In 2026, the Belgian market clearly distinguishes between well-designed properties and the rest. Compactness, orientation and construction choices are levers the investor controls from the sketch stage onwards. Here's how STARC uses them to protect a project's value.
An income property or development is judged on figures: rent, occupancy rate, exit price. Those figures are largely decided long before construction starts, at the point when the volume is drawn, the living areas are placed and the materials are chosen. Here are the design decisions that really affect a property's value, and how we handle them at STARC.
What the 2026 market rewards
The market has picked up again, but it is now more selective. According to the Notaries' Barometer (Fednot) published in April 2026, the average house price reached 359,965 euros in the first quarter at Belgian level. A moderate rise, then, which doesn't benefit every property equally. For G-Home, one of the year's findings can be summed up in a single sentence: the EPB rating (PEB) strongly influences a property's final value.
Transaction studies confirm this. According to an Immoweb analysis, in Wallonia an A rated house costs 12% more on average than a D rated reference. For flats, the gap widens to 14.1%. Conversely, G rated properties suffer an average 8.3% discount. In Brussels, a B rated house sells for 12.2% more on average than a D rated property, while a G rated house is discounted by 6.6%.
For an investor, these figures should be read as the result of a coherent whole: a compact, well oriented, well built building. The EPB rating is merely the visible expression of that.
Compactness, the first lever of value
Compactness is the ratio between the surface area of the walls exposed to the outside and the heated volume. The simpler a volume is, the less energy it loses, and the less it costs to build.
In practice, for a project involving flats or terraced houses:
- a simple volume, with few recesses or projections, reduces thermal bridges and costly construction details;
- shared party walls and stacking dwellings on top of each other greatly reduce heat loss through the walls;
- every corner, dormer window or cantilevered terrace adds to the construction budget, often for only a marginal gain in rental value.
Compactness also applies to the floor plan. An efficient plan reduces shared circulation space and increases the net sellable or lettable area. In a multi storey building, a few square metres of corridor saved on each floor go straight into the bottom line of the project.
The pitfall to avoid is sacrificing all architecture to compactness. A featureless block is hard to let. Our job is to find the balance, concentrating the architectural gesture where it creates perceived value (entrance, living room, opening onto the garden) and keeping the rest simple.
Orientation and light, what lets faster
Vacancy is costly, and it hits dark or overheated homes first. Orientation is decided at the siting stage, and after that it is almost impossible to correct.
The principles we apply:
- placing living rooms to the south or south west, bedrooms to the east, service rooms and circulation areas to the north;
- favouring dual aspect or corner flats, which offer two orientations and natural ventilation;
- avoiding homes oriented solely to the north, which are the hardest to let and resell;
- planning solar protection for west facing facades from the sketch stage onwards (overhangs, brise-soleil, external blinds), since summer overheating is becoming a real deciding factor for tenants.
One well placed window is worth more than three badly oriented ones. It brings in light, limits heating needs and avoids having to install air conditioning later on, which would push up running costs.
Construction choices that age well
Resale value depends on the condition of the property in fifteen or twenty years' time. Some choices age better than others.
We recommend prioritising the building envelope over equipment. Generous insulation, high performance window frames and good airtightness will last the whole lifetime of the building. A heat pump or solar panels can be replaced, walls cannot.
As for materials, fired clay brick, blue stone, slate and well detailed timber have all proven themselves in Wallonia and Brussels. They require little maintenance, fit easily into local planning contexts and reassure buyers.
Finally, flexibility protects the investment. A post and slab structure, accessible service ducts and non load bearing partitions make it possible to combine two studios into a family flat, or split them apart again, depending on the market. We see this in office to residential conversions: the buildings that convert best are the ones that were designed simply.
Regulations pushing in the same direction
The regional framework is becoming stricter, and a property designed today needs to take this into account in order to retain its value.
In Wallonia, for new builds, since 1 January 2026: no more oil or coal boilers, at least 35% renewable energy. Since September 2026, the EPB certificate (PEB) for existing homes includes a renovation pathway towards an A rating, making the gap between high performing properties and energy guzzlers even clearer for buyers. As for the renovation obligation for buyers, the Walloon government approved a draft in December 2025 stating that, for purchases from 2028 onwards, buyers will have five years to reach at least a D rating, although this timetable still needs to be confirmed by legislation.
In Brussels, the trajectory is already set. According to the City of Brussels, by 2033 every home will need to reach at least EPB target 275 (PEB, no more than 275 kWh/m2/year), equivalent to energy class E. The EPB rating also affects rental income: for homes rated EPB E, F or G and let under a lease signed before 14 October 2022, a correction factor reduces the amount of any rent increase.
The lesson for an investor is simple: a property that targets a very high performance level from the outset will not be caught out by these deadlines. A property designed to the legal minimum, on the other hand, risks needing renovation before it has even paid for itself.
How we build in value from the sketch stage
At STARC, we address these questions even before the first detailed plan. Our typical approach for an investor, a developer or a turnkey builder:
- site analysis: sunlight, views, party walls, planning constraints under the CoDT (Walloon spatial development code) or the applicable Brussels regulations;
- comparing two or three siting and massing scenarios, with their consequences for net floor area, dwelling orientation and cost;
- EPB simulation (PEB) from the preliminary design stage, supported by the engineers at Optibim, to check the achievable level without oversizing the equipment;
- a BIM model to make quantities reliable, limit site surprises and keep to budget;
- material choices based on their durability, maintenance needs and acceptance by buyers and tenants in the sector.
This method doesn't cost any more. It simply shifts the effort to the point where each decision has the greatest impact for the least cost.
Do you have a plot, a building to convert or a housing scheme in preparation? We can analyse its potential with you, compare a few scenarios and quantify their impact on your project. Get in touch with the STARC team in Gembloux to discuss your project.
Roxane de Quirini, STARC