Commercial build: Timber frame and thermal mass.

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- CommentAuthorandy
- CommentTimeMar 27th 2007 edited
Hi, I stumbled onto this forum browsing for some eco build answers. The site looks interesting and I look forward to some stimulating discussions!

The eco build query was in reference to a proposed timber built 2 storey office. The main structure is glulam beams with timber I-beam secondary structure. The offices are small 18 x 9m footprint and open plan. 250mm insulation in the walls, 350 in the roof.

This isn't great for thermal mass. Does anyone out there have any experience of incorporating high thermal mass into 1st floors of this type? The idea would be to use the 1st floor for heating / cooling.

Normal practice would be to use a steel frame with pre stressed concrete inserts - I would like to find out if there is an alternative.

Cheers for now,

Andy
- CommentAuthornigel
- CommentTimeMar 27th 2007
Currently constructing a similar project to you.

We ended up building all central services into a heavyweight core of the building with blockwork to provide thermal mass.

You need to talk to your structural engineer about the floors but I would be very surprised if you could achieve thermal mass in the intermediate floor without having to modify your timber frame structure. The only other option would be to build heavy to first floor and then use timber frame for the top storey.
- CommentAuthorPeter A
- CommentTimeMar 27th 2007
Andy,
Have seen in last few months reference to a Givlon screed that can be used on upper floors of timber frame flats, would this be of any use. I would be concerned over a block central core with all the settlement issues associated with timber frame. With correct design you should be able to overcome over heat issues, ie orientation, solar shading, glazing spec and some sort of solar chimney.
- CommentAuthorbiffvernon
- CommentTimeMar 27th 2007
In days of old many timber framed buildings had lime-ash floors. That was all long before steel beams, concrete and structural engineers were invented, but it provided high thermal mass with little embodied energy.

If you want to incorporate thermal mass in a green building the first material of choice has to be earth.
- CommentAuthornigel
- CommentTimeMar 27th 2007
Posted By: Peter AAndy,
Have seen in last few months reference to a Givlon screed that can be used on upper floors of timber frame flats, would this be of any use. I would be concerned over a block central core with all the settlement issues associated with timber frame. With correct design you should be able to overcome over heat issues, ie orientation, solar shading, glazing spec and some sort of solar chimney.

Do you mean movement? Perhaps you could elaborate?

I would expect a timber frame structure to settle less than a solid structure due to its lower bearing pressure.
- CommentAuthorandy
- CommentTimeMar 27th 2007
Thank you all for your input so far! I wasn't expecting such a speedy response :-)

Nigel, the office is an L-shaped plan (9x18m wings) with the services located within the depth of the angle (North facing) the internal angle is chamfered to create an unheated solar space with heat recovery so we have limited opportunity to use the core for mass heating cooling to the majority of the office spaces.

Peter A, Had a quick look at the Gyvlon web details. Do you have any experience using this type of product? I see certain benefits. Are there any environmental implications to be aware of - production / installation / recyclability?

Biffvernon, we had thought of doing something similar. It has the potential to be quite tricky as a service void would be required below the ceiling to minimise disruption (and mess!) of future services installations. This would create an insulating layer detracting from the thermal mass.

We are also looking at hollow section concrete planks - exposed / rendered to underside ceiling soffit.

Your thoughts are much appreciated. I will let you know how it progresses. Any more ideas then please let me know!

Cheers,

Andy
- CommentAuthorLizM
- CommentTimeMar 27th 2007
Watch out only providing thermal mass in the first floor floor. The first floor itself could overheat without thermal mass in the roof. I presume that the building is naturally ventilated? You will have to prove that it does not overheat to pass building regulations.

