This is the first in a series of thought-leadership pieces, where we explore practical solutions in the quest to reaching a net-zero carbon state in the shortest possible time.

Words by Jutta Berns, Ecocentric

How to Net Zero
the role of science-based targets in meeting net-zero pledges in building operations

Zero on the rise

After the signing of the 2015 Paris Climate Accord, the October 2018 IPCC Report (IPCC, 2018) finally and irrevocably shook the world out of its fossil fuel induced slumber: it was clear that to stand any chance of keeping the global average temperature rise to below 1.5°C during this century and to avoid the most catastrophic impacts on the planet, net-zero CO2 emissions by 2050 must be achieved. Fast forward to August 2021 and the release of the 6th IPCC Assessment Report (IPCC, 2021) further finds that “unless there are immediate, rapid and large-scale reductions in greenhouse gas emissions, limiting warming to close to 1.5°C or even 2°C will be beyond reach.”

Since the 2018 IPCC report, the number of companies making net-zero commitments has grown exponentially: in 2019, 16% of the global economy by GDP had net-zero pledges in place. By 2021 this had grown to 68% (UNFCC, 2021).
Where zero is now on everyone’s lips, the built environment sector as a whole – as one of the key contributors to carbon emissions and thus one of the key-stone actors in reducing emissions – is no newcomer to the net-zero game. A drive to net zero has increasingly come to the forefront of thinking over the past decade and a half (see box below); but regardless of all the activities, the December 2020 Global Status Report for Buildings and Construction Report (UNEP, 2020) rings alarm bells: global findings show that CO2 emissions from the operation of buildings have increased to their highest level yet at around 10 GtCO2, or 28% of total global energy-related CO2 emissions. This is dire – and sobering.

So, what is going on? Don’t we have targets? Or do we simply not know how to get there?

Here is the crux: not all net-zero targets are created equal. The meaning of net zero and the way to get to get there is often ambiguous. Having a net-zero pledge in place is of course imperative, because we need everyone to come to the party; such pledges are also ambitious, because we are only just starting to understand how we are going to meet them; and they also may be audacious, where such pledges rely purely on “technological salvation” at a distant point in the future, while emitting unabatedly in the meantime.
As small as it is, net zero is big.

So, what to do? To achieve net-zero in existing building operations, we are advocating two key strategies that go together:

  1. Align net-zero targets to science-based targets
  2. Break down whole building targets into targets by emissions scope

In the first instance, setting clearly verifiable net-zero targets is paramount: align near-term and long-term targets both to climate science and to reporting in line with established reporting frameworks, such as the GHG Protocol Corporate Standard (GHG Protocol, 2004). Guidance developed by the Science-Based Targets initiative (SBTi) (a partnership between CDP, the United Nations Global Compact, World Resources Institute (WRI) and the World Wide Fund for Nature) provides such clear pathways for businesses.

The criteria embedded within SBTi’s science-based net-zero targets require that emissions in the abatement boundary for net-zero targets (Scopes 1, 2, and 3 ) be reduced by an amount that is consistent with achieving global net zero in 1.5°C-aligned scenarios. In other words, if gross global emissions are to be lowered by 90% to keep warming below 1.5°C, a company must set a net-zero target to reduce emissions by 90% between the base year and the net-zero target year. Once science-based targets are set for each scope, it becomes clear how and at what rate companies need to reduce emissions to meet the climate targets.

Net zero is the ultimate zero-sum game – we are either only winners or only losers.

Based on SBTi Net-Zero Manual & Criteria, v1.0 for public consultation, September 2021.

Secondly, what this means in the context of the built environment – and specifically for building operations – is that we must set near-term and long-term science-based reductions targets across each of the emission scopes (Scope 1, 2 and 3). In commercial real estate it is Scope 3 that comprises the lion-share of total emissions, easily amounting to 80% and more. Once unpacked further, it is evident that emissions related to tenant activity (specifically electricity consumption) makes up around 95% of Scope 3 emissions. This in effect means that we can use electricity consumption as a proxy for emissions. This is significant and points to two main strategies:

  1. Firstly, we need to understand what portion of electricity is really under tenant control and what is under landlord control. This will help inform emissions reduction strategies for tenant spaces, as well as building and portfolio-specific emissions.
  2. Secondly, ensure that there is ongoing and close cooperation between landlord and tenants to establish how Scope 3 tenant electricity emissions should be reduced. Green leases as well as tenant fit-out criteria and house rules provide some of the powerful mechanisms that help to bed down shared net-zero targets and can remove traditional barriers between landlord and tenant. While this is a challenge, it also presents a significant opportunity to inspire radical collaboration across the value chain to help tenants decarbonise.

Aligning to both the SBTi’s (SBTi, 2021) and the WorldGBC’s (World GBC, 2021) guidance on net-zero buildings, we can map out a clear pathway to net zero, which will include reducing near-term and long-term emissions across all scopes and neutralising emission in the transition phase. The built environment may just stand a chance to be a significant contributor to a climate positive future.


UNEP. (2020). 2020 Global Status Report for Buildings and Construction: Towards a Zero-emission, Efficient and Resilient Buildings and Construction Sector. Nairobi: UNEP.
IPCC. (2021). Climate Change 2021: The Physical Science Basis. Contribution of Working Group I to the Sixth Assessment Report of the Intergovernmental Panel on Climate Change [eds Masson-Delmotte, V., et al.] Cambridge University Press. In Press
IPCC. (2018). Global warming of 1.5°C. An IPCC Special Report on the impacts of global warming of 1.5°C above pre-industrial levels and related global greenhouse gas emission pathways, in the context of strengthening the global response to the threat of climate change, sustainable development, and efforts to eradicate poverty. [eds Masson-Delmotte, V., et al.] In Press .
Architecture 2030. (2006). Retrieved from
World Green Building Council. (2017). From Thousands to Billions – Coordinated Action towards 100% Net-Zero Carbon Buildings By 2050. WorldGBC.
GBCSA. (2019). Net-Zero / Net Positive Technical Manual.
ASHRAE SA. (2020). A Guide to Developing Net-Zero Carbon Buildings in South Africa.
C40 Cities. (2018). Net-Zero Carbon Buildings Declaration: Planned Actions to Deliver Commitments.
UNFCC. (2021, April 19). The Race to Zero strengthens and clarifies campaign criteria. Retrieved from
GHG Protocol. (2004). Greenhouse Gas Protocol Corporate Standard. Retrieved from
SBTi. (2021). The SBTi Net-Zero Manual & Criteria, V1 for public consultation, September 2021. SBTi.
WorldGBC. (2021). WorldGBC Net-Zero Carbon Buildings Commitment, Introduction: Businesses and Organisation, September 2021. World Green Building Council.