Doesn’t it make “Cents” to $ave money?
By Jenny Bates
What is an Urban Heat Island and what does it have to do with my cool roof system?
Urban Heat Islands occur on the surface and in the atmosphere. A heat island is a metropolitan area that is warmer than surrounding areas due to human activities, rendering surfaces that were once permeable and moist to impermeable and dry. Temperatures are often a few degrees higher in cities than they are in their surrounding rural areas. This temperature discrepancy is the result of a bizarre phenomenon known as the urban heat island effect. As the name implies, the effect makes cities into islands of heat. The temperature difference usually is higher at night than during the day, and is most obvious when winds are weak and is most noticeable during the summer and winter, but can occur year-round. Urban-rural temperature differences are often largest during calm, clear evenings. This is because rural areas cool off faster at night than cities, which retain much of the heat stored in roads, buildings, and other structures
High solar reflectance is the most important characteristic of a cool roof system, helping to reflect sunlight and heat away from a building and diminish roof temperatures. A high thermal emittance also plays a role, particularly in climates that are warm and sunny. Together, these qualities help roofs to absorb less heat and stay cooler than customary, materials during peak summer weather.
Cool roofs are beneficial beyond urban heat island reduction. The benefits include:
1-Reduced energy use with cool roofs results in energy savings, especially in areas where electricity prices are high, a cool roof transfers less heat to the building below the roof, so the building stays cooler and uses less energy for air conditioning.
2-Reduced air pollution and greenhouse gas emissions are decreased by lowering energy use, decreasing the production of associated air pollution and greenhouse gas emissions.
3-Improved human health and comfort by adopting the cool roof system: Cool roofs can reduce air temperatures inside buildings with and without air conditioning, helping to prevent heat-related illnesses and deaths.
A California study found that cool roofs provide an average yearly net savings of almost 50 cents per square foot. This number includes the price premium for cool roofing products and increased heating costs in the winter as well as summertime energy savings, savings from downsizing cooling equipment, and reduced labor and material costs over time due to the longer life of cool roofs compared with conventional roofs…now that makes “cents!”