Publication
Existing daylight standards encourage larger glazed areas, which often results in larger solar gains in the summer and heat losses in the winter. To avoid these, shadings, thicker frames and multiple panes of glass are required to respect operational energy targets. These imperatives in turn influence the embodied carbon of the building. Yet the performance trade-offs between daylight and embodied carbon have so far largely remained overlooked in existing research. More specifically, there is currently no guidance on what reasonable carbon budget should be associated with façade and its components. The present study thus aims to 1) reveal how whole life carbon is affected by improving daylight and 2) define carbon budgets at the façade and its components level. In this paper, an explorative method is proposed and its potential to achieve the study's aims is illustrated through its application to a specific case study. Based on the analysis of 9000 design alternatives, increasing spatial daylight autonomy by 24 % in carbon-intensive facades made of concrete and brick can reduce the embodied carbon by 15 % and 10 % respectively. In contrast, the same daylight improvement in low-carbon façade alternatives made of timber would instead, increase whole life carbon by 65 % for the case study considered. The method also offers prospective insights: for the chosen case study, achieving a well daylit space will be increasingly challenging after 2040, due to a substantial reduction in the façade carbon budget by 2040, which is projected to be nearly half of what it is today.