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Green Building Bible, Fourth Edition
Green Building Bible, fourth edition (both books)
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    • CommentAuthorsteveleigh
    • CommentTimeJan 2nd 2008 edited
     
    My company and RoofKrete Ltd would like to offer to install our airtight thermal cladding system on a suitable existing building (old or new) in return for allowing full monitoring access for at least two years as part of a project.
    This would need to be completed during the first quarter of 2008. We would supply and install an exterior insulated render system complete with valves to monitor airtightness including a new insulated roof to provide a maintainable sealed system and we would also provide a MVHR unit FOC.

    We have a thermal render system which has been installed, over a period of twelve years, as a monolithic membrane (without joints) over thousands of buildings as watertight protection. This system could now be easily adapted to encapsulate a full building as an airtight external thermal cladding system.

    The figures we hope to improve upon with this system are as follows:

    Air permeability 0.25 m3/m2hr @50Pa.

    Thermal bridges 0.1% of wall and roof area.

    Wall and roof aggregate U-Value 0.10 W/m2K

    We have focused our attention on the major weakness of UK building envelopes, air permeability. Most building envelopes will eventually develop air leaks through thousands of tiny fissures and cracks and connections between roofs and walls. Air infiltration can be eliminated by a render system which does not develop unseen fissures and cracks but forms an airtight seal which effectively separates the internal atmosphere from the external atmosphere.

    The Canadians have already attempted to seal buildings during the seventies and eighties and failed because of the inability of render systems to remain airtight. The principle of a sealed building envelope is a sound one because it increases the performance of insulation by as much as 50% and allows building control systems to operate effectively giving the occupants complete control over every fraction of heating or cooling energy regardless of the outdoor climate.

    Our Code 5 Upgrade Project will have no reliance on Government funds in the form of research and development grants and it will be commercially viable (without any form of subsidy) on the social housing market. It will satisfy stringent environmental and sustainable construction requirements.

    We have had a lot of interest from housing associations and we are due to start our first new homes in the second quarter of 2008. However, we would like an environmentalist as an occupant to monitor a building over a two year period. If you have a house which is suitable for upgrading and would like to be involved more details can be found at: http://www.sustainconstruction.com/TC_Project.html or email me at RoofKreteTC@sustainconstruction.com.

    We are confident that we can achieve a code 5 CSH envelope at no extra cost over present new building costs

    Cheers

    Steve
  1.  
    Posted By: steveleighThe Canadians have already attempted to seal buildings during the seventies and eighties and failed because of the inability of render systems to remain airtight.


    Care to provide a citation for this claim? Canadian buildings don't use render systems for airtightness to my knowledge.

    Paul in Montreal.
  2.  
    Very interesting Steve, Please tell me more. Any criteria for the house, Does it need to be detached for example?
  3.  
    Ah, I can see from your website that the house needs to be detached, so that rules mine out:sad:
  4.  
    Paul,

    I have put a PDF online (http://www.sustainconstruction.com/pdfs/TC/BSD-146_EIFS_Problems.pdf ) which shows how external insulation and finish systems (EIFS) have failed in the past.

    Our system does not suffer from the problems outlined in this document. Our system will remain airtight.

    Mike,

    The main reason for the project is to have an environmental occupant like yourself involved in the monitoring. In fact you would be ideal. Why don't you buy yourself a derelict detached house and we'll come and encapsulated it with a brand new code 5 shell. :bigsmile:

    Semi-detached houses are possible but not for this particular code 5 monitoring project.

    Cheers

    Steve
  5.  
    I have the solution, i've got a semi so why not do next door as well :bigsmile:
    • CommentAuthorCWatters
    • CommentTimeJan 4th 2008
     
    Better still DON'T do the semi next door. Then you can compare.
  6.  
    I agree with you it would be a useful comparison. We could seal our system on to a semi but there would be a significant heat loss through thermal bridging between the two houses at the connection (wall and roof) We couldn't guarantee airtightness due to possible air leakage through the party wall. It has to be a total encapsulation on the exterior of the whole envelope to work properly.


