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.

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.
Buy individually or both books together. Delivery is free!


powered by Surfing Waves




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.




Fundamentals: The economics of insulation as an alternative to central heating systems.

Bottom of Page

1 to 29 of 29

  1.  
    • CommentAuthortony
    • CommentTimeApr 12th 2008
     
    Is insulation a good alternative to a heating system? --

    Posted by Simon H recently:-I started down the same route thinking which heating system is best. I've now to to the conclusion tony mentions above - none.

    Here's why.... I've worked out using some spreadsheets and expected U values that by insulating properly I can get my heating demand down from 17.5kW to about 2kW when it's 0 outside. That's by using cavity wall insulation AND external wall insulation, having 300mm loft insulation, getting every nook and cranny and under the floors air sealed and insulated. Air sealing is very important - I found out that for house of my age/size (1960's) - I'll be losing over 6kW in drafts! I may add a 3rd pane of glass on top of the existing double glazing (which needs a lot of work on draft sealing as there's light visible under some of the windows - fitted in 2003!!!!??)

    Once the pressure tests are showing the house isn't leaking too much air I can stick in a mechanical heat recovery system. The idea being that instead of using an extract only in the kitchen & bathrooms, you stick in ducting and run the "wet air" through a heat exchanger and get about 80% of the heat back that would normally get pumped outside you bring the pre-warmed fresh air back into the lounge/bedrooms. Why? If I ventilated naturally I'd lose about 1.6kW of heat to get the required air-changes to stop condensation. By running an electric fan using about 50W I reduce that heat loss to 300W. (Remember I started off with over 6kW).

    This means that remaining 2kW of heat I need (on only the coldest days) most will come from cooking, appliances and body heat. With an additional top up from something else. For now I'm leaving the old gas central heating in, until I find out how much heat I need once things are insulated properly. I may add a smokeless (mmmn??) wood burner , much smaller heat pump, or just stick with a high efficiency condensing boiler for now. My current boiler is non condensing but still 80% efficient - fan assisted and has auto ignition (no pilot light continuously burning gas) about 15 years old so no need to rip it out just yet.

    I've gone the insulation route as I expect it to cost around £10,000 but have no running costs and can be done job by job as I have the cash. Going for a heat pump will cost about £12,000 up front (£4,000 pump, £5,000 borehole, £3,000 underfloor heating and fitting) and still cost around £1,000 a year in electric bills just for the heat pump. The £10,000 on insulation has a 9 year payback. Or a return on investment compared to leaving the money in a saving account of 8.6% tax free. (I save £866 a year on my heating bills for my £10,000 investment).

    Simon


    We may edit the above as we develop the thread.
    • CommentAuthorJeff B
    • CommentTimeApr 12th 2008 edited
     
    Simon H has estimated that the cost of insulating his house will be around £10,000. What proportion of the £10,000 would be spent on just the external insulation - presumably the majority of it?
  3.  
    Or perhaps more!! I have a quote for external insulation to a rear elevation perhaps 21m (gross) x 4.5m and a gable c 7 x 5.9 at £19,689, and another quote for a smaller gable from the same co which was frightening / m2. I strongly believe ext ins is what we need to do, but at these prices???

    Don't let this put you off though. Insulate, insulate, insulate! (after sorting out the air-tightness!)
    • CommentAuthorMike George
    • CommentTimeApr 12th 2008 edited
     
    Had a look at insulation v boiler efficiency a while back. See fig 5 http://www.bsjonline.co.uk/story.asp?storycode=3046194
    • CommentAuthortony
    • CommentTimeApr 13th 2008
     
    Nick the cost of external insulation is relevant , but not the rip off prices you have been given. There are also rip off prices arround for heating systems.

    External insulation should not cost £200+ per square meter: Scaffold = £ 15 , Sheet insulation fixed for £ 10 - 20 Render on mesh £ 30 How ever £ 200?
  6.  
    I too am surprised by the £200/m2 price. I could make an absolute fortune at that rate.