With respect to future services, providing a floor to floor height now which can accomodate future services will be a benefit. If you do end up constructing the building out of insitu concrete then don't put a ceiling in as you want to keep the mass exposed.
- CommentAuthorPeter A
- CommentTimeMar 27th 2007
Nigel, timber frame settles a lot in it's early life, we work on 6mm a floor (it's not quite as simple as that though), if the whole building is timber frame not usually a problem, the problem exists when you marry up trad and timber frame, ie face brickwork, a block staircore etc. Finishes will flex and distort at juncture. The timber settles because of all the joints compressing when the roof load etc are put on it. The foundations don't move it's the timber frame above. The more complex the building the bigger the detailing problems. You wouldn't believe the problems that can happen with incorrect detailing or poor workmanship.
Andy, not yet progressed far enough to answer your questions, I would have though in this day and age that the environmental angle has been fully covered.
- CommentAuthorChris Wardle
- CommentTimeMar 27th 2007
How would you go about constructing a lime-ash floor Biff? I think a friend of mine has just bought a cottage with this kind of floor in it and we were wondering how it was done. He is about to do a loft conversion so I might be able to persuade him to have a go...
- CommentAuthorGuest
- CommentTimeMar 27th 2007
In another thread there is the excellent link to Viking and their way of ensuring thermal mass in, for example, timber framed structures - all to do with decrement delay. See http://www.viking-house.net/decrement-delay for their analysis and case study.
- CommentAuthorfostertom
- CommentTimeMar 27th 2007 edited
Posted By: biffvernonIn days of old many timber framed buildings had lime-ash floors. That was all long before steel beams, concrete and structural engineers were invented, but it provided high thermal mass with little embodied energy.
Mind you, thermal mass is bound to mean massive weight, therefore heavier support structure, partly contradicting one main advantage of pared-down modern timber frame. However, not as much extra loading as one would suppose, as live load already dominates the structural calcs.

Posted By: biffvernonIf you want to incorporate thermal mass in a green building the first material of choice has to be earth.
That's right Biff - a recipe I'm keen to put into practice is barely-peeled pine trunks as massive floor beams (structurally very efficient as the heaviest-loaded outer fibres aren't all mangled by sawing), woodwool slabs, say 400mm of earth and Jill and Jackie's lovely linseed-oiled 50mm thick cob floor tiles, which can be varied clay colours, swiss-rolled, or otherwise encaustic patterned.

Posted By: andy(Gyvlon screed) quite tricky as a service void would be required below the ceiling to minimise disruption (and mess!) of future services installations. This would create an insulating layer detracting from the thermal mass.
Andy, how would that be different with any other massive floor e.g. hollow section concrete planks, as you're considering? You can easily create voids e.g. with cardboard tubes in a thick massive floor, if that's how your services would run in the concrete alternative. Quite right a suspended ceiling would defeat the object.

Posted By: LizMThe first floor itself could overheat without thermal mass in the roof.
How come, Liz? What if the roof really resisted solar gain e.g. dare I say it, by incorporating mulitfoil insulation?

Posted By: Guestdecrement delay
This is the missing knowledge in all these thermal mass debates, which I'm now determined to fill in for myself http://www.aecb.net/forum/index.php?topic=859.0. I'm aware that adding mass unscientifically can easily e.g. deliver stored heat just when you don't want it - this I suspect is the reason for inconclusive/contradictory verdicts in many investigations into whether massive is better than lightweight.
- CommentAuthorGuest
- CommentTimeMar 27th 2007
I worked on a new building system last summer which is to employ moveable thermal mass in the form of water. It is moved from a roof pond through the structure to a ground floor tank. This build was a super strong monocoque structure which seems to answer all of the problems regularly covered in this forum.
- CommentAuthorbiffvernon
- CommentTimeMar 27th 2007
Hey, you could have one of those little turbines to pump the water up to the roof on windy days and then let it down through another turbine on calm days. Have I just invented the domestic micro-pump-storage generator?

Chris, quite a lot of what I know about lime-ash floors is on my page at http://www.biffvernon.freeserve.co.uk/lime_ash_floors.htm
I'd be interested in hearing from your friend if you'd pass on my e-mail address to him.
- CommentAuthorGuest
- CommentTimeMar 27th 2007
Thats sounds like a good idea biffvernon. But reading between the lines I sense a bit of sarcasm. But nice idea I'm sure the guys would have thought of that. They seem to have a very realistic approach to sustainable building.

My background is a computer programmer who has developed maintained airport operations databases at various airports throughtout the world including Guangzhou and Manchester. I became very interested in sustainable buildings after being involved in the monocoque building project last summer.

It seems to me that this forum is very much the wacky end of the sustainable debate i.e. mass produced straw builds, mud huts, and sheep wool insulation without considering methane produce from millions of flatulent sheep.

