One of the biggest queries we have is dealing with the age band to use for dwelling which has been formed following a conversion or material change of use.
If this was done after 2008, the dwelling would have needed a SAP EPC, as per out Guidance on the Appropriate Use of RdSAP. However, the Convention relating to this will soon be changing to reflect better the changes that happen at a change of use.
The update to RdSAP Convention 3.05 (v.11):
After applying Convention 1.01, for a conversion which was a change of use (e.g. barn converted to a dwelling) or where a dwelling has been sub-divided (e.g. house to flats), always use the original construction date, and specify upgraded elements only where documentary or visual evidence is available.
Why are we telling you to always use the original age?
Well, it's pretty obvious, but this is the date that the dwelling was built. With a material change of use, the newly built dwelling is not required to meet all of the requirements of Building Regulations Part L.
For example when we have a conversion for something like a barn conversion, this will likely have thick stone walls which would be visible both inside and out. To meet the full Buildings Standards, these should have been full insulated at conversion. Given you might see the stone walls, these could not have been insulated.
Putting a modern build date would improve the rating of the dwelling by more than it would actually be.
In terms of added insulation, this can either be physically measured, or you can make use of a documentary evidence. A final completion certificate will often only state that work was completed in line with the works outline in an initial notice and/or schedule of works. The initial notice and/or schedule of works will outline all of the upgrades made to the dwelling. The fact that these have been approved with the final notice means that these can be input as documentary evidence for the dwelling.
These changes are much easier to interpret than 'evidence needed that all of the thermal elements have been upgraded', and also ensures that DEAs are checking to ensure that dwellings from a material change of use get the necessary SAP EPC as well.