Brise soleil, French for "sun breaker", is external solar shading: fixed or adjustable aluminium blades, fins or louvres mounted outside the glazing that stop high sun before it reaches the glass, cutting heat gain and glare while keeping daylight and views. Overheating is now a primary design driver on commercial buildings. Uncontrolled solar gain through large glazed façades is a major cause of overheating in offices, schools and healthcare buildings, and adding mechanical cooling is increasingly hard to justify on carbon and running cost. External aluminium brise soleil and louvres are one of the most effective tools designers have for controlling solar gain without losing daylight or views.
How brise soleil works
External solar shading is more effective than internal blinds because it intercepts solar radiation before it reaches the glazing. Once solar energy has passed through the glass and turned into heat inside the building, it is difficult and energy-intensive to remove. An external blade at the right angle can block direct sun while admitting diffuse daylight — maintaining visual comfort without the glare that drives occupants to close internal blinds.
Types of brise soleil and solar shading
- Fixed horizontal brise soleil blades — the most cost-effective option; sized and angled to block high summer sun while admitting low winter sun; best on south-facing elevations
- Fixed vertical fins — effective on east and west elevations where the sun is low; they also provide privacy screening
- Motorised louvres — adjust their angle to the sun's position or occupant preference; the highest level of control, with more maintenance and capital cost
- Perforated metal screens — fixed screens that filter rather than block sunlight, giving privacy and strong architectural character
- Bespoke fins — cantilevered aluminium fins at varying angles and spacings, common on public and cultural buildings where architectural expression matters
| Elevation | Summer sun | Usual shading |
|---|---|---|
| South | High around midday | Horizontal blades or a projecting shelf of blades, which cut off the high summer sun and let the lower winter sun in |
| East | Low in the morning, from the side and almost straight at the glass | Vertical blades or fins, often angled to the façade, or adjustable louvres |
| West | Low in the late afternoon and evening, from the side and almost straight at the glass | Vertical blades or fins, often angled, or adjustable louvres; west glazing gets its sun in the warmest part of the day |
| North | Little direct sun, only early morning and late evening around midsummer | Usually none needed to control solar gain; fins may still be used for the look of the façade |
Brise soleil vs louvres: what is the difference?
The terms overlap. Brise soleil is external shading whose job is to keep the sun off the glass, whether it is a shelf of horizontal blades, a row of vertical fins or a screen. Louvres are rows of angled blades held in a frame, and many brise soleil systems use louvre blades, but louvres are also used to ventilate plant rooms and car parks and to screen rooftop plant, where shading is not the aim. A ventilation louvre is chosen for free area and rain defence rather than sun angles; our aluminium louvres guide explains the types, free area and rain defence, and our architectural louvres page shows the louvre systems we install.
Advantages of brise soleil
- Less solar heat gain, so smaller cooling loads and lower running costs
- Less glare, so occupants keep blinds open and use daylight instead of lights
- Views and daylight kept, unlike solid shading or heavily tinted glass
- A passive measure with no running cost when fixed, which helps with Part L, Part O on residential schemes and BREEAM
- Strong architectural character, with horizontal or vertical lines that give the façade depth
Fixed vs adjustable brise soleil: pros and cons
| Type | Pros | Cons | Best suited to |
|---|---|---|---|
| Fixed | No moving parts or controls; the lowest cost and maintenance, and no running cost | Set at one angle chosen for the elevation, so it cannot respond to dull days or the changing sun | Most commercial façades, especially south elevations |
| Manually adjustable | Occupants change the blade angle with a handle or winding gear; a simple mechanism | Only works if people use it; practical mainly at low level and on terraces | Terraces, balconies and low-rise buildings |
| Motorised | Blades rotate to track the sun or close in bad weather, often controlled by the building management system; the most control of glare and daylight | Higher capital cost, actuators, wiring and controls to coordinate with the façade, and ongoing maintenance | East and west elevations and spaces where the sun angle changes through the day |
| Sliding | Panels of blades slide along a track, so the shading can be moved clear of the view | Tracks and running gear need maintenance | Balconies and windows on residential façades |
Fixed shading is the default because it is passive and needs nothing from the occupants. Adjustable or motorised blades earn their extra cost where a fixed angle would either let in too much low sun or keep out too much daylight for much of the year, which is most often the case on east and west elevations. Our brise soleil blades are available fixed or adjustable.
What affects the cost of brise soleil
- Fixed or motorised: motorised blades add actuators, controls and maintenance
- Blade size and profile: deep, long-span or bespoke extrusions cost more than standard blades
- Support structure: arms, brackets and any secondary steel, and how they fix back through the façade
- Finish: powder coating, anodising or special colours and effects
- Access and installation height, including scaffold or mobile platforms
- The amount of repetition across the elevations
Overheating rules: Part O, Part L, CIBSE TM52 and BREEAM
In England, Approved Document O (Overheating), in force since June 2022, applies to new residential buildings — dwellings, institutions such as care homes, and buildings with rooms for residential purposes such as student accommodation. It does not apply to offices, shops or other non-domestic buildings. For residential schemes, compliance is shown by the simplified method or by dynamic thermal modelling to CIBSE TM59, and external shading is one of the main ways to pass.
