Aircrete concrete blocks are often at the centre of fabric energy efficiency strategies and a crucial part of the specification for Part L and Code for Sustainable Homes (Code) compliance.
This summer has seen a significant shortage of certain types of aircrete blocks with many buyers attempting to overcome the supply chain issue by sourcing lightweight aggregate blocks as an alternative. Technical managers must fully consider the impact of such changes before proceeding with alternative products.
Aircrete blocks typically have thermal conductivity of less than 0.20W/mK and density of less than 750kg/m3. A change in specification from aircrete to lightweight aggregate blocks is likely to more than double these values, resulting in increased heat loss and thermal mass within the property.
We modelled the impact of this simple change in specification and found that for a typical semi-detached property, the changes resulted in a 14% increase in regulated CO2 and associated loss of Code credits.
Such changes can be offset by improvements elsewhere in the design, but must be dealt with as early as possible to avoid expensive non-compliance issues later in the programme.
Posted on July 22nd, 2013