Urban Rooftop Garden Benefits
Living in an urban area can be an enjoyable experience in terms of culture, employment opportunities and public transportation. However, the infrastructure has not been particularly conducive to agricultural aspirations… until now. The trend of gardening within urban properties is looking up… to the tops of roofs. Urban roof gardens are starting to become a staple in many cities for reasons beyond the peaceful serenity a lush landscape of green can bring. Studies have shown that rooftop gardens can have a great impact on the conservation of energy. This can best be explained through the concept of how the sun creates an urban heat island:
- Solar radiation warms up concrete, asphalt and other man-made materials much faster than it warms trees, plants, and greenery.
- This results in urban environments becoming surrounded year-round by a large zone of hot air – a heat island.
During the spring and summer months, the urban heat island affects cities to sweltering levels, forcing air conditioners and other cooling equipment to work harder and longer. The resulting surge in energy demand puts a vast strain on electrical grids and can send energy bills sky high. Fortunately, a green roof system can ease this burden:
- It has been measured that an exposed roof within an urban heat island can get as hot as 160 degrees Fahrenheit on a sunny day, whereas an identical roof, when covered by a green, shady garden, stays anywhere from 65 to 85 degrees cooler.
- Through this “eco roof” cooling effect, a typical 2-3 story building could save 15-25% in energy costs.
Longer Roof Preservation
Throughout the year, most roofs experience a wide disparity in temperature as they are exposed to a diverse range of climate including sun, wind, snow and rain. This causes the roof membrane to shrink in cooler weather and expand in hot weather, which shortens its lifespan. However, a rooftop garden, by drastically reducing temperatures, helps roofs last 30 to 50 years longer. Plus, the amount of money saved by not needing to replace a roof is much more than the cost of installing a rooftop garden.
Another important green roof benefit is the positive effect it can have on the environment from managing stormwater to reducing air pollution. Through the garden’s absorption of rainwater, it acts as a filter by decreasing surface runoff. This helps keep water supplies freer of regular stormwater pollutants, while simultaneously easing the burden on local storm sewer systems. Green roofs also facilitate the decrease of polluting air particles and compounds through the process of respiration. Plants and flowers also produce oxygen through photosynthesis, allowing urban property owners and developers to breathe a fresh sigh of relief with the addition of a rooftop garden.
-Nicole Roa, Program Underwriter for Urban Real Estate