Entrances have not received the same sustainability scrutiny to date as have roofs, furnishings, windows, carpet and other building products, but it is only a matter of time before doors must also respond to the sustainable design requirements now being adopted throughout the architecture and construction communities. And as this happens, the industry is going to have to take a hard look at what makes a door sustainable.
For the most part, architects, builders and building owners have taken their cues from the U.S. Green Building Council (USGBC) and its Leadership in Energy and Environmental Design (LEED) Green Building Rating System. The credit-based system has no explicit specifications for entrances, but its larger, general recommendations for building materials do provide some guidance for specifying “green” doors: In the most general terms, LEED prefers architectural products that are salvaged or reused, made from recycled or rapidly renewable materials, are locally sourced and made from materials that will not emit harmful volatile organic compounds or other environmental pollutants. It does not explicitly address whether a building product should be recyclable, how it is to be eventually disposed of, or even how long it should last.
As a rule, green buildings are designed to last longer and require less maintenance than standard construction. Yet by concentrating on what a product is made of or where it is made, and not how it performs and how long it lasts, the current LEED standard can inadvertently influence the specification of architectural products not appropriate to the institutional and high-traffic commercial environments that have to date made up the largest market for green buildings.
At the end of the day, the most important characteristic of a sustainable component is a factor only assumed in the language of the LEED system, that the product is engineered and employed in a manner that prevents premature failure and unplanned maintenance and replacement. Above all else, a “green” door has to be built to last.
Commercial Doors Are a Particular Concern for Sustainability
In a heavy traffic installation, such as a busy restaurant or school, the main entry door will be subject to constant and sometimes creative abuse — several thousand openings per day and regular impacts from kicking or shoving the door open. Put the door in a high school next to the football locker room and that damage increases substantially. Doors have been known to fail in as little as six months under such conditions. Add in environmental factors such as humidity, harsh winters, extreme heat and direct exposure to sunlight, and the life expectancy of the door will decrease even further. Not to mention threats of graffiti and vandalism. This creates a cycle of door repair and replacement that is the polar opposite of sustainability.
For dealers, there is an obvious benefit in the exterior door being the ink cartridge of architectural products. There are certainly companies out there that appreciate the regular business a problem entranceway can provide. But considering the higher margins that premium, more sustainable products command and the inherent risk in keeping the business of an unsatisfied customer, it is difficult to make a case for the inferior, less sustainable product.
Some proper foresight and product knowledge will allow any dealer to specify an exterior door that is as sustainable as any green building, in the process securing higher margins and a better reputation within the lucrative the green building segment. As with any performance product, but especially those with “green” features or attributes, demand data and documentation to support performance claims.
Structural Strength
This requirement is obvious on the surface level. A door must be durable enough to withstand kicks, shoves and occasional blunt force collisions from human (a run-away cart, a homerun baseball) and natural (high-velocity winds, hail) sources. It must be able to withstand malicious attempts to damage or breach the door.
Not as obvious is that the door must be strong enough to withstand literally thousands of small impacts a day. The inertia created by opening and closing a door subjects it to physical forces that stress the door itself and the hardware that moves it. The door is being stressed and twisted with each use, while the hardware is being strained and struck.
Understanding this requires the recognition that an entrance is actually a system consisting of door, hardware and framing — a deficiency in any one component will affect the entire system — as well as a passing familiarity with the laws of physics. According to Sir Isaac Newton, the energy required to move an object is directly related to the mass of an object. So the heavier the door, the more force required to move it, meaning more stress on the hardware to control it and a more powerful impact on the hardware and framing elements.
What this means is that the ideal door is one that properly distributes the stressful forces of motion. It should not be heavy and rigid but lightweight and flexible. A door only needs to be rigid enough to keep out the elements and secure the building. Any more than that is counterproductive and will increase the wear and tear on its associated hardware. As the hardware and framing components wear out, the door may go out of adjustment and fail to latch properly; creating leaks that will affect weather resistance and thermal integrity.
