From the manufacturing of building materials and construction, operation and maintenance, through to dismantling and recycling – CO2 is produced at every stage of a structure’s use cycle. The construction sector is directly or indirectly responsible for almost half of all global CO2 emissions, and as a consequence, has many touchpoints where reducing CO2 can be addressed. Research and design play an important role in creating more CO2-efficient materials, building-use and resource recovery.
To accelerate a shift in material production and use toward a regenerative pathway, Forrest Meggers, Professor in the School of Architecture and Andlinger Center for Energy & Environment at Princeton University (USA) contributed to the LafargeHolcim Roundtable in preparation for the 6th International LafargeHolcim Forum “Re-materializing Construction”. He asserted the importance of the development and exploitation of the concept of exergy and unique heat transfer mechanisms that facilitate novel architecture, improve comfort and performance, and support new building sensors and control.
Multiplying CO2 reductions through many pathways
Building operations are a significant source of CO2. Heating buildings emits about 20% of all human-generated CO2 and most of these emissions are produced in the northern hemisphere. Though this is in large part a question of which sources are used to supply energy, it is also a material question (at least until a total shift is made to renewable, non-harmful energy sources). Putting thermal mass to use, insulating, or even reflecting upon thermal comfort standards (wearing a sweater is easier than renovating a facade) may all be pathways to reducing the CO2 output from heating through buildings. Cooling buildings currently produces comparatively less CO2 than heating but is expected to increase.
Building material production is also a significant source of CO2 emissions. Cement production releases 5-7% of all anthropogenic CO2 emissions. Steel for construction may represent another 5% of CO2 emissions. These represent significant areas for improvement – through both a reduction in the emissions generated per tonne of material produced, and through more efficient use of building materials. Reducing CO2 output needs to be balanced with improving resource efficiency.
Strategies to re-materialize construction
As the key input to the Forum, the publication 22 Propositions offers strategies for both the material supply chain and material use in buildings. The propositions aim to “re-materialize” construction by rethinking the building material cycle from extraction to processing, design, transport, installation, maintenance, and removal.
The changes proposed would contribute to a construction industry with a smaller ecological footprint and a shift away from the unsustainable assumption that raw construction uses significant amounts of material. Rethinking materials and material use also has tremendous potential to lower greenhouse gas emissions and reduce dependence on resource extraction.
The Materials Book to be published by Ruby Press Berlin in late 2019 will feature the essence of 22 Propositions as well as a selection of additional proposals to re-materialize construction derived from the findings of the Forum.