From cities to suburbs, green roofs are growing across America. More than just a modern design feature, green roofs offer a wealth of benefits to the environment – and to an owner’s wallet.
Modern technology with ancient roots
Green roofs may sound like a trendy new concept, but evidence of the building practice can be traced back thousands of years (the Hanging Gardens of Babylon, for example, were actually a system of green roofs thought to be built around 600 B.C.)
Although green roofs are becoming especially popular in dense, urban environments for their sustainability features and public appeal, they have been a prevalent home feature across Europe for centuries.
So, what is a green roof?
A green roof, or living roof, generally incorporates a system of layers that include waterproofing, drainage, soil and growing vegetation.
Image courtesy of Earth Pledge
Depending on the structure the green roof is being built on, green roofs can either be intensive or extensive:
An intensive green roof is heavier, more expensive and more complex than its counterpart. Intensive green roofs feature additional layers of protection and deeper soil to sustain a wider variety of plants; therefore, they usually require professional irrigation and maintenance. Abundant in New York City, Chicago and London, intensive and semi-intensive green roofs are built most often on top of city buildings, where they can act as functional parks and gardens in the sky.
An extensive green roof, on the other hand, is composed of shallow soil and light vegetation, like mosses and sedums, that can survive without deep root systems. Extensive green roofs are the ideal choice for homeowners, since they are cheaper to install and require little-to-no upkeep.
Benefits of a green roof:
- Reduced heating and cooling costs: A properly built green roof provides an extra layer of insulation that will help a home retain its warmth in the winter. It can even save you up to 25% on cooling bills during the summer months.
- Storm water management: The greenery atop a living roof can retain up to 90% of the precipitation that falls on it, which reduces the amount of runoff during heavy rain and naturally filters it so the water is cleaner when it reaches the drain.
- Improved air quality: The plants on a green roof absorb all kinds of air pollutants, from CO2 to noxious gases, and they release cleaner air for residents below to breathe.
- Home for wildlife: Both extensive and intensive green roofs can be designed with specific flora and fauna that attracts wildlife, such as rare birds and butterflies. City buildings with intensive green roofs are often home to a multitude of creatures that would otherwise not be able to survive in urban environments.
- Reduced UHI (Urban Heat Island) effect: Green roofs are essential in metropolitan areas to reduce high city temperatures (the UHI effect). The UHI effect is a common occurrence in cities, where previously permeable, natural surfaces are overrun with impermeable, dry materials (such as concrete and steel structures).
- New, usable space: From a garden to a vegetable patch to a full-blown park, green roofs can be anything an owner wants them to be.
Big or small, intensive or extensive, green roofs provide lots of environmental and economic advantages to the buildings – and people – beneath.