On non-domestic buildings, solar gain feeds directly into the Part L energy calculation, and where thermal comfort is a design target, dynamic modelling to CIBSE TM52 (The Limits of Thermal Comfort) is the usual method; school projects typically use BB101. Shading must be modelled accurately — blade geometry, spacing, reflectance and any motorised control strategy all change the predicted performance.
BREEAM can award credits under Hea 04 (Thermal comfort) and Ene 01 (Reduction of energy use and carbon emissions) where external shading forms part of a passive design strategy, which can help office projects towards Excellent or Outstanding ratings.
Brise soleil on houses and residential schemes
Brise soleil is not only a commercial product. Domestic brise soleil is usually a fixed aluminium canopy of blades over large south or west-facing bifold or sliding doors, or over a terrace, powder-coated to match the window and door frames and bracketed back to the wall or the structure above the opening. On new homes, blocks of flats, student accommodation and care homes, Part O makes overheating a design requirement and external shading is one of the main ways to meet it. Part O does not apply to extensions to existing homes, but the same rules of orientation still decide whether shading is worth adding. Our aluminium brise soleil page covers residential as well as commercial systems.
How to specify brise soleil
- Commission solar shading analysis at RIBA Stage 2 — blade geometry should come from the building services engineer's analysis of orientation and latitude
- In London (about 51.5°N) the midday sun is roughly 62° above the horizon at midsummer and about 15° at midwinter, which is why horizontal blades on a south elevation can block summer sun while letting winter sun in; blade depth, pitch and spacing should come from the analysis
- Specify aluminium alloy 6063-T6 or 6005A-T6 for extruded blades — a good strength-to-weight ratio and excellent powder-coat adhesion
- Coordinate fixing loads with the structural engineer — brise soleil transfers significant wind and gravity loads into the façade or structure
- Allow for thermal movement — aluminium expands by about 0.023 mm per metre per °C, so a 6 m blade moves around 8 mm across a 60 °C range of surface temperature
On our Hammersmith project in West London, brise soleil formed part of the glazing package for a commercial development, alongside aluminium bifold doors.
Brise soleil and the fire rules for external walls
In England, Regulation 7(2) of the Building Regulations requires materials in the external walls of relevant buildings, broadly those with a storey at least 18 m above ground that contain flats or certain other residential uses, to achieve class A2-s1,d0 or A1. Solar shading devices attached more than 4.5 m above ground count as specified attachments under the regulation, so the parts whose job is to provide shade, such as the blades or slats, must meet the same classification; other associated components are exempt. Aluminium blades are well suited to this, but the classification should be confirmed against the fire strategy.
Frequently asked questions
What is brise soleil?
Brise soleil is external solar shading — usually aluminium blades or fins fixed outside the glazing — that blocks high summer sun to reduce overheating and glare while keeping daylight and views.
What are the types of brise soleil?
The main types are fixed horizontal blades, fixed vertical fins, adjustable or motorised louvres, perforated metal screens and bespoke architectural fins. Horizontal blades suit south elevations; vertical fins and adjustable louvres suit east and west.
What are the advantages of brise soleil?
Brise soleil cuts solar heat gain and glare before the sun reaches the glass, which reduces cooling loads and keeps daylight and views. Fixed systems have no running cost and help with Part L, Part O on residential schemes and BREEAM.
What affects the cost of brise soleil?
The main cost drivers are fixed or motorised operation, blade size and profile, the support arms and secondary steel, the finish, access and installation height, and how much the design repeats across the elevations.
Do fire rules apply to brise soleil?
Yes, on relevant buildings in England, broadly those with a storey at least 18 m above ground containing flats or certain other residential uses. Under Regulation 7(2), the shading parts of a solar shading device attached more than 4.5 m above ground, such as the blades, must be classed A2-s1,d0 or A1.
Does Part O apply to commercial buildings?
No. Approved Document O applies to new residential buildings in England, including dwellings, care homes and student accommodation. Overheating in offices and other non-domestic buildings is usually assessed with CIBSE TM52, alongside the Part L energy calculation.
What are the pros and cons of fixed vs adjustable brise soleil?
Fixed brise soleil has no moving parts, controls or running cost and is the cheapest to buy and maintain, but its angle is a compromise set for the elevation. Adjustable or motorised blades can follow the sun and let more daylight in on dull days, at a higher capital and maintenance cost, so they are mostly used on east and west elevations.
What is the difference between brise soleil and louvres?
Brise soleil is external shading designed to keep the sun off the glass. Louvres are rows of angled blades in a frame; many brise soleil systems use louvre blades, but louvres are also used to ventilate plant rooms and screen plant, where shading is not the aim.
Can brise soleil be used on houses?
Yes. Domestic brise soleil is usually a fixed aluminium canopy of blades over large south or west-facing doors or a terrace. On new homes Part O sets the overheating standard and external shading is one of the main ways to meet it.
Which façades need solar shading most?
South-facing façades suit horizontal blades because the summer sun is high. East and west façades get low-angle morning and evening sun, which vertical fins or adjustable louvres handle better.