Benefits of roof gardens extend well beyond the visuals. Join us as we explore how these green retreats can impact our cities.
Green space within cities is now widely recognised as a way to enhance air quality and reduce overall heat. But a lack of space and very high land prices makes it difficult to increase the number of parks and natural spaces. This is where rooftop gardens come into the picture, and become a staple in new development schemes.
Rooftop gardens look stunning, offer unparalleled views and provide an efficient and attractive way to enjoy a quiet retreat in the heart of the city. Such is their significance they have grown to become the defining feature of new developments in London. But beyond the visual impact, there are a variety of other advantages to including them in our cities.
Roof gardens benefit tenants
Rooftop gardens have become a highly desirable feature for city dwellers, in both residential and commercial buildings. They provide an oasis of green in an area where it can otherwise be sparse. They give people a much-desired connection with nature. There are many benefits to having access to green space. From reduced stress levels through to attracting top talent to your offices. We have explored these benefits in greater detail here.
Reports continue to show that access to green space is one the most sought after features of a residential or office move. Such desirability enables building owners to charge premiums for buildings with extensive rooftop landscapes.
Combating the UHI effect
All green spaces, rooftop gardens included, positively affect the Urban Heat Island (UHI) effect.
The UHI concept is based on the increased temperatures found in urban areas. This is because the sun’s rays warm up concrete faster than grass, trees and natural surfaces. With the amount of concrete and other hard surfaces concentrated in urban spaces, the city becomes a hot spot (a heat island) all year round. Look at a heat map of England and you will notice the increased heat around the major cities. This in turn results in increased demand for air conditioners and other cooling technologies.
The effect reduces the more green spaces we incorporate into the city. This is especially as the rooftop garden will be covering what would otherwise be a concrete roof – one of the main culprits of the UHI itself.
Of course, a single green roof is not going to make a huge difference on it’s own. But numbers of them across the city, combined with other green spaces, can have a noticeably positive impact.
Effective use of rainwater
Rain is a free resource we get from the environment, and rooftop gardens are perfect in making effective use of it. Planting makes use of this water immediately, and sometimes excess is stored for later use in dry spells. During summer periods, rooftop gardens can retain up to 80% of rainfall whilst in winter this can be up to 40%. After this water has been utilised, it is returned to the atmosphere through the plants natural processes.
This also has the effective of decreasing the water run-off from the building, reducing the impact this may have on the city and the possibility of flooding.
Roof Gardens boost energy efficiency
Another of the benefits of roof gardens is that they lead to less and more efficient use of energy. They provide great insulation, retaining heat in winter and keeping temperatures cool in the summer.
A study by the National Research Centre of Canada reported that roof terraces can modify temperature fluctuations and moderate heat flow through the roof. This has the resulting benefit of reducing the demand for heating and air conditioning in the building, saving both energy and money.
Benefits for urban wildlife
Aside from the variety of plant species that rooftop gardens can sustain, they also provide the perfect habitat for birds and wildlife species. Interestingly, London is home to a wide spectrum of birds. Across the span of a year over 300 different species have been detected, and London also has the second highest urban population of Peregrine Falcons in the world. Rooftop landscapes have also been recorded providing a temporary stopover location for migrating species.
As well encouraging effective energy, rooftop gardens are also great insulators against noise pollution. The combination of soil and plants can help to absorb, reflect or deflect sound waves, particularly for low-frequency sounds. This provides a building with improved noise reduction, which could be greatly beneficial for city dwellers, who are often located near busy roads, airports or flight paths.
Extended building lifespans
A combination of the above benefits of roof gardens mean they are potentially effective in helping materials and technologies in the building last longer. This can include the protection of roofing and waterproofing finishes and the decreased use of heating, ventilation and air conditioning systems. Such systems will also require less maintenance as a result.
Create a growing culture
‘Edible gardens’ have become another recent trend enabled by rooftop spaces. This environmentally friendly and booming initiative, sometimes known as ‘urban agriculture’, involves growing fresh produce in city environments. Rooftop and podium landscapes are ideal for facilitating these community allotments, and provide the benefits of being outdoors amid nature.
Grow-your-own areas are also emerging in commercial office buildings too, such as the edible rooftop gardens we have recently installed at Bloom Clerkenwell.