Environmental Design of Buildings

Abstract - There is a growing importance within the construction industry to minimise carbon emissions in response to the climate crisis. In 2019 operational carbon emissions from buildings made up 18% of the UK’s total emissions. A further 13% of that total related to the embodied carbon linked with the manufacturing and construction of building materials (Freeman, 2021). The UK Government has committed to reaching net zero emissions by 2050 (HM Government, 2021b). The route to meeting that target is evolving. In construction, the re- use and improvement of existing buildings - ‘Retrofit’ will play a key part in helping meet that target. Such schemes minimise embodied carbon through the re-use of existing building elements whilst reductions in operational carbon are achieved through measures to make the buildings more energy efficient. Landlords commissioning a retrofit scheme have a plethora of standards and benchmarks they could consider; some more stringent than others.

This paper considers the standards applicable in the UK, their perceived relevance and the target performance requirements associated with them. Based on feedback from a questionnaire to UK construction professionals the following standards have been modelled: Building Regulations, LETI Best and Exemplar standards and EnerPHit. Single measure works deemed from the survey to have the best value were also modelled given they could inform sporadic landlord works or relate to specific BREEAM credits. Those were photovoltaics panels, external and internal wall insulation, increased ceiling insulation and replacement light fittings. The above works were modelled in Design Builder to quantify their impact on the whole life carbon emissions at year 60 of the building’s life. These results were also considered in relation to their estimated cost to understand which standard and single measure might offer the best value. In concluding the analysis, the study acknowledges potential limitations in relation to understanding the impact wholesale measures have on internal comfort and how best to utilise early stage carbon reporting software for retrofit works.

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