Since 1 January 2025, the Brussels-Capital Region has adopted a new way of specifying the number of habitable square metres of a dwelling: the "habitable surface area". The habitable surface area becomes the only valid reference for indicating the area of a dwelling in the context of a residential lease in the Brussels-Capital Region. This method of measurement must be applied when drafting and registering lease agreements via the IRISbox platform.
The new definition, incorporated into the Brussels Housing Code, states that the habitable surface area of a dwelling means the sum of the floor areas of the living rooms located inside the dwelling and having a clear ceiling height of at least 2.1 m under a horizontal ceiling, or 1.5 m under a sloping ceiling or a sloping roof section. Staircases, cellars, garages, built-in cupboards and enclosed technical spaces are explicitly excluded from the calculation (Article 2, 46°, of the Brussels Housing Code). Consequently, the surface area thus measured is generally (much) lower than that indicated under other methods, such as the EPC certificate or the Regional Urban Planning Regulations (RRU).
For landlords, this constitutes a significant and unfavourable change: the reference surface area to be used for advertisements and for the calculation of the indicative rent differs from previous practice, which may have an impact on the amount of rent displayed. In return, this new method offers a clear, objective and uniform framework, both for tenants and for the administration.
To calculate the reference rent of a particular property, the landlord or the tenant can use the regional tool based on this grid (Homepage – loyers.brussels). By answering a few questions about the characteristics (including the "habitable surface area") and the location of the dwelling, the reference rent will be generated and may be mentioned in the lease agreement, in addition to the rent actually requested.
A relevant question remains regarding the application of this reform to leases concluded before 1 January 2025. The Ordinance of 25 April 2024 amending Article 2 of the Brussels Housing Code, as well as the opinion of the Council of State and the parliamentary records, unfortunately do not provide an explicit answer to this question. We must therefore refer to the ordinary law, in particular Article 1.2 of the Civil Code concerning the application of the law over time. In principle, an ordinance does not have retroactive effect, but it may have consequences for existing lease agreements that continue after 1 January 2025. Existing lease agreements concluded before 1 January 2025 remain valid as drafted, even if they do not mention the "habitable surface area". However, for consequences arising after 1 January 2025 (such as a renewal or amendment), the habitable surface area will have to be mentioned. It seems to us that the reference rent calculated before 1 January 2025 using a method other than the habitable surface area can continue to be applied, since deciding otherwise would amount to giving retroactive scope to the ordinance.
You may send your comments or questions to Laurent Delmotte (ld@resolved.law) or Bart Van Hyfte (bv@resolved.law)
