For this property feature, we look at why the letters A to G and the numbers 1 to 100 printed on an energy performance certificate, also known as an EPC, could be more crucial than you think in less than five years.

Although today’s homebuyers and sellers are likely to view an EPC as just another piece of necessary paperwork in the buying and selling process, after 2030, properties with an energy performance rating lower than C could face significant hurdles when selling and obtaining mortgage finance.

What is an EPC Rating?

Energy Performance Certificates, or EPCs, are used to rate a property’s energy efficiency. Homes are rated on a scale of 1 to 100 and split into bands, with A being the highest and G being the lowest. It is generally accepted that properties with a rating lower than a C (D, E, F, and G) indicate higher energy costs and lower efficiency.

In the UK, the rating is based on how much energy the property is estimated to use under standard conditions, factoring in elements like heating, hot water, lighting, and the building’s fabric.

Insulation

Walls: Solid or cavity wall insulation significantly reduces heat loss. Uninsulated walls can drag a rating down to D or lower.

Roof/Loft: Adequate loft insulation (at least 270mm of mineral wool or equivalent) is a significant positive. Flat roofs or rooms-in-roof also need proper insulation.

Floors: Insulated floors, especially in older homes, prevent heat from escaping downward.

Heating System

Boiler Efficiency: A modern condensing boiler (A-rated) with high efficiency (90%+) outperforms older gas or oil boilers (G-rated, ~70%).

Controls: Programmable thermostats, smart controls, and thermostatic radiator valves (TRVs) will help to optimise energy use.

Fuel Type: Switching to low-carbon options like heat pumps (air or ground source) can push ratings toward A or B.

Windows and Doors

Double or Triple Glazing: Upgrading from single-glazed windows to double or triple-glazing with low-emissivity (Low-E) coatings cuts heat loss. A-rated windows are key for top scores.

Draught-Proofing: Sealed doors and windows prevent air leakage. The good news is that it’s a relatively cheap but effective fix.

Building Fabric

Airtightness: Homes with minimal air leakage (tested via pressure tests in new builds) score better.

Construction Materials: Modern homes with high thermal mass or efficient design (e.g., Passivhaus standards) will naturally rate higher.

Renewable Energy

Solar Panels: Photovoltaic (PV) panels or solar thermal systems for hot water can significantly raise a rating, often by as much as a band (e.g., C to B).

Other Systems: Biomass boilers or micro-CHP (combined heat and power) also contribute, although these are less common.

Lighting

LEDs: Full use of low-energy lighting (e.g., LEDs) is an easy way to boost a rating. Older bulbs like halogens or incandescents will lower the score.

Hot Water

Insulated Tanks and Pipes: An efficient, well-insulated hot water cylinder (if not using a combi boiler) reduces standby losses.

Demand Efficiency: Smaller households benefit from on-demand systems over storage tanks.

What the UK Government Expects

The UK government has set a legally binding target to reduce carbon emissions by 100% by 2050. In addition, it has set a target for as many homes in England and Wales as possible to have an EPC rating of C by 2035 and has committed to a 68% reduction of current emission rates from homes by 2030.

Part of this has included the introduction of more stringent energy efficiency standards for rental properties, with a mandate for all rented properties to achieve at least an EPC C rating by 2030. Although many with a keen interest in the property market will likely know its impact on landlords and the rental market, something that needs more attention is how it could affect everyday home buyers and sellers.

For most people, a home will be their biggest purchase/investment. As such, almost without exception, every homeowner wants to ensure that the value of their investment remains safe and that they have as many options as possible.

Currently, there are no legal minimum EPC requirements for owner-occupied properties; however, should energy costs continue to rise, and as we move closer to 2030, lower-rated properties will likely become less attractive, which could create significant hurdles for many down the line.

Will the EPC Rating Impact the Ability to Get Mortgage Finance?

Lenders are increasingly factoring EPC ratings into risk assessments, and this trend is expected to ramp up over the next few years. Properties with low EPC ratings may be viewed as higher risk due to higher energy costs, which could lead to difficulties securing mortgage finance or less favourable terms by 2030.

Properties with higher EPC ratings (A to C) typically have lower energy bills, making them more appealing, especially in the context of rising energy costs.

Research from the House of Commons Library (Energy efficiency of UK homes) indicates that the share of homes with an EPC C or higher in England increased from 12% in 2010 to 48% in 2022, reflecting growing demand for efficient properties.

Properties with ratings below C may face longer selling times or lower offers, as buyers may perceive them as less future-proof.

As mentioned, mortgage lenders are already considering EPC ratings in their risk assessments, driven by environmental pressures and regulatory trends.

HSBC UK’s ‘Can a Low EPC Rating Affect Your Mortgage Application?‘ notes that properties with low EPC ratings (E, F, G) may face application rejections due to higher running costs, affecting borrowers’ ability to meet repayments. Admittedly, this currently falls into the realm of speculation. However, our research shows that this trend will likely intensify closer to 2030, particularly as lenders strengthen their alignment with sustainability goals.

A Kamma Climate article titled ‘The Complete Guide to EPC Data for Mortgage Lenders‘ suggests that future legislation may require lenders to disclose energy efficiency ratings, potentially making it harder for properties with low ratings to secure financing. This could result in less attractive (higher) interest rates or stricter lending criteria, impacting purchases and remortgaging.

Another factor that could affect the value of homes with low EPC ratings is what’s known as the “green premium”. Although not yet fully established, the ‘green premium’ could see lenders offering more attractive lending rates for more energy-efficient properties, disadvantaging properties with ratings below C. The financial incentive for buyers to be more environmentally friendly would impact the saleability of less efficient properties.

Final Thoughts

We all live in extraordinarily changing times, so making predictions between now and 2030 is somewhat challenging. However, there are some things that I don’t expect to change, and one is the huge appetite for Brits to own a home.

Most Brits still view bricks and mortar as the safest of all investments. Admittedly, you can find other, more speculative places to put your money that are likely to offer a better return, but these come with the risk of losing much of, if not all, of your investment.

An often-used English expression is “It’s better to be safe than sorry”, which I don’t believe needs any explanation. My research shows that residential properties with EPC ratings lower than C will likely face challenges selling and obtaining mortgage financing after 2030, putting homeowners in an uncomfortable position where they need to find funding for significant property improvements to maintain the value of their homes or if they need to move.

The emphasis on energy efficiency and sustainability will increase in the forthcoming years, as will market preferences and stricter lending criteria. This will make owner-occupied properties with a rating below an EPC C less attractive. The UK government’s current strategy tends to support this.

I can see 2029 being incredibly busy for qualified and accredited EPC assessors. Provided that little has changed regarding how properties are rated, homeowners who currently have their homes rated as an A, B, or C will undoubtedly want to safeguard themselves by obtaining a newer certificate, which will last for five years at the time of writing.

I’ll end this feature by advising all home buyers to think carefully before committing to a property with a lower energy rating in these times and not to let the heart rule the head. Of course, the decision is yours. But, any purchase without one eye on the future could result in a large, additional home improvement bill after 2030, should your situation change.