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


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.

    • CommentAuthorDiotima
    • CommentTimeJun 12th 2007
    My first post, so - hello! My OH and I have a 1960s bungalow with a suspended wooden floor, the boards are straight planks nailed to the joists, apparently the joists are supported on sleeper walls. This info comes from the people who installed our shower cabinet, we haven't yet taken up the floor to see for ourselves. There's no underfloor insulation.

    We want to install electric underfloor heating plus a good quality wood floor finish. The decision on electric heating is final. We'd appreciate some advice on insulating the floor, please - this is going to be a d.i.y. job apart from connecting the electrics. Is the kind of thin pad or roll insulation that comes with electric UFH systems good enough to insulate to recommended modern standards, or should we just bite the bullet, take the floorboards up and insulate underneath? There's about a foot of air space beneath the boards and I can guess what the answer's going to be, but we'd really appreciate your opinions. Thank you!
    • CommentTimeJun 12th 2007 edited
    Posted By: Diotima

    The decision on electric heating is final.

    This is the green building forum and electric heating is the most expensive and polluting you could choose.
    So perhaps you could explain why the decision is final because otherwise I dont think many forum users will be that keen to assist.
    • CommentAuthortony
    • CommentTimeJun 12th 2007
    Electricity will eventually be the only fuel for the masses.

    It is mad to use it directly for heating. If you use a heat pump you will get 3.5 > 4 kW of heat for each kW of electricity.

    Use a wet system and then you can choose what fuel to use to make it work.

    Insulation should be as good as possible and air tightness is very important too. Something like the value from 20mm of pur over the joists and 100mm between would be a minimum I would say.
    • CommentAuthorDiotima
    • CommentTimeJun 13th 2007 edited
    Thank you for your help Tony.

    As for the reasons for choosing electricity, although not relevant to the question I asked, they are, in no particular order: funds available for the total work needed to the property NOW; space considerations for alternative energy generators; future mobility difficulties forecast for both of us; aesthetic considerations - we presently have oil (non-condensing boiler and which is not suitable for a hydronic system) and radiators which we very much want to get rid of; and most importantly, future security of energy supplies. On this last we have had considerable advice from a close friend who is an energy security expert and adviser to the US State Department, a senior military officer specialising in environmental security threats. Electricity can be UK-generated from a variety of possible sources if we have the will to do it, and both of us very much want not to buy our energy supplies from unstable corrupt dictatorships which we find deeply repugnant. We're putting our money where our principles are. Choosing electricity now also means that should funds become available in the future we will be able to buy the equipment to generate at least some of our own electricity, which is not possible right now.

    And finally, if anyone thinks I have to get political approval for our proposed schemes before I can get advice - there are other forums out there.

    Once again, thank you Tony.

    your friend is not giving you very good advice. Wet systems are by far the most fuel flexible and are not necessarily horrendously expensive. If you're really considering future energy supples, why would you choose a system that only gives you 1kw out for every kw in versus a system which will use only 25-33% of the power (electricity in this case) compared with your solution? The beauty of a wet system is that you have unlimited choice in how you heat the working fluid: could be a condensing boiler (oil, gas etc.) a wood burner (not good for urban areas), solar hot water or even solar PV. The latter is the most expensive so you would be ill advised to install a system which only gets an "efficiency" of 100% - with a heatpump you would need only 1/4 the amount of PV cells to give the same heat output as your inflexible electrical system. It might be cheaper in the short term, but will end up being by far the most expensive in the long run. A case of penny wise, pound foolish? If you're going to do the right thing, do it. Your US military friend might be right that the UK can generate electricity in the future - but surely it's better to minimize the amount of generation that's required? If everyone followed your short-sighted approach, then it would be very difficult to meet the generation load in the future.

    Bite the bullet and put in a wet system - there's plenty of "staple-up" systems with heatspreaders that, with good insulation, are pretty much as effective as wet systems embedded in concrete. You talk about putting your money where your principles are - it doesn't sound like it from where I'm standing.

    Best regards,

    Paul in Montreal.
    • CommentAuthorDiotima
    • CommentTimeJun 13th 2007
    Thank you for your response, Paul. Apart from the fact you don't know what advice we've had from our American friend, our existing oil boiler isn't suitable for powering a hydronic system. And what does all this have to do with my request for advice on insulating our floor?
    • CommentAuthorSolar bore
    • CommentTimeJun 13th 2007
    Diotima Hi I have copied each question and tried to answer each aspect.

    " And what does all this have to do with my request for advice on insulating our floor?"

    If you want advice from this forum You will get the opinion of the writers as well which I largely agree with try reading it and listening to it.

    "Thank you for your response, Paul. Apart from the fact you don't know what advice we've had from our American friend,"

    Maybe you would like to tell us what you have been told so we may take on board this aspect - maybe we will come to the same conclusion as you.

    No-one is suggesting you use your existing boiler for this project, but that you replace it with a Ground Source Heat Pump that will heat your whole property not just one room as one person said this type of machine will turn 1kw of electricity into 4kw of thermal energy which can also be used as cooling i know if I had sufficient ground to site the drill rig I would go for similar system. I live in a terraced house.
    Incidentally the box that does everything is the size of a small fridge How big is your boiler? now.

    "our existing oil boiler isn't suitable for powering a hydronic system."
    What is a """"hydronic system."""" ? Are you trying to say water based or wet system ?

    • CommentAuthorSolar bore
    • CommentTimeJun 13th 2007

    what are "staple-up" systems with "heat spreaders"

    Can you name give me an example so that I /we may learn for future ref.

