When most people look at an Energy Performance Certificate (EPC), their attention goes straight to the energy efficiency rating — the A to G scale that reflects energy consumption. But right below that is another powerful metric that’s often overlooked: the Environmental Impact Rating.
This rating, which also uses an A–G band, tells a deeper story about your home’s carbon emissions — and it can be just as important for future regulations, mortgage approvals, and even property value.
Let’s decode what the Environmental Impact Rating actually measures, how it’s calculated, and why it matters more than ever in today’s carbon-conscious property market.
🌍 What Is the EPC Environmental Impact Rating?
Also known as the CO₂ emissions rating, this score measures your property’s carbon dioxide output per year based on typical usage.
Expressed as a number (1–100+) and a letter grade (A to G)
Based on the amount of carbon emitted in tonnes per year
Higher scores (A/B) = lower environmental impact
🔍 It’s not just about efficiency — it’s about your home’s contribution to climate change.
📉 What Does It Actually Measure?
The Environmental Impact Rating is based on:
Heating fuel type (gas, oil, electricity, biomass)
Efficiency of heating/hot water systems
Building fabric heat loss (e.g., wall/roof/window insulation)
Lighting energy demand
But instead of focusing on costs, this rating reflects your home’s greenhouse gas emissions — primarily carbon dioxide.
🧮 How Is It Calculated?
Assessors use SAP (Standard Assessment Procedure) or RdSAP software to model:
Estimated CO₂ output in kg/year
Per m² performance
Heating, lighting, and hot water emissions
They then convert this into:
A numerical Environmental Impact score (1–100+)
An A–G band (A = best, G = worst)
| Rating Band | Score Range | CO₂ Emissions (indicative) |
|---|---|---|
| A | 92–100+ | Very low (green technologies) |
| B | 81–91 | Low carbon footprint |
| C | 69–80 | Above average |
| D | 55–68 | Moderate |
| E | 39–54 | High |
| F | 21–38 | Very high |
| G | 1–20 | Extremely high |
🔥 Why Is It Different from the Energy Efficiency Rating?
| Energy Efficiency Rating | Environmental Impact Rating |
|---|---|
| Focuses on running costs | Focuses on carbon emissions |
| Favourable to cheap fuels | Penalises carbon-heavy fuels |
| Used for MEES compliance | Used for sustainability reporting |
| May rate oil/gas homes well | Penalises high-emission systems |
⚠️ A home with cheap gas heating may get a decent Energy Rating — but a low Environmental Impact score due to carbon output.
🏡 Real-World Examples
🏠 Property A – 1950s semi-detached with gas heating
Energy Rating: C
Environmental Impact Rating: E
Why? Cheap fuel, but high carbon emissions
🏡 Property B – New build with air-source heat pump and solar panels
Energy Rating: B
Environmental Impact Rating: A
Why? Low-emission, renewable systems
💼 Why the Environmental Impact Rating Matters
✅ 1. Net-Zero Goals and Green Regulation
As the UK moves toward net-zero carbon homes, this rating may be used for:
Future property compliance
Green finance incentives
Planning and building standards
✅ 2. Green Mortgages and Loans
Lenders and insurers are increasingly looking at environmental impact ratings when offering:
Lower rates
Eco-loans for retrofitting
Climate-risk adjusted valuations
✅ 3. Future-Proofing Your Property
A high-impact rating (F or G) could affect:
Resale value
Letting potential
Regulatory penalties for landlords
🛠 How to Improve Your Environmental Impact Rating
| Improvement | Impact on Score |
|---|---|
| Upgrade to a low-carbon heating system | Major boost (e.g., heat pumps) |
| Insulate lofts, walls, and floors | Reduces heating demand |
| Install solar panels | Offsets electrical usage |
| Switch to LED lighting | Lowers electricity consumption |
| Add smart heating controls | Improves overall efficiency |
📸 Document everything: If you’ve installed upgrades, ensure your assessor includes them to avoid default (penalising) assumptions.
📍 EPC Environmental Impact Rating in Legal Context
Not currently used for MEES (Minimum Energy Efficiency Standards), but may become relevant in future legislation.
Used in Home Reports, green mortgages, and corporate ESG reporting.
May be referenced in planning applications or sustainability certifications (e.g., BREEAM, Passivhaus).
✅ Need an EPC That Reflects Your Low-Carbon Improvements?
At EPCrate.co.uk, our trained assessors help you get a fair and accurate Environmental Impact Rating — with advice on boosting your score using smart, cost-effective upgrades.
🌍 Same-day assessments across London
💬 Advice on eco-friendly improvements
📋 Landlord and green buyer-compliant EPCs
Final Thought: Don’t Ignore the Second Scale
The Environmental Impact Rating isn’t just an afterthought — it’s a preview of your property’s climate resilience, regulatory future, and even mortgage favourability. Understanding what it means and how to improve it could save you money — and help the planet.