    We need a small detached house because it is one of the most difficult to upgrade. The airtight figures will be accurate and this is very important for this project
    • CommentAuthorhowdytom
    • CommentTimeJan 4th 2008
     
    steveleigh,
    perhaps you need two identcal detached homes, one left as is, to get a full picture.
    tom
  7.  
    tom,

    I don't think we would gain anything by making a comparison.

    We need accurate figures to monitor airtightness with an MVHR which affect energy use and air quality.

    The problem with the industry is the figures produced by computer models fall very short of the reality after a few years. We're trying to prove we can produce a building that we can guarantee airtight for the life of the building. Instead of the present system where the builder is only interested in obtaining a completion certificate. Then airtightness degradation is not their responsibilty.

    Do you think the NHBC will be interested in the airtightness of a house 12 months after it is built?

    I don't think so. It would cause a massive expense to rectify if a reliance is placed on airbarriers which are constructed within walls!

    This topic is important.

    Uncontrolled air infiltration through insulation is the major energy leakage problem.

    Cheers Steve
  8.  
    Steve, Are detached bungalows in the frame?
    • CommentAuthorPeter A
    • CommentTimeJan 5th 2008
     
    <blockquote><cite>Posted By: steveleigh</cite>tom,


    The problem with the industry is the figures produced by computer models fall very short of the reality after a few years. We're trying to prove we can produce a building that we can guarantee airtight for the life of the building. Instead of the present system where the builder is only interested in obtaining a completion certificate. Then airtightness degradation is not their responsibilty.


    Cheers Steve</blockquote>

    Steve be careful with real time data, I have been monitoring over 30 positive input ventilation units for nearly 18 months and the one thing that we have learnt is that the occupier can have a massive impact on the results, if there are any switches they can play with, they will, this has a big impact on the performance. Try to make sure they can't control anything and lock the windows shut!! As sure as eggs are eggs they will leave the windows open which will make monitoring air tightness difficult when you are not there to keep an eye on things.
  9.  
    Posted By: Peter A... that the occupier can have a massive impact on the results, if there are any switches they can play with, they will, this has a big impact on the performance. Try to make sure they can't control anything and lock the windows shut!! As sure as eggs are eggs they will leave the windows open which will make monitoring air tightness difficult when you are not there to keep an eye on things.


    Which is why the Buildings Research Group of Natural Resources Canada build identical pairs of houses to do their tests and has them unoccupied. Identical pairs give very similar climatic conditions and having no occupants removes the biggest sources of variation in such studies.

    Paul in Montreal
    • CommentAuthorMike George
    • CommentTimeJan 6th 2008 edited
     
    Paul, I'd be interested to know if any papers came out of the Canadian Studies?
  10.  
    Mike,
    A small detached bungalow would be an excellent demonstration of our sealed system. The energy which is normally convected through a huge area of 300mm thick loft insulation and vented away in the cold roof void could now be saved. Normally with smaller buildings it would be almost impossible to achieve an air permeability of 0.25 m3/m2hr @50Pa. because of the proportionately higher envelope area for their volume and especially small bungalows.

    Which only goes to prove that normal envelopes are very leaky indeed. With a sealed system the ratio of envelope area to volume would not be an issue.

    Cheers

    Steve
    • CommentAuthorsteveleigh
    • CommentTimeJan 7th 2008 edited
     
    Peter,

    That is the main reason why we need an environmentalist occupant who will treat the trial seriously and produce some accurate figures for energy use.

