First up: using strawbales as external wall insulation. I'll be posting a blog soon about many of the good reasons to build with strawbale (an unusually fully-referenced blog, as it was written for the MSc course I'm currently on which requires much more rigorous justification of any assertions than has been my practice on this blog!). So for now, in brief: straw is a waste product (much more is produced annually than is needed for animal bedding etc.), it is a good insulator (against noise and heat/cold), is much cheaper than other insulation materials, and it stores lots of carbon dioxide - so as long as your walls don't rot (and if they're well-built, well-detailed, and well-rendered then they won't) you'll be storing lots of carbon that would otherwise be adding to greenhouse effect.
To reduce carbon emissions and energy use, it is essential to improve the insulation of existing buildings. 60% of household energy use is related to heating* - better insulation = less heating = reduced energy use = reduced carbon emissions.
* UK Department of Energy and Climate Change figures, 2013.
There are probably other ways to do this, but here's how we wrapped our bungalow in strawbales. Huge credit here must go to Jakub Wihan (Kuba) who advised us throughout, drew up the plans and constructions drawings, and came onsite to supervise the main bale work. We would have been utterly lost without him.
Above: The structure of the soffits was reinforced with extra timber 18mm thick OSB (we used SmartPly - it's made with waste wood and forestry trimmings, and is bonded without use of formaldehyde resins - unlike standard OSB). The soffits need to be strengthened to allow use of hydraulic jacks to compress the strawbales (shown later...). The vertical sheet of OSB in the bottom right of the photo is to contain the cellulose fibre insulation that was added later - this flowed over the top of the existing wall to reduce thermal bridging (conduction of heat up the wall and into the loft)
Above: another shot of the reinforced soffits, with new rafter at the far end to extend the roof over the gable, to allow wrapping of the wall there. We were lucky that the bungalow already had large overhangs front and rear - it's good practice to have about a foot of overhang above strawbale walls to prevent rain ingress.
Above and below: The bale walls require their own shallow foundations, to ensure the weight of the bales is supported. We dug as far as the top of the existing foundations and built back up from there.
Above: each pair of hazel poles is joined by a length of Douglas Fir batten, with a V cut into each end to slot around the hazel. The packing strap (previously threaded through the eye-screws in the wall) is passed around the outside of each pole, joined by a buckle on the douglas fir batten, and tensioned with a tensioning tool. This clamps the bales firmly to the existing wall and provides some compression of the straw.
Above: small custom bales are made to fit under the window boxes. Again the course of bales below is compressed to fit these in. This is important as it results in a strawbale wall that is all slightly compressed. Compressed bales are stronger, denser, more stable and provide a much better structure to plaster onto.
Above: the wrap up the gable wall. A strong timber and smartply wall plate provides a firm point to bale up to and to compress the bales down from.