Daylight and Carbon Interactions: An Explorative Method to Support Daylight-Driven Decisions Under Carbon Budget Constraints

The global construction industry contributes 37% of energy-related carbon emissions and it is mandated to achieve a 50% reduction in carbon emissions by 2030 as a crucial step towards achieving net-zero targets by the mid-century. As we strive for low-carbon buildings that align with these targets, it is imperative to ensure buildings are comfortable for their inhabitants. Daylight, valued for providing illumination and enhancing well-being, is a key component that also influences the building's carbon emissions. The existing daylight standards encourage larger glazed areas, which often results in larger solar gains in the summer and heat losses in the winter, and therefore in larger shading systems, thicker frames and multiple panes of glass. These directly influence the embodied impacts of the building, as a result of the façade's material and components choices. Yet the interactions between daylight and embodied impacts have so far largely remained overlooked in design decision-making. More specifically, there is currently no guidance on what reasonable carbon budget should be associated with daylight design choices, even though these choices may influence a building's ultimate carbon footprint at least to some extent. This study aims to uncover the relationships that (may) exist between daylight strategies and embodied impacts and to propose an explorative methodology able to support daylight-driven decisions accounting for carbon budget constraints. The method is applied to a specific case study, which further highlighted the increasing urgency of accounting for these interactions from the year 2040 onwards.