Jayne Du says: Two questions: how do you test the strength of the components, as that would probably important to consider when building infrastructure? And second, what of current systems that already use structures like bamboo and rattan to build homes, what would be the difference between these and the products by "ModCell". --Thanks,

Jayne Du says: It is an interesting idea.

Craig White says: Hi Jayne,
We've done lots of structural testing and are able to construct panels that can be used as load bearing elements for buildings up to 3 storeys high. In the UK, above 3 storeys we are required to have a separate structural frame.

To date we have worked with timber, straw and hemp and have a number of completed projects. To see them click onto http://www.modcell.co.uk/

Our approach with regard to other materials is to work bio regionally. ie source materials that are available locally. For example, in the UK we combine hemp shiv (shiv is the woody core of the hemp plant that is a bi-product of making hemp fibres and hemp oil) and bind them together using lime. Lime is available throughout the world and is derived from limestone (Calcium Carbonate). Limestone was created by animals using the dissolved CO2 in the oceans of millions of years ago to make their shells and skeletons or, in other words very ancient carbon capture.

In other parts of the world, for example asia, we are testing bamboo and coconut husks to replace hemp and again bind them with lime.

I hope that answers your questions.

Craig

Tom Miller says: Hi Craig,
First of all, "photosynthetic architecture", sounds fancy
Anyway
Is the straw involved with these panels structural?
What kind of dimensions are we talking about (thickness etc.)?
Does the straw continue to photosynthesise once its in my wall?
Cheers

Craig White says: Hi Tom

It was a toss up between photosynthetic architecture or renewable buildings. Sounds fancy but in essence describes what we are trying to do.

The straw does play a small but contributing a role in the structure of the panel. It acts compositely with the lime render that encapsulates it to provide resistance to wind load and shear load. When we use hemp and lime together the shear load they provide is similar to sheathing boards used in timber frame construction.

A typical panel size is 3m x 3m, the sizes vary depending on the type of building. With regards to width we are 'fat and proud' or 490 mm thick! We do slimmer versions at 390 mm at 350 mm but the best thermal value is achieved with the 490 mm thick.

This thermal performance reduces the heating requirement in a home by 83% and keeps the house warm in winter and cool in summer.

The straw, hemp and wood do not continue to photosynthesise.

However, we do design our buildings to work with the sun's energy, either passively through orientation or, actively by integrating solar hot water and solar photovoltaic panels.

To find out more click onto http://www.modcell.co.uk/.

We are currently building a BaleHaus and we have set up a StrawCam on site where you can see a house being built over the next two days.

Regards

Craig

Craig White says: We have just started building a BaleHaus at Bath University. The house is made from prefabricated straw and hemp cladding panels. The benefit of prefabrication brings great speed in construction on site. For example, the two storey Balehaus at Bath was built in just 3 days. We started on Tuesday and the roof was on by Thursday.

In the UK we have 3m tonnes per annum of straw available as a by product of growing wheat the same goes for hemp although in smaller amounts.

The key benefits of building this way is that we create a home that needs just 20% of a the heat energy of conventional house, all of the materials are entirely renewable, and because they are made from materials created through photosynthesis, the house becomes a domestic carbon bank.

The Balehaus at Bath has banked the atmospheric equivalent of 32,905 kg of CO2. The BaleHaus at Bath, even after accounting for the emissions created through the manufacture and transport of its components, is carbon negative!

Craig White says: To find our more about BaleHaus at Bath click onto:

http://www.bath.ac.uk/features/balehaus/

Manuel Reiband says: Great idea!

I'm sure you have thought through all technical aspects, so I take it for a "proven" concept.

However, given the fact that concepts for sustainable building have been out there for quite some time (although using other methods), it showed that architects and the building industry in general have been very reluctant to adapt such methods.

Do you have any plans as to how you want to tackle that issue. More specifically, once the material is marketable, how will you get people to change their working habits?

I guess that is the question that many of us are facing: how to make people change?

Regards

Manuel

Craig White says: Hi Manuel

Behaviour change is hugely important to reducing our impact on the environment. The construction industry, for example, is responsible for:

60% of the raw materials processed world-wide,
50% of man-made carbon dioxide is produced through the operation of buildings.
20% of all materials delivered to a construction site end up in landfill.

So we as construction professionals have to turn around our behaviour as well as expecting consumers to do the same.

We have been successful in ensuring that the story we have to tell is a good one. We lay as much importance on how we tell that story as we do on ensuring the sustainability of what we do.

