The 5 renovations with the biggest impact on your EPC score

Smart renovating for maximum results

When you want to improve your EPC score, it's important to set the right priorities. Not every renovation delivers the same level of improvement. Here are the five most impactful improvements, ranked from largest to smallest effect.

1. Roof insulation — the absolute number one

The roof is responsible for up to 30% of heat loss in a home. Roof insulation is almost always the first recommendation in an energy audit, and for good reason. The investment is relatively modest (€40 to €80 per m²) and the effect on your EPC label is enormous.

A well-insulated roof can improve your EPC score by 1 to 2 labels. From label E to D, or even from D to C. Moreover, you notice the difference immediately: less draughts, a more comfortable temperature and lower heating costs.

2. Wall insulation — the largest surface area

Walls make up the largest surface area of your home and are responsible for 25 to 35% of heat loss. External wall insulation is the most effective solution, but cavity wall insulation or internal insulation also make a difference.

Expect an improvement of 1 to 2 EPC labels, depending on the current state of your walls. Costs range between €50 and €150 per m² for external insulation, but the subsidies are proportionally higher as well.

3. Replacing the heating system

Replacing an old gas or oil boiler with a heat pump or high-efficiency condensing boiler has a major effect on your EPC score. The heating system is one of the most heavily weighted factors in the EPC calculation.

Switching to a heat pump can make a difference of 1 to 2 labels. A condensing boiler typically delivers a 0.5 to 1 label improvement. The effect depends on the age and efficiency of your current system.

4. High-performance glazing

Old windows with single glass or outdated double glazing are a significant source of heat loss. Replacement with triple glazing or high-performance double glazing noticeably improves your EPC score.

The impact is typically 0.5 to 1 label, depending on the total glass surface area. New windows also improve the comfort and sound insulation of your home.

5. Floor insulation

Floor insulation is often forgotten, but can make a valuable contribution. Through the floor, 5 to 10% of heat is lost. Insulating the basement floor or crawl space is often relatively affordable and straightforward to carry out.

The effect on the EPC score is more limited (0.5 label or less), but combined with the other measures, it can make the difference in achieving one label higher.

The ideal order

The rule of thumb: insulate first, then replace your heating. Why? Because a well-insulated home requires less power, allowing you to install a smaller (and cheaper) heat pump or boiler.

Start with the roof, then the walls, then the windows, and only then look at your heating system. This way, you get the maximum from every investment.

Discover your renovation potential

Curious which works have the most impact for your home? Our free calculator gives you a personalised estimate based on your property type, current EPC label and region.