Home  5  Books  5  GBEzine  5  News  5  HelpDesk  5  Register  5  GreenBuilding.co.uk
Not signed in (Sign In)

Categories



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.

Buy individually or both books together. Delivery is free!


widget @ surfing-waves.com




Vanilla 1.0.3 is a product of Lussumo. More Information: Documentation, Community Support.

Welcome to new Forum Visitors
Join the forum now and benefit from discussions with thousands of other green building fans and discounts on Green Building Press publications: Apply now.




    • CommentAuthorKrispy
    • CommentTimeNov 29th 2012
     
    Hi,

    Been lurking and reading for a while, very helpful, thank you one and all.

    My wife and I, plus two teenage kids away at school/uni term time live in a large house (2 floors, ground area 300m2); I work from home and another 4 or 5 people join me during the day.

    House was built in early 60's. Concrete floor, block-and-beam first floor and flat roof, now with insulation above (too thin I suspect) and pitched roof added.

    Only South facing window is the one at the end of the upstairs corridor - overlooking garage :sad:

    Central heating is cast iron skirting rads. Whole house is a single zone (although: one "out" pipe and two returns, we've put motorised valve on one of the returns but that has, sadly, only isolated rads in 1.5 bedrooms)

    A pair (one for pool) of oil boilers now replaced with batch log boiler and 5 tonnes of hot water spread over two accumulators, also heated by Solar Thermal (6 large panels, South facing) in summer. From that heat exchangers for central heating (in position of original boiler, original unpressurised plumbing remains on CH side), DHW via low pre-heat and high coils in accumulator (i.e. mains pressure, and improvement over previous gravity), and another heat exchanger where the pool's heater used to be.

    Retro fitting good insulation and UFH looks miserable - financial and upheaval.

    We would like a large farmhouse-style kitchen, current footprint doesn't lend itself to achieving that.

    So plan is to replace garage with 65m2-ish two-storey extension which will be due-South facing; kitchen / snug / living downstairs, master bedroom etc. above. Super insulate that and hibernate there in the winter. We can open, and heat, the State Apartments in the main house for highdays and holidays during the Winter, but as I hate entertaining in the Winter it won't be often :cool: I am hoping that rest of the Winter we can set the main house thermostat back to, say, 15C??

    I am sure to have loads of questions in accomplishing that build.

    Before the new build I'm still looking at improvements to main house. Originally built with Crittall metal windows, replaced (by previous owner) about 15 years ago with uPVC double glazed (probably around the time the pitched roof was added). We had cavity filled about 5 years ago.

    Condensation on occupied bedrooms, and kitchen, windows on cold winter nights is significant (wiped each morning with sponge and wrung out to basin). Memory not good enough to be sure, but I suspect this is [worse] since cavity fill. We have some black mould that grows on the seals, don't remember seeing that before cavity fill. We have dehumidifer that we move around the rooms in late Autumn - makes the house feel a lot more comfortable - but by mid November it doesn't extract much water - so probably not doing anything useful?

    Is there some sort of MHVR I can retro fit? I read about air tightness being crucial, and I doubt we have that (but is there a rule of thumb I can use to know if it is good, bad or indifferent?)

    Would it be essential to duct to the ground floor as well? (Easy enough to use the loft space, harder to hide pipework to the ground floor; there are a couple of fitted wardrobes that would do, not enough for every downstairs room though)

    Many thanks.
    • CommentAuthorrhamdu
    • CommentTimeNov 29th 2012
     
    If this was Grand Designs, you would build your extension and move into it. Then you would demolish the old house and rebuild it to guilt-free super-eco standards. This being the real world, presumably you have ruled out that option for economic reasons. Depending on how you do your embodied-carbon calculation, demolishing and rebuilding might also be seriously un-green.

