Good news for owners of pre-1919 buildings: the latest EPC assessment system better recognises energy-saving features like shutters, draught-proofing & secondary glazing 🏛️
Dr Moses Jenkins at Historic Environment Scotland explains the RdSAP 10.2 changes:
Dr Moses Jenkins at Historic Environment Scotland explains the RdSAP 10.2 changes:
How energy performance certificates are calculated - Engine Shed
The way Energy performance certificates (EPCs) are generated has changed. Find out what this means for traditional buildings in Scotland.
blog.engineshed.scot
November 3, 2025 at 12:00 PM
Good news for owners of pre-1919 buildings: the latest EPC assessment system better recognises energy-saving features like shutters, draught-proofing & secondary glazing 🏛️
Dr Moses Jenkins at Historic Environment Scotland explains the RdSAP 10.2 changes:
Dr Moses Jenkins at Historic Environment Scotland explains the RdSAP 10.2 changes:
Floors are treated as uninsulated in rdSAP unless the surveyor has personally crawled underneath and photographed the insulation for evidence.
Very frustrating, I too have many photos of my floor insulation, but the surveyor didn't have time to lift floorboards during the EPC visit.
Very frustrating, I too have many photos of my floor insulation, but the surveyor didn't have time to lift floorboards during the EPC visit.
October 14, 2025 at 11:37 AM
Floors are treated as uninsulated in rdSAP unless the surveyor has personally crawled underneath and photographed the insulation for evidence.
Very frustrating, I too have many photos of my floor insulation, but the surveyor didn't have time to lift floorboards during the EPC visit.
Very frustrating, I too have many photos of my floor insulation, but the surveyor didn't have time to lift floorboards during the EPC visit.
It might sit with us in DESNZ. Permeability of walls is a variable in SAP and the new Home Energy Model - although it is not an input in RdSAP, so it will not affect your EPC rating.
October 9, 2025 at 7:45 AM
It might sit with us in DESNZ. Permeability of walls is a variable in SAP and the new Home Energy Model - although it is not an input in RdSAP, so it will not affect your EPC rating.
Technical term 😅
But obviously we have a basic disagreement here. I know it's not bollocks because I know how it's done (& also because I created RdSAP) but I'm not paid to explain it to you, I'm happily retired now
But obviously we have a basic disagreement here. I know it's not bollocks because I know how it's done (& also because I created RdSAP) but I'm not paid to explain it to you, I'm happily retired now
November 17, 2024 at 7:43 PM
Technical term 😅
But obviously we have a basic disagreement here. I know it's not bollocks because I know how it's done (& also because I created RdSAP) but I'm not paid to explain it to you, I'm happily retired now
But obviously we have a basic disagreement here. I know it's not bollocks because I know how it's done (& also because I created RdSAP) but I'm not paid to explain it to you, I'm happily retired now
.. could be calculated from the data, too.
I think I said at the start of this chat that multiple metrics are possible using RdSAP but at some point, the government has to decide which metric is going to define whether a house may be legally let or not.
I think I said at the start of this chat that multiple metrics are possible using RdSAP but at some point, the government has to decide which metric is going to define whether a house may be legally let or not.
May 2, 2025 at 9:16 AM
.. could be calculated from the data, too.
I think I said at the start of this chat that multiple metrics are possible using RdSAP but at some point, the government has to decide which metric is going to define whether a house may be legally let or not.
I think I said at the start of this chat that multiple metrics are possible using RdSAP but at some point, the government has to decide which metric is going to define whether a house may be legally let or not.
EPCs are still calculated using the 2012 version of rdSAP which is wildly out of date for solar and electric tariffs and doesn't include batteries at all.
Might get updated to the 2020 version of SAP next year, and replaced by HEM a few years later.
Might get updated to the 2020 version of SAP next year, and replaced by HEM a few years later.
December 28, 2024 at 1:06 PM
EPCs are still calculated using the 2012 version of rdSAP which is wildly out of date for solar and electric tariffs and doesn't include batteries at all.
Might get updated to the 2020 version of SAP next year, and replaced by HEM a few years later.
Might get updated to the 2020 version of SAP next year, and replaced by HEM a few years later.
