Introduction to Solar Shading
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, except for Low-rise Residential Buildings (ANSI, ASHRAE’s, USGBC, IES 189.1). In addition to energy savings through reduced cooling loads exterior sun controls can enhance a building’s appearance, as well as provide filtered day lighting and reduced glare.
An exterior sun control is a shading system that blocks a certain amount of the solar radiation from entering the building. They are ideally designed to maximize natural daylight while controlling solar heat gain and glare. We offer an extraordinary range of sun control products from static aluminum, to fully automated photovoltaics.
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).
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.
South Facing Façades
For a predominately South facing façade, a small amount of solar shading can be achieved using a fixed horizontal brise soleil.
In the mornings and winter such a device cannot stop direct rays of the sun penetrating the building since the sun is much lower. However the heat gain and solar glare is greatly reduced in winter and therefore this may not considered to be a major problem.
East or West Facing Façades
With a predominantly East or West facing façade, a fixed system will not perform well throughout the whole 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.
To overcome this problem, effective solar shading can be achieved using a movable solar shading system.
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 optimise the flows of heat and light energy through the façade. This in turn may have 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.
This reduces the likelihood of overshading or undershading and will result in the optimum shading angle at all times.
Form and Function
Colt offer a wide range of fixed and moveable sun shade systems, using solid or perforated aluminum, glass, PV, fabric, translucent acrylic and terracotta. For more detailed information please see our product pages.
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