    The idea of abandoning the 'old' house in winter sounds odd but a lot of holiday homes suffer the same fate. Whether this waste of space is justifiable in a country with a housing shortage... well, I shall stop short of suggesting you open your unused accommodation to Crisis at Christmas. But if you really are not using it, why heat it to 15C? Do you need to do more than stop the pipes freezing?

    I am surprised that you can basically build a whole new house for less than the cost of refurbishing the old one. But I do know from personal experience that a refurb is a whole lot easier if you are not also trying to live in the place.

    You hint that the loft insulation could be improved. That's easy, cheap, quick and can give a lot of benefit.

    The windows, too. If they are 15 years old, they were never as good as modern windows, and they have may have deteriorated. Replacing windows might be a cost you could bear, and it should improve the comfort and thermal efficiency of the building. Choose your price-point. You don't have to go for top-spec triple-glazed timber... though if you can afford it :bigsmile:

    Why not go for the less expensive and disruptive upgrades, and put wall insulation on the back burner? And with the money you save, buy a real holiday house? :wink:
    • CommentAuthorKrispy
    • CommentTimeNov 29th 2012
     
    Good points.

    The South end of the house is currently the garage. Significant issue for us is that there is a nice view to the South, we currently have no Southerly solar gain, and we would like a large kitchen / living space, so we had always planned to make the garage into that space. Thus the intention to do this existed before we realised that insulating it well, and living in it (i.e. relocating master bedroom to also be in the new extension, and have the benefit of the views) would give us a comfortable, and cost effective, living space for the winter.

    Only reason for, subsequently, heating the main part of the house in the Winter is that my colleagues come in to work. They are in a couple of rooms that can be heated independently, but they wander to the loo, kitchen for a cuppa etc, but my "15C" was intended to be whatever temperature would not disrupt the building, and wouldn't be too cold for the inhabitants.

    Would dropping the temperature to frost-free all winter have no impact on carpets and fittings?

    We would like to replace the windows - the house would benefit from something that had less chunky appearance than the uPVC. I had assumed it would be very expensive and wasteful to replace windows that seems to me to be "quite young" - will we be thinking that today's windows are "rubbish" in 10 years time?

    Definitely worth investigating though, thanks for the pointer. I wonder if an alternative is to consider some sort of insulation for the existing windows? Perhaps some [thermal] shutters that could be closed semi-permanently in rooms rarely used in winter, and at night in the other rooms? Perhaps more eco-friendly than physically replacing the windows?
    •  
      CommentAuthordjh
    • CommentTimeNov 30th 2012
     
    Posted By: KrispyI wonder if an alternative is to consider some sort of insulation for the existing windows? Perhaps some [thermal] shutters that could be closed semi-permanently in rooms rarely used in winter, and at night in the other rooms? Perhaps more eco-friendly than physically replacing the windows?

    That can work quite well. There are no products, though, as far as I know. So you would have to DIY or pay somebody to make custom. There are various possibilities: hinged shutters, sliding shutters, lift-out shutters. There's also the choice of internal or external. It might be worth making shutters for one window to give you a better idea of whether you want to try and do it for most or all of your windows, or whether indeed it is even possible at all.
    • CommentAuthorKrispy
    • CommentTimeNov 30th 2012
     
    Thanks DJH.

    We had folding shutters in a previous (Georgian) house. With just one hinge (on each window-half) they parked in the reveal, so I guess the reveal must have been at 45 degrees.

    Half the width of my window is 60cm, and the reveal is 17cm :sad:

    Maybe they could open against the reveal and then hinge at 17cm and the remaining 43cm park along the wall - behind the curtain. Bit of a PITA holding the curtain away each time.

    Maybe changing the reveal to be at 45 degrees and create a casing (is that the right word?) for the shutter is doable for DIY? I quite fancy spending the winter evenings making shutters for all the windows :)

    I think lift-out and hang-on-wall is a bit of a nuisance, and likely to get biffed.

