Straw cuts energy bills by 90%

Dec 13, 2013 by Katrina James
Straw cuts energy bills by 90%
The straw bale LILAC community has experienced far lower than average energy bills.

While the UK is consumed by arguments about the cost of energy, fuel poverty and market failure, some have managed to sidestep these issues altogether.

Residents of a unique new housing development in Yorkshire are enjoying exceptionally low energy costs having spent six months in their new homes which are made from straw bale panels.

The LILAC (Low Impact Living Affordable Community) homes in Bramley, Leeds, is the UK's first ecological affordable cohousing project, and has been constructed using straw bale technology developed by our researchers here in the Department of Architecture and Civil Engineering, and straw technology company Modcell.

The community consists of 20 homes and is home to 35 adult and 8 child residents, who have just received their first quarterly .

As a result of the increased insulation provided by straw, the community has managed to reduce its gas bills by 90 per cent compared to the average for Leeds.

Energy saving starts with the basics at LILAC. The homes are designed not to use energy in the first place – they are super insulated, using straw bale external walls and roofs and triple glazed windows. They are also very airtight, so they don't leak heat to the outside through drafts.

Straw cuts energy bills by 90%
In a LILAC shared guest cottage there is an 'honesty panel' showing the straw walls.

The homes cleverly recycle waste heat back into the building through what is called MVHR - Mechanical Ventilation Heat Recovery. Heat from warm stale air leaving the building is extracted and exchanged to cool fresh air drawn in by the system. This not only reduces heating bills even further, but results in better indoor air quality.

Using renewable energy across the community has resulted in even lower fuel bills. There is a 29 kW array of community owned solar panels across the site. The feed-in tariff income from these is placed into a shared account to pay for the communal water, gas and electricity used on site. Solar hot water panels provide most of the hot water requirements for bathing and washing up.

Dr Andy Thomson said: "We are involved with LILAC as part of our current EACi funded research project; EuroCell. The energy performance that the residents have reported for the buildings so far is really pleasing. We're looking to take thermal images of the homes in use this winter to get a clear picture of just how much heat is retained compared to a typical brick and mortar structure in the region."

Paul Chatterton, and his partner Tash Gordon, live in one of the four bedroom houses at LILAC with their young son. Their annual gas bill is likely to be just £30 and their electricity bill £160. A combined energy bill of £190 compares favourably with their previous house, where the annual energy bill was £1500. This is a significant reduction of 87 per cent that will repeat year on year.

Straw cuts energy bills by 90%
Homes in the LILAC community look no different to any other modern house.

Jenny March moved to LILAC in May with her partner, and lives in a two bedroom flat. She said: "The big difference we've noticed is that there is no draught, it is always warm in our flat. We have a lot of space, our rooms are large, but they are costing so little to heat and to keep warm. Our heating is usually on for only a couple of hours a day. Another big benefit of the straw walls is that they insulate noise, so the flat is really quiet. I've lived in other flats where I could hear everything my neighbours said or did, so this is another huge benefit!"

Craig White from Modcell said: "What LILAC shows is that straw bale housing, modern energy generation and storage technologies and a mutually cooperative approach to living can deliver significant economic benefits to a community through cheaper bills. It also reduces carbon emissions at a neighbourhood level and eradicates fuel poverty. LILAC is a fantastic place to live and shows that a modern lifestyle can be achieved without costing the earth financially or environmentally."

Dr Thomson added: "These buildings are extremely low impact, as the straw locks in carbon dioxide, and by working with local farmers the panels are assembled local to the site of construction. The Modcell panels are pre-fabricated and straightforward to use, so any construction company could build with them. This means that ModCell will be able to scale up production and that more communities will be able to benefit from the construction of these homes in the future."

Explore further: First of four Fukushima reactors cleared of nuclear fuel

More information: To find out more about the LILAC community see www.lilac.coop/ and for more on building with straw see www.bath.ac.uk/research/case-s… -straw-bale-building.

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Eikka
3.1 / 5 (7) Dec 13, 2013
They are also very airtight, so they don't leak heat to the outside through drafts.


They tried that here in the 70's and the end result was that the houses developed mold and the people became sick.

Problem being that when you install thicker wall insulation the outer layer of the wall goes cold below the dew point when the outdoors temperature drops. Warm air with water in it diffuses through the insulation and when it meets this cold point inside the wall all the water condenses and wets the insulation. They tried to prevent that by wrapping the house up in plastic so the moist air would never get through, but that in turn caused the inside of the walls to retain moisture next to the plastic barrier and just made the problem worse.

To have a good healthy house, the walls have to leak just enough that the moisture can pass through instead of being trapped inside. Mechanical ventilation only helps up to a point because it isn't uniform. Some parts dry, others remain wet.
Modernmystic
1 / 5 (3) Dec 13, 2013
They tried that here in the 70's and the end result was that the houses developed mold and the people became sick.


This may be a problem in humid areas but it's not an issue where I live. As long as you do proper maintenance on the house it never gets wet enough for this. I've known a guy that's lived in a straw bale house for 15 odd years without a problem and I've seen his energy bills (he's very proud of them....) they're quite impressive.

