Thatched Cottages

If you look at a straw bale you think of a house in the country, but usually straw is never associated to a possible building material. In itself the straw is essentially a natural material, so its use fully reflect the parameters that are considered when performing a type of sustainable design, which then seeks to respect the environment.

The aspect that are usually considered in the building industry is that related to its thermal properties of insulation. In fact, the straw bales can be used in building walls to achieve high thermal performance, these present the excellent characteristics from the point of view of thermal insulation, but will be less efficient if we consider their thermal inertia.

Currently there are studies to understand at best the thermal performance of these walls made of layers of straw, in view to popularize their use for the construction of houses of straw.

Through a series of comparisons that have been made, we have seen how, compared to the composition of the different packages casing vertical range of services provided by the various types of walls made of straw bales. These different types were then compared to each other and compared with wallboard made by using the traditional technologies, in order to assess the primary energy consumption.

Advantages of the walls in straw

From the different studies carried out, we have come to define that the walls of straw bales coated with hydraulic lime plaster, thickness divided in this way 3 +45 +3 cm, are able to ensure an average transmittance of about 0.14 W /mqK. These same thermal transmittance values you can get if you seek traditional masonry empty box, posing in their package of incorporation of the chemical nature of insulating materials thicker than 20 cm.

However, a problem that remains is related to the massiveness of the wall. To solve it you might think to adopt the same system that works for wooden structures, which in itself as we do not have large thicknesses. It then opts for the insertion of massive layers on the inner side of the wall as a thermal flywheel, this massive consistency can be given using, for example of the plaster very thick and heavy, so as to be able to improve the thermal comfort conditions both during the winter season and the summer.

Another possible solution could be to use recycled materials, energy efficient, and with low environmental impact, which are able to ensure high levels of performance of the building envelope.

In the collective imagination, straw is understood simply as the waste material from the manufacturing process of cereal grains. This material has good thermal insulation properties and being of plant origin, it also brings benefits in terms of sustainability. If straw is understood as the insulating nature of the plant, and if it was grown specifically to be used as a thermal insulator, the positive effect of its use would be reduced significantly coming to be comparable to that of normal insulation products of synthetic origin.

To avoid running into this problem, we can consider acceptable if the cultivation of straw only occurs under certain conditions, ie without taking the place of other crops. In fact, for this type of production are preferable uncultivated lands or hardly exploitable in another way. Working in this way you would be able to achieve both an improvement in the physical - chemical properties of the soil, because this type of cultivation tends to bring environmental benefits, as it should be to reclaim the uncultivated areas, and economic, as it would increase production on territory of cereals, but also having a flap in the field of building.

In conclusion, as a result of all these considerations made on straw, we expect new products in the field of construction that allow us to take full advantage of the characteristics of this material, natural and economic.