Insulating to Min Building Regs

[gravelld]

But what is a "pass" in SAP?

[Jeremy Harris]

18 minutes ago, gravelld said:

But what is a "pass" in SAP?

 

Being strictly accurate, there is no "pass" or "fail" as such, but in order for the house to meet the requirements, and so be signed off by building control, the Dwelling Emissions Rating (DER) must meet or exceed the calculated design stage Target Emissions Rating (TER).  The TER and DER is calculated using the combination of the fabric standards (which must not be less than the minimum in Part L1A), airtightness, MVHR (if fitted), fuel type, any renewable energy elements, so is a balance of all these factors.  The DER is calculated using the "on construction" details, to account for changes that may have been made between the design stage (when the plans were approved by building control) and the completed dwelling.

 

It's worth downloading and playing with the free version of Stroma FSAP to get a feel for how it works, as that does flag up non-compliance at the element level with red or green fail/pass indicators.  The SAP worksheet is quite complex, and includes climate related weightings, to allow for things like solar gain variation and heat loss variation over a year.  The ratings are calculated by summing the monthly means of pretty much every loss or gain.  Attached is a copy of our SAP 2009 regulations compliance report worksheet which may give an idea of the process (although SAP has changed a bit since, the principle is much the same):

 

Self-Build.pdf