The big question! In the rental market, the 1st market to have limits put on acceptable energy performance, I'd definitely say running cost limits are needed to protect the tenant. This isn't necessarily the case for other RdSAP uses. I think having more metrics could allow for such differences
May 2, 2025 at 12:32 PM
The big question! In the rental market, the 1st market to have limits put on acceptable energy performance, I'd definitely say running cost limits are needed to protect the tenant. This isn't necessarily the case for other RdSAP uses. I think having more metrics could allow for such differences
I have been pointing out recently that ScotGov had painted itself into a corner, trying to address everything in a single Bill: energy efficiency, clean heating, flats, houses, private rent and owner occupier. And all against a changing compliance context with coming RdSAP update and EPC cert reform
March 12, 2025 at 10:48 AM
I have been pointing out recently that ScotGov had painted itself into a corner, trying to address everything in a single Bill: energy efficiency, clean heating, flats, houses, private rent and owner occupier. And all against a changing compliance context with coming RdSAP update and EPC cert reform
SAP and RdSAP are capable of so much more than just outputting the rating. I just wish HMG wasn't so afraid of using it's full potential
January 23, 2025 at 9:00 PM
SAP and RdSAP are capable of so much more than just outputting the rating. I just wish HMG wasn't so afraid of using it's full potential
Doh I just remembered, rdSAP 2025 uses the same prices as the 2012 version, for comparability. So well over a decade out of date.
Also, they are inflation corrected so don't match up with actual real world prices.
Also, they are inflation corrected so don't match up with actual real world prices.
August 9, 2025 at 11:44 AM
Doh I just remembered, rdSAP 2025 uses the same prices as the 2012 version, for comparability. So well over a decade out of date.
Also, they are inflation corrected so don't match up with actual real world prices.
Also, they are inflation corrected so don't match up with actual real world prices.
Gemini (don't @ me) suggests that RdSAP using prices from 2017(!)
August 9, 2025 at 9:13 AM
Gemini (don't @ me) suggests that RdSAP using prices from 2017(!)
..Apparently, there's an updated version of the EPC methodology due to be rolled out on 15th June, called RdSAP 10, which will recognise PV battery storage. Maybe we should have waited a fortnight.
June 7, 2025 at 4:29 PM
..Apparently, there's an updated version of the EPC methodology due to be rolled out on 15th June, called RdSAP 10, which will recognise PV battery storage. Maybe we should have waited a fortnight.
The existing 2012 version of rdSAP predicts that PV will improve the EPC by a lot, as exports are treated as having the same tariff p/kW as imports.
PV will become less favourable for EPCs under the next software, which has a low export tariff price. So less incentive for landlords to fit PV.
PV will become less favourable for EPCs under the next software, which has a low export tariff price. So less incentive for landlords to fit PV.
December 28, 2024 at 1:30 PM
The existing 2012 version of rdSAP predicts that PV will improve the EPC by a lot, as exports are treated as having the same tariff p/kW as imports.
PV will become less favourable for EPCs under the next software, which has a low export tariff price. So less incentive for landlords to fit PV.
PV will become less favourable for EPCs under the next software, which has a low export tariff price. So less incentive for landlords to fit PV.
One practical problem with linking via software is identifying the property. Design SAP often recorded by plot number rather than address, and with the RdSAP EPC you only know the address and property URL
November 18, 2024 at 8:26 PM
One practical problem with linking via software is identifying the property. Design SAP often recorded by plot number rather than address, and with the RdSAP EPC you only know the address and property URL
📣 UK Landlords: Significant EPC updates are coming on 15 June 2025 with the rollout of RdSAP 10. Expect more detailed assessments, a greater need for documentation, and potential changes in property ratings. Ensure you have all records of energy efficiency improvements to avoid lower ratings.
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June 4, 2025 at 3:38 PM
📣 UK Landlords: Significant EPC updates are coming on 15 June 2025 with the rollout of RdSAP 10. Expect more detailed assessments, a greater need for documentation, and potential changes in property ratings. Ensure you have all records of energy efficiency improvements to avoid lower ratings.
Tbf the recent (last few years) EPCs on my neighbours (1950s semis) actually get solar PV about right, even if the other recommendations are objectively daft
I'm glad I understand why RdSAP does it what it does now though
I'm glad I understand why RdSAP does it what it does now though
April 19, 2025 at 1:27 PM
Tbf the recent (last few years) EPCs on my neighbours (1950s semis) actually get solar PV about right, even if the other recommendations are objectively daft
I'm glad I understand why RdSAP does it what it does now though
I'm glad I understand why RdSAP does it what it does now though
The surveyor has to follow the rdSAP methodology which iirc uses CoP of 2.7 for heat pumps.
If your particular make and model has been assessed and documented in the SAP product database, then s/he can use the database figure for scop.
If your particular make and model has been assessed and documented in the SAP product database, then s/he can use the database figure for scop.
October 14, 2025 at 11:37 AM
The surveyor has to follow the rdSAP methodology which iirc uses CoP of 2.7 for heat pumps.
If your particular make and model has been assessed and documented in the SAP product database, then s/he can use the database figure for scop.
If your particular make and model has been assessed and documented in the SAP product database, then s/he can use the database figure for scop.
I'd lay bets on the reason for that being that the recommendation logic hasn't been amended since RdSAP was created nearly twenty years ago.
