A new Urban Ideas Research Paper published by the Urban Taskforce titled: “Standing Tall” has been released and it finds that the construction of high rise buildings results in the lowest embedded carbon-emission when compared with other development types, such as townhouses or suburban homes. That is – the carbon footprint of the total build per dwelling (occupying the same number of people) is the lowest for high rise developments (58 storeys).

The Standing Tall report ensures that the analysis has no in-built bias and all units of analysis are comparable. Our report utilises the investigation done by USA based architects Adrian Smith + Gordon Gill Architecture (AS+GG).

AS+GG have analysed the embedded carbon (the green house gas emissions generated through the development of the building inputs and the actual construction) associated with various housing models, using standard construction materials, for enough of each building type to produce 2,000 new homes.

Their analysis compares the following different buildings: supertall, high rise, low-rise and single-family homes for their environmental impact. In particular, the designed nine hypothetical communities are: suburban home, urban home, 3-story 3 flat building, 4 story courtyard, and buildings with 16, 34, 58, 123 and 215 stories.

When comparing the various models against the following environmental indicators: land use, energy demand and life cycle carbon emissions, the most environmentally friendly dwelling type is high rise (58 stories) apartment buildings while the second-best green option came in at 34 stories.

Lending weight to the independence of the analysis, it should be noted that AS+GG are experts in designing skyscrapers and are the architects of the next world’s tallest tower (around 1km high!) in Saudi Arabia. Yet their modelling shows that “Super tall” (above 121 stories) and mega tall (213 storey) buildings are environmentally inefficient because of the need for massive foundations and supporting structural components.  There are no Super-tall or Mega tall residential buildings in Australia.

High rise apartments provide the best land use as you can fit many homes (vertically) in a relatively small plot of land. By constructing more homes per square meter of land, we can make homes more affordable. Millennials are increasingly looking to get a foot on the housing ownership ladder and they are turning to apartment living as an affordable option which is well serviced by public transport and neighbourhood amenity.  Apartments offer many a home that is close to work, cafes, restaurants and entertainment. It turns out that this trend is also good for the environment.

The Urban Taskforce “Standing Tall” report goes beyond the present and investigates what would these results mean for the cities of tomorrow. Would high rise buildings still be the greenest option for Sydney in the next couple of decades?

The answer is yes. In fact, they will be even greener than the buildings we have today.

Our analysis looks at three ways in which buildings are becoming more energy efficient and sustainable.

Firstly, the construction materials used for new structures are more sustainable and have less embedded carbon. Secondly, high rise buildings offer a lot of opportunities for using new technologies and the Internet of Things to reduce their energy demand.  Thirdly, high rise buildings will do both – produce their own energy and use more renewable energy thereby reducing their operational carbon emissions.

Buildings are increasingly likely to have renewable energy generation solutions on site. The Standing Tall report provides one example of a proposed building in Melbourne which will generate 20% of its energy requirements through the use of its ‘solar skin’ – a PV cladding that will wrap a significant part of the building. This emerging trend is likely to grow further. As seen through the recent history in the photovoltaic industry – solar panels are becoming cheaper and more efficient energy producers. Moreover, there are other ways to produce energy on site for the high rise buildings, including installing small wind turbines.

Of course, it is possible that not all high rise buildings will have energy generation or energy recovery systems on site. Even in this scenario, these structures become ‘greener’ because the energy they use will be increasingly made up of renewable sources. We have looked at the latest projections of renewable share of generation published by the Department of Industry, Science, Energy and Resources. The analysis shows that by 2030 (only 8 years away!) high rise buildings in NSW will likely be powered by a grid that generates 84% of the electricity from renewable sources. As a result, buildings will have a significantly reduced operational carbon emissions.

Considering that high rise buildings are the cleanest way forward, we must ask the question if our planning system and planning controls are designed in a way that will help Sydney achieve its aspiration of a green metropolis.

The lesson for planners and policy makers is clear.  The so-called protection of the “local character” of Sydney’s Eastern suburbs, inner west. North shore and inner south manifests in strong demand for homes pushing prices up and millennials out of the market.  Worse – this represents un un-sustainable future.  Public policy analysts and politicians would be wise to take note.