Help Your Office Building Compete
February 11, 2021 0
|An efficient fenestration system appeals to tenants and saves on operating costs.|
Help Your Office Building Compete
Energy-efficient fenestration in an office building attracts satisfied tenants.
Rich Walker, American Architectural Manufacturer
As the construction deep-freeze thaws, as it eventually will, the competitive environment will make it more important than ever for new or remodeled commercial buildings to attract investors and prospective tenants. Determining the optimum combination of building performance and functionality to achieve such appeal depends heavily upon the building’s fenestration system, which involves careful attention to a number of design considerations. Many of these are of greater concern and consequence for commercial projects than for residential applications.
Today, green credentials demonstrably move projects to the top of the desirability pecking order. The 2008 Green Building Survey, conducted by National Real Estate Investor, New York, states that corporate respondents are willing to pay an average of 4% more for LEED-certified buildings; developer respondents say they can charge an average of 3% higher rents for green properties. This fact is not lost on developers and owners. According to New York-based Turner Construction Co.’s Green Building Barometer, 75% of commercial real estate developers, rental building owners, brokers, and others say the credit crunch will not discourage them from building green. A full 84% of respondents said their green buildings have resulted in lower energy costs, with 68% reporting lower overall operating costs.
For these reasons, green building is one of the growing bright spots for the U.S. economy. Verifying the trend, New York-based McGraw-Hill Construction’s Green Outlook 2009 report states that the value of green building construction starts increased five-fold from 2005 to 2008 and could triple by 2013.
For fenestration products, green building encompasses a variety of design considerations. Energy efficiency is the key element, together with beneficial daylighting to supplant electric lighting, and an emphasis on products with minimal environmental impact throughout their lifecycles.
The building’s location determines outdoor design temperatures (winter lows and summer highs), which dictate the windows’ required level of heat-transfer coefficient (measured by U-value), as well as solar heat gain (measured by the solar heat gain coefficient, or SHGC). Because energy use in commercial buildings is typically dominated by cooling loads, a lower SHGC is often desirable. However, buildings in northern climes can benefit from higher SHGCs as a means to offset thermal transmittance losses. These values are optimized as needed by the use of insulating glass units (IGU) with inert gas infill, and warm edge spacers separating the inner and outer lites (panes), framing with inherent or engineered integral thermal barriers, and glass with special coatings such as reflective glazing or high-performance low-e coatings.
AAMA (American Architectural Manufacturers Association, Schaumburg, IL) is developing a point-system-based green certification program for scoring the green credentials of window and door products. The program is intended to help designers and specifiers select products that will maximally contribute to whole-building green rating systems such as the LEED program, and the Green Globes assessment and rating system for commercial buildings.
Windows must meet certain basic requirements for structural performance. The International Building Code (IBC) requires that windows meet the performance requirements of AAMA/WDMA/CSA 101/I.S.2/A440-08, NAFS-North American Fenestration Standard/Specification for Windows, Doors, and Skylights or a referenced predecessor. These standards define minimum structural performance requirements, as well as the window’s ability to resist air infiltration and water penetration due to wind-driven rain. For a product to gain entry to one of these performance classes, it must be tested to withstand progressively higher minimum design pressures derived from the maximum wind velocity likely to be experienced at a given geographical location. Several different performance classes are defined by their minimum design pressure, water penetration resistance, and air-leakage resistance requirements and identified according to their typical application: R, LC, CW, and AW. Windows for most office buildings, particularly multi-story ones, are likely to fall within the CW or AW classes.
Studies indicate that office productivity increases when intrusive racket-from traffic, airplanes, mass transit systems, and other outside noise-is reduced. For noisy urban environments, products identified as acoustic windows should be chosen and tested for sound-transmission loss, and assigned a sound-transmission class (STC) and an outdoor-indoor transmission …