Vertical Brisesoleils

Horizontal Awnings

Intercepting the sun rays before they impact the glass curtain wall is a much more efficient way to prevent overheating. 

What kind of shields are possible ? Nature provides clouds 

and trees that, when placed between the building and the sun, prevent the solar radiation to reach the glass facade.

We can create equivalent "eclipses" putting man-made objects in a similar manner.

A horizontal surface can block the sun rays.

A horizontal panel -like a small roof- can be added next to a window and protect it from the sun rays that come from the front and above. 

If these rays came only from that exact direction, this would be a very effective solution.

But the horizontal panels will perform this task for only a very limited time, if the sun will keep declining, making them irrelevant.

The shadow cast by the horizontal panel may fully cover the window, and even more when the sun is very high, but it will cover a fraction of the window that keeps getting less and less as the sun goes down.

The sunshades in these pictures actually intercept the sun rays before they hit the window.

This image shows the shadow has become so small that very little of the window is protected from the sun rays.

Examples of this phenomenon can be seen everywhere, everyday.

At this time, this horizontal panel has no effect whatsoever in preventing the heat to reach the window. 

If horizontal panels do not perform any useful function, traditional vertical interior curtains and stores are deployed.

When the sun is somewhere else and does not represent a threat, solid horizontal panels obstruct the admission of natural light.

This is a time in which a dematerialized horizontal panel that obstructs less the admission of natural light is preferable.

Adding less weight to the building's facade is also better.

Even with this improvements, the benefits that horizontal panels facing the west can bring are considered not worthy, so they are rarely included in new projects. What is even worse, in many cases where the investment in them has already been done, horizontal panels in facades facing the west have ended being removed.