When trying to boost your Energy Performance Certificate (EPC) rating, two popular upgrade paths often come to mind: switching to low-energy lighting or improving your home’s insulation. But which one actually makes the bigger difference?
The short answer? Insulation wins—hands down.
But both have their place. Let’s break down the comparison so you can invest wisely and get the EPC score (and energy savings) you’re aiming for.
1. Why the EPC Rating Matters
Your EPC rating determines:
Legal rental eligibility (e.g., Minimum Energy Efficiency Standards)
Property value and saleability
Running costs and energy efficiency
Access to green mortgages or government grants
The higher your rating (A being best, G being worst), the better your home performs in terms of energy use and carbon footprint.
2. Lighting: A Quick, Low-Cost Improvement
LED and low-energy lighting is:
Easy to install
Inexpensive
Visibly reflected in EPC reports
Often considered a “tick-box” upgrade
But the impact is limited. Lighting usually accounts for less than 10% of household energy use.
EPC Impact of Lighting:
Upgrading to 100% low-energy lighting may improve your SAP score by 1–3 points.
Rarely moves your property up an EPC band on its own.
✅ Best for: Quick EPC improvements, preparing for re-certification, or meeting basic compliance.
3. Insulation: The Game Changer
Insulation improves your thermal envelope, reducing the amount of heat lost through:
Walls
Roof
Floors
Windows and doors (via better U-values)
This directly reduces heating demand—a major driver in EPC calculations.
EPC Impact of Insulation:
| Upgrade | EPC Impact (SAP Points) |
|---|---|
| Loft insulation (none to 270mm) | +10–15 points |
| Cavity wall insulation | +5–12 points |
| Solid wall insulation | +10–20+ points |
| Floor insulation | +5–10 points |
✅ Best for: Major EPC band improvements, real-world energy savings, and long-term value.
4. Which Should You Prioritise?
| Factor | Lighting | Insulation |
|---|---|---|
| Cost | Low | Medium to high |
| Installation Time | Minutes | Hours to days |
| EPC Impact | Small | Significant |
| Energy Bill Savings | Minimal | Substantial |
| EPC Band Change | Unlikely | Very likely |
👉 Verdict: If you want the most EPC impact per upgrade, go for insulation.
If you want a fast, affordable improvement, LED lighting still has value.
5. Bonus Tip: Combine for Maximum Effect
Some of the best EPC improvements come from combining measures:
Upgrade lighting to 100% LED
Insulate your loft and cavity walls
Seal air leaks and draughts
Consider double or triple glazing
Together, these can elevate your EPC by one or two bands—a major boost for landlords, sellers, and eco-conscious homeowners.
Final Thought: EPCs Reward What Saves Heat, Not Just Energy
EPC software prioritises heating efficiency and fabric improvements over general energy savings. That’s why insulation—which directly reduces heat loss—has a much bigger impact than lighting, even if both contribute to sustainability.
Need help improving your EPC rating efficiently?
Book your EPC assessment now and get advice tailored to your property and budget.
📍 Final Takeaway
The EPC graph is just the beginning. When you know how to read between the lines, your report becomes more than a score—it becomes a blueprint for saving energy, reducing emissions, and increasing property value.
Ready to unlock the full story of your EPC?
📅 Book your expert EPC assessment today at EPCrate.co.uk.