The building project I was involved in was passivehaus standard, zero waste, earthquake proof, recyclable, reusable, fireproof, non-toxic, very low embodied energy and can be mass produced to any design. The icing on the cake is it easily meets code level 6 ' code for sustainable homes'. Plus dealing effectively with water conservation issues, which I feel the 'code for sustainable homes' doesn't address properly.

I challenge you and all the other ecological boffins to try and find a sustainable requirement that this house cannot exceed. I will give total explanation for any challenge set.
- CommentAuthorJeff Norton (NZ)
- CommentTimeMar 27th 2007
In my simplistic way of thinking use the ground the building is sitting on as thermal mass (& around if there is room) and keep the whole structure light weight. You can remove warm air from top of building through ducts (passively or mechanicaly, with water or without) and route ducts/pipes through foundation and ground to remove heat. The incoming air through ground (with separation from outlet) in the bottom of building to complete the loop.
Earth pipes I think it is called, cools in summer and preheats in winter!
- CommentAuthorGuest
- CommentTimeMar 27th 2007
as thermal mass responds more effectively to direct solar gains as opposed to casual gains does anyone see any benefit to locating the mass around window reveals and floor slab just in front of the windows and adding more structural strength in this location only while the rest of the timber frame is as normal
- CommentAuthorfostertom
- CommentTimeMar 27th 2007
Not sure if that's true Guest - once the solar heat's inside the 'greenhouse' (windows) it's going to reflect/re-radiate/disperse around until it finds a home (i.e. until equilibrium is reached, between cool masses and heated lightweight or first-incidence surfaces, in the room)
- CommentAuthorPeter A
- CommentTimeMar 28th 2007
Posted By: GuestThe building project I was involved in was passivehaus standard, zero waste, earthquake proof, recyclable, reusable, fireproof, non-toxic, very low embodied energy and can be mass produced to any design. The icing on the cake is it easily meets code level 6 ' code for sustainable homes'. Plus dealing effectively with water conservation issues, which I feel the 'code for sustainable homes' doesn't address properly.

Dear Guest, interested to know where the passivhaus standard structure is that you built and how much it cost extra over to meet this standard. I could build a level 6 home tomorrow it's the cost that makes it completely unrealistic and the fact that probably won't have a big enough roof to flood it with pv's. I await your response with baited breath.
- CommentAuthorandy
- CommentTimeMar 28th 2007
LizM, thanks for your comments. Yes, naturally vented. GFL floor to ceiling is 2.7m. Proposal is to use the underside of thermal mass for cooling / radiant warmth. 1FL will be open trussed, so much larger volume of space. Looking at venting at ridge level.

fostertom, my comments referred to biffvernons idea of mass using earth or similar within the floor - not the screed idea. Exposing the surface as a ceiling finish would mean the ceiling material would be holding a loose material. By future proofing this building I would not want the local maintenance company drilling holes and emptying bays of material as has happened within many older buildings of similar construction.

Guest, do you have any more info on the water cooled building? Was it fully monocoque or hybrid? Are there any web links?

Jeff Norton, the earth pipe idea is great and am looking into it a little more. I'm based in the north of Scotland so looking for more info on suitability. Do you know of any worked examples?

Cheers again,

Andy
- CommentAuthorfostertom
- CommentTimeMar 28th 2007
A
Posted By: andy...mass using earth or similar within the floor...exposing the surface as a ceiling finish would mean the ceiling material would be holding a loose material...I would not want the local maintenance company drilling holes and emptying bays of material as has happened within many older buildings of similar construction.
I was thinking of say 100thk woodwool slabs as the ceiling (spanning between the trunk-beams) and actually cob on top - i.e. mixed with clay and laid wet enough to bind together.

Back to your idea of hollow section concrete planks, or any other exposed massive ceiling, how would you then do the servicing in a commercial building, without suspended ceiling?

Posted By: fostertomcreate voids e.g. with cardboard tubes in a thick massive floor
From your conservatory apex, you could pipe hot air through the massive floor all day and out by a passive-exhaust stack; at night reversed with cold air backflowing. Mix that in with Jeff Norton's idea!
- CommentAuthorGuest
- CommentTimeMar 28th 2007
Peter A

Sorry for my ignorance about the electrical generation requirement on Code 6. But does the excellent water management capabilities of the system not offset this somewhat? The structure can be super insulated to passive house and the price - from what I overheard - will be substantially lower cost and much faster build than anything presently available.

