Benefits Of Green Roofs
The installation of a green roof (or wall) can prove beneficial in a range of ways, both ecologically and financially.
Ecological benefits of green roofs
There are many ecological benefits when creating a green roof. The benefits are usually increased with greater substrate depths - the benefits associated with installing shallower, extensive green roofs are on the whole far more modest than those offered by intensive ones due to the smaller range of vegetation that can be grown, the reduction of water retention and many other factors.
- Lower carbon footprint due to reduced heating and air conditioning demand. This is achieved by adding mass and thermal resistance value.
- As green roofs and walls reflect less solar radiation and absorb less heat than regular roofs and walls, they have the effect of reducing the urban heat island effect. Urban heat island effect decreases air quality and increases the production of pollutants such as ozone. It all also decreases water quality as warmer waters flow into area streams and put tress on their ecosystems.
- Creation of habitats for animals and insects. Green roofs cool and humidify the surrounding air, creating a beneficial microclimate in urban areas. Planted roofs and walls can compensate for ‘green’ areas lost in building development, often making a big difference in planning permission approval, especially in green zones.
- Absorption of carbon dioxide and pollutants. The vegetation in green roofs bind dust and toxic particles helping to filter out smog. Nitrates and other harmful materials are absorbed by the plants and within the substrate filtering out these pollutants and heavy metals. This also helps improve local air quality, which can benefit both humans and animals.
- In the case of intensive green roofs it may also be possible to grow food or crops.
- Water management. Depending on the green roof design, the immediate water run-off can be reduced considerably, by up to 90%. This has been proven to greatly reduce stress on drainage systems and in turn localised flooding. This can help your rainwater management system, greatly reducing construction costs.
- Noise protection. Plants and trees provide natural sound insulation; they can reduce reflective sound by up to 8 dB. They have been proven very effective in noisy areas.
- Green roofs can help ensure that new developments are designed to adapt to climate change.
- The ecological and environmental benefits outlined above are usually increased with greater substrate depths - the benefits associated with installing shallower, extensive green roofs are on the whole far more modest than those offered by intensive ones due to the smaller range of vegetation that can be grown.
Another important benefit offered by the intensive variety of green roof is the possibility of using the roof space (in the case of flat roofs with safe roof access) for leisure activities, such as gardening.
Financial benefits of green roofs
There are several practical, business-scenario benefits to green roofs. Among other things new rebates and tax deductions crop up that could help ease the financial burden. Green roofs can help community and state costs, a study completed by researchers at the University of Michigan found that greening 10% of Chicago roofs would result in public health benefits of between $29.2 and $111 million, due to cleaner air. Whilst this doesn’t help in individual project costs, the economic benefits of green roofs to our government will most likely only become more apparent as further studies are taken into consideration.
The financial benefits to the individual project are as follows:
- Potentially reduced energy bills for both heating and cooling, as green roofs and walls insulate buildings from sunlight and cold air (though the exact amount saved is unknown.)
- Potential increase in property value. Due to the nature of a green roof and their aesthetic qualities.
- It has been suggested that the lifespan of the building’s roof and walls can be increased (in some cases, doubled). This is due to the protection from temperature differentials and the resulting expansion and contraction that normally shortens a roof’s lifespan. They also provide protection from severe weather damage.
- The presence of green roofs and walls in business premises will also present a positive image to customers and boost a company’s green credentials.
- It has also been suggested that in temperate climates green roofs can reduce the risk of fire (though this view has been contested.)