Cool Roof Technology: a Low-cost Way to Reduce Energy Consumption and Carbon Emissions
Want a huge decrease in carbon emissions, a reduction in summertime cooling costs and a more efficient home? Cool roof technology can do all that. Cool roof technology has the potential to eliminate billions of tons of carbon dioxide at a very low cost.
If you’ve ever spent time on a black asphalt roof or up in an attic during the heat of summer, you understand how much heat energy is added to a home during summer months. This is heat that many of us pay to remove by using air conditioners and other means.
But what if, just by a better design and choice of materials, we could have a far cooler house that uses far less electricity each month? That is what people in the Mediterranean and other hot climates have been doing for centuries. White paint and chimney-style ventilation that distributes cool air from lower areas of the house are low-tech examples of cool roof technology that works.
Modern cool roof technology is similar. Most are just like regular roofs but are designed to reflect sunlight and shed heat, to keep buildings cooler in the summer. According to a study by the National Renewable Energy Laboratory (NREL), cool roof technology could reduce energy consumption for cooling by up to 20%. The study also found that energy savings from cool roof technology could eliminate up to 1.4 billion tons of carbon dioxide emissions annually in the United States. The equivalent of taking 300 million cars off the road!
According to Lawrence Berkeley National Laboratory, if all North American cities with populations over 1 million people adopted cool roof technology, air conditioner use would fall by one-third.
The Human Cost of Heat
The savings aren’t just in terms of money and carbon emissions. Climate change has disproportionately increased temperatures in urban areas. An urban landscape largely covered in asphalt, concrete and black roofing materials is far hotter than one covered in greenery or reflective materials, a phenomenon known as the urban heat island effect.
The urban heat island effect is the phenomenon of cities being warmer than surrounding rural areas. This is because cities have more dark surfaces, such as black roofs, which absorb sunlight and heat up the air. The heated air then rises, creating a convection current that draws in cooler air from surrounding areas. This process can lead to increased temperatures in cities, which can have a number of negative consequences, such as increased energy consumption for cooling, decreased air quality, and increased heat-related illnesses and deaths.
Black roofs also radiate energy directly into the atmosphere. This energy is then absorbed by clouds and trapped by the greenhouse effect, further contributing to global warming.
Type Depends on Location Climate
There are a number of different types of cool roof technology available, including:
- Reflective roofs: Reflective roofs are the most common type of cool roof. They are made of materials that reflect sunlight, such as white or light-colored tiles, metal roofs, or paints. Reflective roofs can reflect up to 90% of the sun’s heat, which can help to keep buildings cooler in the summer.
- Evaporative roofs: Evaporative roofs are made of materials that allow water to evaporate, such as clay tiles or metal roofs with a water-absorbing coating. As the water evaporates, it cools the roof and the building below. Evaporative roofs can be effective in hot, dry climates.
- Phase-change materials: Phase-change materials are materials that change their state from solid to liquid and vice versa. When these materials change phase, they absorb or release heat. Phase-change materials can be used in cool roofs to store heat during the day and release it at night. This can help to keep buildings cooler in the summer and warmer in the winter.
- Cooling paints: Cooling paints are paints that are applied to roofs to make them more reflective and to help them cool down. Cooling paints are effective in hot, sunny climates and typically contain titanium dioxide, a highly reflective pigment.
- Cooling granules: Cooling granules are small, reflective beads applied to roofing materials like shingles. The granules reflect sunlight and help to keep the roof cooler. Like cooling paints, cooling granules are most effective in hot, sunny climates.
Green Roofs are Cool Roofs
Another type of cool roof technology is the green roof. Green roofs are made of a waterproof membrane with a layer of soil and vegetation on top that helps to insulate the roof and reflect sunlight. Green roofs can reflect up to 70% of the sun’s heat, which can help to keep buildings cooler in the summer. In some cases, they can provide vegetable gardens or just a nice place to sit and enjoy the feeling of being surrounded by nature – while in the city.
Green roofs also have the effect of providing bird and pollinator habitat as well as reducing stormwater runoff. Because of the benefits, many cities are now mandating the installation of green roofs on new construction. New York, San Francisco, Chicago, Seattle and Portland all require green roofs on new construction on buildings with roof areas over a specific set size. That said, retrofitting an existing building is often cost prohibitive due to the structural requirements to support the additional weight.
Cool roof technology is a promising way to reduce greenhouse gas emissions and improve the energy efficiency of buildings. As the technology continues to develop, the potential for cool roofs to reduce carbon dioxide emissions will likely increase.
This is an easy way to make big gains in carbon reductions, saving homeowners and businesses money. Something we can all get behind.
Source Happy Eco News
