sulation. “We’ve seen some new materials, such as vacuum-sealed insulated panels and fasteners with thermal breaks that are helping to
requirements and standards currently in line with today’s commercial roofing systems. The hatch reduces harmful condensation since it is thermally broken, which means interior and exterior metal surfaces are separated by non- conductive material to eliminate heat transfer. It is particularly benefi- cial in buildings in which there is a wide fluctuation in temperature. The hatch helps keep heat inside the building when a roof is covered by snow and on cold, dreary winter days but helps air-conditioned build- ings keep cool as the sun beats down on sweltering summer months. The BILCO thermally broken roof hatch is supplied with the standard features on the company’s standard roof hatches, including engineered lift assistance for easy, one-hand operation to a fully open or closed position. Other standard features include a fully gasketed cover for weathertightness, an automatic hold-open arm, and a slam latch with interior and exterior padlock hasps. The product is constructed of alu- minum for corrosion resistance and has a high solar reflective index. A World-Wide Commitment From a simplistic standpoint, the role of the roof has not changed. Its purpose is to keep the elements out of the building. While their primary function has not altered, technical details in roofing have grown signifi- cantly. Architects, builders, and roofing companies can offer options that would never have been dreamed of a century ago. The current trend is directed at improving energy efficiency and it’s not just in the United States. In India, 40 percent of the population is expected to live in cities by 2030. More than 60 percent of the roofs trap heat are made of concrete, metal, and asbestos, which can trap heat. “Further, buildings account for more than 30 percent of India’s electricity consumption and a significant share of annual carbon diox- ide emissions,” Arvind Kumar and Rajkiran V. Biloikar wrote in The Indian Express. “It is thus imperative that any effort towards energy conservation must include a focused approach to urban areas and more specifically on buildings and built-up areas.” The article says govern- ment mandates on improving energy efficiency are on the horizon. Other nations can expect to see similar government mandates. Change will not come swiftly. The clean energy movement is going to evolve over time, and there is a lot of work that has to be done. While still in the infant stages, some government leaders and international institutions are pushing for change to occur sooner rather than later. “In the building and construction sector, much attention was concen- trated on operational energy efficiency, the energy used in buildings and which can be influenced by building design, insulation, passive solutions for heating and cooling, appliances, and systems improvements as well as maintenance and usage,” said Martina Otto, head of the United Na- tions Environment Program Cities Unit. “But we also need to look at materials to reduce pressure on natural resources and embodied carbon (the amount of CO² or CO² emission to produce a material).”
improve energy efficiency.” Understanding R-Values
The United States is divided into seven climate zones for commercial and industrial buildings and homeowners to reach recommended insu- lation levels. Energy codes for commercial buildings are established by the International Energy Conservation Code. “There’s not a one-size-fits-all approach for commercial construction,”Clap- per said. “Requirements vary based upon climate zone and building type. R-value and solar reflectance are also factors that have to be determined.” The seven climate zones in the U.S. are defined along state and county lines. The zones establish a baseline for energy efficiency by setting performance standards for the building envelope. The codes account for mechanical systems, lighting systems, and service water heating systems in homes and commercial businesses. The zones are identified by their mix of weather. Zone 7, for instance, is classified as “very cold” and includes almost all of Alaska and por- tions of some other states. Zones 5 and 6 stretch across the nation, and includes states such as Pennsylvania and Massachusetts in the Northeast and Nevada and Nevada and Oregon in the West. Zone 2, which endures hot and humid weather, includes states such as Florida, Louisiana, and Texas. The climate zones, coupled with different building types, construction costs and material selection can make the roofing task on any build- ing exceedingly challenging. “Each building is unique in its energy demands,” said Andrew Imbus, Product Manager for Imbus Roofing, whose company has been part of the Cincinnati community since 1873. “Roofing is just one element of a building’s architecture. Roof- ers, architects and even legislatures governing building codes need to consider regional demands for energy efficiency, building typology demands, and architectural demands.” Maintaining Efficiency With roof construction, it is critical for architects to maintain the build- ing’s energy efficiency and construction integrity when adding roof openings. Besides keeping moisture, debris, and pests out of the build- ing, holes for accessibility to mechanical equipment and ventilation must also integrate with the building envelope to control energy costs. “The R-value of insulation hasn’t increased on a product-by-product basis, but recognizing that attachment methods for insulation, the inclusion of air barriers and vapor retarders into roof designs will im- prove energy efficiency,” Kirby said. One of the most popular sellers for the roofing industry in recent years has been a thermally broken roof hatch, manufactured by The BILCO Company. The product features a thermally broken frame and cover design to minimize both heat transfer and effects of condensation. The product features three inches of polyisocyanurate insulation with an R-value of 20.3 in both the cover and curb. The R-value meets code
THOMAS RENNER writes on building, construction, manufacturing, and other trade industry topics for publications based in the United States and Canada.
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csengineermag.com
november 2020
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