    I could make good money at Tony's rates as well. Doesn't seem to be much demand in Soth Wales though. Mostly Government contracts which are taken on by the big boys
    • CommentAuthorPDobson
    • CommentTimeApr 13th 2008
     
    I have been quoted around £50/m2 for 30mm celotex type insulation on a new build - The scaffolding is already in place - does that seem reasonable? (Farnham - Surrey/Hampshire border)
  8.  
    No, not good. Cost price of 30mm PUR insulation around £5/m2 max. Also if you are going to go with external insulation then 30mm will not even comply with bregs.
    • CommentAuthorPDobson
    • CommentTimeApr 13th 2008
     
    Sorry - should have explained its in addition to 100mm of Drytherm between blockwork. The price also includes installation and application of through colour render.
    • CommentAuthortony
    • CommentTimeApr 13th 2008
     
    Still well high -- why not learn how to render its easy!
    • CommentAuthorJeff B
    • CommentTimeApr 13th 2008
     
    According to this website:

    http://oxfordsolar.energyprojects.net/links/tech_solidwall.htm

    external insulation should cost between £45 and £65 per sq.m. "depending on the selected product, installer, the condition of the exterior surface and its complexity". They provide a link to INCA (the Insulated Render and Cladding Association) so I presume they know what they are talking about?

    I checked the INCA website (inca-ltd.org.uk) and they have a list of approved installers. I might contact a few of those who are based near me (South Wales) and see what I can glean.

    Nick Parsons - can I ask, was the company that quoted you the £200/sq.m. price one of those listed in the INCA directory?
    • CommentAuthorSimonH
    • CommentTimeApr 14th 2008 edited
     
    My original comments of costing £10,000 were based on a rough estimate of what I thought was a reasonable budget to spend on insulation - given the savings potential from the theoretical U values. My heating bill is currently £1,000 a year, and it should end up around £100-200 (my calcs said £125). I did a trawl of builders merchants websites to see how much the insulation products cost as supply only to validate whether £10,000 was a reasonable budget and how much DIY I'd need to do. Given I need to do 110 m2 of external wall, plus under floors, about 3 tonnes of silicone sealer guns, and a MHVR system it seems do able.

    I've just been to the Homebuilding and Renovating show at the NEC. I was given ball park figures from £55-£95 /m2 installed price. My guess is you can save an awful lot on those prices by doing DIY.

    I had a good chat to the guy on the EuroBrick stand as they have a nice system that has channels pre formed in the insulation to take brick slips. The boards a 8'x4' and to get thicker than 50mm you lay them horizontally and vertically. It's definitely a DIY job for someone who knows how to use a drill & spirit level and is safe working at height! I'd suggest a ladder and powerdrill are not a good mix for extended periods and hiring scaffolding would be a no brainer. The system used the expanding foam type stuff though and the bricks are then glued on (so not as as sustainable as I'd like) and then pointing is piped on (like icing sugar). For the rendered sections I'll be hiring a plasterer. I did a lot of garden wall rendering once, and abotu 1/3 of it fell off within a year :shamed:

    I also had a chat to a company who install using the Wetherby system http://www.wbs-ltd.co.uk/ who's website has great technical details of how it's installed on the "Technical Support/Standard detail drawing" section along with completed examples in the "EWI Refurbishment" section. I can't remember the name of the installer but I have their leaflet at home. They had a photo of a typical 3 bed interwar semi (the one with a bay and arch front door). Said that had cost £15,000 to do. Each quote is dependent on the work required - e.g. moving waste pipes, changing the roof over hangs, and cill work required.

    I was trying to find someone who uses wood fibre as an external cladding system. No suppliers there, but came across an architect using it on timer frame systems and lime rendering over it. The supplier is nbt systems - who I've come across before. http://www.natural-building.co.uk/pavatex_pavaclad_masonry_external_wall_insulation.htm . However as far as I can tell it doesn't have a BBA certificate yet.

