Two in every three homes in Belgium still do not have a valid energy-performance certificate, according to the Certinergie inspection body.

However, existing ratings cannot be compared across the country’s regions.

In its 2016-2025 barometer, the organisation said each region applies its own thresholds, meaning the same letter rating can reflect very different levels of energy consumption.

Rating disparities between the regions

As an example, Certinergie said a C rating in Brussels corresponds to consumption of between 96 and 150 kWh per square metre a year, while a C rating in Wallonia covers between 170 and 255 kWh per m2.

“This barometer offers an opportunity to pause and analyse building energy certification at the national level in a factual way,” said Adrien Pourbaix, an industrial engineer specialising in energy and a consultant at Certinergie.

He said the review highlights not only the system’s strengths and opportunities, but also its weaknesses and risks.

Mortgage rates linked to energy certification

According to Certinergie, more and more banks are adjusting mortgage rates according to a property’s energy certificate.

A strong rating can help borrowers secure better terms, either through a lower interest rate or a longer repayment period.

Over 20 or 25 years, the difference can significantly affect the total cost of a loan, especially at a time when interest rates are high and expected to remain so, the organisation said.

Brussels has lowest energy consumption, but worst average rating

Although energy performance certification remains a regional responsibility, Brussels records the lowest energy consumption of the three regions while also posting the worst average letter rating, at F. That compares with an average rating of E in Wallonia and D in Flanders.

Certinergie said the EU’s revised Energy Performance of Buildings Directive, known as EPBD 4, provides for a harmonised A-to-G labelling scale.

The organisation concluded that reliable and comparable data will be essential to guide building renovation policy.