How to Calculate EPC Rating: Don\'t Let a Low Score Catch You Out

Landlords

Posted in Oct 30 , 2026

Understanding how to calculate EPC rating can help you see what affects your property's energy performance. Here is how the assessment works and what landlords should check before spending money on upgrades.

How Is an EPC Rating Calculated?

An Energy Performance Certificate (EPC)rating is calculated using information about a property's size, construction, insulation, heating, hot water and lighting. An approved government calculation method then estimates its energy performance under standard conditions.

You can also read our guide on how to obtain an Energy Performance Certificate.

For existing homes in England, assessors generally use the Reduced Data Standard Assessment Procedure (RdSAP). The current version is RdSAP 10.0.1. New homes use the Standard Assessment Procedure (SAP), currently version 10.3.

The process involves three main steps:

Property inspection: An accredited energy assessor records details such as room measurements, wall construction, windows, insulation, and heating systems.
Calculation: The information is entered into approved software, which estimates the property's energy performance.
Final rating: The property receives a numerical score and an A-G rating, alongside recommendations for possible improvements.

The current domestic rating is based on estimated energy costs per square metre under standard assumptions. It does not simply use your tenants' actual gas and electricity bills.

You can read the government's Standard Assessment Procedure (SAP) guidance for more information about the calculation methods.

What Factors Affect Your Property's EPC Score?

An assessor considers the property as a whole. Several features can influence the EPC score:

Insulation: Loft, wall and floor insulation can affect how well the property retains heat.
Windows: Glazing type and window performance influence heat loss.
Heating system: The type of boiler or heating system, its fuel and its controls all matter.
Hot water: The system used to heat and supply water forms part of the assessment.
Lighting: The energy efficiency of fixed lighting is also considered.
Property construction: The building's age, size, layout and materials can affect the calculation.

What EPC Score Do You Need for Each Rating?

The current domestic Energy Efficiency Rating uses a numerical score from 1 to 100, divided into seven bands.

EPC band	Numerical score
A	92-100
B	81-91
C	69-80
D	55-68
E	39-54
F	21-38
G	1-20

For example, a property with a score of 68 receives a D rating. It needs to reach 69 to enter band C. This difference can matter when planning improvements, particularly if you are a landlord preparing for future energy-efficiency requirements.

Why Is Your EPC Rating Lower Than Expected?

A propertycan receive a disappointing rating even after improvements. There are several possible reasons.

The improvement was not enough: Replacing a boiler or upgrading windows may help, but the final result depends on the property's other features too.

The assessor used an assumption: Some property details may be recorded using standard assumptions where evidence is unavailable. If you have invoices or installation records for insulation or heating upgrades, make them available during the assessment.

The potential rating is being confused with the current rating: An EPC can show both the property's present performance and the rating it could achieve after recommended improvements. The potential score is not your property's current rating.

If you believe the certificate contains incorrect information, check the recorded property details and contact the assessor or accreditation scheme.

How Can Landlords Improve a Low EPC Rating Before 2030?

Start with the recommendations on your current EPC. They provide a useful starting point for identifying improvements that may suit your property. Depending on the building, these could include:

Improving loft or wall insulation.
Installing more effective heating controls.
Replacing inefficient lighting.
Considering a more suitable heating system.
Addressing other sources of unnecessary heat loss.

Do not choose improvements based only on the assumption that they will move your property into a particular band. Check the likely impact, suitability and cost before arranging work.

There is also an important deadline for landlords to understand. The current minimum energy-efficiency standard for relevant privately rented homes in England and Wales is generally EPC E, unless an exemption applies.

The government has confirmed a higher standard for private rented homes from 1 October 2030. Properties will generally need to meet a C-grade or above for fabric performance and either heating system or smart readiness, unless a qualifying exemption or transitional arrangement applies.

The government also plans to introduce reformed domestic EPCs in the second half of 2027. These will show four headline measures: energy cost, fabric performance, heating system and smart readiness.

You can check the government's guidance on improving energy efficiency in privately rented homes for the confirmed policy details.

How Cribs Estates Can Help You Prepare Your Property

Cribs Estates works with accredited assessors to help landlords arrange EPC assessments and understand the recommendations. Its property management service also includes checking valid EPCs and coordinating property maintenance.

If you want support with your rental property's compliance and ongoing management, explore our property management services in London.

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How to Calculate EPC Rating: Don't Let a Low Score Catch You Out

