Zero is Hero

By Mary Anne Constable

First published in Green Economy Journal

The Green Building Council South Africa (GBCSA) presented a compelling case for creating net zero buildings at their annual Green Building Convention in October 2018. This requires a huge mindset shift in the building industry and a deeper understanding of what it really means to be net zero.  

It’s widely-known that buildings world-wide contribute to around a third of carbon emissions through their construction and operation, and consume half the planet’s energy and resources. While over the last 11 years, the GBCSA’s green star rating tools have completely transformed the “conventional” building model for many property developers, it’s become clear that building “green” is not enough. More needs to be done.

Net zero energy buildings have zero net energy consumption which means the amount of energy consumed by the building on an annual basis is equal to the amount of renewable energy generated on site. It’s about bringing the balance between consumption and production down to zero, and this same concept can also be applied to other resources such as water, treating of waste, and environmental impact.

Convention 2018, keynote speaker and American environmentalist Paul Hawken’s message was that achieving net zero is “a threshold and not an endpoint”. It is the moment where we stop to pause, take our foot off the gas, and rethink before taking our next move. We now need to move beyond net zero and swing the pendulum in the opposite (positive) direction.

Following in the footsteps of the World Green Building Council’s global Advancing Net Zero project, the GBCSA is promoting and supporting the acceleration of all new buildings to be net zero carbon (energy) by 2030, and all buildings by 2050. So far, four of South Africa’s major cities – Johannesburg, Cape Town, Tshwane and eThekwini – have joined the pledge to achieve net zero carbon buildings under the C40 Cities South Africa Building’s Programme. It’s essential that cities are involved in developing net zero policies to guide development on an urban and building scale. The GBCSA also encouraged the private property sector to pledge to achieve these net zero goals across their building portfolios, and several projects have already been certified under the four new Net Zero/Net Positive rating tools, while more are in the pipeline.

To some, implementing net zero may seem impossible, but the key is efficiency as a starting point. Architect Robert Pena explained that “efficiency is energy”. When it comes to providing renewable energy on site for example, there is often not enough space (on the roof or elsewhere) to provide enough solar panels for a “conventional” building’s energy needs. The solution: bring down the building’s energy usage to match what can be generated. In practice, this reveals a (sometimes large) gap between the energy consumption of even a green building and the amount of energy able to be generated. Thus, net zero buildings are being asked to achieve an unprecedented high level of energy efficiency. Yet in the space of the unknown, innovation happens.

Chilu Lombe from Solid Green said that “solving the energy efficiency gap is where the business case is [for net zero]”. This is where we need to show that making a building highly energy efficient does not have to be an expensive exercise. One major change that will likely be seen going forward, for example, is how buildings are ventilated. Air-conditioning is a major consumer of energy and often unnecessary or at least oversubscribed in buildings. Edward Garrod from Integral Group is a strong contender for natural ventilation and believes that all buildings should be “breathable” – it’s all about the design of the building’s skin. The best part is that natural ventilation, in contrast to air-conditioning, is free. Recent statistics from the IPD South Africa Annual Green Property Index for 2017 show that green star certified buildings outperform similar uncertified buildings by 3.8%. Occupants are healthier, more productive and buildings are more consistently tenanted.

So as cities grapple with the challenge of developing strong net zero policies as they race towards the 2030 goal and built environment professionals innovate to achieve ever increasing levels of efficiency, the net zero concept will become more and more commonplace, until…the pendulum begins to swing in the right direction and we begin to regenerate, rebuild and heal our world. Next year’s convention will continue to push the envelope by going beyond buildings, to how we shape sustainable cities.