    However, the airtightness of the envelope can be proved because we could fit a valve into the outside wall of every house and this would mean that envelope integrity can then be easily tested at any time. We are suggesting that the builder is only responsible for the airtightness of the wall/roof envelope fabric and not the energy performance. The openings into the envelope are controlled by the occupant therefore the energy efficiency of the building would be governed by the actions of the occupant. The builder could obtain a correct figure for envelope airtightness by temporarily taping windows, doors and vents. If a builder is to guarantee the envelope he would need to be able to prove this regardless of the behaviour of the occupants or deterioration of window frame opening light seals etc.

    We have developed a method of fixing triple glazed units directly into the RoofKrete skin. This will eliminate window frames altogether but of course this then raises the issue of escape from fire. The draft pdf can be found at http://www.sustainconstruction.com/pdfs/TC/RoofKrete%20CS18.pdf

    Also we have discussed the possibility of glazing units with steel mesh starter edges which can be fixed directly into the RoofKrete Skin.

    Cheers
    Steve
    • CommentAuthorsteveleigh
    • CommentTimeJan 7th 2008 edited
     
    Mike
    I'm replying to this from another post "appearance doesn't matter".

    Posted By: Mike George

    Steve, Re the elimination of thermal bridging, do you have any details showing how this is going to be achieved? for example at ground floor perimeters and eaves.

    I'm also very interested in your [our] argument that air leakage has a far more significant effect on insulation than is commonly percieved. Placing figures on this however is rather difficut in my view. You've said that you don't think there is much to be gained by comparative testing, how then are you going to draw the conclusions you suggest?


    Thermal bridges are dramatically reduced because our system is moulded and fitted over an existing building like a snugly fitting tea cosy. We are hoping to reduce thermal bridging down to less that 0.1%. The illustrations of ground floor and eaves are on the following pdf http://www.sustainconstruction.com/pdfs/TC/RoofKrete%20CS20.pdf.

    We cannot compare a sealed system with a breathing wall system because insulation in a sealed system will perform differently for the following reasons.

    (1) The moisture present within the wall/roof insulation of a breathing system is a variable dependent on weather conditions and moisture coming from within the structure. In a sealed wall/roof system the moisture is more or less constant because it is controlled by the internal systems and would be as low as an internal relative humidity of say 40 or 50% would allow. (Moisture within insulation will reduce it’s performance or R-value) - by how much?)

    (2) Thermal bridges can be reduced to about 0.1% of the wall/roof area

    (3) Air infiltration would be reduced to practically still air within the wall/roof fabric because external pressure would be removed. The only pressure present within the wall/roof fabric would be that from the MVHR unit, which is fully controllable.

    I think that we will very quickly prove, with our first installations, that the thickness of insulation required to achieve a code 5 envelope can be reduced dramatically .

    The standard we want to establish is that a building envelope can be made and maintained (code level 5) airtight for the life of that building. To even compare two identical occupied homes would be impossible without having a full record of window and door openings. Energy saving and superior air quality can be a positive result of having our sealed system but it would very much depend on the occupants.

    Cheers

    Steve
  11.  
    Posted By: Mike GeorgePaul, I'd be interested to know if any papers came out of the Canadian Studies?


    Lots of papers:

    http://www.sbc.nrcan.gc.ca/publications_reports/publications_reports_e.asp#residential

    Of particular interest to airtightness, there's this one:
    "Measured Airtightness of 24 Detached Houses Over Periods of Up to Three Years"
    http://www.sbc.nrcan.gc.ca/documentation/pdf/publications/R26/Airtightnessof24DetachedHouses.pdf

    The summary states that timber frame buildings using a tyvek type of air barrier showed no degradation during the study period - refuting Steve's claim earlier:
    Posted By: steveleighThe Canadians have already attempted to seal buildings during the seventies and eighties and failed because of the inability of render systems to remain airtight.