    One thing I should point out, from this April - it may be possible to get grants under the CERT scheme for external wall insulation. This is the scheme where energy suppliers fund cavity wall & loft insulation, light bulbs, boilers and efficient appliance discounts (at comet and the like). From this year there's a whole new raft of measures that are eligible to count towards the energy suppliers Carbon Emissions Reduction Target. Including external wall insulation (also internal, heat pumps, wood burners, PV etc). As yet I've not seen any new grants announced from energy suppliers - but doesn't mean that with some encouragement they won't appear ;-)

    My own project is still at the research stage - once I'm a bit more sure of what I want - I'll be going out to architects to get some designs done (we're extending too). I've seen some "face lift" properties that look great, but one or 2 that had me thinking mmmmn. :confused:

    Simon.
    • CommentAuthortony
    • CommentTimeApr 15th 2008
     
    Can we get say anything about new builds now? Like an extra £ ? spent on insulation makes a heating system unnecessary?

    Is it right to talk about insulation vs heating in isolation? MHRV will be needed what ever.

    What are the pay back times?

    Do these arguments also apply to renovations?
  14.  
    That's all lovely chaps but what about hot water....

    J
    • CommentAuthortony
    • CommentTimeMay 14th 2008
     
    This thread was talking about heating vs insulation. Hot water is best produced by solar thermal and if needed a back up system not costing thousands.
    •  
      CommentAuthorfostertom
    • CommentTimeMay 14th 2008
     
    I do think that multifoil as part of an external insulation system, should be at least considered. Even if you're in the unconvinced camp, you'll probably accept the Cellotex-plus-Thinsulate formula, which will give at least as good insulation as any other system of equivalent overall thickness, though will certainly be expensive by comparison. The calculation to be made, is whether multifoil will eventually be proved to perform far better than the mediocre Thinsulex certification. In that case you'll find you've insulated externally to a standard unimaginable by any other means, let alone in that thickness.
    • CommentAuthorchuckey
    • CommentTimeMay 14th 2008
     
    One problem with hanging external insulation and rendering it is in all the details. The window frames might have to be changed if the new increased thickness of the reveals run over the glass. They will have to have drip trays installed under the insulation and special attention required to their side. The same for doors. All the down pipes and stack pipes will have to have special fixing to bridge the depth of insulation. Drains will have to moved from being adjacent to the wall to 3" away. The gutters as well. All lights/cables (mains and TV/satellite) on the house walls will have to be relocated.
    The principle is easy but I would need to have a 25 year guarantee on the work and its knock on effects, i.e. the possibility that a moved drain starts to leak after 10 years.
    I would walk around the property and list every feature that stops it being a square blank box. Then figure out what can be done with each feature. Even the roof over hang might be too small when the gutter is moved out 3".
    So much for £50 square metre!
    Frank
    • CommentAuthortony
    • CommentTimeMay 16th 2008
     
    This does not apply to new builds. The classic candidate for external insulation is an end terrace -- usually no pipes, wires or windows.

    Nothing wrong with burying TV/GPO/satellite cables. Drains are easily moved if necessary but often a couple of shallow at or below ground level will do the trick.

    Window details can be overcome generally within the cost. Hundreds of pounds a square meter is far too heavy.
    •  
      CommentAuthorfostertom
    • CommentTimeMay 16th 2008 edited
     
    One of the beauties of multifoil insulation is that because of its flexibility and thinness, with thoughtful detailing it can maintain full-value insulation seamlessly right to the window frame, with minimum (but still not insignificant) thickening at the reveals - a big compromise/weak spot in other systems. This applies equally to internal/within thickness insulation, as to external.
    • CommentAuthorFred56
    • CommentTimeSep 6th 2008
     
    Re. this external insulating thing. The Housing Corporation reckon that the costs for external insulating render systems in the UK are around 3x the cost in Germany. You can read their Fit for the Future publications. The general thrust of the argument is that external insulating render is technically better than internal insulation but often not used on the ground of costs. The major problem is that the UK industry is unified in protecting its market position. To gain approval the systems require certified installers and this is tightly controlled by the industry that can then impose higher costs - proof UK costs around 3x German costs. The Housing Corp also point out that the associated works can be pricey, and I've seen this in my work life, extending eaves and verges, rearranging drainage, uncomfortable treatment around windows and doors. If you're ripping out the internals anyway for the re-vite you may as well just go for internal insulation and suffer the reduced floor area. The other big issue are the planners. Try proposing external render on a conversion, once asked about a 1950s brick milking parlour - absolutely no chance! Impairment of the character.
    • CommentAuthorJackyR
    • CommentTimeSep 8th 2008
     
    Posted By: tonyThe classic candidate for external insulation is an end terrace -- usually no pipes, wires or windows.