The concept we have proved through a number of buildings already

(check out http://www.modcell.co.uk/page/projects)

but we have also been successful in marketing and awareness. We won Off Site Construction Magazine's Best Product of the Year 2008 (offsite construction magazine is all about Prefabrication of buildings) and we beat of competition from a number of multi national organisation with well established industry track records.

This year we won Sustain Magazine's Product of the Year 2009 for our sustainability of ModCell.

We have worked hard to promote our ideas in the media and we delivered the UK TV Channel 4's Grand Designs - The House that Kevin Built for Kevin McCloud, where we built a house live on television over 5 days, going out live every night nationally. (http://www.channel4.com/4homes/on-tv/grand-designs/grand-designs-extras/grand-designs-live-the-house-that-kevin-built-08-06-20_p_1.html)

Where originally we found scepticism from the world of mainstream construction, we now find enthusiasm for what we do and we are currently working with a world famous architect to deliver one of the largest straw bale constructions in the world.

Watch this space for more!

For us the simply relying on the sustainability of photosynthetic materials is not enough. We think the message and how it is put across should not harrang people into changing their behaviour. Rather, it should be seen as the coolest option!

Craig

valère Hofstetter says: Dear Craig,

It sounds like a fantastic idea, but I wonder if your carbon negative house is really one in the long term. It would be one only if you can guarantee that the house will never burn or decompose in a few hundred years and that the truckload of mined limestone you are using is CO2 free.
Otherwise, I still think it is a great idea for small and medium scale using existing by products.
We are already competing for fresh water and fertile land to put food in our belly. Early bio fuel made our stomachs compete with our cars, I hope our stomach won’t have to compete with our houses in addition.

Valere

Craig White says: Valère

Your absolutely right to question the end of life scenario for ModCell. There are a number of outcomes that need to be considered. If we were to throw straw, hemp and wood into landfill and let it decompose anaerobically, it will produce methane, which is very bad! Methane is 23 times more impactful than CO2 as a greenhouse gas.

This is the worst case. There are others:

1. In 60+ years from now landfill for construction material, will simply not exist in the the EU. We will need to find other options.
2. The material value of timber will be too high to not recover for re-use.
3. Low grade re-use would be to aerobically compost the materials, which has no methane output. Methane is a product of anaerobic decomposition.
4. Medium grade re-use as biomass, which returns the carbon to atmospheric CO2. Giving a neutral cycle if FSC or PEFC timber is used with the re-planting ratio of + 3 to 1 which expands the forest carbon sink on an ongoing basis. (Some European forestry systems claim a 1 felled to 9 planted ratio).
5. Because the ModCell is a component assembly system all the materials can be separated into their original material constituents with no contamination, allowing for higher grade re-cycling or re-use.
5. Medium grade recycling would be to deploy the timber in chipped or particle boards.
6. High grade re-use - the system can be de-mounted and relocated. The panels can be redeployed in different buildings. We are currently building a BaleHaus at Bath University where half of the panels have already been used before to build a The House that Kevin Built for Grand Designs Live.

A BaleHaus is designed to meet a minimum design life of 60 years and will survive beyond 100 (the oldest straw bale house is over 110 ten years old). After 100 years the Global Warming Potential of the CO2 that would be emitted by the renewable building materials if they were to be burnt is discounted in a GWP calculation.

Wikipedia definition - Global Warming Potential (GWP) is a measure of how much a given mass of greenhouse gas is estimated to contribute to global warming. It is a relative scale which compares the gas in question to that of the same mass of carbon dioxide (whose GWP is by definition 1). A GWP is calculated over a specific time interval ie 100 years.

The Life Cycle Assessment research work we are carrying out shows that a BaleHaus has half the GWP of a conventionally built house.

None of the renewable materials used in ModCell would require a shift in agricultural practices that would take us down the BioFuels versus food scenario.

The straw and hemp shiv used in the system are by products. The straw is a by product of the existing food production system. In the UK alone, we produce 3m tonnes of straw annually, a typical 2 bedroom BaleHaus uses about 5 tonnes of straw. We would have to shift the entire UK house building programme over to straw and still only use half of the already available by product straw.

On a smaller scale the hemp we use is also a by product. Hemp is grown under license for its fibre and oil (licensed hemp is non narcotic) we use the woody core of the stem, known as shiv. Up until the end of the 19th century in the UK anybody farming more than 10 acres of land was obliged to grow hemp as a field crop to support the production of rope and sail cloth.

