Energy efficiency has taken on new meaning in the world of design and construction. Today it means more than building energy-efficient structures designed to achieve LEED certification, or reducing a carbon footprint; energy efficiency has become one of the most important factors in managing costs and reducing overhead in the operation of commercial buildings. In fact, it's estimated that reducing energy consumption by 30 percent can result in a savings of $25,000 per year for every 50,000 square feet of office space.
Thermal breaks are just one element of improving thermal performance in storefronts and entrances
According to an Energy Efficiency Trend study by the U. S. Department of Energy (USDOE) and McGraw-Hill Construction Data, the overlap of energy-efficient building trends and the economic recession has necessitated technological advances to reduce energy consumption in an economically efficient way, such as higher thermal efficiency.
As architects and building owners across North America explore ways to decrease a building’s energy consumption and energy costs, the need for thermally efficient products has increased. While style and aesthetic appeal remain important factors when choosing materials for storefronts and entrances, energy efficiency and long-term energy savings are playing a much larger role in product specification.
Even before energy efficiency and energy costs became a major concern for architects and building owners, the building envelope and doors were the focus of keeping the indoor building environment at a comfortable and easily regulated temperature. Choosing storefront framing systems and doors with high thermal performance is one of the best ways to ensure comfortably controlled temperatures with lower energy consumption.
This need for improved energy efficiency and thermal performance has resulted in the development of doors and framing systems that are truly thermally broken, versus thermally improved. A truly thermally broken product includes those with a minimum of 5.3-mm separation provided by a low conductance material or open air space. A thermal break or thermal barrier is an element of low thermal conductivity inserted between members of higher conductivity aimed at reducing or preventing the flow of thermal energy. Thermal breaks made of substantially rigid, low thermal conductive polyurethane can be more than a thousand times less conductive than aluminum and a hundred times less than steel.
Choosing framing and door systems that provide a true thermal break, eliminating thermal bridging, not only lowers energy bills, but also helps to achieve the maximum benefits of building-wide insulation. An ultra-thermal framing system, such as the Kawneer Trifab 601UT (Ultra Thermal) Framing System from Norcross, Ga.-based Kawneer Co. Inc., with a dual thermal break, can greatly enhance energy efficiency in the building envelope. Besides the inherent energy savings from reduced thermal loss, the more advanced thermally broken systems allow building owners to take advantage of tax incentive programs in addition to green building certifications, such as LEED.
Compared to other parts of the building envelope, doors are often the most problematic components, based on heat loss from operation, improper or worn weathering components, and heat loss through the space of the door itself. The thermal performance of any door depends on many factors, including the style of the door, the intended use, and the materials from which the door is made.
By combining critical elements within the product design, thermally broken doors create a superior thermal roadblock that enhances thermal performance. Examples include pour and debridged urethane systems, crimped-in-place plastic isolator systems, and pressure-glazed systems with intermittent fasteners.
Aluminum (or steel) framed doors that are incorporated into a storefront assembly can have thermally broken frames and insulating glass units, which provide improved thermal performance. One newer construction method is the use of polyamide struts to create the thermal break or barrier separating the exterior surface from the interior surface. While polyamide struts are certainly not new to the industry, they are still somewhat new to door product offerings. Doors that offer the highest levels of thermal efficiency include thermal breaks in the door, door frame and threshold that simultaneously isolate the interior components from the exterior components. Examples of this type of door construction are the AA250 and AA425 Thermal Doors from Kawneer. They include stile and rail designs with the polyamide strut, thermal breaks and double air cavities, which provide an added layer to the thermal barrier. Additional dual weathering around the perimeter of the door in conjunction with a low conductance polymer door stop minimizes air infiltration.
The more aware the design and construction community is of alternative design practices and technologies that lead to more efficient buildings, the easier it will be to lessen the overall use of energy and control ongoing energy costs. As the industry continues to move toward more energy-efficient building solutions, it may not be long before thermally broken products become the standard versus the option.
Elizabeth Cotton is the product manager, storefronts, entrances and framing at Kawneer Co. Inc., Norcross, Ga. To learn more, visit www.kawneer.com.