The push towards sustainability in the built environment has turned the building industry on its head. This evolution has seen the Australian green building industry blossom from a niche sector focusing on single dwellings to a mainstream industry encompassing large-scale projects, communities and entire cities.
Although many sustainability initiatives lie beneath the visible surface of a project, one of the more conspicuous results of this movement is the use of plants in multi-residential projects. Increasingly, plants are being incorporated into builds to create a healthy, tranquil and enjoyable space for residents.
According to the CEO of the Green Building Council of Australia, Romilly Madew, architects are using plants in their projects both internally and externally in a variety of ways.
“Green walls are being used in building interiors and on external façades, and plants are being used to create lush interior oases [as well as] on roofs to combat the heat island effect,” she explains.
Green roofs and walls have been found to reduce what is known as the ‘Urban Heat Island Effect’, whereby an urban area is significantly warmer than the surrounding areas. This is due to human modification of land surfaces that results in sunlight being converted into heat. This heat is then stored and released, raising local temperatures.
This effect has been demonstrated in research by Melbourne City Council. While looking into the heat island effect, the council found that average temperatures within Melbourne's CBD are up to 4°C higher than in surrounding suburbs. In some instances, the recorded difference is a massive 12°C higher during the evenings.
A study by the University of Melbourne found that rooftop gardens are effective at combatting over-heating within the urban context. At the same time, the use of air conditioning can be cut by up to 38 percent in buildings that have rooftop gardens installed.
“External green walls can reduce the urban heat island effect and enhance a building’s façade, while reducing the surface temperature of walls. [By shading] windows, [it can also] limit solar gains and, [subsequently], the need for artificial cooling,” explains Madew.
Another recognised benefit of using plants in both the internal and external elements of buildings is to improve the physical and mental health of a building’s occupants.
Research undertaken by the University of Technology Sydney found that certain plants are able to ‘scrub’ many of the Volatile Organic Compounds (VOCs) from the air. Not only does this clean breathable air, it also decreases carbon dioxide levels, increases oxygen levels and adds to the comfort levels within a building.
“Because plants are not naturally found indoors, they work hard to survive in their artificial environment,” says Madew.
“In the process, the plant system – leaves, roots and potting media – absorb VOCs from the air and convert them into less harmful substances which can be stored or broken down in the soil.”
The use of plants also has benefits for mental wellbeing. Research shows that people feel happier and more productive in spaces with plants, because they connect them with nature.
“Introducing plants into your building is one way to make it more sustainable, healthy and attractive to building occupants,” Madew says.
While there is plenty of literature on how green roofs, walls or façades provide ongoing savings in energy usage, there is very little published research dealing with how they effect property values.
However, there was a Canadian study that estimated buildings with a recreational green roof can achieve up to an 11 per cent increase in value, while buildings with views onto green roofs were found to have a 4.5 per cent increase in their value.
PUTTING IT INTO PRACTICE: ONE CENTRAL PARK, SYDNEY
One Central Park in Sydney is touted as “Australia’s greenest urban village”. The structure stands out from a mile off, characterised by rooftop gardens, green walls and smart-metering systems.
The two residential towers, built around Chippendale Green, achieved a 5-star Green Star rating for design and construction. More than just a surface-level addition, sustainability is integral to One Central Park’s design.
One Central Park has transformed a previously forgotten corner of Sydney’s CBD into a sustainability showcase, featuring stunning vertical gardens, heliostat, on-site water recycling and thermal tri-generation plants.
Frasers Property Australia and Sekisui House used the Green Star rating system to benchmark its design initiatives against best practice and beyond.
The most eye-catching sustainable innovation of the project is the 120-metre vertical garden enveloped by 35,000 plants. Designed by French botanist Patrick Blanc, the green walls – some 1,120 square metres in total– are fed hydroponically.
Frasers Property Australia’s general manager for sustainability, Paolo Bevilacqua, says the green wall is “truly integrated” into One Central Park’s concept, and has delivered a range of co-benefits.
He lists improvements to air quality, plants as carbon sinks, the psychological and productivity impacts on workers, increased retail spend, and enhanced biodiversity. Bevilacqua says vertical walls often attract new bird species, reduce the urban heat island effect, minimise water runoff and improve building efficiency.