Replacing windows or installing new doors does not fall under the same regulatory framework depending on whether the building is new or existing. The RE2020, which governs new constructions and certain extensions, imposes thermal performance and carbon footprint thresholds in successive tiers. In renovation, it is the thermal regulation for existing buildings that applies.
This distinction determines the relevant materials, available aids, and the performance level to aim for.
Summer comfort and joinery: a criterion that glazing alone does not resolve
Comparisons of joinery focus on winter insulation, measured by the Uw coefficient. A low value limits thermal losses when temperatures drop. However, since the implementation of RE2020, summer comfort weighs as much as winter insulation in the regulatory calculation for new buildings.
The mechanism is counterintuitive. A large south-facing bay window, performing well in winter due to a good solar factor (high Sw), also massively captures summer heat. Without external solar protection (shutters, sunshades, blinds), the indoor temperature rises beyond the comfort thresholds defined by discomfort degree-hours (DH).
In other words, a window that performs well in winter can degrade comfort in summer if the overall design (orientation, ventilation, solar protections) does not support the choice of glazing. This parameter primarily concerns new builds, but it deserves attention in renovations when enlarging glazed areas or modifying the orientation of openings.
Professionals like Menuiserie Deule support this reflection by integrating solar protections from the project’s design stage, rather than treating them as a secondary addition.
Carbon footprint of materials: wood, PVC, and aluminum facing RE2020 requirements
The choice between wood, PVC, and aluminum is no longer just a matter of taste or budget. The carbon requirements of RE2020, which are strengthened in tiers, introduce a measurable environmental dimension in the selection of joinery for new builds.
For a material to be considered in the regulatory carbon calculation, it must have verifiable environmental data. The Environmental and Health Declaration Sheets (FDES), registered in the INIES database, provide this data. A product without FDES is assigned a default penalizing value.
What this changes concretely for each material
- Wood benefits from a structural advantage: it stores biogenic carbon, improving its balance. However, it requires regular maintenance (stain, paint) whose cost over the product’s lifespan remains significant.
- PVC generally shows good thermal performance for a moderate purchase cost. Its carbon balance heavily depends on the composition and manufacturing process, which vary from one manufacturer to another.
- Aluminum, more energy-intensive to produce, is improving thanks to recycling channels and low-carbon profiles.
No material excels across all criteria simultaneously. Wood wins on carbon balance, PVC on insulation/price ratio, and aluminum on profile slimness and durability without maintenance. Field reports vary on the actual longevity of PVC in heavily sunlit exposures.
Renovation of joinery: order of work and financial aids
In renovation, a common pitfall is replacing windows before insulating walls. The result: new joinery installed on poorly insulated frames, with thermal bridges at the window sills reducing the actual gain.
Insulating the walls before changing the joinery optimizes the return on investment. The thickness of insulation applied to the sills modifies the dimensions of the opening. Reversing the sequence sometimes requires redoing the finishes or even reinstalling the frames.
Available aids for window replacement
Replacing single-glazed windows with double or triple glazing remains eligible for several schemes. The conditions particularly concern the Uw coefficient (thermal transmission) and the Sw coefficient (solar factor), with thresholds varying according to the type of aid.
The available data do not allow for a universal amount: the remaining costs depend on the type of housing, household income, and the number of openings involved. A detailed quote from a certified contractor remains the only way to obtain a reliable estimate.
Interior joinery: natural light and partitioning
Exterior joinery captures attention, but interior choices transform the perception of a space. An interior glass wall redistributes light without eliminating acoustic partitioning. This is a relevant solution when opening a load-bearing wall is not feasible or too costly.
The choice of material for the glass wall (steel, aluminum, wood) influences both the slimness of the frames, thus the usable glazed surface, and the overall style.
For interior doors, pocket doors (sliding into the wall) free up floor space but require sufficient wall thickness, which should be planned from the design phase.
The choice of joinery, both interior and exterior, benefits from being considered as a system rather than a succession of isolated products. Orientation, wall insulation, solar protections, ventilation, and materials form a whole whose coherence determines the final result, far beyond the technical sheet of a window taken individually.