    Many years ago I went on a guided tour of Wellington's house at the end of Park Lane. In the Salon, upstairs, there were floor to [high] ceiling windows. The guide first closed the conventional shutters and then a mirror, the height and shape of the window recess, pulled out of the casement and rolled across the window; it must have made the room look fantastic at night! I have no idea what that sort of intrusion into a modern [normally filled] cavity would do? Not easy to retrofit I suppose, but something I would like to consider for the new extension.

    Presumably I need to make something air-tight otherwise there will be condensation issues behind a closed shutter?

    And ideally backed with Kingspan or somesuch?

    Maybe I should just spray some water on the windows and press some offcuts of bubblewrap on for the winter ...
    •  
      CommentAuthorSteamyTea
    • CommentTimeNov 30th 2012
     
    Two things to consider, internal insulation, maybe Aerogel backed ply and a skim of plaster, can be done room by room and if done right can improve the airtightness. Which brings me onto the MVHR. Without a sealed house it is probably pointless.
    You can tell when a house is airtight enough, it soon starts to smell strange.
    You say you get no solar gain, if you have a south facing wall you do get some, just not accompanied by brightness. But sounds like you have set your heart on the extensions, so go for it as it will give you a view and will lower the overall U-Value of the rest of the place.
    Get the loft sorted this weekend, doing mine, which was not too bad anyway, halved my heat load.
    On the subject of heat load, do you know how much your place currently uses? We have a thread running about this and you can possibly compare your place to similar ones and decide just how bad it is.

    What is the nearest town to you so we can get an idea of the weather regime. Weather makes the biggest difference, my heating season is possibly two months less than up-county even though my mean temperature is not so different.
    • CommentAuthorKrispy
    • CommentTimeDec 1st 2012
     
    Posted By: SteamyTeamaybe Aerogel backed ply and a skim of plaster, can be done room by room and if done right can improve the airtightness.


    I'd appreciate if someone can explain airtightness to me, or point me at a description.

    I understand that air can flow under my front door, and perhaps my uPVC windows don't fit tightly (but I can't feel a draught). But I think this also relates to air moving "though" the walls? If so I'm stuck on understanding that one.

    Which brings me onto the MVHR. Without a sealed house it is probably pointless.


    Thought that might be the case.

    Get the loft sorted this weekend, doing mine, which was not too bad anyway, halved my heat load.


    OK. No doubt I should have done it years ago. When they put the pitched roof on (over the original flat roof) they just left a hatch in the outside of the roof; no access from indoors. Its a pain to get a ladder up, unscrew the cover, and get inside. Upside is that its just a single clear space inside, no water tanks, wires, etc. so I can just lay more on top of the existing.

    What depth should I be aiming for? I'm comfortable with spending a "reasonable" amount of over-spec.

    I just add more on top? or does there come a point where the underside of the roof needs insulating, instead of more on top of the "ceiling"?

    On the subject of heat load, do you know how much your place currently uses?


    How would I measure that? We are burning logs now. I can find out how much oil we used to burn, before logs. Bit muddied by the fact that some oil would have heated the pool, but I may be able to guestimate Winter/Summer usage. Ah! I have measurements of "height of oil in tank" from back in those days, which I think I converted to Litres of oil / day. Dunno efficiency of the old boiler, but it was old and knackered - would that be any use?

    I'm near Bury St Edmunds, Suffolk

    I feel badly just asking questions ... if anyone needs any advice on gardening I may be able to reciprocate.
    •  
      CommentAuthorSteamyTea
    • CommentTimeDec 1st 2012
     
    Posted By: KrispyI'd appreciate if someone can explain airtightness to me, or point me at a description.

