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What are the legal obligations with regard to thermal insulation?

The EPB regulations (Energy Performance of Buildings) are currently the only direct measure that imposes a specific level of thermal insulation in Brussels.

  • Which buildings are concerned? Every building with heating and/or air conditioning in which building, conversion and reconstruction work is carried out for which a town planning permit is required.
  • What is required by law?
    • a general insulation level for the building as a whole (K value): this value may not be more than 40;
    • an insulation level for each individual building element, such as the roof, floors, walls, etc. (U value): this value may not be more than 0.3 W/m²K for roofs and 0.4 W/m2K for outside walls.

De EPB regulations as a reference

The legal obligations on energy, particularly with regard to thermal insulation, are regularly made more stringent. Why are changes made so often? To give private individuals and construction professionals time to adapt. In response to the Kyoto accords, Europe has taken a number of decisions aimed at saving energy. And the member states are obliged to abide by these decisions.

In Belgium, housing is a regional competence. In practical terms, therefore, the government of the Brussels-Capital Region is gradually imposing various measures. These are the so-called ‘EPB’ regulations (Energy Performance of Buildings). 

What does the current Brussels legislation state?

  • Since 2008, every home for which a town planning permit is required for construction or renovation has had to meet minimum insulation standards for the various structural elements.
  • Outer shell of the building: K ≤ 40. The general level of insulation of the building, the K-level, may not be higher than 40 for individual and collective housing (45 for offices, services and education). The K value is mainly determined by the level of insulation of the outside walls and the compactness of the building. The lower this value, the more efficient the insulation.
  • Building elements: U = 0.4 to 2.5 W/m²K depending on the wall. For each new or altered building element (roof, walls, floors, etc.), a ‘maximum heat transfer coefficient’ has to be observed. This is the U value, the amount of heat that the wall lets through (per second and per m² with a temperature difference of 1°C (1°K) between the two sides of the wall). The lower this value, the better the insulation.
  • Outside walls: U ≤ 0.4 W/m²K
  • Roof and ceilings: U ≤ 0.3 W/m²K
  • Floors: U ≤ 0.4 to 0.6 W/m²K
  • Windows: U ≤ 2.5 W/m²K
  • Glazing: U ≤ 1.6 W/m²K

For roofs and outside walls, for instance, these values correspond to 15 cm of glass wool or 12 cm of synthetic foam.

  • There are no obligations regarding the type or thickness of the insulating material used, as long as the required results are achieved.
  • The owners of buildings that do not meet these standards may receive fines amounting to thousands of euros.

How do you meet the requirements?

With a building project or far-reaching renovation work, the architect determines what measures have to be taken to comply with the EPB standards. If the architect does not do this, then an approved EPB adviser has to check and validate the measures taken.

With simple renovations you do not have to call upon an approved EPB adviser. If you wish, you can request the assistance of an architect or the EPB officer in your commune.

Incentives to do more

The EPB regulations stipulate the minimum quality requirements to be observed, but you can, of course, go further if you wish! More stringent conditions than the ‘legal minimum’ are required for most energy grants for insulation.

So do not hesitate to insulate better. Not only will you be financially rewarded, but you will also be anticipating future – more stringent – laws.

For instance, as of 2015 every new building project in Brussels must be a passive building (this already applies for office buildings). Heating a passive building takes the equivalent of 1.5 m3 of gas or 1.5 litres of heating oil per square metre per year, which is only possible with particularly good insulation!

Other insulation-related obligations

There are another two legal obligations that have an indirect impact on insulation.

To calculate the E level, account is taken of the compactness of the building and its airtightness, any energy produced (e.g. using solar panels), the type of ventilation, the awning and finally the insulation. This legal performance obligation therefore also has an indirect impact on the insulation.

  • The E-level In addition to compliance with the maximum K and U values, buildings for which a town planning permit is required may also not exceed a specific total level of energy consumption: this is the ‘E level’. This value represents the total energy consumption of a home (lighting, heating, warm water). In Brussels, this value may not exceed 70.

Consequently, a poorly insulated house or apartment is less attractive to buy or rent. Although this certificate does not impose any specific measures with regard to insulation, it does put pressure on the real-estate market. Given the law of supply and demand, this certificate therefore encourages better home insulation.

  • The EPB certificate. Since 2011 an EPB certificate must be produced for houses and apartments that are put up for sale or to let. This certificate indicates the strengths and weaknesses of the house or apartment as regards energy, and in particular the insulation.

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