Granted this guy is very type A and his house is about 40% of his life. It's just his thing...but it can be done without a problem in the right climate is my point.
TransmissionDump
1 / 5 (2) Dec 13, 2013
The first little piggy built his house out of straw.
Look what happened to him..
kochevnik
1.5 / 5 (2) Dec 13, 2013
Humidity drops to zero in subfreezing temperatures. An air exchanger will solve condensation issues
obama_socks
1 / 5 (4) Dec 13, 2013
A dehumidifier and an air purifier with a Hepa filter to prevent mold should help in warmer weather.
Eikka
2.3 / 5 (3) Dec 13, 2013
This may be a problem in humid areas


Not really just in humid areas, but areas where it gets below freezing in the winter. The problem is the humidity produced by the occupants when they sweat, take showers, cook food, wash clothes and hang them to dry... all that puts moisture in the indoors air, which then condenses into the structures because the temperature gradient along the depth of the wall puts the dew point inside the wall instead of outside of it.

Traditionally built houses used to have a wind gap in the wall where the dew point would naturally form, so there was a cavity where air was blowing around and carrying the water off. The house effectively had a double shell, one cold against the cold outdoors, and another warm against the warm indoors, and a draft of air rising up in the middle to carry the condensing vapors away.

But of course that's less energy efficient because the draft cools down the structure by convection.

kochevnik
1 / 5 (2) Dec 13, 2013
Not really just in humid areas, but areas where it gets below freezing in the winter. The problem is the humidity produced by the occupants when they sweat, take showers, cook food, wash clothes and hang them to dry...
All these activities vent moisture outside in modern housing. Maybe not in your Davie Crockett cabin in the woods. But then I think you should focus more on bears than humidity

Who exactly hangs their clothes to dry inside?
obama_socks
1.8 / 5 (4) Dec 13, 2013
I would like to experiment with this straw-bale method by building a doghouse first to see how it works out. The bales would have to be wrapped with thick UV proofed clear plastic to keep out moisture and insects, but if it keeps the dogs warm in the cold weather, it would be worth the effort.
ryggesogn2
1 / 5 (3) Dec 13, 2013
Monolithic concrete domes have concrete and rebar on the inside for thermal mass with insulation on the outside.
Another design used concrete slabs with straw or other lightweight aggregate as interior walls with insulation on the outside.
Eikka
1 / 5 (2) Dec 13, 2013
Who exactly hangs their clothes to dry inside?


People who don't want them to get wet hanging outside in the rain.

That said, even tumble-dried clothes are somewhat moist right when you pull them from the machine, and should be left hanging for a moment before folding away. Otherwise they tend to develop a smell. Especially linen.

All these activities vent moisture outside in modern housing.


Of course they do. If they didn't, the problem would be much much worse. Still, they're not perfect, and indoors air is humid.

If it wasn't, you'd be quite uncomfortable living in the house.
Egleton
2.6 / 5 (5) Dec 13, 2013
Make them stop! Dont you see where all this is headed?
If they dont have to pay huge energy bills that means they can get out of debt. And then where would the poor bankers be? They may have to get a real job.
This is just too cruel.
omatwankr
1 / 5 (2) Dec 14, 2013
"They tried that here in the 70's and the end result was that the houses developed mold and the people became sick."

to bad innovation stopped in the 70s

"Ted Butchart. In The "The Last Straw, he claimed that few organisms are able to decompose straw, which is why "grain straw is so often burned rather than being turned back into the soil." But high moisture levels in straw bales—over 70%—can provide a habitat for fungi and lead to decomposition, so careful design for moisture avoidance is critical.""

"The first little piggy built his house out of straw.
Look what happened to him.." you should write for Faux News if you believe in fairy tales
Eikka
1 / 5 (2) Dec 14, 2013
to bad innovation stopped in the 70s


it didn't.

The million pound question is, have these people really managed to bypass the problem? It's one thing to say they have, and another thing to prove they actually did. It was the same thing back then - in theory it should have worked but in practice it didn't.

But we'll see that in about 5-10 years.
Cocoa
1 / 5 (1) Dec 15, 2013
Eikka: "But we'll see that in about 5-10 years."

Why wait 5-10 years? There are many thousands of straw bale houses being all over the world - many in high humidity areas such as Ireland, and northern England - and many are decades old (some hundreds of years old). Straw bale has an excellent record in terms of the quality of life it can provide. As others have pointed out - using a heat exchanger allows the humidity to be vented - but the heat to be recycled.

Here is a neat site if you want to see many examples of straw bale homes in Britain.

http://www.bing.c...ORM=VDRE

goracle
not rated yet Dec 16, 2013
Not really just in humid areas, but areas where it gets below freezing in the winter. The problem is the humidity produced by the occupants when they sweat, take showers, cook food, wash clothes and hang them to dry...
All these activities vent moisture outside in modern housing. Maybe not in your Davie Crockett cabin in the woods. But then I think you should focus more on bears than humidity

Who exactly hangs their clothes to dry inside?

People who don't like nosebleeds every night when in cold, dry weather. The little bit of moisture (I'm not talking dripping wet, just damp or moist) made a difference in -30 C weather.

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