    Our old friend Damon has a bit about improving his house, maybe start here and hunt around his site:
    http://www.earth.org.uk/note-on-desktop-humidity-RH-and-temperature-meter-HTC-1.html
    Airthightness is really about blocking off holes, there is an ongoing thread about walls 'breathing' here:
    http://www.greenbuildingforum.co.uk/forum114/comments.php?DiscussionID=9383&page=1
    Gets a bit technical, but from your point of view nothing to worry about as you have what you have. What is often forgotten about is the void between floors and where it interfaces with the wall, and where any pipework exits the building. These are the 'hard to treat' areas but are important.
    Posted By: KrispyWhat depth should I be aiming for? I'm comfortable with spending a "reasonable" amount of over-spec.
    absolute minimum of 300mm (a foot) but some suggest 450mm. It is a law of diminishing returns, doubling the thickness does not halve the loss, but it does delay the heating season and the overall amount needed. Be careful though about blocking off any ventilation the rafters as this can cause condensation, you still need air movement above the insulation.
    Posted By: KrispyI just add more on top? or does there come a point where the underside of the roof needs insulating, instead of more on top of the "ceiling"?
    In this situation it makes no difference, pile it on top.
    Posted By: KrispyHow would I measure that? We are burning logs now.
    Weight the logs and multiply by 4.5. So 5 kg of timber will release 22.5 kWh. Oil is about 10 kWh/litre.
    Posted By: KrispyI'm near Bury St Edmunds, Suffolk
    I went to Bury St Edmonds, not to praise him:bigsmile: So dry, cold and sunny. Have you thought of PV?

    Posted By: KrispyI feel badly just asking questions ... if anyone needs any advice on gardening I may be able to reciprocate.
    Most of us came on here to ask questions, some of us have stayed, I cant even remember what I wanted to know now, think it was about plumbing.
    • CommentAuthorKrispy
    • CommentTimeDec 1st 2012 edited
     
    Posted By: SteamyTea
    Posted By: KrispyI'd appreciate if someone can explain airtightness to me, or point me at a description.

    Airthightness is really about blocking off holes. What is often forgotten about is the void between floors and where it interfaces with the wall, and where any pipework exits the building.


    I'll read the link, thanks. Your description above may mean I am better off than most?

    We have concrete floor downstairs, block & beam 1st floor and also for the original flat roof. All pipes are sealed into the floor (screed, or more). We do have [lowered] false ceiling under one bathroom, for pipework, but in floor above its all sealed back in again. Upstairs ceiling has no cables/pipes passing through (and no recessed lights). All wiring is "mineral wiring" [if I have the right term] and buried in the plaster, so nothing trailing in loft!!

    There is no external pipework. All foul pipes are in vertical ducts within the building - discretely built into corners of rooms.

    Might that mean that I could consider MHVR? I'd have to sort the wooden front door for sure (its not bad, and you come through a second, inner, door to get into the house - dunno what that's called - Vestibule perhaps?). The other external doors are uPVC and hopefully relatively tight fitting.

    Posted By: KrispyI just add more on top? or does there come a point where the underside of the roof needs insulating, instead of more on top of the "ceiling"?

    In this situation it makes no difference, pile it on top.


    OK. Leads to my next question. I've only been into the "loft" once (accessed from roof, so needs ladder), so my memory a bit hazy. My recollection was a sea of pink insulation. Any tips on how to get around up there to lay more on top? Presumably I should not be trampling on existing insulation and compressing it?

    Posted By: KrispyHow would I measure that? We are burning logs now.
    Oil is about 10 kWh/litre.


    Last complete winter figures I have is 2007/8. Looks like didn't started using boiler until beginning of November (which sounds about right for average Autumn). Figures based on weekly measurement of height-of-oil-in-tank

    Nov '07 16-20 L/day
    Dec '07 20-24 L/day
    Jan '08 20-28 L/day
    Feb '08 16-28 L/day
    Mar '09 14-16 L/day

    Not sure when stopped as final central heating use occurs at same time as initial heating of the pool (so might have been end-March, or some time in April)

    The boiler was used also for DHW. Taking a period mid-summer when we would not have needed to heat the pool (before ST installed) looks consistent at 4 L/day to heat DHW (towel rails used to pull DHW around the gravity circuit, so maybe most of that energy was space heating, per se. Much smarter systems in place now.)

