Throughout my 25 plus years in the window covering industry, I have always been amazed at the poor performance of treatments designed without considering function before form. This misdirection on intent has led to increased stress on the window covering itself, showing up in the constant need for repairs not to mention the added stress on the user and the space it is intended for.
While researching the sustainability of window coverings, I came upon this statement on sustainability from the AIA website. “Sustainable design is a collaborative process that involves thinking ecologically—studying systems, relationships, and interactions—in order to design in ways that remove rather than contribute stress from systems.”
To remove rather than to contribute stress from systems. This is exactly my point when it comes to designing and specifying window coverings for commercial applications. Of course this may not be the case in residential design, where design may trump function such as an installation over inward opening French Doors where the treatment interferes with the doors opening and the client approves this loss of function.
There are many examples in commercial design where good function must dictate design. You can see it in hospitality installations where the draperies barely last a few months before the guests damage the draperies. In restaurants, where the design interferes with the work flow of the staff. Also, in offices where poor choices in solar shade fabrics and control systems, impinge upon worker productivity.
To address this concern of reducing stress in window covering design, let me begin with the US Green Building Council’s LEED points achieved with window coverings. There are five main areas where a building can earn LEED points with thought out design with window coverings, that can also reduce stress from building systems. These are Daylighting, Light Pollution Reduction, Energy Reduction, Recycled Content and Indoor Environmental Quality.
Daylighting
The quote from the USGBC on Daylighting states the following: “Glare control is perhaps the most common failure in daylighting strategies. Large windows provide generous amounts of daylight. If not controlled, properly, this daylight can produce unwanted glare and affect interior lighting quality. Measures to control glare include light shelves, louvers, blinds, fins, and shades… Glare control is required for each window.”
Glare control is required for each window. This can be achieved by selecting solar shading fabrics that effectively reduce glare and the stress it adds to the occupants. I will explain which fabrics have a higher performance in glare reduction in the section on fabrics.
Light Pollution Reduction
Another quote for the USGBC says, “All exterior openings, such as windows, must have shielding that can be automatically controlled and programmed to close from 11:00 p.m. to 5:00 a.m.” This means that in order to achieve points on Light Pollution Reduction, the window coverings must be motorized and timed. This topic of motorization and controls will be discussed later.
Energy Reduction
I consider Energy Reduction the biggest contributor to reducing stress from building systems through the strategic use of window coverings. Energy reduction through solar shading and window coverings may be quantified in two primary categories; reduction of solar energy entering a space and thereby reducing the amount energy used for cooling and reduction of thermal energy leaving the space and thereby reducing the energy required for heating.
These stress reducing strategies are achieved by designing window covering systems that reduce the unwanted energy entering a space and keeping the necessary energy from leaking from the space.
Recycled Content
Recycled content can be defined as materials used in the production of products that have been directed from the waste stream. Usually these materials are associated into two categories, pre-consumer and post-consumer. Pre-consumer recyclable materials are items directed from the waste stream during the manufacturing process. These materials do not include rework items or materials that would have gone back into the standard work flow, but rather materials which would have been strictly wasted. Post consumer recycled materials are those generated by households, institutions or commercial facilities, which can no longer be used for their intended purpose.
GreenScreen Revive is a solar shade fabric made from post-consumer plastics such as water bottles.
Indoor Environmental Quality
Indoor environmental contaminants can originate within the building or be drawn in from outdoors. IEQ problems are often caused by ventilation system deficiencies, overcrowding, off gassing from materials in the office and mechanical equipment, tobacco smoke, microbiological contamination, and outside air pollutants. Today’s solar shade fabrics offer VOC products that pass the GreenGuard® Air Quality Certified® and GreenGuard® for Children and Schools SM standards. All GreenGuard Certified Products have been tested for their chemical emissions performance including for formaldehyde, volatile organic chemicals (VOCs), respirable particles, ozone, carbon monoxide, nitrogen oxide, and carbon dioxide.
Fabrics
Let’s zoom in on the product specific areas where we can reduce stress from window coverings. In commercial applications, solar shades are the most widely used covering on windows. Solar shades are typically chosen because of the fabrics ability to reduce heat in the space, reduce glare and provide the occupant visibility through the fabric.
How do you select a fabric that provides the desired visibility. While I think this is the least important consideration when choosing solar shade fabric, there is one basic rule of thumb to know: the darker the color of the fabric, the better the visibility. Below is a series of photos that compare a light color fabric alongside a dark color fabric with four different openness.
As for reducing heat gain in a space, color and openness are the key components to reducing these stress points. It is obvious that lighter colors are more effective at reflecting then darker colors are. Openness refers to the percentage of the fabric that is open. When selecting a openness percentage such as 1, 3, 5 or 10%, the orientation of the windows usually is the main concern. As an example, south and west facing windows typically needs 3 or 5% openness to filter the sun. So if heat is causing stress upon the HVAC system, choosing lighter colors and more closed weaves would be the correct choices.
Another important high stress issue that fabrics can address is the problem of glare control. Daylighting strategies as mentioned in the LEED opportunities can cause glare issues for the occupants of the space. Darker colors provide better glare control properties then lighter colors do.
Controls
The last area that I would like to discuss is that of controls. Controls are the backbone to any successful solar shading system. This can also be the area where the most stress is experienced. Through a lack of understanding the controls are often specified either incorrectly or with critical information missing causing the contractor and subcontractors to provide estimates that lack what may be needed to complete the project.
Architect’s need to work with a qualified solar shade expert who can provide vital and complete system design, so motorized shading systems are specified correctly and consequently estimated accurately by the subs.