A Sustainable View from the Top

How green roofs and rooftop gardens can make the most of your space

Each year in Australia, offices, retail spaces and educational institutions account for close to 40 per cent of energy consumption and are significant contributors to greenhouse gas emissions, playing a role in the environmental damage being experienced by urban centres. One way to accommodate the increasing environmental strain being place on urban centres is to better utilise all available spaces to improve well being and maximise the benefits experienced by building owners, occupants, and neighbouring communities.

Undeveloped rooftop space accounts for some of the most underutilised outdoor space in urban centres, and happens to be one of the largest heat generators. When concentrated, this heat has a negative impact on the surrounding communities and the environment as a whole, placing strain on a building or a neighbourhood’s energy and drainage systems.

Green roofs, through their conscious design, absorb rainwater, reduce storm water runoff and preserve clean water, decrease local air temperatures, and reduce the heat island effects experienced in urban areas. Green roofs are also capable of reducing heat loss is the winter and energy consumption used for cooling in the summer months. As well, green roofs and their counterparts, rooftop gardens, can provide considerable private and public benefits, both short and long term, in the areas of aesthetics and cost savings, and result in positive returns on investments.

Rooftop gardens serve as one of the easiest and most cost effective environmental adaptation strategies for homes and businesses today, and arguably offer the greatest benefit maximised for the greatest number of people.

Green roofs are quickly establishing themselves as a successful and effective green building solution. Green roofs are technical systems that exist over a conventional roof comprised of layers of insulation, drainage and vegetation that are becoming more popular and have been accommodated by many local governments, by changes to building standards and by-laws. In the US where there are an increasing number of green roofs and rooftop gardens, demand for air conditioning decreased 75 per cent in the summer months. Green roofs and rooftop gardens improve air quality, insulate from noise pollution and increase a building’s ability to achieve green certifications, all while substantially preserving the roof’s lifespan and decreasing the requirements of HVAC systems.

Builders can consult certified professionals to custom design and build rooftop gardens and establish green roof capabilities (both modular and fixed) once they have considered all the variables that are required to ensure that environmental targets are achieved. When considering a green roof, time and analysis must be taken to ensure the slope and load capacity of the existing roof will support this green project build. As well, there must be a review of the building’s existing drainage system, electrical and water supplies and the potential for the current roof’s materials to ensure a successful design and build.

Green roofs exist in two forms, intensive and extensive, and are typically comprised of six to seven layers of materials. The costs vary in relation to which type of green roof is being built, generally ranging in price from $15-25 per square foot.

The categorisation of green roofs as intensive or extensive depends on the level of accessibility and levels of maintenance required, as well as the type of plant life it can sustain (this varies according to climate, soil depth, load capacity, slope and irrigation capacities). Intensive green roofs are characterised by their ability to grow large plants and trees as they boast larger planting depths, a solid system of irrigation and a strong, flat foundation which may have initially require additional engineering to ensure load capacity is met. These roofs serve the same function as parks and other community spaces; they are designed for human enjoyment. They require regular maintenance and this maintenance is generally quite labour intensive, designed to facilitate easy access to their elaborate gardens with a strong emphasis on aesthetic value, from the layout to the choice of plants and foliage.

Extensive roofs, by comparison, are designed to require far less maintenance and thus decrease the demand for labour intensity. These spaces are designed to be self-sustaining and are not typically reserved for recreational uses. They can exist on roofs with slopes up to 33 degrees. As a result, extensive roofs are more cost effective and require less complex systems of fertilisation and irrigation. Plants that are chosen for extensive green roofs are traditionally self-sufficient, hearty and drought tolerant, such as grasses, mosses and self-seeding flora. Wildflowers are also a good choice for these growing conditions.

Although green roofs require a substantial financial commitment upfront to achieve their environmental ends, these roofs will end up being paid off in no time, while significantly contributing to a space’s value and output. Green roofs improve the quality of life and business by consciously improving a building’s aesthetic value and overall functional efficiency, increasing the marketability of the building’s profile through the creation of an adaptable built environment which makes the space a more attractive place for residents, employees, customers, clients and future investment.

Green roofs are typically designed with a sophisticated water management system, decreasing storm water runoff and recycling water in order to maintain the gardens efficiently, decreasing maintenance costs and reducing strain on sewage systems. Indeed, during the summer months, green roofs can retain 70 to 90 per cent of water in the substrate and 25 to 40 per cent in the winter months. The gardens, through their dew and evaporation cycles, can have a cooling effect, especially when used to absorb light energy that would have otherwise been converted into heat.

Such living roofs have astounding benefits for the environment but also for all those who enjoy spending time outdoors. There is a significant improvement in terms of air quality and in turn decreased episodes of smog and extreme heat – mitigated when the hottest surfaces in the urban environment are covered, in this case by carefully planned natural materials. The plants and design of the gardens serve as a filter for dust, airborne particulate matter and noxious gases. The green roofs provide quality insulation, and the improved roof will offer security in terms of durability and increased fire retardation.

By simply investing in the built environment in urban centres, converting unused rooftop space to achieve far reaching benefits, flow-on increases can be attained made in sales, lease outs, property value, efficiency, and overall health and wellbeing. These new spaces provide an environment in which new employment opportunities are created and can serve as a community hub, increasing social cohesion and empowerment and improving overall public safety. Whether these new amenity spaces are used to serve as community gardens (which extend nutritional and educational benefits), new commercial or consumer space, or simply recreational space, there are clear private and public benefits from these environmental design adaptations.

In order to reap the many benefits of green roofs, which can help any project on its way to green certification, simply consult a certified professional to help plan and customise a rooftop garden or green roof that will meet your unique environmental demands, such as regional climate and current rooftop design, in order to create new spaces for new opportunities to grow.

Home Automation

Call it ‘domotics,’ and you are likely to receive a blank stare, but refer to it as ‘smart home’ or ‘home automation,’ and you will get a nod of acknowledgement. For the past few years, consumers have heard the word ‘smart’ attached to countless products and services, from food and drink to snacks like popcorn and mobile phones, which no one seems to refer to as a ‘cellphone’ anymore. Yet what, exactly, constitutes ‘smart’?

August 18, 2022, 8:29 PM AEST