    Also of interest is this dual-house experiement:

    "During the winter heating season of 2002-2003, the Canadian Centre for Housing Technology (CCHT) ran a series of trials to determine actual energy savings from thermostat setback, and to examine the resultant house temperatures and recovery times. The report can be examined at http://irc.nrc-cnrc.gc.ca/pubs/rr/rr191/rr191.pdf "

    More papers from the CCHT are available here:

    http://www.ccht-cctr.gc.ca/documentspapers_e.html

    Paul in Montreal
    • CommentAuthorsteveleigh
    • CommentTimeJan 7th 2008 edited
     
    Paul,

    Our system is a rendered system which is an airtight/waterproof dual purpose shell on top of external insulation which is easily maintained for the life of the building.

    A simple question to consider when making a building airtight.

    Is the airtightness of the chosen system maintainable for the duration of the building's life?

    If not how do you replace it and and what cost to the environment and the house owner?

    Posted By: steveleighThe Canadians have already attempted to seal buildings during the seventies and eighties and failed because of the inability of render systems to remain airtight.


    Apologies to the Canadians who I have the upmost respect for. It was The Americans who attempted and failed to seal buildings :bigsmile:


    Cheers

    Steve
  12.  
    Posted By: steveleighA simple question to consider when making a building airtight.
    Is the airtightness of the chosen system maintainable for the duration of the building's life?


    Agreed. And the research I cited seems to indicate that standard Canadian construction techniques using timber frame with a polyethylene air barrier such as Tyvek seem to maintain their air tightness properties. As far as I know, stucco rendering systems in Canadian buildings are not designed to be air barriers but are in addition to a Tyvek-type layer.

    Google "pressurized rainscreen construction canada" for many papers on the type of construction used over here.

    Cheers,

    Paul in Montreal
  13.  
    Posted By: Paul in Montreal
    Agreed. And the research I cited seems to indicate that standard Canadian construction techniques using timber frame with a polyethylene air barrier such as Tyvek seem to maintain their air tightness properties.


    I'm not disputing a level of airtightness can be attained by expertly fitted membranes within walls. But with our system we are talking about a maintainable airtightness standard that cannot be matched by any other system in the world. Encapsulating the roof and walls in one continuous joint free shell similar to a 'tea cosy'.

    Its obvious that plenty of materials can maintain their airtightness qualities for a few years but will eventually fail.


    We want to raise airtightness to a level which could never be attained by fitting membranes inside walls and roofs even if the level of expertise required to fit them properly can be maintained.

    The weaknesses inherent in the membrane system such as ageing of tapes and mastic seals and also general ageing of the petrochemicals, which are normally the basic ingredients of these membranes, will prove them not to be durable and they may even start to fail when we will be least able to fix the problem in the expected energy famine.

    We need to make everything super-durable now because we may well be very weak energy and resource wise in the future.

    Cheers

    Steve
  14.  
    Steve, Are you able to divulge the exact nature of the materials used for your system?
  15.  
    What about airtightness at the known most vulnerable spots for air tightness, ie junctions with openings, service entries/exits etc...?

    I suppose a good analogy would be the difference between a dry suit and a wet suit, the former being water tight but a lot warmer in cold water... then again water's not the same as air (or ground) and the air in the dry suit is a good insulant...

    J
  16.  
    Posted By: Mike GeorgeSteve, Are you able to divulge the exact nature of the materials used for your system?


    Yeah no problem. RoofKrete System 4 membrane on top of insulation. :wink:

    Seriously, I know its made of natural minerals and has been investigated by Greenpeace, Design Council for Millennium products Award and many others. They all agreed it is sustainable. The simple fact is it works and thats good enough for me.

    Posted By: James NortonWhat about airtightness at the known most vulnerable spots for air tightness, ie junctions with openings, service entries/exits etc...?


    All the vulnerable spots can be maintained airtight because they are visible and on the external surface. Probably DIY which is what is required for the future.

    We have no control of the occupant leaving doors and windows open. However, as energy gets more expensive they'll soon realise or can be educated about the financial and environmental benefit of closing doors and windows too allow MVHR to provide fresh air.
   
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