Lime render does have a higher embodied CO2 footprint, and our LCA takes account of this. As lime render cures it does re-absorb CO2, but does not have a negative greenhouse value.

A long answer to your very good observation!

Regards

Craig

valère Hofstetter says: Thanks a lot Graig,

I have learnt a lot from my small question. I did not know there used to be good old days where you were legally obliged to grow hemp.

Sure, the straw could be anaerobically degraded in nature,.. if it gets a chance to get underground before being some insects or mushroom lunch in between.

I also heard about using that type of by-products for methane production in bioreactor for bio fuel for car or heating.
I did not realised how small the entire UK house-building programme is compare to the bio fuel market. Because I have been told (maybe I should have closed my ears) that all agricultural by-product could only cover a fraction of our fuel demand.

After all, if we get a choice between building our house, heating it or driving home, it fine with me.

Good luck for your business anyway!

Valère

Dan Frederiksen says: you're talking about building houses out of wood and straw? that's the brilliant idea that was chosen among the 10...

I understand that wood is made with sunlight and takes carbon out of the air but then it takes a bit of energy to process it into a house. and it's not easy to use wood as insulation or as windows and then there is nature that thinks that dead wood tastes good.

and how close it is to being a real profitable business?
and how will you convince people to buy wood and straw houses

and is it really a novel thought

giovanna barbaro says: This idea is not new. In Italy this type of construction is called "malta in paglia" and was traditionally used in low cost, self-construction since the Middle Age . It has many drawbacks.
a) The walls cannot carry weight since their compression resistance is just 19 kN/m2 (1/100 of a light cement). So they can just serve as divisions.
b) It is well known that cellulose in contact with alkaline substances like lime hydrolyse into sugars, loosing its mechanical properties. This effect was researched in China with bamboo fibers used to reinforce concrete. So the durability of the straw bale wall will be less than 10 years, and much less in moist climates.
c) It is not an accident that the ancient Italians mixed the straw with mud or clay and a very little amount of lime. Once hardened, lime was used to plaster the wall. This kind of wall never carried load, it was always placed inside wooden or stone bearing structures.

Craig White says: Giovanna and Dan

Apologies for replying to you both in one post.

Dan, our approach is to prefabricate the use of renewable materials using an Ikea-like flatpack system using solid timber engineering, ModCell is the first to have done this commercially at scale.

To see examples of this click onto: www.modcell.co.uk

We don't expect everyone to want a BaleHaus but the system has already been successfully used on a number of projects and we believe is commercially viable.

Encapsulating the straw or hemp in lime, which is aseptic, seals them into a breathable envelope and we do not have any issues with insect infestation as a result.

Giovanna,

Your correct to point out the load bearing capacity of straw is about 19 kN/m2, however the ModCell system takes vertical loading through the ModCell Frame. The rendered straw contributes in shear and wind-load, the whole panel acting compositely.

As a result we can build up to 3 floors high using ModCell as the structural and stability system for the building. Above 3 floors, in the UK, all buildings require a separate structural frame to avoid something called progressive collapse.

Again if you check out www.modcell.co.uk you can see exactly the approach we have taken.

best regards

Craig

Ilona Ludewig Mack says: Hiya, congratulations on your being a finalist.

I hope you still look at this discussion, as I have a question after seeing the Balehouse construction video:

You build strong thick lovely walls for insulation, yet then put in a flimsy thin floor - why? There must be a way to find a flooring system that meets both needs for sound proofing and minimum weight... it would be great if you could crack this too!

Good luck with it all

Ilona

Craig White says: Hi Ilona

Thanks for your best wishes. I'm amazed and delighted to have got this far in the competition.

A BaleHaus floor is made of solid, cross laminated timber, which acts as the structural slab. it is 120 mm thick and does not need to be any thicker. What the video does not show is that we then put on top of this 100 mm of wood fibre insulation, into which an underfloor heating system can be installed and then on top of that we put a timber floor finish. This gives us the acoustic performance you identify as being needed and a low energy heating system. It also looks good.

If you click onto:

http://gallery.me.com/modcell#100214&view=carouseljs&sel=0

You can see a gallery of photos of the just completed BaleHaus at Bath showing the finished flooring.

I hope this answers your question.

Regards

Craig

Truyen Pham says: Congratulation! Step it up!

We are responsible entrepreneurs.

Mr.Truyen Pham
Vietnam

Phil Griffiths says: Hi Craig.

