When plants of different varieties are planted on rooftops to facilitate increased plant matter, their function can range from aesthetic to practical insulation or food source.
A green roof is a flat roof that may be systematically planted with, for example, varieties of sedum, moss, or grass, but also with perennials and even bushes and trees.
A green roof improves the appearance of a building, and in big cities especially, it serves as a ‘substitute garden,’ thus boosting the residential value of the property.
Planted roofs positively influence the environment through, for example:
- Plants store a large proportion of the rainwater and allow it to evaporate later on.
- Trap dust and pollutants, thus improving the quality of the air.
- In winter, a green roof acts as a heat insulation layer while it protects the interior from high temperatures in summer. The
- result of such specifics is well-tempered rooms and reduced energy costs.
- Planted roofs create living space for animal species.
- Green roofs reduce noise reflection by up to 3dB. Interior noise reduction improves by up to 8dB.
- Beautifying the built environment and increasing investment opportunity.
- Prolonging the life of waterproofing membranes, reducing associated waste.
- Decrease the amount of CO2 and other polluting by-products released into the air.
- Green roof reduced the daily energy demand for air conditioning in the summer by over 75%
Green roofs help reach the principles of smart growth and positively affect the urban environment by increasing amenity and green space and reducing community resistance to infill projects. Green roofs can serve any number of functions and uses, including:
- Community gardens (e.g., local food production or co-ops)
- Commercial space (e.g., display areas and restaurant terraces)
- Recreational space (e.g., lawn bowling and children’s playgrounds)
Increasing biodiversity can positively affect three realms:
- Ecosystem – Diverse ecosystems are better able to maintain high productivity levels during periods of environmental variation than those with fewer species.
- Economic – Stabilized ecosystems ensure the delivery of ecological goods (e.g., food, construction materials, medicinal plants) and services (e.g., maintain hydrological cycles, cleanse water and air, store and cycle nutrients)
- Social – visual and environmental diversity can positively impact the community and psychological well-being.
All three types of roofs require specific layers of roofing materials not found on regular roofs. The basic anatomy of a green roof consists of vegetation, growing medium, filter membrane, drainage layer, waterproof/root repellant layer, roofing membrane support for plantings above, thermal insulation, vapor control layer, and structural roof support.