    • CommentAuthorDiotima
    • CommentTimeJun 13th 2007
    Hi Solar Bore

    Thank you for your response. What I asked was about insulation of a suspended wooden floor, and this is what I need an answer on. If this forum has people willing to answer that question without driving me nuts - I'm a very busy web developer and my clients' deadlines are usually 'last week' - I will, *perhaps* revisit our choice of heating. Along with the heating system, we also have to deal with replacement windows (more choices), widening doorways; making the bathroom and kitchen suitable for a wheelchair-bound user; new front entrance and ramp; rewiring; and redecoration after all that. One of us also has a medical condition which means that noise generation has to be taken into account.

    All this is going to stretch our budget severely. We have 40 square meters of unshaded south-facing roof and we hope to have the money sometime in the future to install solar panels for hot water.

    From having a further look around this forum I get the strong impression it is dominated by a small group bent on promoting their personal agendas regardless of the question asked. Perhaps this is why such a potentially valuable forum only has something under 600 members. A professional list I'm on - webdesign-l.com - has more than 10 times that number, perhaps because we stay on topic and answer the questions we're asked, and don't respond when we can't.

    Thank you for your input.
    • CommentTimeJun 13th 2007

    You have registered on the Green Building Forum and I think its in your interests that we highlight the poor choice of energy source.
    Peak electricity can cost between 8and 10p per Kwh. Oil and wood pellet costs approx 5p Kwh and a heat pump might cost you 3-4p Kwh.
    So whilst you say you are limited on funds - how are going to pay for your ongoing energy use?

    This is not a personal agenda what you are hearing is good advice and perhaps you really will revisit your decision.

    As for going off topic why are you now trying to belittle the forum when all we trying to do is give good advice.
    Also if the issue of using electric heating is not relevant then why include it in your question?
    • CommentAuthorDiotima
    • CommentTimeJun 13th 2007
    It is good advice, it's just not practical for the situation my partner and I are having to cope with, and *it's off topic for the question asked*. The specific question was about insulating a particular type of floor, and I anticipated I would find the most knowledgeable, up to date, advice here. I included the comment about electric heating because the question specifically refers to the insulation generally used in that type of heating - relevant, I think. We're limited on capital for the necessary works, not on income to pay for our electricity usage which is monitored carefully, but we don't intend to remortgage as our plans are to sell this property in six to seven years and retire abroad.

    I came here looking for advice on a clearly defined question, my partner and I having made decisions, after much research, on how to cope with difficult circumstances, and have been berated for making a choice not to the liking of certain members of this forum who don't know the circumstances and don't have to deal with what we have to. My comment about the forum is valid, it's the impression I have. Deal with it.

    Apparently this forum is moderated, so I shall be contacting the moderator to have my membership cancelled. I won't be posting in this forum any more, or even reading it, it's clearly a waste of my time.
    • CommentAuthormoogaloo
    • CommentTimeJun 13th 2007
    If you where to insulate under the floorboards the floorboards would have to be removed and relaid, this is a costly process in the scheme of things (I Know because I have just been through it with an underfloor wet system).

    I agree with the others on your choice of heating, however if you want to do a DIY job spend a minimum amount of money, then there are changes you can make to your existing radiator system which might be less costly then electric underfloor (certainly in the long term) leaving you with some funds to look at changing your boiler for something else, you might want to consider a thermal store and perhaps some solar assistance.

    Certainly you could takle you hot water situation along, by looking at solar hot water.
    • CommentAuthormook
    • CommentTimeJun 13th 2007
    More or less to reiterate waht moogaloo has said... i started to lift my floorboards, firstly to insulate and inspect the joists. By the time i'd insulated (lots of time and effort involved) I felt i was 75% of the way to installing UFH, so thats the route I went down. We are installing wet system fed from an accumulator tank, heated with a pellet boiler. If you have access to a large south facing roof i would consider, as the others have said a wet sytem, with a thermal store/accumulator tank which can house more tahn one coil so you can heat the tank from solar/other sources. In the long run this will give the most flexibility.
    Posted By: Solar borePaul

    what are "staple-up" systems with "heat spreaders"

    Can you name give me an example so that I /we may learn for future ref.



    "Staple-up" systems are usually PEX tubing that is stapled to the subfloor above. They are quick and easy to install, but don't have the thermal mass of concrete embedded systems. Aluminium heat spreader plates can help with evening out the heat. Good insulation is required beneath the tubes, though, otherwise the efficiency is rather poor as would be expected.

    Hope this helps,


    p.s. it is quite easy to install such systems DIY - though a good amount of googling is not a bad idea to figure out the capacity of the system before hand. This site: http://www.healthyheating.com has lots of good info on radiant heating in general.

    pps Sorry that the links aren't clickable - I don't seem to be able to post links and quote at the same time
    • CommentAuthortony
    • CommentTimeJun 13th 2007
    "Staple up" means walking around in the basement and fixing to underneath of the ground floor boarding easy! Might not be so nice in the UK as even crawl spaces are rare here as you know.
    • CommentAuthorBluemoon
    • CommentTimeJun 13th 2007
    My plumber advised me not to combine the radiator heating system in the rest of my house with UFH under the ceramic-tiled bathroom floor(ground floor concrete on earth). So as it is only for making the floor comfy, not for heating the room, I have decided to install electric UFH(shock/horror!) But, perhaps if I also install some pipe as well, so that in future if another owner decides to change the heating, it will be ready. After all, the floor is being relaid and insulated, so it could be done at a minimum of expense. I have room and pipes nearby to install a small radiator if needed.
Add your comments

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

© Green Building Press