The big change with Psi-Values in SAP 10.2
Psi-Value Scheme Coordinator Steven Cross explains what’s changed with psi-values and how you can calculate your own.
What’s changed with Psi-Values in SAP 10.2?
The big change has been that the Accredited Construction Details scheme (ACDs) no longer features in the new version of Building Regulations and SAP, which came into effect in June.
That’s big news because under the new tougher Building Regulations most jobs are not going to achieve compliance using default values. Therefore assessors will either have to use pre-modelled values, use the services of a Psi-Value Modeller or model them themselves.
Many of the modelled psi-value sources come from manufacturers to encourage you to use their products. You can use psi-values from a combination of schemes, however it depends on what you’re building as to whether they’re relevant and can be used – it will not be acceptable with Building Control Bodies if the details are used incorrectly.
Why were the ACDs removed?
ACDs were based on quite outdated, generic build-ups and requirements but gave psi-values, which meant that good results could be achieved in SAP assessments, which shouldn’t always have been the case. The ACD psi-values also did not change as the performance of the thermal elements surrounding the junction did, which is not in line with current understanding. In some cases this also resulted in people misusing them and for that reason the Department for Levelling Up, Housing and Communities (DLUHC) decided to remove them.
What if people want to model their own?
Psi-Value modelling isn’t for everyone. It’s a niche area of energy assessment and can be challenging, but it can be very rewarding!
Since the SAP and regulation changes we’ve had a lot of people calling up asking for the details of Psi-Value Modellers because they’ve simply not got the time to do the work themselves on top of their existing SAP work. So in that respect it’s been a great opportunity for those on our Psi-Value Modelling scheme because they’re getting more work!
If you want to model your own Psi-Values you can join our 2D or combined 2D & 3D course. Those who are already 2D Psi-Value Modellers can also upskill to include 3D modelling by attending one our upcoming combined courses. Please speak with the team to find out more.