Chemical, Corrosion and Weather Resistance
Long-lasting commercial doors will feature non-corroding materials, lifetime factory finishes and easy-cleaning surfaces. This will provide protection against graffiti and abrasive cleaning agents that could stain or corrode the surface of the door. Be especially wary if the door is installed in a humid environment or near the ocean, at industrial facilities and water or wastewater plants, pools or in locations likely to face wind-driven rain or snow. Even sidewalk salt can take a heavy toll on a door.
A door with components that are glued together might not hold up to the weather on a good day either. Door skin temperatures can reach 200 degrees Fahrenheit in direct sun. In a temperature controlled building, that can mean a difference of more than 100 degrees between the two sides of the door. In another application of basic physics, this temperature variance will cause the opposite faces of the door to expand or contract at different rates, introducing unseen forces that pull the sides of the door in opposite directions, stressing the glued bonds of the door and conceivably tearing it apart. Glue is also a source for harmful gasses that will negatively impact the indoor air quality of the structure.
Moisture Resistance
With all the aforementioned precipitation that a door will come in contact with, it is critical that the door be properly sealed and protected against condensation. An unsealed door can collect rainwater, condensation and dirt. Not only is this known to cause rust, there is also a potential for mold growth within an unsealed door, as the only requirements to grow mold are water and the mold spores and nutrients found in dirt.
Thermal Performance
Although only a small portion of a structure’s surface area, exterior doors can play an important role in the overall energy efficiency of a building. As with windows or walls, care should be taken to specify components that limit thermal exchange. The best way to keep the heat in during winter and out during summer is to use the minimum amount of glass necessary to ensure safety and security. Glass provides a direct thermal transfer point, so specify full-face doors and insulated side panels whenever possible. Use insulated glass of at least one-inch thickness.
Also, look for insulated door panels and thermally improved framing, and when examining a product, be sure that any claims are for tests on the door itself and not the base material of the door.
Indoor Air Quality
Some building products are manufactured with materials that will over time emit noxious fumes, pollutants or harmful volatile organic compounds. This can come from paint, adhesives and certain plastics, and can also be introduced during maintenance and cleaning. Specify a door that will require very little regular maintenance and seek out products that have earned indoor air quality accreditations from a third-party verifier such as GREENGUARD or Scientific Certification Systems.
Function over Form
When identifying sustainable products, it is necessary to look past form and instead concentrate on function. It is not as simple as specifying bamboo, reclaimed wood or CFL light bulbs. There needs to be careful consideration of how the product will work in the application.
The best case scenario for an architectural product is not to evaluate it by its contribution to LEED credits but by a Life Cycle Assessment that takes into account not only where and how it was made but how it will work and for how long. Doing so will better satisfy the intent of the LEED system and limit indirect negative impacts elsewhere, such as on the heavily weighted energy efficiency credits. A wood or steel door, for example, appears to be favored by the LEED materials credits, but neither is comparable in durability or energy efficiency to a tightly-sealed aluminum door or a fiberglass reinforced polyester (FRP) flush door.
For all of the reasons discussed here, it may be necessary for dealers to ask their customers if the goal is to satisfy the language of the LEED system or the intent behind it. If exterior doors are chosen only for their ability to help earn LEED credits, it is likely that “brown” doors will end up in those green buildings. Only if a door is chosen for the longest possible service life and the lowest maintenance requirements have you chosen a truly sustainable door.
Dan Depta is manager of marketing at Decatur, Mich.-based Special-Lite Inc., which manufactures complete entrance systems consisting of flush, monumental, wood grain and colonial doors, panels and framing for new construction and replacement installations in commercial, institutional, and municipal applications. Special-Lite entrance products were the first to earn GREENGUARD Indoor Air Quality Certification, including the stringent Children & Schools Standard. For more information, visit www.special-lite.com.
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