Specifying Shades in a Performance-Based Design
Designer Mieke Gerritzen said, “Design is where science and art break even.” Modern architecture highlights this notion, setting a new bar for innovation that emphasizes optimizing performance and aesthetics. Owner expectations are high and the impact of these considerations on the occupant is critical. For architects and designers, clearly defining design intent and specifyingappropriate,technologically-advancedbuilding products early in the process is crucialto the success of the project.
Building design often begins with the fenestration system, which includes the glazing and framing system, doors and entryway, curtain walls, skylights and more. Yet, another component of the fenestration, window treatments, tends to be an afterthought in the Architecture and Design (A&D) community.
A detailed understanding of innovations in solar shading, as well as how they can be used to enhance overall building performance and occupant comfort,is a valuable tool forany architect or designer. With this information, you can better recognize and convey the solutions’role in helping achieve the balance between science and art for a building, inside and out.
Performance-based design is about the occupant.
Architects in particular have a unique opportunity to demonstrate their commitment to innovation by selectingproducts that not only look beautiful, but also contribute to energy efficiency and occupant comfort. Don’t make the mistake of specifying fabrics based purely on room-side appearance without at least giving thought to performance-related factors such as shade color and Openness Factor (OF), or the percentage of holes in a solar shade:
- Shade fabric color plays a significantrole in building performance and occupant comfort. For example, light-colored shade fabrics typically reflect a higher percentage of solar energy and reduce interior heat gain better than dark-colored shade fabrics, creating a more comfortable space. However, light-colored fabrics allowhigher visible light transmission (Tv) values, which may add togreater visual discomfort and glare. Dark-colored shade fabrics more effectively manage glare and, consequently, create better views to the exterior.
- In addition to color, architects and designers can selectthe densityof a shade’s weaveto achieve optimal levels of daylighting, privacy, and view through. Openness factors of 1, 3, 5, and 10 percent progressively allow more daylight and enhance views to the exterior, which can be valuable based on client desires or occupant needs. Higher openness factors have been popular in many modern buildingsas architects strive to create people-centric designs that provide occupants with a connection to the outdoors. In fact, occupants with views of nature aresix to 12 percent more productive than occupants without such views[i]. Still, an emerging design trend is towards tighter OFs in order enhance privacy and minimize solar heat gain within a space.
In many cases, specifying shading fabrics to enhance occupant comfort can be markedly more important to the bottom line than the energy cost savings they help provide. To illustrate that point, consider that companies spend, on average, up to 100 times more on employee compensation than on their building’s energy consumption, according to a study done by the Rocky Mountain Institute.
Balance the interior and exterior design intent.
One of the most important considerationsfor an architect or designer is whether certain products help to achieve an intended design result. While some still believe shade fabric appearance only affects aesthetics to the interior, the reality is quite different.
In addition to performance, shade fabric color affects a building’s outward appearance when combined with the aesthetic properties of the glazing. Light-colored shades are often more visible from the street-side and can appear slightly green behind clear glass due the levels of iron content in the glass.When manually lowered to different levels, light-colored shades can create a ‘snaggletooth’ look that is visually distracting during the day. To protect the integrity of the selected glazing’s reflected color, darker shades can provide an aesthetic continuity to the exterior façade no matter how far they are raised or deployed. Dark shades tend to simulate the darker interior cavity of a building when the more dominate light source is on the exterior.
One performance-related drawback of specifying a dark-colored interior shade fabric, however, is that it will absorb the energy that is created by the near infrared wavelength and can create a lot of heat.
KOOLBLACK® Technology is an example of a shading innovationthat solves this problem.By increasing its near infrared reflection (NIR), a dark shade fabric can maintain visibility and glare control benefits while enhancing energy reflection comparable with light fabric.As modern building design continues to trend toward large glass facades, expect demand to steadily increase forthis and other technologies that can enhance aesthetics and performance, both inside and out.
Glazing and solar shadinggo hand-in-hand.
Architects who consider shade selection in conjunction with glazing are at the forefront of a paradigm shift in the industry. With the help of new software, the industry will soon be able to quantify the performance values of innovative shade fabrics and glazing combinations. This data will help answer the question: “How does a particular shade impact the overall system performance?”
The glazing industry has already created guidelines for calculating energy performance.
Following in those footsteps, the Department of Energy and the Attachments Energy Rating Council (AERC) are working to determine rules for quantifying complete building envelope performance with shading solutions. Their work should help shrink the gap between understanding the aesthetic and performance characteristics of different shading and glazing combinations. As a result, architects and designers will be able to see the benefits of specifying these components concurrently.
Use affects how shades perform.
In contrast to other window treatments, including applied films, awnings and drapes, shade fabrics offer the ultimate adjustability to balance daylight, glare, and view preservationaccording to occupant needs. On the same token, a shade is only effective if it is deployed to the correct position at the appropriate time.
For building occupants positioned neara west-facing façade that receives intense afternoon sunlight, adjustability is critical to help control heat and glare. Completely lowering the shade, however, may force interior lighting to be raised and increase energy expenditures to a degree. Fully deploying shadeson a dark, cloudy day would have a similar effect, particularly with a tight opennessshade fabric designed for glare control.
Automated shade controls mitigate these potential issues and are often considered an integral part of a long-term energy saving strategy. Window light sensors and/or interior lighting systems share data with an automated shading system, raising or lowering it based on the current angle of the sun, weather conditions, interior temperature and other factors.
This technology ensures the performance characteristics of the specified shade meet daylighting and energy requirements. It is especially beneficial in large, shared spaces such as lobbies and conference rooms.Still, manual overrides are a valuable feature in automation, as individual building occupant preferences change based on mood and task needs.
Bring your vision to life.
There’s no doubt that the A&D community is one of the most innovative collections of people in the world. Each one of us wants our own innovation to shine through in the buildings and the spaces we create. In terms of the fenestration, the next step forward is to understand how the innovative products we choose can work together to achieve a specific design intent, and elevate beautiful designs with an increased emphasis on performance.
Colin Blackford is the Innovation Manager for Mermet USA
[i]Stetzenbach L.D., et al. 2008. Building Performance Characterization, Energy Usage, and Indoor Environmental Quality in High Performance Buildings, National Center for Energy Management and Building Technologies, Alexandria, VA, Final Report NCEMBT (Task 06-06)