By the CFFA – Vinyl Roofing Division
The term “heat islands” might conjure images of a relaxing tropical getaway, but the truth is far more serious. It describes the phenomenon of cities being markedly warmer than surrounding communities, and the destructive effects inherent to it. Daytime temperatures can average up to 7 degrees hotter in urban settings, with the possibility of isolated spikes of over 22 degrees hotter.
Why? Because the topography of an urban area is covered with man-made structures such as buildings, roads, and other infrastructure that absorb and re-emit the sun’s heat more than natural landscapes such as forests and bodies of water. Urban heat islands cause increased energy consumption, higher emissions of air pollutants and greenhouse gases, as well as compromised human health and comfort.
It’s a problem that is increasing, with the number of recorded extreme hot days nearly doubling since the 1980s.
Use of sustainable PVC membrane roofing can help reduce the urban heat island effect and its consequences. A white PVC roof can reflect 80% or more of the sun’s rays and emit at least 70% of the solar radiation a building absorbs. A dark-colored asphalt or rubber roof only reflects between 6 and 26% of solar radiation, resulting in greater heat transfer to the building interior and greater demand for air conditioning.
The U.S. EPA has identified cool roofs as a key strategy in mitigating heat islands, citing their ability to reduce energy use, air pollution, and greenhouse gas emissions, while improving health and comfort. A cool roof transfers less heat to the building below and can reduce air temperatures inside buildings with and without air conditioning, helping to prevent heat-related illnesses and deaths.
PVC roofing meets the emittance and solar reflectance index criteria for LEED, Green Globes, and California’s Title 24. It is a high-performing, low slope, single-ply roofing solution that has protected and kept buildings cool in climates around the world for decades. Regardless of climate, when the sun beats down, a cool roof will counteract the effects of heat islands to keep ambient temperatures low.
In addition to the obvious cooling benefits, the long service life of PVC roofing membranes — combined with recyclability, relatively low use of non-renewable resources, inherent energy efficient characteristics, and suitability for green roof assemblies — make them the sustainable choice among commercial roofing systems. l
About Chemical Fabrics and Film Association — Vinyl Roofing Division: The Vinyl Roofing Division of the Chemical Fabrics and Film Association [https://vinylroofs.org/] was created to educate architects, specifiers, building owners and roofing contractors on the attributes of PVC/vinyl as a durable, reflective, heat-weldable material for single-ply roofing systems. Representing all of the leading manufacturers of thermoplastic PVC roofing systems in North America, the Division is committed to making available sound, scientifically backed information on the environmental and functional performance of energy-efficient PVC roofing membranes.