Cool roofs, cool pavements, cool cars, and other cool products provide many great ways to beat the heat. Lawrence Berkley National Lab’s Heat Island Group, CCAP’s The Value of Green Infrastructure for Urban Climate Adaptation, the EPA’s compendium of strategies to reduce the urban heat island effect, EPA’s Science Corner, and Georgetown Climate Center’s Adapting to Urban Heat: A Tool Kit for Local Governments discuss these in depth. Today we highlight some great Problem-Solution images from the Heat Island Group, Lawrence Berkeley National Labs.
Cool roofing products are made of highly reflective and emissive materials that can remain approximately 50 to 60°F (28-33°C) cooler than traditional materials during peak summer weather (150 to 185°F or 66-85°C). The Cool Roof Rating Council (CRRC) maintains a third-party rating system for radiative properties of roof surfacing materials. The EPA’s Cool Roofs suggests that the cost to use some of these surfacing materials can be very cheap; for instance creating a cool roof by painting it white costs about the same as painting the same roof a traditional dark color. Due to material availability and low cost, cool roofs are becoming more common. For instance, NYC °Cool Roofs has applied a reflective surface to almost 3 million square feet of roofs to help reduce cooling costs, cut energy usage and lower greenhouse gas emissions. Note green roofs can offer multiple benefits beyond cool roofs such as water retention and flood management (per our previous blog).
According the EPA’s Cool Pavements, conventional concrete and asphalt pavements can reach peak summertime surface temperatures of 120–150°F (48–67°C), contributing to urban heat islands (especially at nighttime) and impairing water quality. Summer 2012 saw roads, sidewalks, and multiple other structures buckle and break due to extreme heat, renewing interest in cool pavements. While a “cool” pavement has no standard, official definition, typically it refers to a range of established and emerging materials that store less heat and may have lower surface temperatures compared with conventional products. For instance, cool pavements can be made from traditional paving materials, such as cement concrete. New cement concrete has a solar reflectance (SR) of 30–50 percent. There are also novel cool-colored coatings for asphalt concrete pavements that reflect about 50 percent of sunlight. Another approach is to use a clear binder that reveals highly reflective (light-colored) aggregate. Another possibility is to paint bike lanes white.
Ever compare the temperature inside a white car and a black car on a hot summer day? The white car is a bit cooler, simply because of its color. A light-colored, or cool-colored, car shell reflects more sunlight than a traditional dark car shell. This cools the cabin air and reduces the need for air-conditioning. A recent study found that after parking in the sun for an hour, a silver Honda Civic (shell SR 0.57) had a cabin air temperature about 9-11°F (5-6°C) lower than an otherwise identical black car (shell SR 0.05). Modeling indicates that substituting a silver (or white) shell for a black shell would allow the specification of a 13 percent smaller (lower capacity) air conditioner, thereby improving fuel economy. The Car Shell Reflectance Database contains specifications of a multitude of car shell products from various manufacturers.
This post is part of CCAP’s blog series, “What Does Climate Resilience Look Like,” which highlights adaptation images from around the world addressing a variety of climate impacts and resilience solutions. Have a climate resilience image to share? Please send us the photo by Twitter, Facebook, or email. (Please include the Who What Where: Who took the photo? What is the adaptation technique? Where is it located?) We are especially interested in examples that advance multiple goals such as GHG emission reductions and sustainable economic development.