After selecting to use a green roof or cool roof the roofing contractor must look at the pros and cons of each in order to decide which would be best for the property.
Green roof and cool roof.
A cool roof prevents heat absorption by reflecting the sun s heat and then emitting its radiation back into the atmosphere.
The term green roof may also be used to indicate roofs that use some form of green technology such as a cool roof a roof with solar thermal collectors or photovoltaic panels.
Green roofs may not reflect as much as a cool roof but do have other benefits such as evapotranspiration which cools the plants and the immediate area around the plants aiding in lowering rooftop temperatures but increasing humidity naturally.
Cool roofs green roofs and pv are all excellent options for improving the environmental performance of a building.
Cool roofs reflect sunlight and heat back into the atmosphere while green roofs help absorb the sunlight and heat before it can enter the building.
Green roofs use soil and vegetation as living insulation.
Which system or combination of systems is most appropriate for an individual roof will need to be evaluated on a case by case basis.
While the term cool roof is sometimes used to describe any roofing surface that is cooler than a standard rooftop green certification programs such as leed energy star the u s.
Green roofs provide shade remove heat from the air and reduce temperatures of the roof surface and surrounding air.
Both reduce building energy use for heating and or cooling.
Cool roofs reflect solar energy.
The primary reasons for using this type of roof include managing storm water and enjoying a rooftop open space.
A green roof or rooftop garden is a vegetative layer grown on a rooftop.
Using green roofs in cities or other built environments with limited vegetation can moderate the heat island effect particularly during the day.
Moreover some green roofs need maintenance such as regular watering.
Green building council and the department of energy building technology program base their respective cool roof credentials on a roofing material s ability to reflect the sun solar reflectance and release absorbed heat emissivity.
Green roofs are ideal for urban buildings with flat or shallow pit roofs and can include anything from basic plant cover to a garden.
By doing this cool roofs allow for a more comfortable and controlled indoor environment.