Andy

I do not have any info on the water cooled building only that it can be built with hollow walls which can be filled with water on a south facing wall then drained out to be replaced with a low pressure vacuum. The water follows the sun around the house - does that make sense??

I hope I am not sticking my neck out too much because everybody on the build had to sign a confidentiality agreement. It is very frustrating for me to read all the many problems which have to be overcome to achieve sustainable buildings when I have been involved in a project which has quite clearly solved all sustainable construction problems. I can say this with a good degree of certainty because I was present at a meeting (albeit in a very minor helping out capacity) with about thirty architects when one of them said â€˜this system ends the debate on sustainable constructionâ€™ and these where senior architects from Atkins Global etc I might add that all these architects where astonished at the design potential of the system to quote one â€˜I will not sleep for weeks thinking about the design potential of this systemâ€™

I just hope that the developers of this system will not take the money and run, it is the result of twelve years in development, all the tools and machines have been developed for mass production of the system.

It is fully monocoque built with a type of flexible ceramic material about 5/8 inch thick stiffened by 8 x 5/8 inch webs/beams. The whole structure can be cut up and reformed again indefinitely without losing any structural capabilities. It just sits on the ground without the need for foundations. I do not know of any web links at present but it must be imminent. I think that the developers are talking to the large developers in the UK and also the Chinese.

If they got the Chinese to use this system it could solve the carbon problem for us also because it would mean that the Chinese would avoid having to establish a massive manufacturing base to produce all the many thousands of items which got into a house structure. The Indians too of course. This system can be designed to suit any design requirements. It is simple to use. I was on this for three months from the beginning and I would now say that I am fully confident in the methods and able to build a house without any problem.

What would the sight of ship loads of low cost quick build Code 5 homes from China do for our construction industry ?
- CommentAuthorAds
- CommentTimeMar 28th 2007
This sounds as if it falls into the "if it sounds too good to be true..." bracket, especially if it hasn't been heard of during its 12 years of development. However, if the Atkins Global etc senior architects are rather impressed there may well be some merit in the method, although a few architects have been astonished/impressed by some quite unedifying projects in the past!

Clearly the amount of energy required in this construction would need to be verified, and most buildings require some form of foundation, if only to create a level surface above damp levels. Without knowing more it is not possible to even consider other questions - don't think I'll hold my breath yet.
- CommentAuthorJeff Norton (NZ)
- CommentTimeMar 28th 2007
Here are a couple of links about earth pipes/tubes
http://www.thenaturalhome.com/earthtube.htm
http://www.earthshelters.com/Other_const.html

Deep dry ground is the key for year round usage! worst case senario is ambiant temperature of ground (@ 1metre deep) is still warmer in winter and cool in summer.
- CommentAuthorGuest
- CommentTimeMar 28th 2007
Ads

History proves that revolutionary products are always "too good to be true". Because nothing exists too compare them with, no standards or prior testing methodologies exists for monocoque structures but we have built a full size example of a monocoque structure inside an industrial unit in Devon.

The incremental method of advances in the building industry can no longer be applied because WE HAVEN'T GOT YEARS to deal with the major issue of resource conservation. The current building materials and methods cannot supply the houses for the billions of people who will need them. The only way forward is mass production which produces fully structured sections of buildings which can be seamlessly joined together on-site in any design configuration at low cost.

Instead of discussing new ways of how to position a vapour barrier timber walls etc. lets instead deal with the major issue of billions of people in China and India who want new homes, all this tweaking is absolutely pointless and a waste of energy - speaking of waste and energy this system is almost zero waste in production and on site and is very low embodied energy, but does this matter anyway in a everlasting material?

The building system I have been describing to this forum is real, it does exist, and all the tools and machinery have been designed and tested. I have been there and used the tools and machinery together with a team to produce an incredible structure. I do wish I could give more details but I cannot without permission from the owner of the IP. Has I have already said in this forum all the people involved with this project have been made to sign a confidentiality agreement. I am extremely frustrated about this gagging situation. I intend to approach the owners to find out if I can give you a website of the base material being used in another application. I know it is in use on a famous sustainable building by Buro Happold. I also believe that the vast knowledge displayed in this forum about ventilation and home generating technology etc could be of use in this system. By the way the system is being designed as total indoor climate control, with a knob on a wall which controls Relative Humidity - it is a sealed almost 100% airtight system - the ideal healthy house - breathing walls sounds positive but is actually negative it means that water molecules are travelling through the walls depending on inside or outside pressure - (this should start some people off!)

