We have recently prepared a thorough report comparing the ‘true’ carbon cost of building straw bale houses (often described as zero or negative carbon) to natural limestone. In short, straw bale house might be environmentally friendly if it wasn’t for the following.
- Each crop is sprayed seven times with pesticides, and fungicides, possibly killing the bumble bee population along the way as well as insects and birds.
- The crop is sprayed with a chemical called glyphosate prior to harvest (with the aim of killing the crop in order to start the ripening/drying process of the wheat. A dirty trick paid for by the bread consumer, glyphosate is carcinogenic.
- Straw is not washed or cleaned, meaning residual quantities of chemical will be encapsulated with the straw when used as insulation meaning a potential harmful chemical could be seeping through the walls into your home.
- Straw bales are very wide and take up more valuable living space than necessary, resulting in a smaller house and effecting the property value.
Misconceptions include the theory that straw is a throw away by-product form the wheat harvest (this helps with labelling it as zero carbon). In reality this couldn’t be further from the truth, straw is extremely well sought after within the UK and is listed as a commodity in it’s own right. Straw sells for more than, for example, sugar beet. How is that a throwaway by-product?
Straw houses are often propped up by steel frames, one of the most carbon costly building products produced. If people want to build straw bale houses because it’s ‘funky’ they should say so and not quote carbon statistics. Many other insulations are better in carbon terms. Limestone is a totally innocent building material with a carbon cost of little more than rammed earth or clay. Read the full report. It’s eye opening.