How we turned a failing ‘F’ rating into a compliant ‘D’ for a complex historic venue.
Project Summary
- Property: Walton Castle, a Grade II listed 17th-century historic venue.
- Location: Clevedon, North Somerset.
- Service: Commercial Energy Performance Certificate (EPC)
- Outcome: Improved from F (30) to D (94)
The Challenge: An Outdated and Mismatched Rating
Walton Castle is a stunning Grade II listed 17th-century hunting lodge, now operating as an exclusive-hire venue. However, despite being a premium commercial business, it was stuck with a legacy residential EPC from 2017 that was not only outdated but poorly suited to the property’s commercial use.
This old assessment rated the property as an ‘F’ (30)—a failing grade that put the venue at risk under Minimum Energy Efficiency Standards (MEES).
Why was the rating so low?
The previous assessment treated the castle like a standard house. Residential EPCs calculate efficiency based on fuel cost. Because the castle relies heavily on electricity (which is expensive per unit), the software penalised it heavily. The report suggested that even with expensive renovations, the castle could only ever reach an ‘E’ rating.
The Solution: A Strategic Commercial Assessment
Our Lead Sustainability Consultant, Richard Millard, recognised that the castle’s usage was purely commercial. By switching to a Commercial EPC methodology, we changed the metric from Cost to Carbon Emissions.
Because the UK electricity grid has decarbonised significantly since 2009, electric heating/cooling systems now have a much lower carbon factor. This shift allowed us to unlock specific technical wins that the residential assessment ignored:
- VRF Air Conditioning: We modelled the castle’s turret accommodation using detailed non-domestic HVAC profiles. The Variable Refrigerant Flow (VRF) air conditioning system, which was penalised in the residential report for being “expensive to run,” was now rewarded for being “low carbon” and highly efficient.
- Pool Heating Accuracy: The previous report failed to account for the efficiency of the pool’s heating system. We were able to input the specific data for the swimming pool heat pump, ensuring the renewable energy contribution was fully credited to the building’s performance.
- Detailed Fabric & Systems: We identified that one of the boilers was significantly newer than assumed in the previous 2017 survey. We also updated the specifications for the electric water heaters and fan heaters in the turrets, removing the “default data” penalties applied by the previous assessor.
The Result: Improved Performance and Potential
By applying the correct methodology and stripping away outdated assumptions, the results were transformative.
- New Rating: The score leapt from a failing F (30) to a strong D (94).
- Beating the “Potential”: The new score actually outperformed the maximum potential score predicted by the old report.
- Accurate Sizing: We corrected the officially assessed floor area from 474 m² to a more accurate 648 m².
Walton Castle is now fully compliant, marketable and accurately rated, without the owners having to spend a fortune on unnecessary physical renovations.
Client Testimonial
I should like to say thank you so much to Rich and the team at Building Energy Experts for their efficiency and helpfulness in completing our commercial EPC survey in record time.
Assessing a historic property like Walton Castle requires real expertise, and your team delivered exactly that. Not only did they complete this survey with a very quick turnaround but they went above and beyond by providing extra information and guidance which has been extremely helpful.
We are delighted with the final result and once again thank you from both myself and the team at Walton Castle.
Margarita Hamilton, Walton Castle
Do you own a complex or listed building?
A “standard” assessment often misses the details that make historic buildings unique. If your property has a low rating, it might not be the building’s fault—it might be the wrong assessment method.
Contact us today to ensure your building is getting the rating it deserves.
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