    Ooh, do you mean it's worth doing the terrace end even if you can't do the front/back? I live in a conservation area, so this is a key question....
    • CommentAuthorAds
    • CommentTimeSep 9th 2008
     
    I asked this question before and Tony (I think) reckoned it would be fine. For my end terrace the only obvious things to take into account are an external gas pipe and the probable need to extend the roof to cover the thicker wall (although I have no idea how that would be done - any thoughts?).
  23.  
    Insulating the gable on its own is a great idea - it's probably the largest surface are of wall anyway.

    Extending the roof is doable as well -easier in a tiled roof than a slated one. Any good builder will be able to do either.
    • CommentAuthorJackyR
    • CommentTimeSep 9th 2008
     
    I love you all! (Tho' him wot'll have to stump up might not...) :bigsmile:
    • CommentAuthorLegolas
    • CommentTimeNov 16th 2008
     
    I'm new to this site, so forgive my chipping in on a slight tangent, but when calculating the environmental cost of projects like this, are the ancillary factors taken into account? By that I mean stuff like:

    Earning - if you're a higher rate taxpayer and want to spend £10,000 on insulating, you'll need to earn around £18,000 before tax to pay for it. That could be a lot of overtime which includes travel, consumption of consumables etc. not to mention having had to generate commerce/sales/work whatever, much of which is based on consumption of resources of one sort or another in our existing economy.

    Manufacturing of materials - Having recently been hacking away at a load of Celotex for my loft conversion, I can't believe that there can be anything natural in its manufacturing process (though I admit I stand to be corrected on that one). It is truly horrible stuff! Ultimately resources of one sort or another are consumed in the manufacture of everything. Does the fuel required to produce it add up to to less than the fuel required to heat a home without it?

    Waste - Again, from experience, the volume of offcuts when insulating is horrific (and that's with supertightfist me trying to eek every last inch out of every last board). If you calculate you need to insulate X square meters of area, you'll have to allow for, at a guess, X + 15% to allow for wastage. Can it be recycled (again, I look to the wise here for the answer to that one). If not, and every house in the land did it, that's a lot of landfill.

    Toxicity of new materials - Back in the day you could use rough sawn timber for building roofs. 3 x 2 rafters were common and there was no such thing as roofing felt. Nowadays all timber has to be pressure treated in toxic chemicals to reduce its tendency to rot due to the fact that we want to shroud it in insulation and prevent as much natural airflow round the material to maintain heat - airflow that previously kept it rot free (well, sometimes it did). We also have to use more timber to build the same roof. Our loft conversion rafters are 5 x 2 to fit the insulation in and there are those who said we should counterbatton further to add even more insulation. That's nearly a 50% increase in the amount of wood needed from, say, 100 years ago, to build a given roof.

    These are just the factors that Joe Idiot me has come up against on one small loft conversion. Scale these issues up to take in the global picture and there must be millions of similar anomilies and factors to take into account.

    Are these factors added in to the overall environmental sum? I don't have any answers to this, but my sister works in the marine ecology field and the more I talk to her on the complexity of the big picture, the more questions and the fewer answers I seem to have.
    • CommentAuthorludite
    • CommentTimeNov 18th 2008
     
    Dear legolas (are you really blond with pointy ears?).

    I hear where you're coming from. When I responded to one post on this forum I suddenly realised (at 3:30 in the morning) that burning COAL, might be a green option for some people.

    Taking your first point - about cost of installation for higher tax payers:

    We've just had our kitchen - the hottest room in the house - insulated after 36 years. The guys who were doing it asked why we hadn't gone for the 'free government insualtion'. I told them that even though we were probably able to get it - due to grandma being 'old', we couldn't guarentee that they would put it in properly, or put enough in.

