Bath’s straw Balehaus

Modcell

Credit: Modcell

I toured White Design’s Balehaus at the University of Bath one very rainy night recently with Professor Peter Walker and researcher Katharine Beadle who are performing detailed monitoring on its thermal performance over the next year. Although I’d like to think that renewable straw bales could provide a viable building material for volume housebuilding, I’m waiting to be convinced.

The material is indeed renewable, non-toxic and insulates well (and passed a 30 minute fire test recently), but it’s hardly flexible or inviting. It is local. The 3.0m x 2.9m panels by Modcell were assembled on a local farm 4 miles away. Walls are 490mm thick (standard bale size) with 30mm of lime render inside and out. The panels have the precision and airtightness (measured at 1.3, but expected to be below 1 when complete) of off site fabrication, but little of the handmade feel of natural materials. All glazing is full height panels (except for one window in a hemp panel), so there was too much glazing in one area (shutters - which are shown in some of White Design’s CGIs - or external blinds could address this) and not enough anywhere else. The 2.68m ceiling height felt generous and even gracious, but spatially and visually it all felt worthy and green, but hardly somewhere one would queue up to live. Granted this is a research prototype and that is to be commended. On the positive side, this house is very low energy, meeting PassivHaus standard though it has yet to be certified. To see other Modcell buildings, click here.

Craig White of White Design explains that the Bath Balehaus was built ‘to a tight budget with Technology Strategy Board funding to the lowest common denominator.’ All the second floor panels were recycled from ‘The House that Kevin Built’ at Grand Designs last year. This prototype is all about testing the fabric, which will be monitored for 1 year. Twelve sensors inside and 66 embedded in the walls will monitor temperature, relative humidity and moisture content every 30 seconds from a weather station on the roof. That’s a lot of data for one small house. White explains that the house is extremely responsive to body heat. Two occupants for 30 minutes registered an 1/2° temperature increase.

The target market for the Balehaus is the small housebuilder who produces 400 houses annually; twenty panels make up a house. Approximate build cost for an 86m2 house is £130,000. White Design sees biorenewables as an important way forward for providing affordable sustainable housing and has already had enquiries from Australia, Canada, Russia and China.   DECC is pushing biorenewables in its recent grant programme.

On another note, Walker - in conjunction with FeildenCleggBradley - has developed a clay block that looks extremely promising. It will be launched at EcoBuild by NBT.

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One Response to “Bath’s straw Balehaus”

  1. [...] to Footprint, a blog of the Architects’ Journal, the estimated build cost of an 86 m2 house is £130,000.  By U.S. standards at today’s exchange rate, that’s [...]

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