    Average 20.48 L/day over 147 days (inc 4L for DHW). Oil Boiler was rated 70kW and ran for about 4 hours a day (which is a bit adrift if I should be doing 20.48 L per day x 10 kWh per Litre / 70 kW which would give me 2.93 hours burn which I think is too short, even worse taking off 4L for DHW. But maybe 4 hours burn would not be at full fuel rate ... just looking to see if sanity-check looks OK)

    (Footprint is 300m2, 2 storey)
    •  
      CommentAuthorSteamyTea
    • CommentTimeDec 1st 2012 edited
     
    Posted By: KrispyMight that mean that I could consider MHVR?
    You could get a blower test done so you really know where you are.
    Posted By: KrispyAny tips on how to get around up there to lay more on top? Presumably I should not be trampling on existing insulation and compressing it?
    Temporary boards laid over the existing, if should return to the existing height after an hour or two. The stuff comes tightly wrapped after all.
    Posted By: Krispywhich would give me 2.93 hours burn which I think is too short
    Implies a boiler efficiency of 75%

    If I had known the value of initial measurements, I would have done a lot more sooner, you seem to have a lot of the data needed to start making proper decisions as to where is the best place to spend the money.
    Do you put a cover over your pool when it is begin heated, a lot of energy is lost though evaporation, or can you use the warm air in the pool house to to heat the main house for your workers. What is the winter temperature in there like, are they stable or greatly affected by solar gain. If you use a ASHP to grab excess energy from the pool area, make sure it can cope with the chlorine/bromine. I have seen a few rotting A/C units fitted into pool houses.
    • CommentAuthorKrispy
    • CommentTimeDec 1st 2012
     
    Posted By: SteamyTeaHave you thought of PV?


    In a way.

    Would have liked to help myself to FITs. South flat garage roof already taken up with ST. Did not want to move PV after (and onto) extension once built. Certainly did not want to store it for a year during build. So decided to wait.

    Extension will include replacing the uPVC pool enclosure with a "building" of some sort (there is a tricky cost equation for us on that one!) but the uPVC is utilitarian/ugly, probably nearing the end of its life, and would be a major annoyance if snow-load or high-wind destroyed it.

    Design for replacement has double-ridge roof East-West, so the more Northerly ridge could have PV on the South facing slope (i.e. invisible from ground level). Need to allow for the shadow cast from the more Southerly ridge in winter.

    Pool enclosure footprint is 25M E-W and 12M N-S - so in principal could have a 25M run of PV panels. I would quite like to put the ST there too ... but its some distance from the Accumulator, so may put ST on the South facing roof of the extension for more direct/shorter route to Accumulator.
    •  
      CommentAuthordjh
    • CommentTimeDec 4th 2012
     
    Posted By: KrispyPresumably I need to make something air-tight otherwise there will be condensation issues behind a closed shutter?

    Internal insulated shutters need to be reasonably air tight for that reason, since the surface of the glass becomes a lot colder than normal. Doesn't have to be perfectly airtight, though. External shutters don't suffer from that problem, but obviously wind blowing between the shutter and the window would rather defeat the purpose, so they do have to fit reasonably well.

    And ideally backed with Kingspan or somesuch?

    Indeed. I did some tests with XPS and my ultimate plan is phenolic (i.e. Kooltherm) because I don't like the behaviour of PIR/PUR in a fire.

    Maybe I should just spray some water on the windows and press some offcuts of bubblewrap on for the winter ...

    Certainly a lot simpler, and quite effective. My father used to put up secondary glazing each year and that worked well. It was the sort with a plastic seal around the edges.

    I'm near Bury St Edmunds, Suffolk

    Me too :cool:
Add your comments

    Username Password
  • Format comments as
 
   
The Ecobuilding Buzz
Site Map    |   Home    |   View Cart    |   Pressroom   |   Business   |   Links   
Logout    

© Green Building Press