    Not only that, but if we go for a 'proper installer' I have a sneaking suspicion they add more to their price in order to reap the benefits. . . . . .if you see what I mean.

    I think, that at the end of the day, you have to individually try and balance the joys of modern living with 'what you REALLY need'.

    In other words, YES, we could all go back to hunter gatherer, sleep under a hedge bottom and forage - which would be 'green'.

    On the other hand, indoor flushing toilets, lights to work with when the sun has gone down, windows, mobile phones, antibiotics. . . . . . . .it all makes our lives so much. . . .easier.

    ho-hum. . . .once again I seem to be drifting off the point. . . . . . but there you go! Try and read between my lines and decipher what I'm trying to say. . . . . .
    • CommentAuthorLegolas
    • CommentTimeNov 18th 2008
     
    Thanks for your thoughts Lud, I think I kind of know what you're driving at.

    And I concur on the government grant thing. The companies almost certainly simply add the grant to the quote. Even if they don't, it won't be as cheap (or, as you say, as thorough) as doing it yourself.

    My concern is that legislatively there is no option. If I were a single man wanting another room in my house, I could well do the sums and arrive at a design which costs a fraction of the money, uses half the (untreated) timber, has tiny windows, thick curtains, newspaper insulation and thick jumper central heating. But by the time you get into planning permission, building regs, fire regs and all the rest of it, you are forced into massive resource consumption on every level, all (supposedly) in the name of environmentalism.

    Of the things you list that make our lives easier, for me, only the lights after dark count as a necessity. I really don't feel that I would be any the poorer if all the others disappeared tomorrow. And if mobile phones went I would be far the richer!

    Like I say, I've got no answers, just observations of how the state forces me to do more environmental damage than I feel is necessary.

    And, no, I'm afraid I'm neither blonde nor do I have pointy ears - more ginger with cauliflower ears. Which I suppose means I should have called myself Gimli.
    :)
    • CommentAuthorludite
    • CommentTimeNov 18th 2008
     
    Fancy that! I'm a ginger too, - got ears - 2 of them, but when it comes to characters out of books, I've always totally wanted to be granny weatherwax - age indeterminable.

    Getting back to the point, Glad to see you could decipher my ramblings. I'm constantly stunned at the things we are allowed to do, and the things we are prevented from doing. Just take a look at all the problems people on this site have with the planning departments. It fair takes your breath away.

    Just try and keep on making as little environmental impact as possible, keep your head down, try not to get noticed and make sure you have an escape plan if you get captured - it's the best advice i can give.:bigsmile:
    • CommentAuthorSimonH
    • CommentTimeNov 20th 2008
     
    <blockquote><cite>Posted By: ludite</cite>Dear legolas (are you really blond with pointy ears?).

    I hear where you're coming from. When I responded to one post on this forum I suddenly realised (at 3:30 in the morning) that burning COAL, might be a green option for some people.
    .</blockquote>

    Yep - people on electric. Why burn coal to get 40% of it as electrons at your fan heater, when you could just burn it in a stove and get 75% of it as heat in your room. (Presuming smokeless coal!).

    I must correct you on the "government installers".

    These are the same guys who uinstall it if you pay them direct. They do the same job for the same price. The difference in the grant system is that £300 or thereabouts, gets paid to the installer by your energy company Bringing the price to you down to around £200. That £300 comes from the CERT fund - which is paid for by energy customers - i.e. me and you. So as as an energy cusotmer you've paid into the fund - but aren't getting annything out of it.


    That stands for cavity wall insualtion. For loft insualtion - I'd do it myself - make sure the edgesd are neat - and I also want to build an area to put suitcases and "baby stuff". However - if you don't need a special and just want insualtion - it's better to get blockes in suits to handle the itchy stuff.

    Simon.

1 to 29 of 29

  1.  
Add your comments

    Username Password
  • Format comments as
 
Back to Discussions Top of Page
   
The Ecobuilding Buzz
Site Map    |   Home    |   View Cart    |   Pressroom   |   Business   |   Links   
Logout    

© Green Building Press