South-Facing Veranda: Avoid Overheating Without Losing Light (2026)

Why Does a South-Facing Veranda Overheat?

A south-facing veranda is a major asset: it provides exceptional brightness and a sense of space. However, in summer, it can become a tropical greenhouse. Solar radiation passes through the glazing and converts light energy into heat (greenhouse effect). Without protection, indoor temperatures can exceed 40 °C, making the space uncomfortable and increasing air conditioning consumption.

The problem is amplified by the south orientation, which receives maximum sunlight during the hottest hours. If the veranda is attached to a living area, heat can spread throughout the house. It is crucial to implement effective solutions to avoid overheating while preserving natural light.

Choosing the Right Glazing: The First Barrier

Glazing plays a decisive role in thermal regulation. For a south-facing exposure, it is recommended to use solar control glazing with a solar factor (g-value) below 0.30. This factor indicates the proportion of solar energy that passes through the glazing. The lower it is, the less heat enters.

Modern glazing can combine low emissivity (to retain heat in winter) and solar control (to limit overheating in summer). There are also electrochromic or photochromic glazing that changes tint based on light intensity, but they are more expensive.

Regarding financial aid, the Klimabonus Wunnen 2026 program (in effect since January 2022, replacing the old PRIMe House) offers a subsidy of 70 EUR per m² of replaced glazing for energy renovation. This aid can be combined with the reduced VAT rate of 3% for homes older than 2 years.

External Solar Protections: Essential

The best way to avoid overheating is to block sunlight before it reaches the glazing. External solar protections are by far the most effective. They include:

• Adjustable slat blinds: allow modulation of light while blocking heat.
• Bioclimatic pergolas: their adjustable slats can be closed in summer to create shade, while letting light through in winter.
• Roller shutters or hinged shutters: very effective, but they completely block light.

These protections are particularly effective if installed outside, as they prevent solar energy from entering the veranda. In contrast, internal blinds (curtains, Venetian blinds) only reflect part of the heat, which remains trapped between the glazing and the blind.

Natural Ventilation: A Free Ally

Good ventilation is essential to evacuate hot air accumulated in the veranda. Several strategies can be implemented:

• High-level openings: hot air rises, so provide windows or transoms at the top of walls or roof to let hot air escape.
• Cross ventilation: opening opposite windows creates an air current that naturally cools the space.
• Mechanical ventilation (MVHR): a double-flow ventilation system with bypass can be integrated to renew air without losing heat in winter.

It is also possible to install a Canadian well (or Provençal well) that uses ground temperature to cool incoming air in summer and warm it in winter. This is an ecological and economical long-term solution.

Vegetation and Outdoor Layout

Nature offers elegant solutions to combat overheating. Planting deciduous trees in front of the veranda provides shade in summer while allowing sunlight in winter when leaves have fallen. A vegetated pergola with climbing plants (vines, wisteria) creates natural and aesthetic shading.

Additionally, a canopy or roof overhang properly dimensioned can protect the veranda from summer sun while allowing light in winter. The sun's angle varies by season: in summer it is higher, so a roof overhang of about 60 cm may suffice.

Complementary Technical Solutions

For periods of intense heat, technical solutions can complement the above:

• Mechanical ventilation with extraction: air extractors can be installed to force hot air out.
• Reversible air conditioning: as a last resort, an air-source heat pump can cool the veranda, but it consumes energy and should be considered as a backup.
• Adjustable sun breakers: adjustable slats can be integrated into the roof to modulate sunlight.

It is important to note that Luxembourg regulations require respect for privacy (CNPD) when installing solar protections that could affect neighbors. Check with your commune for any planning permissions.

Financial Aid in Luxembourg

Since January 2022, the Klimabonus Wunnen program replaces the old PRIMe House. It is managed by the Klima-Agence and offers subsidies for energy renovation works, including those related to a veranda. Main aids are:

Additionally, VAT is reduced to 3% for renovation works in homes older than 2 years. To benefit from these aids, certain conditions must be met and a request must be submitted before starting work. Procedures are done online via the Klima-Agence website or the guichet.lu portal.

Designing a Bioclimatic Veranda

To avoid overheating without losing light, it is essential to adopt a bioclimatic approach. This means the veranda design must consider orientation, climate, and solar gains. Here are some principles:

• Orientation: a south-facing veranda is ideal in winter, but effective solar protections must be planned for summer.
• Thermal inertia: walls or floors made of heavy materials (stone, concrete) can store night coolness and release it during the day.
• Double skin: a veranda with double glazing and a ventilated air gap can reduce heat transmission.

Finally, it is recommended to hire a qualified professional to design and install your veranda. A thermal engineering office can perform simulations to size protections and glazing. Local artisans know the specifics of Luxembourg's climate and available aids.

Example Project

Consider a house in Luxembourg with an existing 20 m² veranda facing south. The owner wants to replace the glazing and install external blinds. Estimated cost is 12,000 EUR. Thanks to Klimabonus, he can receive 70 EUR/m² for glazing (if 15 m² of glazing is replaced, that's 1,050 EUR). Additionally, the 3% VAT reduces the total cost by about 2,000 EUR. Thus, the remaining cost is about 8,950 EUR, making the project more affordable.

Note that aids are subject to conditions and invoices and justifications must be provided. It is advisable to contact Klima-Agence before starting work.