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RDSAP10 effect on existing heat pump EPC rating?

 
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Government Schemes, Regulations, Planning & Organisations
Last Post by Aaron 6 hours ago
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 Aaron
(@aaron)
Active Member Member
Joined: 4 months ago
Posts: 9
17/06/2025 10:46 pm  

There is  a real disconnect between how performance is captured for RHI and what ends up being used for EPCs via RDSAP.

The SPF of 4.1 you got  probably reflects the real-world performance of your GSHP. But RDSAP, being a cut-down version of the full SAP methodology, often uses default or oversimplified figures—hence that laughable COP of 1.7. That number doesn’t reflect the capabilities of a modern MCS-certified system like MCS HP0016/08, especially if it’s been properly designed and commissioned.

To improve the EPC rating and get a COP/SCOP that reflects reality (especially at 40°C flow temp), you ideally want to use the Product Characteristics Database (PCDB). If your heat pump is listed in there, SAP can pull in the correct performance figures. If not, RDSAP defaults will drag the rating down every time.

And no—SPF and COP aren’t interchangeable. SPF takes into account the whole system and how it behaves across seasons, whereas COP/SCOP is a performance figure under fixed conditions. Related, yes. Swappable? No.

Honestly, if you’re aiming to push the rating from a D to a C and you’ve already got detailed performance data from the RHI assessment, it’s far better to do a full SAP. It’s more work and takes longer, but it allows you to input all the real data properly—emitters, controls, flow temps, measured demand, and system design. That’s where you stand a decent chance of getting the rating


   
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