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Working in a LEED-certified building can be a pleasure because they are designed and built with sustainability and occupant health in mind. However, a common problem for occupants is a marked drop in cell phone signal level, which can usually be traced to the use of low-emissivity (low-E) glass in their construction. In this article, we will discuss the necessity of using low-E glass, how it affects the electromagnetic waves used to transmit cell phone signals, and how a distributed antenna system (DAS) can mitigate its effects.
Low-E glass has a thin coating that minimizes the amount of energy passing through it and is categorized based on the manufacturing process and type of coating used. Hard-coat low-E glass uses a metallic coating, usually tin, that is sprayed onto the glass surface at high temperatures. It is favored in colder climates due to its tendency to allow some of the sun’s heat to pass through and aid in heating the building interior. Soft-coat low-E glass generally uses a silver lining sandwiched between panes of glass in a vacuum chamber and is significantly more expensive. It is preferred in warmer climates where it reduces air conditioning costs by minimizing heat transmission into a structure. Both glasses achieve their goals while allowing visible light in, albeit at varying levels of effectiveness.
Low-E glass is one of the mainstays of modern building construction, where the Leadership in Energy and Environmental Design (LEED) system dictates many design decisions. The LEED system assigns a rating to a building based on the number of sustainable and environmentally friendly features included in its design. A higher rating can not only ensure lower operating costs but also yield significant tax credits from local governments. Given this, it is unsurprising that a number of manufacturers, such as Trulite, Guardian Glass and Vitro, dedicate sections in their marketing literature to boasting about how their products improve LEED ratings.
Unfortunately, LEED ratings do not take into account an issue with low-E glass that can be a nuisance for a building’s occupants in today’s technological world. The ability of low-E glass to reflect energy and improve insulation also impacts transmissions to and from cell phone towers, preventing them from penetrating buildings through the glass. The result is high signal attenuation (a reduction in signal strength) and poor indoor coverage, leading to a degraded customer experience.
A distributed antenna system alleviates the issue of poor coverage by using a network of indoor antennas spread throughout the building. An external donor antenna is used to supply the signal to the indoor antennas through media such as optical fiber. Users can be served directly by antennas within the building rather than making do with poor reception from signals having to travel through low‑e glass windows. Users gain the energy efficiency of low-E glass and the benefits of a high LEED rating without suffering from intermittent coverage and disappearing bars on their phones. They can achieve their goal of owning and working in a sustainable, environmentally friendly building without negatively affecting their modern lifestyles.
To find out more about DAS and how it can help solve signal issues in buildings with Low-E windows, read our Guide to Distributed Antenna Systems or reach out to our turn-key DAS design and installation team.