How to Improve Your EPC Rating: A London Landlord's Guide

Your property's EPC rating has never mattered more. The Minimum Energy Efficiency Standards (MEES) regulations already prohibit letting properties rated F or G. The government has signalled a minimum C rating requirement by 2030 — and the clock is ticking. For London landlords, many of whom own Victorian and Edwardian properties that were built without insulation, upgrading a poor EPC rating requires a clear understanding of what works and what does not.

This guide covers the most cost-effective improvements for London rental properties, what the ratings actually mean, and how to approach the new EPC certificate after works are complete.

Why Your EPC Rating Matters for Landlords

The Energy Performance Certificate assigns your property a rating from A (most efficient) to G (least efficient). For landlords, the rating matters for two reasons:

Legal compliance: Under the MEES regulations (The Energy Efficiency (Private Rented Property) (England and Wales) Regulations 2015), landlords cannot grant a new tenancy or continue an existing tenancy for a property rated F or G unless a valid exemption applies. There are very few valid exemptions — claiming that improvements would cost too much has a specific financial threshold test.

Section 21 validity: You must provide the tenant with a valid EPC before the tenancy starts. Without a valid EPC, you cannot serve a Section 21 notice. As the Renters Rights Act 2025 changes the eviction landscape, having your compliance documentation in order becomes even more important.

The proposed 2030 minimum of EPC C will require substantial investment in many London properties. Starting early — particularly before the legislation is confirmed — gives you access to better-funded improvement schemes and allows costs to be spread over several years.

What the Ratings Mean

| Rating | SAP Score | Typical annual energy cost | |---|---|---| | A | 92–100 | Under £500 | | B | 81–91 | £500–£900 | | C | 69–80 | £900–£1,300 | | D | 55–68 | £1,300–£1,800 | | E | 39–54 | £1,800–£2,500 | | F | 21–38 | £2,500–£3,500 | | G | 1–20 | £3,500+ |

These are approximate figures based on a standard property. The SAP (Standard Assessment Procedure) score is calculated by the energy assessor based on the construction, insulation, heating system, lighting, and renewables present in the property.

The Minimum E Rating Requirement

Since 1 April 2020, landlords in England and Wales have not been permitted to let properties on new tenancies rated F or G without a valid exemption. Since 1 April 2023, this has applied to all tenancies — not just new ones.

The exemptions are narrow:

• Cost cap exemption: If the cost of improvements to reach E exceeds £3,500 (including VAT), and the property still cannot reach E within that budget, the property can be registered as exempt on the PRS Exemptions Register.
• Devaluation exemption: Where a surveyor's report confirms that improvements would reduce the market value of the property by more than 5%.
• Consent exemption: Where the tenant has refused access to allow improvements.
• New landlord exemption: Six months from when you became a landlord (e.g., inherited the property).

Exemptions must be registered on the government's PRS Exemptions Register. They are not automatic and are time-limited (typically five years).

Top Improvements by Cost and Impact

Loft Insulation — The Highest Return

Loft insulation is the single most cost-effective improvement for most London properties. A property with no loft insulation — or thin, old insulation — loses a significant proportion of its heat through the roof. Adding 270mm of mineral wool loft insulation typically:

• Cost: £300–£600 installed
• EPC point improvement: 4–8 SAP points
• Annual energy saving: £150–£300
• Practical notes: Only possible if there is accessible loft space. Flats on lower floors cannot benefit. Check whether existing insulation just needs topping up or replacing.

For top-floor flats and maisonettes with accessible loft space, this is usually the first improvement to consider. Payback in energy savings typically takes 2–4 years.

Cavity Wall Insulation

Properties built from the 1930s onwards (and some late Victorian terraces) often have cavity walls — a gap between two leaves of brick. Injecting insulation into this cavity significantly reduces heat loss.

• Cost: £400–£1,200 depending on property size
• EPC point improvement: 4–10 SAP points
• Annual energy saving: £200–£400
• Practical notes: Requires a cavity — not suitable for Victorian solid-wall properties. Should only be installed by a BBA-certified installer. Poorly installed cavity wall insulation can cause damp, so use a reputable contractor.

LED Lighting

Often overlooked, lighting contributes to the SAP calculation. Replacing all fixed lighting points (ceiling roses, spotlights, and wall fittings) with LED bulbs is cheap and straightforward.

