مقررات محیطی در سقف شینگل
Environmental concerns have affected products containing volatile organic compounds (VOCs). With some products, the VOC (commonly referred to as “solvent”) content has been reduced. In other instances, there has been a move to water-based rather than solvent-based products. It is uncertain how successful the reduced VOC products and the newer water-based products will be.
Environmental concerns resulted in the following roof design trends beginning in the mid- to late-1990s:
- Cool Roofing and Heat Island Issues: LEED® and UFC 3-400-01, “Energy Conservation”, promote the use of cool roofing, and increased energy conservation through additional insulation. Cool roof design shall follow the requirements in Chapter 1, Cool Roofs. Consider that when cool roofing is used with insulation R values greater than 24, the ‘cool roof’ surface has little if no influence on the energy performance of the building. Additionally, designers should be aware of the possible negative impacts of using cool roofing that may result in unintended consequences. Poor design of cool roofs in ASHRAE climate zones 4 and higher have resulted in the unintended consequence of condensation below the membrane—a result of the material’s inability to warm and drive moisture downward. Roofs that experience this condensation have had to be replaced. Other unintended consequences include the overheating of masonry walls, interior spaces, roof top piping and mechanical equipment as a result of the reflected UV rays. See The NRCA Roofing Manual: Architectural Metal Flashing, Condensation and Air Leakage Control, and Reroofing. See Cool Metal Roofing.
- High Emittance Roof Surfaces: In cooling-dominated climates, there has also been interest and regulations regarding high emittance roof surfaces.
- Vegetative Roofs: Sometimes called “green” roofs, vegetative roofs offer several potential environmental benefits, including, reduction of the urban heat island effect (via evapotranspiration and reflectivity), oxygen generation, and reduced storm water runoff. See Vegetative Roofs.
- Photovoltaic Collectors: However, around the early 2000s, a new generation of rooftop solar collector was introduced. Available in rack mount or PV laminate application photovoltaic systems are common today. Laminated systems are not recommended at this point due to damages and failures experienced to date. See Building Integrated Photovoltaics (BIPV).
- Sustainable Roof Design: Highly reflective roofs, vegetative roofs and use of solar collectors can all be considered as elements of sustainable design. However, sustainable design for the building envelope considers and incorporates many other issues. See The NRCA Roofing Manual: Architectural Metal Flashing, Condensation and Air Leakage Control, and Reroofing.
- Higher levels of insulation.
Greater emphasis on the importance of controlling airtightness.