Urgent action needed on net zero buildings, warn WBCSD and Arup ahead of COP28

Despite the UN goal for buildings completed after 2030 to be net zero operationally, the report shows that there is not one national policy requiring buildings to produce net zero emissions now or in the future. Buildings in operation are currently responsible for around 28% of global energy-related carbon emissions.

The report maps the landscape of emerging policies and certification systems around the world, and shows a route towards a common framework for net zero operational buildings globally. It examines the buildings themselves and the energy that supplies them, highlighting that net zero buildings must use clean energy and be sufficiently energy efficient to align that use with the wider energy grid transition in their location.

Authors warn that without major progress, the built environment will be unable to reach the UN 2030 built environment breakthrough goal – which stipulates that all new and refurbished buildings completed from 2030 should be net zero carbon in operation.

The WBCSD and Arup are calling for an internationally agreed definition for net zero buildings, to help stimulate more robust national and local government policies and industry standards. They call for a greater distinction between net zero enabled buildings and buildings that are verifiably net zero operationally.

For a building to be classed as net zero, authors say clear principles must be established for its energy demand and how it is supplied. These are:

• Have reduced its energy demand sufficiently to be consistent with the transition to 100% renewable energy for the market in which it operates;

• Be capable of operating on 100% renewable energy sources (electricity/thermal);

• Purchase 100% renewable energy through a tariff or Power Purchase Agreement that is demonstrably additional to national renewable obligations;

• In emerging markets where the above is not feasible, purchase carbon offsets to a recognised international standard would be an alternative means of achieving operational net-zero in the short term while transitioning toward net-zero.

The report also calls out examples around the world of buildings using innovative solutions to make sure they are truly net zero operationally, such as:

• The Bullitt Center in Seattle, Washington, USA: uses all electric reversible heat pumps, exchanging thermal energy between the building and 120 metres underground to radiantly heat the building in the winter and cool it in the summer. Its roof holds a large array of photovoltaic solar panels, producing 230 MWh of electricity per year, helping the building sell excess electricity to the grid in the summer.

• The Ridge, Cape Town, South Africa: provides heating and cooling through a combination of mechanical air conditioning equipment such as heat pumps, passive cooling and natural ventilation. These take advantage of the climate and optimise the amount of sunlight that penetrates the building through a ‘zigzag façade’.

Net Zero Operational Buildings: State of the Art is part of a series of reports examining how to make progress and achieve global consistency on the journey to net zero in the built environment.

Previous editions highlighted the significant issue of embodied carbon in the built environment, estimating that less than 1% of building projects calculate and report their full carbon footprint, and showing the way to halve these emissions.