Building a house rarely starts with the choice of tiles or facade color. The starting point is a series of technical decisions that condition everything else: building orientation, thermal performance of the envelope, structural choices between wood framing and traditional masonry. These decisions, made early with an architect, determine the final budget as much as daily comfort.
Embodied energy and building materials: the criterion that plans do not show
Have you ever compared two seemingly similar houses and wondered why one costs significantly more to heat? The answer often lies in the materials chosen, not just in the visible insulation.
Embodied energy refers to the energy consumed to manufacture, transport, and implement a material. A reinforced concrete wall and a solid wood wall can offer the same mechanical resistance, but their overall energy balance differs significantly. According to Le Bau, the SIA 380/1 standard now explicitly includes the embodied energy of materials in the thermal calculation of buildings. The MoPEC 2025 reinforces this requirement by prohibiting fossil heating in new constructions.
In practical terms, this means that a new construction project must anticipate from the sketch stage the type of load-bearing structure and its carbon impact. Designing the house with SIA Architecture allows for the integration of these regulatory constraints from the design phase, before choices become irreversible.
Wood framing, for example, stores carbon instead of emitting it during its manufacture. Low-carbon concrete reduces the footprint but remains more energy-intensive than a bio-sourced solution. The structural choice is made before the building permit, not after.
Mandatory photovoltaics during a roof renovation: what MoPEC 2025 stipulates
Building your dream house does not always involve new construction. Many projects start from an existing building, with a heavy renovation that completely transforms the living space.
The MoPEC 2025 introduces a constraint that few future homeowners anticipate: replacing a roof covering or waterproofing can trigger a photovoltaic production obligation. The application timeline varies by canton, with a gradual implementation until 2030 according to Le Bau.
For a renovation project, this rule changes the financial equation. The roofing budget is no longer limited to tiles and insulation: it must include the installation of solar panels, connection to the grid, and potentially a storage system. An architect familiar with these obligations can guide the project from the outset so that the roof is designed to integrate photovoltaics, rather than as a late addition that complicates the structure.
Anticipating the cantonal timeline
Each canton sets its own deadlines. A project launched in a canton that already applies the rule in 2026 does not have the same margins as a project located in a canton that postpones it to 2029. Checking the cantonal timeline before submitting the permit avoids unpleasant surprises during construction.
Impulse Program 2025: the aids that change a construction budget
The Building Program has been supplemented by a new Impulse Program, launched on January 1, 2025, according to the Federal Council. This initiative specifically targets the replacement of decentralized electric heating and large fossil boilers.
Why is this relevant for new construction? Because these aids influence the choice of heating system. An air-water heat pump, a district heating network, or a geothermal system do not have the same installation costs. The available subsidies can tip the balance in favor of a more efficient but more expensive solution to purchase.
- The replacement of a fossil boiler with a heat pump has received enhanced financial support since 2025, reducing the payback period to a few years.
- Decentralized electric heating (storage heaters, convectors) is targeted by the program: their replacement entitles homeowners to specific aids.
- Cantons have allocated larger budgets in 2025 for energy renovation, according to data from the Confederation, which expands the number of eligible projects.
Combining federal and cantonal aids can significantly reduce the cost of the energy system of a new or renovated house. The classic pitfall: submitting the permit without checking eligibility for subsidies, only to discover that another system would have been subsidized.
Architect and house builder: how to divide the roles
The confusion between architect and individual house builder remains common. Both are involved in the same project, but not with the same responsibilities or interests.
The architect designs the building based on the land, the program (number of rooms, uses, budget), and regulatory constraints. They coordinate technical study offices (structure, fluids, thermal) and oversee the construction site to ensure that the execution complies with the plans.
The builder, on the other hand, carries out the work according to a contract that is often fixed-price. Their business model relies on standardization: adapted standard plans, materials negotiated in bulk, optimized timelines.
When the architect makes a difference
On a sloping site, a narrow plot, or a project with future expansion, the architect adapts the project to the site rather than the other way around. A builder will often propose an adjusted catalog model, which may work on a flat and regular plot but generates significant additional costs as soon as the plot deviates from the norm.
The other concrete advantage: the architect has no commercial ties with construction companies. They can put artisans in competition for each lot (masonry, framing, electricity), giving the project owner real visibility on prices.
A custom construction project is not just about designing a beautiful facade. The decisions that matter, those that set the budget, thermal comfort, and the property’s heritage value, are made in the first few weeks. This is when the choice of a competent architectural interlocutor weighs the most heavily.
