The defining characteristic of aircrete (as the name implies) is the thousands of air bubbles captured within the structure of the material. As air is a terrific insulator, the resulting blocks give impressive thermal performance.
Our Standard Grade blocks have a λ value of 0.15 W/mK, compared to around 1.50 W/mK for dense concrete and 0.3 W/mK for Lightweight aggregate. For even higher insulation values, we also have our Solar Grade blocks, coming in with a λ value of 0.11 W/mK.
For the record, solid timber will have a λ value of 0.12 – 0.14 W/mK – similar to our Standard Grade blocks, but without the thermal mass, sound insulation and resilience of a masonry material.
These figures are for just for the block. The significant figure for builders is the thermal performance of the entire wall construction – the U-value. Using a block that is providing thermal insulation on its own is a good start, and walls built of aircrete require less additional insulation to meet the requirements of building regulations, which can lead to narrower cavity widths.
To help with the calculations required in designing high-performance wall constructions, the technical team at H+H have produced a number of technical data sheets giving standard thermal calculations.
Our U-value calculations describe a range of solid and cavity wall constructions with their stated U-values (as low as 0.11 W/m2K).
As the thermal performance of the wall construction gets more efficient, so the impact of thermal bridging becomes more significant – particularly at wall junctions where linear thermal bridges can account for as much as 30% of the heat lost through the building fabric. To help with the thermal modelling required in new house designs, H+H has produced over three thousand standard calculations covering every application of all of our products. These are available as free downloads.
The overall thermal efficiency of aircrete wall structures is demonstrated in their use in homes built to the highest performance standards such as Passivhaus. Examples include this one-off self-build home and this social housing project, providing tenants with warm homes and exceptionally low heating requirements.
We’ve been working with British builders and national building regulations for over 70 years. Our products and technical support are designed to support the way houses need to be built now, and for the future. We only make aircrete and this absolute focus ensures we are committed to providing the best possible partnership for our customers.