What are the considerations when designing a solar shading system?


The movement toward sustainable building designs is being driven largely by environmentally-sensitive building owners and/or their prospective tenants. As these owners and their consultants weigh their design objectives and alternatives, they often find that exterior sun controls are an ideal part of the "green" solution for their buildings.

Exterior sun controls can dramatically reduce the air conditioning loads caused by the sun’s radiation penetrating the building’s windows. Indeed, some form of exterior sun controls is now part of the prescriptive design requirements in the new Standard for the Design of High Performance Green Buildings, (ANSI, ASHRAE, USGBC, IES 189.1). In addition to energy savings through reduced cooling loads, exterior solar shading products can enhance a building’s appearance, as well as provide filtered day lighting and reduced glare.

An exterior solar shading system blocks a certain amount of the solar radiation from entering the building. It is ideally designed to maximize natural daylight while controlling solar heat gain and glare. We offer a wide range of solar shading products from static aluminum through to fully automated photovoltaic cells.

Solar geometry

The sun rises in the East and sets in the West. The sun travels in an arc, reaching its highest altitude in the South (for the Northern hemisphere).

Solar Geometry

Orange Line - Solar Altitude for 21st December

Yellow Line - Solar Altitude for 21st September

Red Line - Solar Altitude for 21st June

An important requirement of the design process is to ensure the building is shaded from the sun for as many hours as possible throughout the whole day, during the course of the entire year, especially with the need to meet LEED requirements. However a balance must be achieved in order to ensure that the level of natural light entering the building is not unacceptably reduced.

East or west facing facade

With a predominantly East or West facing facade, a fixed system will not perform well throughout the entire day as the altitude of the sun is much lower. Sunlight will pass directly under most horizontal shading systems as shown in the illustration below.

East or West Facing Facades

To overcome this problem, effective solar shading can be achieved using a movable solar shading system such as Colt Solarfin.

Controllable fins, unlike fixed, can hang vertically in front of a window and still optimise solar shading and visibility thanks to specially written computer software which controls the louvers to follow the path of the sun.

Controllable solar shading systems enable the building to react to the changes in the weather and to the sun's position so as to optimize the flows of heat and light energy through the facade. This in turn has a positive effect on reducing the heat load and glare, and enhancing the use of natural daylight, thereby reducing the operating costs of the building.

Controllable VSA

Controllable solar shading systems reduce the likelihood of over-shading or under-shading and will result in optimum shading angle at all times.

Optimum shading angle

South facing facade

For a predominately South facing facade, effective solar shading can be achieved using a fixed horizontal solar shading system such as the Colt Solar C Shading System.

South Facing Facades

In the mornings and during the winter, such a device cannot stop direct rays of the sun from penetrating the building since the sun is much lower on the horizon. However, the heat gain and solar glare is greatly reduced during the summer months and therefore this may not considered to be a major problem.

Function and form

Colt offer a wide range of fixed and moveable solar shading systems, using solid or perforated aluminum, glass, PV, fabric, translucent acrylic and terracotta. For more detailed information please see our product pages.

Custom solutions

Find out about Colt's capability to develop specialized solutions. Read more.

Colt Projects

Read about our projects in North America and around the world.

Next steps

Contact us. We have considerable experience in the design and supply of solar shading systems. 

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