Building owners invest in green infrastructure for a variety of reasons, from boosting sustainability credentials and building ratings to showcasing brand identity. But one of the strongest drivers of interest in green roofs for commercial buildings at the moment is health and well-being.
Staff costs, including salaries and benefits, account for 85 to 90 per cent of business operating costs, which means even a modest improvement in employee health or productivity can have a huge financial implication for businesses.
Finding ways to boost health and well-being in the workplace is therefore a key focus for many organisations, and providing access to natural views and spaces is one means of doing so.
Research shows that introducing biophilic elements to the workplace, such as natural views, daylighting and vegetation, can significantly enhance productivity in the work space. For example, a 2015 study from the University of Melbourne found that individuals who took a short break from a work task to view a flowering green roof made fewer errors and were able to maintain concentration for longer than those who viewed a bare concrete area. Similarly, in the United Kingdom, researchers who compared productivity in two offices, one with natural elements and one without, found that the offices with natural elements saw a 15 per cent rise in output amongst employees after three months.
Installing green infrastructure, such as green roofs and vertical gardens, therefore, presents an amazing opportunity to improve staff health and performance in the work space.
But how do you optimise staff health and productivity outcomes from a green roof?
Research demonstrates that variety and change are crucial attributes in a garden if you want to optimise its effect on human health, cognitive functioning and productivity. Luckily, change is a natural part of gardens. It comes in a variety of forms – with the seasons and the years. Many plants change with the seasons, and all plants grow to some degree over the years and exhibit long term growth.
Variety – in texture, shape, colour, density, height – is also a feature of what many people consciously or subconsciously label a ‘natural’ garden style. Variety and diversity are indeed integral to ecology, even if in gardens their existence may reflect a considerable investment in cultivation.
What does this mean for management of a green roof?
Change and variety are not difficult to achieve, but both attributes run somewhat against the grain of conventional approaches to building management. By their nature, they require responses that adapt to specific needs which vary from plant to plant and also over the course of the year, and over several years.
A key point to keep in mind is that although change and variety require a little greater effort and skill in the management and maintenance of the green roof, they also deliver far more valuable returns. It is critical that the building owner and indeed all stakeholders in the green roof asset understand this relationship between the value of the inputs into, and outputs from, the green roof.
Here are a few tips for anyone managing change and variety on a green roof designed to achieve health and productivity outcomes:
- Anticipate variation in expenditure on maintenance as requirements fluctuate with the seasons. You will need to spend more in spring and autumn than in winter. In temperate parts of Australia, your water bill may increase in summer and decrease in winter.
- Your maintenance crew may either need to grow in size or spend longer on the roof in spring and summer. Note that access requirements will vary with the seasons.
- Ensure that maintenance is responsive to use and access of the green roof. For example, benches and seating, feature areas and walkways need to be maintained to encourage active use of the green roof.
- The maintenance crew will need to understand the design intent of the garden, and the purpose that different plants achieve. For example, species may have been selected for a sensory purpose; whether visual, textural or for scent. Maintenance needs to be responsive to this design.
- Ensure maintenance staff are aware of any key species on the roof and their expected growth cycle throughout the year.
- Communicate change which takes place in the roof garden to the building community in advance. Celebrate the natural cycle of the species, particularly any iconic species which are due to bloom or attract wildlife. This point is key! Whereas many people find unexpected changes confronting, if you communicate in advance what they can expect to see and experience on the roof garden – and what makes this interesting or exciting – you will inspire continuing interest and engagement with the roof.
Designing green roofs for variety and change
If you are not just managing a green roof, but also managing its design and construction and your desired outcomes are health and productivity, here are some ideas to consider:
- Think about the people who will use the garden and take their ages, interests and abilities into account when drawing up your design. For example, raised garden beds and hanging baskets are easier to access than garden beds at ground level, and present options for hands-on garden experiences.
- Provide seating and spaces that encourage people to pause and enjoy the space.
- Consider irregular or winding walkways through the garden. These present a more natural pattern and invite users to slow down and look around.
- Plant flowers of varying colours and consider the light conditions of the season in your plant selection. For example, white flowers look more luminous in low light, and planting bulbs helps to bring colour during the winter months. Likewise, make use of plants with different textures in your design, this adds to the sensory experience.
- Include plants with variegated leaves and mixed colour foliage and make use of contrast in your design.
- Consider planting long grasses and making use of draping canopies – this allows for plant movement in the wind and adds to both the visual and auditory experience.
- Consider installing a water feature. The look and sound of water is soothing, and may help to attract birds and other wildlife.
- Consider the view from inside the building and include interesting plant and flower displays outside windows.
Most gardens offer visual appeal, but the diversity of species and style of a garden, and the way it is managed over time, plays a huge role in the way that people engage with the garden – and in the health and productivity outcomes that result.