Have you upgraded your rental property but still received a lower EPC rating than expected? A new boiler, better windows, or added insulation does not guarantee a higher score. The result depends on several features working together.Understanding how to calculate EPC rating can help you see what affects your property's energy performance. Here is how the assessment works and what landlords should check before spending money on upgrades.How Is an EPC Rating Calculated?An Energy Performance Certificate (EPC)rating is calculated using information about a property's size, construction, insulation, heating, hot water and lighting. An approved government calculation method then estimates its energy performance under standard conditions.You can also read our guide on how to obtain an Energy Performance Certificate.For existing homes in England, assessors generally use the Reduced Data Standard Assessment Procedure (RdSAP). The current version is RdSAP 10.0.1. New homes use the Standard Assessment Procedure (SAP), currently version 10.3.The process involves three main steps:Property inspection: An accredited energy assessor records details such as room measurements, wall construction, windows, insulation, and heating systems.Calculation: The information is entered into approved software, which estimates the property's energy performance.Final rating: The property receives a numerical score and an A-G rating, alongside recommendations for possible improvements.The current domestic rating is based on estimated energy costs per square metre under standard assumptions. It does not simply use your tenants' actual gas and electricity bills.You can read the government's Standard Assessment Procedure (SAP) guidance for more information about the calculation methods.What Factors Affect Your Property's EPC Score?An assessor considers the property as a whole. Several features can influence the EPC score:Insulation: Loft, wall and floor insulation can affect how well the property retains heat.Windows: Glazing type and window performance influence heat loss.Heating system: The type of boiler or heating system, its fuel and its controls all matter.Hot water: The system used to heat and supply water forms part of the assessment.Lighting: The energy efficiency of fixed lighting is also considered.Property construction: The building's age, size, layout and materials can affect the calculation.What EPC Score Do You Need for Each Rating?The current domestic Energy Efficiency Rating uses a numerical score from 1 to 100, divided into seven bands.EPC bandNumerical scoreA92-100B81-91C69-80D55-68E39-54F21-38G1-20For example, a property with a score of 68 receives a D rating. It needs to reach 69 to enter band C. This difference can matter when planning improvements, particularly if you are a landlord preparing for future energy-efficiency requirements.Why Is Your EPC Rating Lower Than Expected?A propertycan receive a disappointing rating even after improvements. There are several possible reasons.The improvement was not enough: Replacing a boiler or upgrading windows may help, but the final result depends on the property's other features too.The assessor used an assumption: Some property details may be recorded using standard assumptions where evidence is unavailable. If you have invoices or installation records for insulation or heating upgrades, make them available during the assessment.The potential rating is being confused with the current rating: An EPC can show both the property's present performance and the rating it could achieve after recommended improvements. The potential score is not your property's current rating.If you believe the certificate contains incorrect information, check the recorded property details and contact the assessor or accreditation scheme.How Can Landlords Improve a Low EPC Rating Before 2030?Start with the recommendations on your current EPC. They provide a useful starting point for identifying improvements that may suit your property. Depending on the building, these could include:Improving loft or wall insulation.Installing more effective heating controls.Replacing inefficient lighting.Considering a more suitable heating system.Addressing other sources of unnecessary heat loss.Do not choose improvements based only on the assumption that they will move your property into a particular band. Check the likely impact, suitability and cost before arranging work.There is also an important deadline for landlords to understand. The current minimum energy-efficiency standard for relevant privately rented homes in England and Wales is generally EPC E, unless an exemption applies.The government has confirmed a higher standard for private rented homes from 1 October 2030. Properties will generally need to meet a C-grade or above for fabric performance and either heating system or smart readiness, unless a qualifying exemption or transitional arrangement applies.The government also plans to introduce reformed domestic EPCs in the second half of 2027. These will show four headline measures: energy cost, fabric performance, heating system and smart readiness.You can check the government's guidance on improving energy efficiency in privately rented homes for the confirmed policy details.How Cribs Estates Can Help You Prepare Your PropertyCribs Estates works with accredited assessors to help landlords arrange EPC assessments and understand the recommendations. Its property management service also includes checking valid EPCs and coordinating property maintenance.If you want support with your rental property's compliance and ongoing management, explore our property management services in London.

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Receive rent or related payments that fall within the scheme's rules. You generally cannot use the scheme if the room is unfurnished or the accommodation is not part of your main home while it is let. Renting out a separate property does not normally qualify either. If you are a tenant planning to take in a lodger, check your tenancy agreement and whether you need your landlord's permission. The scheme's tax rules do not remove your other housing responsibilities. What Happens If Your Lodger Pays More Than £7,500? Earning more than £7,500 does not automatically make all your rental income taxable. You can usually choose between two methods for calculating the taxable amount. Suppose your total receipts from a furnished room are £9,000 in one tax year. Option 1: Use the Rent a Room allowance You calculate the amount above the threshold: £9,000 - £7,500 = £1,500 potentially taxable Under this method, you cannot deduct expenses from the amount above the allowance. Option 2: Calculate your actual profit You deduct allowable expenses from your total receipts and pay tax on the resulting profit. For example, if your receipts are £9,000 and your allowable expenses are £2,000, your profit would be £7,000. In this example, the actual-profit method may be more favourable. Your final tax bill depends on your wider income and circumstances. HMRC explains both methods in its Rent a Room tax calculation guidance. Does the £7,500 Allowance Apply to Each Person? The full £7,500 limit does not automatically apply to every person involved in letting a room. If another person also receives income from letting accommodation in the same property, the limit is generally £3,750 for each person. This may matter when a home is jointly owned or the rental income is shared. For example, if two people share the income from a lodger, they should check how the receipts are divided and which limit applies to each of them. 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What Is RTM? A Guide for Leaseholders Who Want More Control

Rising service charges, delayed repairs, and unanswered questions about building maintenance can leave leaseholders feeling they have little control over their own homes. What is RTM, and can it help? RTM stands for Right to Manage. It allows qualifying leaseholders of flats to take over certain building management responsibilities from their freeholder without buying the freehold or proving that the current management has done anything wrong.Can We Take Control of Our Building Without Buying the Freehold?The Right to Manage (RTM) gives qualifying leaseholders the legal right to take over the management of their building through an RTM company. This company is responsible for managing the building once the right takes effect.RTM does not transfer ownership of the building. The freeholder still owns the freehold, but qualifying leaseholders gain control over the management functions covered by the law.You also do not need to prove that your current managing agent has performed poorly. 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