• Cost: £100–£300 for a full property
• EPC point improvement: 1–3 SAP points
• Annual energy saving: £50–£120
• Practical notes: Only energy-saving light fittings (those that cannot physically accept an inefficient bulb) count in the SAP assessment. Simply inserting LED bulbs into existing fittings that could accept a halogen may not register.

Boiler Upgrade — A to G-Rated Boiler

Replacing an old G-rated or inefficient boiler with a modern A-rated condensing combi boiler is one of the most impactful single improvements, though also one of the most expensive.

• Cost: £2,500–£4,000 installed (including removal of old boiler)
• EPC point improvement: 8–15 SAP points
• Annual energy saving: £300–£600
• Practical notes: A boiler more than 12 years old is likely to have a seasonal efficiency below 70%. Modern condensing boilers achieve 90%+. The improvement to the EPC rating can be substantial — sometimes enough to move from E to D or D to C on its own.

At My Landlord Certificate, our boiler installation service covers full supply and installation from £2,499 with a 10-year manufacturer warranty.

Smart Thermostat and Heating Controls

Upgrading from a basic on/off room thermostat to a smart thermostat with weather compensation and individual room controls contributes to the EPC assessment.

• Cost: £200–£600 installed
• EPC point improvement: 2–5 SAP points
• Annual energy saving: £80–£200
• Practical notes: A programmable room thermostat must be installed and set correctly to benefit from the EPC assessment. Smart thermostats such as Nest or Hive also give tenants more control over their heating, which can reduce complaints and improve tenant satisfaction.

Double Glazing

Single-glazed windows are a significant source of heat loss. Replacing single glazing with double glazing is effective but expensive.

• Cost: £4,000–£10,000 for a full property
• EPC point improvement: 3–6 SAP points
• Annual energy saving: £100–£250
• Practical notes: The EPC improvement for double glazing alone is often not large relative to the cost. It is most cost-effective as part of a wider improvement programme. In conservation areas, secondary glazing or slim-profile heritage double glazing may be required with planning permission.

Draught Proofing

Simple draught proofing — sealing gaps around doors, windows, skirting boards, and loft hatches — has a disproportionate impact for the cost.

• Cost: £50–£300 DIY or installed
• EPC point improvement: 1–2 SAP points
• Annual energy saving: £50–£150
• Practical notes: Not a dramatic improvement on its own, but combined with other measures it adds up. Easy to do between tenancies.

What Works in London Victorian Properties

Victorian terraced houses — the most common rental property type in inner London — present specific challenges:

The solid wall problem: Victorian terraces were built with solid brick walls, typically 225mm thick. There is no cavity to fill. The only options are external wall insulation (cladding applied to the outside of the building) or internal wall insulation (reducing room size). Both are expensive (£8,000–£20,000) and complex, and may require planning permission in conservation areas.

What does work in Victorian terraces:

• Loft insulation (if not already present)
• A-rated boiler replacement
• Smart heating controls
• LED lighting
• Secondary glazing or slim double glazing
• Underfloor insulation if suspended timber ground floor

A well-executed combination of these improvements can typically take a Victorian terrace from E or F to D, and potentially to C — but it requires investment and a realistic assessment of what is achievable without structural alteration.

The EPC Improvement Recommendations Report

Every EPC includes a recommendations section listing the improvements that would raise the rating. Each recommendation shows:

• The improvement type
• The estimated improvement to the SAP score
• A rough cost band (low/medium/high)
• The potential improvement to the rating

This report is a good starting point — but the recommendations are computerised estimates, not detailed surveys. For structural changes like solid wall insulation, a specialist survey is advisable before committing.

The EPC recommendations do not form a legal obligation on the landlord — they are advisory. However, they are relevant when considering whether you have exhausted all cost-effective options before claiming a MEES exemption.

How Much Does a New EPC Cost After Improvements?

Once improvements are complete, you will need a new EPC to demonstrate the updated rating. The old EPC will not automatically change.

At My Landlord Certificate, an EPC assessment costs from £89.99 for a studio or small flat, with next-day appointments across all 33 London boroughs. The certificate is registered on the national EPC register and emailed within 24 hours.