As urban areas become more populated, heat islands continue to grow, which worsens the effects of greenhouse gases and energy usage. Green roofs are great ways to combat heat islands and can be used in just about any building application. Below we will examine the various types of green roofs and learn about the benefits associated with this fully adaptable roofing option.
What is a Heat Island?
Heat islands are found in densely populated urban areas where the population exceeds 1 million people. They are formed when there are too many harsh infrastructure elements, such as commercial buildings and asphalt, that have replaced natural vegetation. Typically, green areas remain permeable and moist, keeping the air temperature a consistent temperature when compared to the surrounding rural areas. In heat islands, the area is no longer permeable and becomes dry, which causes temperatures to spike. During the day, temperatures in heat islands can be 1.8-5.4 degrees F hotter than surrounding areas. At night, the difference in temperature is even more striking, sometimes rising to over 22 degrees F hotter in urban areas. These spikes in temperature can be damaging causing an increase in energy demands, greenhouse gas emissions, and personal risk with an elevated risk of heat-related illnesses.
Green Roof vs. Cool Roof
Parks, open land, and vegetation can help restore the urban temperatures to a comparable level. Green roofs are great ways to introduce vegetation to urban settings. Alternatively, cool roofs have also had remarkable success reducing ambient air temperatures. Let's examine the difference and benefits of each:
● Extensive Green Roof: This type of roof requires about 2-4 inches of growing medium for plants to survive. Typically, small, hearty plants are used in extensive green roof applications. These roofs are lightweight and rarely require any additional structural elements to support the weight of the roof.
● Intensive Green Roof: Sometimes resembling more of a park atmosphere, these roofs are very complex and can incorporate trees in the design. These roofs will look more like a conventional garden but can be more costly up front. Often, additional structural support will be needed to handle the weight associated with the garden.
● Cool Roof: Certainly not interchangeable with a green roof, a cool roof uses certain reflective materials to help reflect sunlight. These materials allow the building to stay cooler. While cool roofs do not last as long as a green roof, the cost is certainly cheaper and are a great option for budget conscious building owners.
Benefits and Cost Savings
The biggest advantage to a green roof is the energy cost savings. Green roofs are able to remove the heat from the surrounding air through a process called evapotranspiration. By doing so, your energy costs will drastically decrease, saving money on cooling expenses. Green roofs act as a giant insulator for the building so people also see benefits in reduced heating costs in the winter. Additionally, green roofs are good for the environment. They increase indoor comfort by reducing the effects of heat waves and heat stress in people. Green roofs also reduce greenhouse gases, improve storm water quality through filtration, and can reduce the amount of stormwater runoff.
Green roofs are a great option for any sized building, ranging from residential homes to large industrial facilities or office buildings. At Gausman & Moore we want to do our part for the environment and are eager to implement the great benefits of green roofs into our construction projects. To learn more about our green building practices, contact us today.