The benefits of green roofs are well-known by now, but how do we create truly great ones?

First, let’s be clear about how you can tell when a garden is a green roof. Put plainly, a green roof is a garden on a roof. Some green roofs are integrated into the very structure of the building and extend from edge to edge, while others use more superficial structures. The key points about them are that they are gardens, they are supported by engineered structures and they are on buildings.

Green roof technology can also be applied to balconies. For all intents and purposes, balcony gardens are also green “roofs” as they are gardens supported by engineered structures on a building.

So what is a great green roof?

This may sound obvious, but it is critically important. A great green roof is a green roof which delivers value in the eyes of its owner or owners. This means that, at a bare minimum, it serves the purpose for which money is invested in it.

Why do people invest in green roofs?

Rather than focusing on why people should invest in green roofs, it is more logical to look at why people do invest in green roofs. In different places, people invest in green roofs for different reasons. Looking specifically at Australia, we at Do it on the Roof have identified more than 40 reasons why people create green roofs in Australia. Top reasons include, in roughly this order, the desire to:

  1. Create beauty
  2. Attract talent to workplaces
  3. Blend in with the surrounding landscape
  4. Increase productivity
  5. Increase the value of the real estate
  6. Create an oasis in an entertainment area
  7. Improve the amenity of an outlook so as to obtain planning approval
  8. Reduce the demand for air conditioning in the floor below or a room overlooking the roof
  9. Improve the performance of solar panels
  10. Grow produce for the benefit of the community in the building.

How might these drivers change?

Of course, the reasons people create green roofs in Australia change over time. In our assessment, attracting talent to workplaces and increasing productivity are growing in popularity as reasons for creating green roofs in Australia. This is partly because productivity has a huge effect on the financial health of any business, and partly because rating tools such as GRESBE and WELL are leading building owners and managers to focus on the performance of buildings, not just their design and construction. Included in performance is social performance.

Green roof

Green roof in Docklands, Melbourne
Image via Do it on the Roof

To a lesser extent, increasing the value of real estate and improving the amenity of an outlook so as to obtain planning approval are also growing in popularity as reasons for creating green roofs in Australia. Investors have really only recently, and in relatively small numbers, grown aware of the relationship between green roofs and real estate value, and between green roofs and amenity of outlook. Expect these two drivers to exercise greater influence in future.

Beauty will probably remain the number one reason why people think about creating green roofs. Human beings crave beauty. That’s why beauty sells. When it comes to green roofs, some investors are reticent to admit that creating beauty is a factor in their desire for a green roof, but as the connection between creating natural beauty and attracting talent and increasing productivity and cognitive functioning become more widely known, expect investors to grow bolder in declaring their desire to create natural beauty on their buildings.

The desire to blend in with the surrounding landscape is declining in relative popularity as a reason for creating green roofs in Australia. In our analysis, this is not because the desire itself has declined, but rather, because of a relative increase in the desire to create green roofs in cities, as opposed to rural or natural settings. The desire to blend in the surrounding landscape rarely catalyses the creation of a green roof on a city building, but we are starting to encounter a related desire to support biodiversity playing a role in decisions to invest in green roofs.

Reducing the demand for air conditioning on the floor below a green roof, and improving the performance of solar panels are emerging as growth drivers for green roofs in Australia. Familiarity with these infrastructural functions of green roofs is embryonic, but with several projects underway for these very reasons, we are likely soon to witness change.

The desire to grow produce within striking distance of the workplace or home is perennial, but rarely the chief reason for investing in a green roof. Until a better business model emerges for a commercial rooftop farm in Australia, we do not expect this desire to dominate reasons why people create green roofs. However, the romantic appeal of growing produce is not likely to disappear, and having some capacity to produce food is likely to remain a common subsidiary purpose of many green roofs.

The point is, Australian green roofs may serve one or more of many purposes. But a great green roof delivers value from its owner’s perspective: it serves the specific purpose for which money is invested in it. It is essential to be clear that the purpose of a green roof must correlate to the reason for investment. It is the job of the designer get this right, and it is the job of the installer to ensure it is installed as designed. But it is the job of the green roof maintenance crew, and whoever manages the maintenance crew, such as the facility manager of large buildings, to grow the value of the asset so that it realises its potential and fulfils the purpose for which money is invested.

What role do maintenance crews and facility managers play in great green roofs?

A crucial point is that at the date of installation, a green roof is a basic asset. At this point in time green roofs are rarely, if ever, capable of fully serving the purpose for which money is invested in them.

Green Roof

Where green roofs are concerned, the roles of the maintenance crew and facility manager are not to maintain the status quo, but rather to grow the value of the asset. And just what represents value varies from roof to roof, so the first information facility managers and maintenance crews absolutely must obtain is the reason the owners have invested in the green roof and the purposes of the green roof.

Having obtained these fundamental facts, green roof maintenance crews and managers next need to know the technical functions by which the green roof will fulfil its purpose. But this is a story for another day.