

    “Too much insulation” can never be the problem.
    • CommentAuthortony
    • CommentTimeJun 20th 2020
    • CommentAuthortony
    • CommentTimeJun 20th 2020
    That article is the worst one I have ever seen in that newspaper.
    • CommentAuthorCliff Pope
    • CommentTimeJun 21st 2020
    Surely it's a matter of what you are used to? The levels of temperature that the article quotes are commonplace for a lot of natives around the world, and probably would be considered cool by many in some countries.

    I am accustomed to living in older houses with only rudimentary groundfloor heating, and having never lived in a house with central heating find all modern houses oppressively hot. A bedroom temperature of 19/20 sounds ghastly :)
    • CommentAuthorgoodevans
    • CommentTimeJun 21st 2020
    Posted By: tonyThat article is the worst one I have ever seen in that newspaper.
    The particularly outstanding feature is the conversion from 1% to 5 minutes 24 seconds average per night which added significantly to the clarity for the reader. :confused:
    It's sympathy with the notion that new energy efficient windows and doors cause houses to get mould where there was none before
    • CommentAuthorowlman
    • CommentTimeJun 21st 2020 edited
    <blockquote><cite>Posted By: Ed Davies</cite>The only ways I can see a house overheating in the UK, apart from the odd summer weeks of very high temperatures we can occasionally get, are incompetent design resulting in:

    1) too much window area facing the wrong way or

    Energy-saving is usually not the only consideration when building, indeed, I don't think it's the main one. Many other aspects of beauty, design, aethetics, liveability, and in the above instance, the view, and with it the re-sale potential, will most ikely trump it.
    • CommentAuthorEd Davies
    • CommentTimeJun 21st 2020
    There are all sorts of reasons for having windows: letting in light, outside awareness, view, means of escape, etc. None require large windows, particularly not facing south or west.
    • CommentAuthorJonti
    • CommentTimeJun 21st 2020
    Is ventilation as important as airtightness then?
    The newspaper report seems to be based on jazzing up a fairly sober and sensible government study published 6 months ago.

    It's looking at whether to change English building regs to include more measures against overheating, in view of climate scenarios for 2050 and 2080. They are looking at the cost-benefits of: blinds, low-g glazing, external shading, heavyweight partion walls and reversible heat pumps.

    "The analysis shows an average net benefit or a near zero cost of incorporating measures
    to mitigate the risk of overheating in new homes in the south of England over their life. The
    analysis also shows a net benefit of incorporating risk mitigation measures in flats in the
    north of England. Allowing for VAT in the analysis gives a near zero cost on average for all
    new build homes in England."

    "The current overheating assessment methodology in SAP lacks the rigour to
    both comprehensively assess the risk of overheating as well as model the impact of
    mitigation strategies on winter heating demand. ”

    "Critically the legislation would need to consider the year round energy and carbon
    performance of dwellings in an integrated way so that trades offs between winter energy
    performance and overheating in summer can be adequately assessed."

    • CommentAuthortony
    • CommentTimeJun 21st 2020
    It seems to me to imply that air leakage is good as it reduces temperatures!

    It also seems to have been written to promote the air cooling sector.

    Allowing for VAT and net zero cost an awful lot of good things could come about, better insulation, 3g, MVHR, solar, rain water recycling, shutters, the list goes on.

    Over what timescale and why is it any different north or south?
    Tony, where exactly does it say that ???!!

    Don't think hyperbole is helpful, on either side of the argument....

    As we know, air doesn't carry much heat, so you'd need an awful lot of air leaks to reduce the night time temperature. Providing enough openable secure windows, on the other hand, would be sensible?

    And they said that the point of mandatory passive cooling features, would be to avoid occupants fitting air-conditioning later in the lifetime of the building as the climate gets warmer.

    They used future climate scenarios for the North and South of England and obviously the climate in the South is expected to be hotter.
    • CommentTimeJun 21st 2020
    Posted By: JontiIs ventilation as important as airtightness then?

    Well-designed ventilation is essential in an airtight house. (and all houses should be airtight)

    Posted By: Ed DaviesNone require large windows, particularly not facing south

    There's no problem with south-facing windows, as long as they're properly shaded.
    • CommentAuthortony
    • CommentTimeJun 21st 2020
    Both ventilation and airtightness are important -

    Agree about the shading
    • CommentAuthorvord
    • CommentTimeJun 21st 2020 edited
    A ridiculous article from the Telegraph. I was brought up in Scotland and most of the insulation I have added is to reduce summer heating so I can feel more at home.

    Has a knock on advantage of reducing winter heating bills which is handy for those of us with deep pockets and short arms.

    Maybe Telegraph might complain a little more about houses designed to look nice and bright but are poorly designed. Cynicly designed maybe? Very little about a mainstream modern house I would buy in to. Ones I have visited have been very poorly performing. Cost a lot more to heat than my country pile, and horrid in summer.
    • CommentAuthorJonti
    • CommentTimeJun 21st 2020
    Posted By: djh
    Posted By: JontiIs ventilation as important as airtightness then?

    Well-designed ventilation is essential in an airtight house. (and all houses should be airtight)

    I agree about the airtightness (most people would probably understand draughtproof better) but it surprises me how poorly many people in the UK are at airing houses. Having lived in countries with summer temperatures in the mid to high 30s C I appreciate the importance of the ability to air through the building as a way of keeping indoor areas comfortable.

    • CommentAuthortony
    • CommentTimeJun 21st 2020
    My wife opens the bedroom windows every morning for half an hour and the door when big cooking

    We have MVHR
    • CommentAuthorgoodevans
    • CommentTimeJun 22nd 2020 edited
    Insulation is a factor here - but the culprit for overheating is probably poor ventilation exacerbated by solar gain (or to put it another way poor design) - many poorly designed houses with little or no wall insulation would have benefited from cool nights keeping the average wall temperatures down.

    Obviously sleeping in the open air would rarely, if ever exceed 26 deg C at night (but would be very cold in winter!) - However a well insulated house WITH good ventilation is ideal and better than a poorly insulated house with good ventilation.

    However a well insulated house with poor ventilation is really noticeable in summer (not so much in the winter poor air quality is not readily noticeable) - the heat gains from household activity, or solar can only be lost through the windows - if you live in a single aspect flat with no cross ventilation it's worse, where the widows can not be left open overnight because of noise or security and you have a real problem.
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