EPC accuracy and financial decisions?

EPC accuracy and financial decisions?

10:09 AM, 6th March 2023, About A year ago 3

Text Size

Hello, Landlords are relying on an EPC to be accurate. Significant decisions are being made based on the EPC information. These decisions will affect tenants.

I did comment in the following thread:

Two-thirds of landlords doubtful about purchase of non-EPC compliant properties

I wasn’t being prickly. I am genuinely trying to understand.

We had an EPC done less than 3 years ago and to get our property up to scratch we would basically have to forego a year’s rent.

This EPC result was a key factor in our decision to sell.

We were recently offered a free EPC by our mortgage provider and so took it.

We therefore have back to back EPC results less than 3 years apart.

We got a significantly different result. This time minimal investment required to achieve the required ‘C’.

So, would those who understand these things in far more depth than I indulge me please?

Make it as technical as you need (I will understand).


All assessments used RdSAP

25 November 2010

D60, potential C74, Enhanced rating B 86

We carried out cost effective recommendations.

54% of light fitting were low energy so we changed all light fittings to be ‘low energy’.

2011 we renewed the loft insulation and increased the depth to something ludicrous.

2011 we filled the cavity walls.

Cumulatively, these changes offer a potential C71
5 November 2020 (10th Anniversary)

D 61, potential B 87.

Oh dear.

We have gone backwards despite improvements made.

I noted that there is no longer a separate ‘enhanced’ rating as it seems rolled into the ‘potential’ rating. Presumably this in part recognises the rapid change in and cost and availability of ‘newer’ technology.

We now require a significant investment to achieve ‘C’.
20 February 2023 – the free EPC

D 68, potential B 86

Zero changes to the property since the last EPC.

Only 1 ‘unit’ below ‘C’ and minimal investment required to achieve it.

What is going on?

Band ‘D’ is 14 ‘units’ wide.

Compare 2020 & 2023 and the difference is 7 units.

There is clear subjectivity too. Assessments changed viz.

• Wall Cavity wall, filled cavity changed from ‘Average’ to ‘Poor’

• Main heating control Programmer and room thermostat changed from ‘Average’ to ‘Good’

• Hot water From main system changed from ‘Average’ to ‘Good’

• Window Fully double glazed changed from ‘Good’ to ‘Average’


Our 2020 EPC result and the consequent investment required was a significant factor in our decision to issue our tenant with a S21 and sell.

Continuity of assessor is clearly important. If the same assessor is presented with improvements then the new rating has to be better than the last one unless the methodology is changed. But assessors die, retire, change career, get promoted etc.

Consistency of training and application of methodology is clearly important.

If there are changes in EPC calculation methodology since the last EPC then key influencing changes are not articulated in the EPC.

There is clearly quantitative error. In its most benign form, an example would be 3 different measurements for the property area : 83, 79, 80m^2. That’s 5%-ish : range (83-79)=4m^2 divided by the average 80.7m^2 x 100.

There is clear potential for human error.

There has to be an agreed, articulated, acceptable error, an industry standard allowable error that Joe public can read. Each measured element of the EPC would have an error bar. And then there’s a subjective human attached.

I would like to think that the data gathering and calculation methodology has been ‘desensitised’ to potential corruptions.

Is any Landlord equipped with the knowledge to challenge the result they are given?

If it’s your first EPC, how would you know it’s wrong?

What would happen if we had C69 and a new tenancy only to have a 10th anniversary reassessment a few months later that downgraded us by an ‘error’ of 7 units to D62?

Am I immediately in contravention of the rules?

Am I going to get told off if I am discovered?

Would I have to carry out immediate remedial work … if I could find the cash?

Would I be able to serve a S21?

OR should I simply look for another assessor?


Share This Article


Judith Wordsworth

Become a Member

If you login or become a member you can view this members profile, comments, posts and send them messages!

Sign Up

13:28 PM, 6th March 2023, About A year ago

EPC assessments seem to be wholly dependent on the assessor's judgement, or lack of.

Barry Cook

Become a Member

If you login or become a member you can view this members profile, comments, posts and send them messages!

Sign Up

17:51 PM, 6th March 2023, About A year ago

We have two identical properties 6 doors apart. Both renovated to exactly the same spec.

Property 1 breezed a C
Property 2 rated at D

The difference being EPC inspector for property 2 prefaced cavity wall and loft insulation entries with the word "assumed".

I was always taught that to assume makes an Ass out of U and Me.

I'm going to vet the next inspector personally and be there during assesment.

Jireh Homes

Become a Member

If you login or become a member you can view this members profile, comments, posts and send them messages!

Sign Up

15:49 PM, 11th March 2023, About A year ago

No surprising significant difference between 2010 and 2020 surveys as over that period major changes to methodology and conventions. Whilst minor changes in conventions since 2020 these should not have have resulted in the 7 points difference. Now it may be the DEA for the 2020 assessment under-evaluated whilst the DEA for 2023 assessment over-evaluated the property, but clearly this points to accuracy of the survey / competence of the DEA.

In terms of descriptions, the DEA is not able to edit the "assumed", this being standard text depending of the selected fabric construction. Likewise for the recommendations as auto-generated by the software (depending on input data).

This example stresses the importance of engaging a local DEA who is competent and takes sufficient time to properly conduct the survey (and who are generally not the lowest cost).

Leave Comments

In order to post comments you will need to Sign In or Sign Up for a FREE Membership


Don't have an account? Sign Up

Landlord Tax Planning Book Now