Life cycle based climate regulations for buildings

QC 20241108

Abstract

Accounting for 37% of global CO2 emissions in 2023, buildings and the constructionsector’s contribution to climate change is now well documented and acknowledged. Theneed to reduce these emissions is emphasised and increasingly reflected in regulation.Scholars have advocated for the use of life cycle based regulatory mechanisms to reducebuildings’ greenhouse gas emissions (GHGe), especially in relation to national andglobal climate goals. In the past decades, raising awareness have led to the developmentof life cycle based regulations in Europe. In parallel, research have been directed toinvestigate the trade-offs between operational and embodied GHGe. However, littleattention has been given to the investigation of trade-offs between upfront and futureembodied GHGe. This means that potential different practical steering effects whenconsidering upfront only or jointly with future embodied GHGe in regulatoryperformance requirements need further investigation. Besides, a common feature ofthese preparatory works is the focus on new-build while research and policy work onassessing renovation project is still at its infancy. This leads to question potentialmethodological challenges and related practical implications in implementing climateregulations for renovation projects in a similar fashion as for new-build.Therefore, this licentiate thesis has the aim of investigating the effect in practice of lifecycle based climate regulations regarding embodied GHGe from new buildings’ usestage, and renovation of existing buildings. In response to this aim, quantitative analysesusing GHGe assessments based on the EU standard EN 15978:2011 are performed onreal cases of new-build and on one real renovation project case. The GHGe assessmentsperformed are following three Nordic countries’ life cycle based methods andapproaches for climate regulations in the form of climate declarations and limit values(preliminary for renovation projects).A first point of investigation concerns if, how and why different system boundaries forlife cycle based GHGe assessment lead to differences in practical steering effects.Assessment of embodied GHGe for new-build is of focus, to analyse practical effects ofclimate regulations with limit values regarding building envelope design. A comparativeanalysis on a sample of Swedish real new-build cases of apartment, office and schoolbuildings is performed, based on GHGe assessment results for two different systemboundaries (SBs). The two SBs differ in how embodied GHGe are included in thecalculations, between upfront and future GHGe. Results show buildings’ capacity torespect suggested Swedish limit values does not differ between the two SBs. Further,results suggest that the choice of system boundary would have very limited impact onthe choice of building envelope materials in the context of respecting a climate limit.Consequently, the choice of SB is not expected to lead to different overall steeringeffects on envelope building design in the current context and practice for calculatingclimate impact in a life cycle perspective. This thesis discusses the applicability of theseresults to other contexts and the practical relevance of considering recurring embodiedGHGe in regulatory performance requirements.A second point of investigation concerns the method-related challenges of GHGeassessment for building renovation projects, in the context of life cycle based climateregulations and their practical implications. The Swedish, Finish and Danish preliminaryapproaches for GHGe assessments in climate regulations for renovation projects, asunderstood in January 2023, are applied on a real renovation project. The renovationconcerns a Danish apartment building from the 1970s. The results show that for this casestudy, renovation leads to less GHGe than demolishing and building new regardless ofwhich of the three approaches to calculating GHGe is applied. However, methodologicaldifferences regarding the inclusion of existing building products and biogenic carbon orconsideration of operational GHGe lead to differences in results. This thesis discusseshow this can impact decision processes based on GHGe assessments in climateregulations for renovation projects especially regarding renovation versus new-build orreuse practices. The benefits of better visualization of when in time GHGe take placeare also highlighted.This study concludes in suggesting that introducing a limit value on upfront GHGe canbe a first and important step to effectively and rapidly address GHGe from new-build.Similarly, initially introducing climate declarations for upfront embodied GHGe forrenovation projects is the least practically complex while still most effective approachto address current GHGe. Including embodied future GHGe in climate declarationscould raise awareness on the impact of design and a first step towards better consideringthe emissions associated with the future life of the building. Developing climateregulations for renovation projects show potential in incentivizing reuse practices andrenovation rather than demolition and building new. However, this also depends onmethodological choices such as the inclusion of the existing building products,operational energy or biogenic carbon.This study, however, also points to the shortcomings of current methods for modellingfuture emissions to effectively steer towards considering building products ‘life span anddesign for adaptability, disassembly or reuse. Finally, based on the result of the study, itis advisable to better visualize when in time GHG are emitted in climate declarations forboth new-build and renovation projects. This can improve the understanding on theorigin, type and timing of GHGe and differentiate verifiable calculations for currentGHGe from future scenario-based GHGe calculations and related inherent uncertainty.To conclude, this thesis reveals shortcomings regarding current methodologicalapproaches of life cycle based GHGe assessment regarding embodied GHGe from newbuildings’ use stage and renovation of existing buildings. These shortcomings hinderlife cycle based climate regulations’ ability to promote climate reduction strategies theyare expected to steer. Additionally, this thesis emphasizes the importance of carefullyconsidering which incentives are to and can be promoted, and the practical complexitiesinvolved when designing calculation methodologies for these regulations.

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