Insulation and energy label: what do you really save?
Insulation is one of the most important levers for a better energy label. But which building component gives the most benefit? How many label steps do you really save? And why does insulation rarely suffice alone for label A? In this blog, we explain how insulation counts, which Rc-values matter, and when you need additional measures.
Why insulation matters: 25-30% of heat loss through the roof
Approximately one quarter to one third of heat loss in a home occurs through the roof. This is followed by the walls and the floor. This is why insulation matters so much for your energy label: each component you insulate better saves heat loss and therefore energy.
In the NTA 8800 calculation method (the standard for your energy label), the entire building envelope counts. In this blog we look at the closed parts: the roof, the walls and the floor. Together they account for most of the heat your home loses.
Which building component delivers the most benefit?
Not all insulation is equal. Some components have more impact than others:
- Roof: up to 25-30% heat loss. This is usually the winner.
- Walls: 20-30% heat loss (depending on house type).
- Floor: 10-15% heat loss (much smaller, unless there's a large crawl space).
So the biggest gain per euro is usually in the roof. In practice, many people still start with the floor, because it is relatively easy to insulate from the crawl space. Which order you choose is entirely up to you. An insulation company such as Randstad Isolatie can help you with that.
Rc-values: how good is your insulation?
Insulation quality is expressed in Rc-values (thermal resistance). The higher the Rc, the better the insulation.
Current target values for a good energy label:
- Roof: Rc ≥ 3.5 (ideal ≥ 4.5 for label A/B)
- Walls: Rc ≥ 2.5
- Floor: Rc ≥ 2.0
If your home is older, these values will be lower. That's exactly where insulation investments count: you raise the Rc-values.
How many label steps can you save with insulation?
This is the question homeowners want answered. The answer: it depends.
Roof insulation alone: usually 1-2 label steps, depending on how poorly the roof is currently insulated. A poorly insulated roof (Rc 0.5-1.0) improved to Rc 6 can deliver 2 steps.
Wall insulation alone: usually 1-2 steps.
Combination of roof + walls + floor: this can be 2-3 steps, for example from D to B.
But: these are estimates. The actual savings depend on your household, build year, house type, and current label. That's why an accurate home inspection is so important — only then do you know which insulation investment will be most worthwhile.
Why insulation rarely suffices alone for label A
This is the big point: insulation is the foundation, but usually not enough for label A or B. Why?
Because the NTA 8800 method also counts installations:
- Solar panels: This is the giant in the calculation. 5-8 solar panels can help your label more than perfectly insulated walls.
- Heat pump: This also significantly improves the label, especially for heating.
- Boiler: A modern high-efficiency boiler helps, but solar panels and heat pumps are more powerful.
The practical consequence: many households go from D to C with insulation alone, but for A or B they add solar panels or a heat pump.
Practical example: a 1970 terraced house
A terraced house from 1970 was built without insulation. Without proof of insulation, the energy label then uses the default values for that period: roof Rc 0.86, walls Rc 0.43 and floor Rc 0.17. With a condensing boiler, such a house usually comes out at label D.
What insulation does here:
- Insulating the roof from Rc 0.86 to Rc 6: the biggest jump, as the roof is the weakest part and often the largest area.
- Cavity wall insulation: from Rc 0.43 to well over 1.5. Relatively cheap with a solid effect.
- Floor insulation from the crawl space: from Rc 0.17 to 3.5 or higher.
- Result: with these three measures, this house typically ends up at label B, sometimes C.
We deliberately leave glazing out here: replacing double glazing with HR++ does almost nothing for the label. Only replacing single glazing really counts.
For label A, this house too almost always needs solar panels, possibly combined with a (hybrid) heat pump. And note: have the insulation documented with photos or invoices, because without proof the label keeps calculating with the 1970 default values.
Do you have to insulate everything at once?
No. Smart insulation means setting priorities:
- Roof first: most impact, often most cost-effective relatively.
- Walls: bigger budget? This helps a lot too.
- Floor: only if really poor.
You can also combine this with installations: roof + solar panels first → label B. Walls later → label A.
Don't forget: subsidy opportunities
Insulation investments can improve your label, but they cost money. Fortunately, there are subsidies available. For 2026, various support schemes apply. It's worth calculating this with an expert.
Frequently Asked Questions
Does my existing insulation count toward the label?
Yes, absolutely. We measure everything: existing insulation, cavity insulation, roof layers — the calculation sees it all.
How much can I save on energy costs with better insulation?
That varies widely: €500-€1,500 per year for a poorly insulated roof that you fully insulate. But that's outside this article; for accurate advice, it's worth consulting an energy advisor.
Can I install insulation myself?
For many insulation materials you can, but installation should be professional. Poor workmanship won't help your label. Many people have it done by professionals.
Get your energy label calculated — we'll tell you what insulation really delivers
Find out what insulation means for your home's energy label and which combination is most cost-effective. In a home inspection of 60-90 minutes, we measure everything, including your existing insulation. Afterwards, you get the exact energy label — and the advice you can work with.
Energy label from € 220. Including inspection, calculation and registration.