Definition and methods for the carbon handprint of buildings 8.2.2021 Authors: Tarja Häkkinen [email protected] Sylviane Nibel [email protected] Harpa Birgisdottir [email protected] 2 Table of contents 1 Background ..................................................................................................................... 4 2 Objectives........................................................................................................................ 7 3 Methods and execution of work ...................................................................................... 8 Study of literature ................................................................................................................... 8 Study of possible handprint cases for buildings ..................................................................... 9 Study of relevant standards .................................................................................................. 10 4 Study of literature.......................................................................................................... 11 Definitions and approaches .................................................................................................. 11 Handprint thinking................................................................................................................ 13 Needs and barriers for the handprint concept ..................................................................... 14 Measures that improve carbon handprint ........................................................................... 15 Absolute and relative carbon handprints, carbon neutrality and compensations ............... 16 Calculation methods and assessment approaches ............................................................... 18 Concluding remarks for Section 4 ......................................................................................... 20 5 Alternatives for climate benefits regarding buildings ..................................................... 22 Carbon sequestration and long-term storage in wooden products ...................................... 22 Carbonation of concrete ....................................................................................................... 30 Carbon capture in the manufacture of building products .................................................... 32 Carbon uptake through photosynthesis by trees and vegetation and accumulation of soil organic carbon ...................................................................................................................... 34 Surplus energy / energy positivity ........................................................................................ 37 Offering space for systems that supply renewable energy for others ................................. 42 Versatility .............................................................................................................................. 45 Flexibility / Adaptability ........................................................................................................ 48 Easy disassembly enabling easy recycling or reuse of components and elements............... 50 Recycling and reuse of components and elements .............................................................. 54 New technologies - Photobioreactors (artificial or enhanced photosynthesis) and DAC systems ... 57 Different kinds of improvements that lower others’ carbon footprint ................................. 60 Compensating actions .......................................................................................................... 64 3 6 Viewpoints from LCA experts ......................................................................................... 68 General feedback on the concept of handprint .................................................................... 69 Specific feedback on the list of handprints ........................................................................... 70 7 Discussion...................................................................................................................... 74 Carbon sequestration and long-term storage in wooden building products ........................ 74 Carbonation of concrete ....................................................................................................... 75 Carbon capture ..................................................................................................................... 75 Carbon uptake through photosynthesis by trees and vegetation and accumulation of soil organic carbon ...................................................................................................................... 76 Surplus energy ...................................................................................................................... 76 Versatility .............................................................................................................................. 77 Flexibility/adaptability .......................................................................................................... 77 Easy disassembly .................................................................................................................. 78 Recycling and reuse of components and elements .............................................................. 78 New low-carbon solutions and doing good for others ......................................................... 79 Compensating actions .......................................................................................................... 80 8 Maturity assessment ..................................................................................................... 81 9 Conclusions and policy recommendations...................................................................... 84 Carbon handprint and carbon footprint ............................................................................... 84 Carbon handprint in relation to benchmarks for buildings .................................................. 84 Manufacturers’ carbon handprint ........................................................................................ 84 Aspects of building performance as handprints ................................................................... 85 Carbon storage in wooden products as handprint ............................................................... 85 Compensating actions as handprints .................................................................................... 85 Carbon accumulation in soil and vegetation as handprint ................................................... 85 Summary of recommendations ............................................................................................ 86 References ....................................................................................................................... 87 4 1 Background Assessment of climate impacts of buildings through life cycle assessment – or whole life car- bon assessment - is gaining more attention in Europe. France has already implemented those requirements for new buildings and renovation through voluntary carbon-related labels. France will also publish soon an energy and carbon regulation for new buildings with LCA- based carbon thresholds (applicable from mid-2021). The Nordic Council of Ministers have initiated a work for Nordic harmonization of building regulations concerning climate emis- sions (Nordic co-operation, 2020). Finland is preparing new legislation to promote low-car- bon building. The target is that life-cycle-based carbon footprint regulations are applicable by 2025. In May 2020, Denmark launched a voluntary sustainability class for buildings1, which also has been announced to become obligatory requirements in the building code in 2022. The voluntary sustainability class includes requirements for conducting LCA, but still without reference values. To inspire the construction industry for rapid product development, the opportunity to apply the carbon handprint concept alongside the footprint concept has also come up for discus- sion. The first version of the Finnish “Method for the whole life carbon assessment of buildings” defines that carbon handprint refers to climate benefits that can be achieved during the life cycle of a building and could not be created without a construction project (Kuittinen, 2019). In Finland, the planned assessment method considers the potential benefits – called the carbon handprint - in addition to carbon footprint. The issue of carbon handprint has raised much discussion in Finland. However, it is not the case in the French context, excepted for exported energy, and the term of “handprint” is not known. The use of handprint has not as such been discussed either in relation to the definition of the Danish LCA methodology for buildings for the voluntary sustainability class. However, some of the subjects that could be covered by handprint are either partly included or some ideas for how to include them in the future have been discussed. To apply the handprint approach, common definitions and clear rules for the assessment would be needed to ensure equal treatment of different building projects and correct com- parison of alternatives. The carbon handprint should also be quantifiable, and its assessment should be possible in typical construction projects. The target of this study was to collect information about potential climate benefits and discuss