I'm out of the loop now and could be wrong, but if there have been changes since 2008, they've not been particularly radical
I'm out of the loop now and could be wrong, but if there have been changes since 2008, they've not been particularly radical
September 3, 2025 at 7:30 PM
I'd lay bets on the reason for that being that the recommendation logic hasn't been amended since RdSAP was created nearly twenty years ago.
I'm out of the loop now and could be wrong, but if there have been changes since 2008, they've not been particularly radical
I'm out of the loop now and could be wrong, but if there have been changes since 2008, they've not been particularly radical
The consultations in England and Scotland are linking new EPCs to the HEM software (previously SAP11) which is delayed until >2027.
I'd be up for a rapid update of rdSAP to 2025 energy prices as a quick win, rather than waiting for HEM.
(Sorry.... ranting a bit... EPCs have that effect!)
I'd be up for a rapid update of rdSAP to 2025 energy prices as a quick win, rather than waiting for HEM.
(Sorry.... ranting a bit... EPCs have that effect!)
January 23, 2025 at 7:19 PM
The consultations in England and Scotland are linking new EPCs to the HEM software (previously SAP11) which is delayed until >2027.
I'd be up for a rapid update of rdSAP to 2025 energy prices as a quick win, rather than waiting for HEM.
(Sorry.... ranting a bit... EPCs have that effect!)
I'd be up for a rapid update of rdSAP to 2025 energy prices as a quick win, rather than waiting for HEM.
(Sorry.... ranting a bit... EPCs have that effect!)
Definitely highly relevant in real life! Don't think the fund asks tho (SHD targets now dropped) "Energy savings must be based on modelling via ... SAP, RdSAP, or PHPP" though could be wrong (apols only just started studying the info). And not sure standard MCS assess measures permeability either?
November 27, 2024 at 5:48 PM
Definitely highly relevant in real life! Don't think the fund asks tho (SHD targets now dropped) "Energy savings must be based on modelling via ... SAP, RdSAP, or PHPP" though could be wrong (apols only just started studying the info). And not sure standard MCS assess measures permeability either?
RdSAP 10 is to be introduced 15th June this year.
It will recommend a heat pump IF that improves the property SAP score ( fuel costs) AND other heating upgrades (new oil/gas/biomass boiler or storage heaters) don't score better.
It will recommend deep insulation first, and no heatpumps in flats ☹️
It will recommend a heat pump IF that improves the property SAP score ( fuel costs) AND other heating upgrades (new oil/gas/biomass boiler or storage heaters) don't score better.
It will recommend deep insulation first, and no heatpumps in flats ☹️
April 18, 2025 at 4:22 PM
RdSAP 10 is to be introduced 15th June this year.
It will recommend a heat pump IF that improves the property SAP score ( fuel costs) AND other heating upgrades (new oil/gas/biomass boiler or storage heaters) don't score better.
It will recommend deep insulation first, and no heatpumps in flats ☹️
It will recommend a heat pump IF that improves the property SAP score ( fuel costs) AND other heating upgrades (new oil/gas/biomass boiler or storage heaters) don't score better.
It will recommend deep insulation first, and no heatpumps in flats ☹️
...and if people aren't suspicious of "claimed savings" after all the nonsense spouted in RdSAP - based schemes like Green Deal and ECO-driven CWI - then they should be. Modelling should always be questioned - even when it's my own husband's 😂
November 20, 2024 at 9:08 AM
...and if people aren't suspicious of "claimed savings" after all the nonsense spouted in RdSAP - based schemes like Green Deal and ECO-driven CWI - then they should be. Modelling should always be questioned - even when it's my own husband's 😂
I know. We couldn't persuade them of the necessity to link RdSAP surveys to the data already obtained from plans for newbuild assessments either 😕
November 17, 2024 at 11:26 PM
I know. We couldn't persuade them of the necessity to link RdSAP surveys to the data already obtained from plans for newbuild assessments either 😕
RdSAP 10 should fix this so "any home that is reasonably well insulated may have a heat pump recommendation appear on its EPC". Last government inexplicably delayed its implementation from early 2024 until "early 2025" and it still hasn't happened 😠
April 19, 2025 at 7:05 PM
RdSAP 10 should fix this so "any home that is reasonably well insulated may have a heat pump recommendation appear on its EPC". Last government inexplicably delayed its implementation from early 2024 until "early 2025" and it still hasn't happened 😠
Since the RdSAP 10 regime was adopted on 15th June, homes with heat pumps and heat recovery ventilation can now get a sensible rating. Why A99 not A100 in this case? Didn’t want to litter the roof with higgledy piggledy solar panels
June 30, 2025 at 3:37 PM
Since the RdSAP 10 regime was adopted on 15th June, homes with heat pumps and heat recovery ventilation can now get a sensible rating. Why A99 not A100 in this case? Didn’t want to litter the roof with higgledy piggledy solar panels