Installing the wrong heating system doesn't just increase running costs — it can collapse an EPC rating, trigger MEES compliance failure, and leave landlords facing thousands in wasted expenditure. This real case from a rural property shows how quickly things can go wrong when heating systems are replaced without EPC or Retrofit guidance.
Case Study: How a Property Dropped to G – 5 Points
Original System
Rural property with no gas connection. Had a working oil boiler.
First Mistake
Landlord removed the oil boiler and installed an all-electric hot water heating system. EPC collapsed to G – 5 points. Running costs became extremely high.
Second Mistake
Landlord replaced the electric system with an LPG boiler, hoping to reach an E rating. LPG performs poorly in EPC scoring. The property still failed to reach E.
Outcome
Over £3,500 spent across two system replacements. Property still legally unrentable under MEES.
That's the bad ending — someone who spent thousands without asking first. Here's what happens when a homeowner asks before spending the money.
Case Study: Wrong Advice… Caught in Time
Air Conditioning Isn't Always an EPC Upgrade
Property Type
All-electric home with standard electric panel heaters and hot water cylinder.
Original EPC
E Rating.
EPC Solution
After modelling the property, upgrading the hot water cylinder insulation and replacing the panel heaters with High Heat Retention (HHR) storage heaters on an appropriate off-peak tariff would increase the property to a C rating. The homeowner left with a clear upgrade plan.
Then the Advice Changed…
A few days later the homeowner contacted me. An electrician had recommended installing an air conditioning unit instead, explaining that it would improve the property's EPC rating.
Why That Advice Was Wrong
There's a common misconception that all air conditioning systems are treated as heat pumps within an EPC. They aren't. Only systems that meet the recognised EPC methodology for heat pumps receive the efficiency benefits. Simply installing an air conditioning unit does not automatically improve an EPC rating.
Fortunately…
Before committing to the work, they asked me to check.
The Outcome
- Customer avoided unnecessary expenditure.
- Original improvement plan remained the most cost-effective route.
- Property still had a realistic path from E to C.
£3,000–£5,000+ spent
£0 wasted
EPC improvement uncertain
Proven route to C
May still fail MEES
Clear upgrade plan
Lesson Learned
Never assume that because a heating system is more efficient to run, it will automatically improve an EPC.
EPC ratings are calculated using government-approved methodology — not marketing claims or general heating efficiency.
Always check with an EPC Assessor or Retrofit professional before spending thousands on replacement heating.
Why LPG and Electric Wet Systems Score Poorly
- Extremely high assumed running costs
- Very low EPC performance score
- Not suitable for rural homes
- Catastrophic impact on EPC band
- High carbon factor in SAP methodology
- Heavily penalised in EPC scoring
- High assumed running cost per unit
- Often fail to reach E in older rural properties
What Would Have Worked Instead
A modern condensing oil boiler would have maintained or improved the EPC score, typically achieving an E rating in rural off-gas properties.
- Strong EPC performance in rural homes
- Suitable for off-gas properties
- Often achieves E rating or above
Paired with an off-peak overnight tariff, HHR heaters can achieve an E rating and significantly reduce running costs compared to standard electric systems.
- Excellent EPC performance
- Works best with off-peak overnight tariffs
- Ideal for properties without oil or gas
The Big Lesson for Landlords
Heating Installer
Focuses on heating performance and installation quality.
Landlord
Focuses on upfront cost and short-term affordability.
EPC Assessor
Focuses on MEES compliance, carbon factors, scoring methodology, and long-term running cost impact.
Without EPC or Retrofit advice, landlords risk wasting thousands and still failing compliance. Always model the EPC impact before replacing any heating system — especially in rural or off-gas homes.
MEES Compliance: What Landlords Must Know
To legally rent a property in England and Wales, you must achieve an EPC rating of E or above. Failure to comply carries serious consequences:
- You cannot legally rent the property
- You may face enforcement action from the local authority
- You may need to apply for a MEES exemption
- Exemptions are not guaranteed and require evidence
How to Avoid EPC Failure Before Spending Money
- Get EPC modelling before replacing any heating system
- Request a Retrofit assessment to compare all options
- Compare oil, LPG, HHR, and electric options against EPC scoring
- Check MEES compliance pathways for your specific property
- Review running cost projections for each fuel type
- Confirm exemption eligibility before committing to spend
Your EPC & Retrofit Checklist
Related Reading
Free Landlord Guide: Avoiding EPC Failure
A practical, free guide for rural and off-gas properties — covering heating system choices, MEES compliance, and how to avoid costly mistakes.
Seek EPC or Retrofit advice before replacing any heating system. The cost of getting it wrong far exceeds the cost of getting it right first time.
Download Free PDF GuideFree · No sign-up required · Instant download
Phil Handsaker — Accredited EPC Assessor
Phil is an accredited EPC assessor and TrustMark registered surveyor with years of field experience across rural and off-gas properties. This case study is drawn from real-world EPC assessments.
