Green Roofs
Type of Development
New development, Restoration
Topography
Valley, Baylands
Longevity
Short Term
Environment
Urban
Maintenance
High
Cost
Green roofs can be more expensive depending on type of development and structural capacity of buildings. Upfront costs are around $10-$25 per square foot, on-going maintenance is required. Retrofitting is often necessary. The return on investment (energy savings) is shown to be anywhere from zero to twenty years.
Overview
A green roof is an added green space to the top and/or side of buildings to decrease flooding and urban heat. Green roofs include a base layer of a waterproof membrane, drainage and filtration layers, soil, plants, and irrigation. They can be designed solely for stormwater management and urban heat control or they can be used as gardens, small farms, and educational spaces. The photosynthesis of plants reduces direct heat while evapotranspiration cools the surrounding air. Root systems and soil collect, store, use, and control rain water and reduce runoff. Plants such as succulents, short grasses, mosses, sedums, and herbs are commonly found in green roofs. There are two types of green facades– ground-based facade green walls have plants rooted in the ground and growing up trellis, while facade-based green facades are rooted in soil within the wall.
Function
Green roofs store and reuse stormwater, sequester carbon, reduce urban heat, and increase efficiency of climate control in buildings.
Benefit
Green roofs and facades lower costs of climate control systems in big office buildings and warehouses by absorbing solar radiation through photosynthesis, thus redirecting sunlight away from buildings and surrounding areas. They create cleaner air by reducing pollutants through carbon sequestration. According to nrc solutions, transforming building roofs to 80% green roofs, lower average ambient temperatures by 32.5°F and 37.4° F degrees. Indoor temperatures are reduced by 36.14°F on average. Green roofs also increase property value and the visual appeal of buildings. The many uses allow space for educational areas, small community farms, break areas, and more.
Dependency
Building material, sunlight, structural viability
Development Considerations
Green roofs are complicated and intricate. There are many development considerations to keep in mind, most importantly the structural capacity of the building's roof, filtration, water, and soil layers.
Environmental Considerations
Native plants and soil should be used. Sunlight and water requirements for plants should be considered.
Maintenance Consideration
The life expectancy of waterproof membrane is 40 years, compared to 17 years of a conventional roof. However the green roofs require regular maintenance. Maintenance is especially important during the first years of installation.
Cost Considerations
Green roofs can be more expensive depending on type of development and structural capacity of buildings. Upfront costs are around $10-$25 per square foot, on-going maintenance is required. Retrofitting is often necessary. The return on investment (energy savings) is shown to be anywhere from zero to twenty years.
