Louvred pergolas have become an increasingly popular shading system in recent years. They have a modern look, provide shade, allow air circulation, and form a structure that protects against rain when the louvres are closed.
However, there is an important difference between a lightweight louvred pergola (a cheap, manually operated bioclimatic) and a properly engineered bioclimatic system. This difference is hard to tell from product descriptions and photos alone.
If you're considering buying a cheap, manually operated louvred pergola from a building supplies store, a website, or a local supplier, this guide has been written to help you understand what you're actually buying.
A louvred pergola is a shading structure made of rotating horizontal aluminium blades, commonly called louvres. Depending on the system, the louvres can be moved manually with a handle or mechanically with a motor/actuator. By changing the angle of the louvres, you can adjust the amount of sunlight and airflow entering the space, and protect against outside elements such as rain and wind.
When the louvres are open, air and sunlight can pass through freely. When they're partially closed, you can create shade while still allowing ventilation. When fully closed, they form a fully sealed roof that protects against rain and wind. This opening-and-closing movement is fundamentally the same as in bioclimatic systems. So what's the difference between these systems?
No, definitely not.
This is one of the biggest misunderstandings in the pergola market.
Louvred pergolas are essentially a cheaper version of the bioclimatic system concept, made to fit any budget. However, even though two products can look almost identical and move their louvres on the same principle, they are different products.
A lightweight louvred sunshade (a cheap, manually operated bioclimatic) is typically designed for purposes such as protection from sun and rain, use as a pergola cover in a residential garden, seasonal use, and low-cost installation. A bioclimatic system, on the other hand, is designed around factors such as structural loads, wind resistance, snow loads, large spans, permanent installation, motorised operation, long-term outdoor use, and optional side enclosure systems. Wind and snow load capacity are among the most fundamental distinctions between these systems.
This is also one of the fundamental differences between the two systems.
A lightweight shading system is a perfectly good product for what it was designed to do. But that doesn't automatically make it suitable for creating an enclosed living space.
Once you buy a lightweight, manually operated bioclimatic and add systems such as sliding glass, guillotine glass, or windows to it, the system moves well beyond the purpose it was manufactured for.
Adding glass doesn't add extra weight to the structure, but the wind acting on enclosed side panels starts to behave very differently from wind acting on a system with open sides. The idea of turning this system into a room by enclosing its sides can expose the structure to loads it was never designed for.
This is especially important in regions that get snowfall. It should be kept in mind that louvred pergolas are essentially designed as a sunshade. In heavy snowfall, if the louvres are left closed, snow can build up on them, and if the snow load exceeds the value the system was designed to carry, this can deform the frame, bend the louvres, and damage the mechanisms or anchoring, and in some cases the system can even collapse. This is why snow-load capacity should always be checked before buying a pergola in a snowy climate.
"Aluminium is strong" is a claim that shouldn't simply be accepted. Yes, aluminium systems are strong, but being made of aluminium doesn't automatically mean a system's structural integrity is equally strong.
Besides snow load, another important difference is insulation. The louvres used in bioclimatic systems are wider and taller than those used in louvred pergolas. Bioclimatic systems also have EPS (polystyrene foam) or PU (polyurethane) filling inside the louvres to improve insulation. If you're considering buying a louvred pergola to use in winter as well, you need to accept the heating costs that will arise in winter, and the fact that you'll have a room that still won't warm up despite those costs.
Especially people living in hot climates want to buy a louvred pergola, enclose it with glass systems, and create a cool shaded spot in their garden. But in this situation too, the bioclimatic system comes out ahead of the louvred pergola. On a hot summer day, a louvred pergola with thin louvres and no insulating fill essentially turns into an oven, so to speak, once its sides are enclosed. People who buy this system specifically because it's cheap also tend to buy single-glazed or standard double-glazed glass systems, again because they're cheaper. This causes the incoming sunlight to act like a magnifying lens once it reaches the glass, making the light more intense, and causes the space to behave like a greenhouse.
Given these reasons, if your home is in a hot climate, you need to build such a room using an insulated roof system and glass such as solar low-E glass that cuts the sun's intense effect.
Bioclimatic systems use a significant amount of aluminium. Aluminium is also a commodity that is continuously bought and sold on metal exchanges. Its price per kilogram changes by the second depending on exchange movements. This is exactly why manual bioclimatics, in other words louvred pergolas, came about. They're manufactured on the logic that the less you use of a material whose price constantly fluctuates and changes instantly, the lower the price.
For example, depending on the design, a bioclimatic system can use 4 times more aluminium per square metre than a lightweight, garden-type manually operated bioclimatic. This figure is not an exact value. The amount of aluminium used changes according to width and opening dimensions. On top of this, factors such as the foam fill used inside the louvres, motor options, and movement types make the bioclimatic system more expensive than the louvred pergola. But the principle is simple. More material means a higher price. A cheap system is cheap because it's designed for a different purpose.
This is one of the important points. If your goal is a stylish, attractive system that you can enclose with a curtain or a lightweight system, spend time in your garden with a small heater on days that aren't too cold, stay cool on sunny, hot days, get ventilation, and get strong protection from rain and sun, then a louvred pergola is a very suitable option for you. In that case, paying for a heavy-duty structure designed for high snow loads, large spans, and year-round enclosed use is an unnecessary expense.
With these systems, the problem is buying a sunshade and expecting it to perform like an insulated room.
Do I just want a sunshade? If yes, a lightweight, manually operated bioclimatic / louvred pergola is an excellent choice.
Do I want a year-round outdoor room? In that case, what you need to look for is a properly engineered bioclimatic roof system along with suitable side enclosure systems.