I realise that I'm coming from a completely different background (as discussed in previous posting). But, I am very excited about this project because of the potential to solve global sustainable construction problems. So I'm viewing all the issues with different eyes from yourselves.

The material is impervious and the base is reinforced with beams every 400mm it can be built in a swamp and remain dry inside. Regarding the twelve years of development ten years was spent proving the material.
- CommentAuthorbiffvernon
- CommentTimeMar 29th 2007
I hope I never have to live in one
- CommentAuthornigel
- CommentTimeMar 29th 2007
If it sounds too good to be true then it probably is.

Did the BCO have to sign a confidentiality agreement too or is the building still in an industrial unit?

And I think your story might be more credible if you were to reveal your identity.
- CommentAuthorPeter A
- CommentTimeMar 29th 2007 edited
Posted By: GuestPeter A

Sorry for my ignorance about the electrical generation requirement on Code 6. But does the excellent water management capabilities of the system not offset this somewhat? The structure can be super insulated to passive house and the price - from what I overheard - will be substantially lower cost and much faster build than anything presently available.

Dear Guest, having had to sign a confidentiality agreement recently it's probably best that you remain a guest.

Unfortunately the Code for Sustainable Homes has certain minimum scores for each different element so it's not possible to trade off as it was under Ecohomes. The water cooled home and electricity generation would be grouped under one section, a Code Level 6 needs to be 145% more efficient that current building regs, this is because the current software (NHER may do) does not factor in electrical useage of the likes of tv's, cooking, pc's, irons, kettles etc and these are deemed to be about 40-45% of a typical homes total energy demand.

Taking an educated guess the structure (it sounds quite complicated) focuses on the heating and cooling demands of the building, did it need a heating system? Is it a commercial building, how was hot water catered for? Hot water being 30% possibly more of a homes total energy demand.

Does the building look a bit whacky? Will anybody want to buy one?

It must have a seriously impressive ventilation system if it's 100% airtight?

You've dropped a few clues will see what an internet search brings up.
- CommentAuthorGuest
- CommentTimeMar 29th 2007
Peter A

I have talked with another person involved with this system and he has said that the confidentiality agreement expired on the open day November 2006 and that it is okay now. But he did say that the owner wanted to talk only to specifiers in the industry about mass production because he does not have the time to get involved with individual house designs at this stage. I think I have already explained that the whole emphasis of this project was to develop a low cost high specification social house for developing nations to avoid them having to develop a huge energy and resource hungry manufacturing base producing thousands of different building materials. This is the only way to tackle the carbon and resource depletion problem - down to the fundamentals. This is the main reason I am involved in this project.

Continuing my construction education I was watching some grand design programmes the other night and the complicated structural steelwork and hundreds of complicated fixings and bits and pieces which go into buildings are a complete nightmare compared to this system. This system is absolutely ideal for bespoke designs, I reckon that I could cut construction time by 90%. And I am now seriously thinking about starting my own building company specialising in this system and constructing one off designs.

I hope to talk with the owner sometime today to check out this confidentiality thing so I maybe back later with some contact details.
- CommentAuthorandy
- CommentTimeMar 29th 2007
Guest, it sounds like something from an Isaac Asimov novel! Potentially interesting.

Until it can be revealed to the rest of the world it looks like I'll have to content myself with wood and earth...

Our own construction is going to be a little less modern. We are now looking at 9x3m prefab. floor cassettes supported on glulam beams. Cassette construction from underside: 12.5mm glasroc, 300mm timber I-beam with 75mm very weak sand mix between joists, 50mm insulation, service void, timber access floor

I look forward to hearing more about the new construction method, thanks for your input!

Andy
- CommentAuthorPeter A
- CommentTimeMar 29th 2007
Dear Guest, looking forward to learning more, perhaps with some lateral thinking it could work in the UK , Andy's comment re Asimov made me smile, when writing my earlier post was thinking about colonizing the moon!

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Commercial build: Timber frame and thermal mass.