Exterior Sun Control Devices: Daylight and shading devices are a design strategy

by Jonathan McGaha | March 31, 2013 12:00 am

With today’s emphasis on building synergy architects have had to design buildings with form and function in mind. LEED and green building is focused on building these synergies identified as whole building design/integration. Within whole building design an architect must identify strategies and products that will support the function of a building and will enhance the occupant’s experience. Energy reduction, thermal comfort and the connection to outdoor spaces have been identified as being major contributors to increasing both building function and the occupant experience. Addressing these three factors often leads to energy savings and longer tenancy for building owners/managers, and productivity for business owners. Including these factors in the building design will also help a building earn LEED points. Exterior sun control devices/sunshades are a design strategy used to increase synergies created in the whole building design process.

 

When designed properly, sunshades will help eliminate the transmittance of light and heat into the building during peak sunlight hours. The sunshade also acts as a reflective barrier for the building. This helps reduce absorption of heat by the building, thus reducing the heat island effect. ASHRAE 90.1 addresses this concern by quantifying the reduction in the solar heat gain coefficient (SHGC) when using an exterior sun control device. Green building codes are also starting to address the importance of shading by including minimum projection factors over fenestrations as part of the building design for western and southern facing elevations.

 

Often times there is some sort of compromise between shading and day lighting where, as on a sunny day the window blinds may need to be closed to prevent glare and unwanted heat gain but completely cut out any day light from entering the building and eliminate any views to outdoor spaces. A sunshade that cantilevers out over the window will reduce direct sunlight from entering the building while allowing day light to still enter the building. Without the physical barrier of Venetian blinds or roller shades occupants will also have access to outdoor views.

 

From a building owner’s perspective the use of shading and day lighting has some financial rewards. Heating and cooling are typically the largest energy users in any building, thus the largest costs associated with operating a building. By decreasing the amount of sunlight that directly enters the building we can reduce the energy required to cool the building. And by increasing the amount of natural light that enters the building we are able to reduce artificial lighting costs, which directly affects cooling costs as artificial lighting is one of the primary contributors to heat in a building.

 

When deciding to use an exterior sun control device several factors should be taken into consideration. These include but are not limited to geographic location, building orientation and building use. Sunshades can be integrated into the building in a variety of methods. Sunshades should be installed to a structural component of the building whether it is curtain wall, CMU, or steel framing. The manufacturer should specify the material thickness and fasteners types to be used for installation. Structural engineering calculations are also highly recommended to ensure that the sunshade can withstand wind, snow, and ice loads. Most sunshades cantilever above a window however they can also be installed directly in front of the window as a vertical shade or to the side of the window as a fin.

 

Extruded aluminum is the material of choice for sunshade manufacturers due to the variety of standard and custom shapes available, weight, machinability and its resistance to the elements. Most commonly, sunshades are fabricated by the use of stainless steel mechanical fasteners. This allows for clean lines and strength. Welding is no longer recommended due to the fact that welding can reduce the strength of aluminum. Common finishes available include Kynar PVDF, anodic and powder coat. These finishes are often times provided with a one- to 20-year warranty.

 

Exterior sun control devices are able to serve up some fairly significant savings for the building owner, and when used in conjunction with efficient glass the savings are multiplied. While most sunshade manufacturers offer a standard line of products, many sunshades are customized to make the building both aesthetically pleasing and functional encompassing the whole building design.

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Brett Reinhardt is the marketing manager for Delano, Minn.-based Industrial Louvers Inc., a family-owned and
-operated business in which he is third generation. His primary responsibilities include developing and maintaining sales and marketing tools, technologies and strategies. He also manages the drafting/design and engineering departments for ILI. To learn more, visit www.industriallouvers.com[1].

Source URL: https://www.metalarchitecture.com/articles/exterior-sun-control-devices/

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