I'm very interested in your concept and progress having some small scale experience of straw bale building myself (through Amazon Nails).

I have a few questions, which I can't find answers for:

1. What's the recommended method of construction of the foundations. I'm assuming you use limecrete. There doesn't appear to be much of a water barrier in the Bath Uni construction?

2. Do you use lime render on the inside and outside? I thought the preferred material was clay for internal walls? Is this just a matter of logistics of manufacture and economies of scale?

3. What do you do about internal wiring?

4. How do your prices compare to traditional methods such as brick or block? This will be one of the main argument from the construction industry no doubt?

Good luck in the competition.

Regards
Phil.

Axel Baumhoefner says: Hi Craig, this part of your comprehensive work is a detailled and excellence idea to make sustainable architecture. And: It even looks very stylish as seen at the baleHaus-project. Good luck in the competition from your german fans.

regards,
axel

Craig White says: Phil

Thanks for the support. In answer to you questions:

1. We can do a variety of foundations types, but ground conditions will dictate to some extent. We have used screw piles to support a solid timber floor. When we use a concrete slab we use cement replacement using GGBFS at levels up to 65%. We haven't used limecrete yet.

The slab is topped with a DPM and the ModCell frame lifts the straw 200 mm above the DPM

2. We do both rendered and dry lined versions of called ModCell Lime and ModCell Lite. We render using lime both internally and externally. The external finish is combed back to to get a natural textured finished and offer a variety of internal grade finishes that get as smooth as plaster work. We rely on the lime render to both faces to resist wind loading. We can do other finishes including clay.

3. we can install cabling into the panelling in the Flying Factory, through the frame and into the face of the rendered straw or hemp.

4. Currently we are more expensive than brick and block, but far exceed its thermal performance and we also guarantee an air-tightness of 1 m3/m2/hr at 50Pa. In fact, we have just done the air-tightness test at the BaleHaus at Bath and achieved 1.36 m3 first time round and this was down to a faulty seal in a window and a slab connection, which has now been fixed. We will be re-testing shortly and will get below 1m3.

I hope this answers your questions and say high to Barbara at Amazon Nails next time you see her.

Regards

Craig

Craig White says: Axel

It's great to know we have fans in Germany!

Craig

Mary Keutgen Genoud says: 83% reduced energy consumption sounds great. I plan next year to remodel my attic and fill-in & cover the areas between beams. Where can I buy your ModCell in Switzerland???? Kindly, Mary

Craig White says: Hi Mary

You can find out more about ModCell at http://www.modcell.co.uk/

ModCell is a new build system, and what you are proposing is a really good retrofit approach.

Did you know that we currently source our timber from Switzerland? we work with Schilliger Holz (http://www.schilliger.ch/)

Regards

Craig

Christian Quaade says: Hi Craig,

Great idea. I'm sure also the interior milieu will improve in many homes, with use of such breathable materials.

You mention "carbon sequestering materials" in your pitch. Can you explain that claim? Is your material getting heavier over time?

Craig White says: Hi Christian

We mean that by building with renewable building materials, such as straw, hemp and wood, we can exploit nature’s ability to capture carbon through photosynthesis. For example, 1 m3 of wood has the atmospheric equivalent of 800 kg of CO2, a straw bale has the equivalent of 37 kg of CO2 locked into it and lime render will re-absorb CO2 over the lifetime of the building.

Photosynthesis uses the simplest of ingredients - sunlight, water and CO2. Plants, as they grow, absorb CO2 from the environment. They return the oxygen atoms to the atmosphere, and keep the carbon to make cellulose. Photosynthesis is bio-evolved, solar powered carbon capture. By product - oxygen.

A typical 3 bedroom BaleHaus has banked 40 tonnes of CO2.

The thermal efficiency of a BaleHaus reduces heating bills by 85% and CO2 emissions by 60%.

The average UK heating bill is £800 per annum. This is reduced to just £120 saving £680 year on year.

As you point, out a building built using ModCell is also a breathing building which improves the occupants health and well being.

We believe Modcell is good for business, people and planet.

Regards

Craig

Paul Jones says: Dear Craig, I have heard about straw build before from 'Grand Designs' but was impressed by the way you have transformed in into a modular system.I am based in the UAE and wonder if there would be any potential for such a system in such an extreme environment? (High temperatures+humidity)
Abu Dhabi is building a 'Carbon Neutral City' http://www.masdar.ae/en/home/index.aspx
which shows at least there is some will here at least!