Assessment methods as a basis for mitigation actions
Climate Exp0 impressively showed the intensity and diversity of efforts to secure the natural basis of life for the future by reducing man-made greenhouse gas emissions. There are many initiatives in a wide variety of fields of action, declarations of intention and proposed solutions. To ensure that this is going in the right direction, it is necessary to quantify and monitor the efforts and the success of reducing environmental impacts. This applies to greenhouse gas emissions and other environmental impacts which threaten life on earth. To this end, the provision and use of suitable methods is of great importance. Using the example of buildings, we will briefly explain how this is done.
The manufacturing of construction products, as well as the operation of buildings, account for about 40% of global greenhouse gas emissions when viewed across sectors. This highlights the importance of buildings as a key area in addressing climate change. Of this 40%, three-fourths can be attributed to the direct and indirect emissions from buildings operation and one-fourth to the manufacturing of construction products which constitute an input not only to new buildings’ construction, but also to the maintenance and refurbishment of existing buildings.
In the case of new highly energy-efficient buildings, depending on the type of building (residential or non-residential) and climate zone, the share attributed to manufacturing and processing of construction products needed for realising and maintaining these buildings, the so-called ‘embodied greenhouse gas emissions’, usually escalates to more than 50% of all greenhouse gas emissions occurring in their life cycle. When refurbishing existing buildings, part of the embodied emissions can be transferred to a second life cycle through the continued use of components, thus relieving the burden on the environment.
But can we be sure that we will not cause more greenhouse gas emissions with new buildings and refurbishments than we can avoid later through energy-efficient operation? What about the environmental payback period? Only the development and provision of methodological principles, data and calculation tools can provide an answer to this. Furthermore, the consideration of environmental aspects beyond greenhouse gas emissions, such as radioactive waste, particulate matter, biodiversity losses caused by land use and resource use, is indispensable to ensure that no undesirable side effects occur elsewhere.
Many national governments, especially in Europe, are currently discussing the introduction of legal requirements to limit greenhouse gas emissions over the entire life cycle of buildings. For this purpose, in addition to addressing still open methodological questions, reliable and legally binding benchmarks and target values are required, to wit now. Buildings that we construct or refurbish today will still be part of the building stock in 2030, 2040 and even 2050 — and they should be climate-neutral by then. (Net) zero emissions in operation are achievable with technologies available today, but we should not forget the embodied emissions share. These emissions are immediately charged to our remaining budget. They need to be reduced to net zero well before 2050.
The ongoing international project IEA EBC Annex 72 which focuses on assessing life cycle-related environmental impacts caused by buildings deals with such questions in the form of an international cooperation with experts from 25 countries. It broadens the scope of the successfully completed IEA EBC Annex 57 project by looking at the full life cycle of buildings and addressing a broader scope of environmental impacts in addition to primary energy and greenhouse gas emissions. The purpose is to offer methodological rules and recommendations, as well as practical solutions, that will help countries and institutions to further develop their climate protection programs. A sound scientific basis is not only a prerequisite for the calculation, assessment and eventual reduction of greenhouse gas emissions, but also for trust and credibility. Preliminary results are already available, while the final reports will be published in 2022.
You can also find the work of some of the Annex 72 experts in a recent Special Issue of Buildings & Cities. If you are interested in learning more about our work, view our presentation on demand “New mitigation solutions in construction: use case for assessment methods” (Authors: Lützkendorf, T.; Frischknecht, R.; Balouktsi, M.; Röck, M.; Houlihan Wiberg, A.; Satola, D.; Passer, A.; Birgisdottir, H.; Nygaard Rasmussen, F. ; Chae, C. ; Palaniappan, S.) via the Climate Exp0 website.
A second presentation by us titled “Defining (net) zero greenhouse gas emissions buildings: a key mitigation pathway” (Authors: Houlihan Wiberg, A ; Satola, D ; Lützkendorf, T ; Balouktsi, M ; Frischknecht, R ; Gustavsen, A) can also be found at Climate Exp0’s Media Library.
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