This research examines how dynamic façade variables influence the embodied and operational carbon of mid- to high-rise residences during the early design phase, addressing growing environmental concerns from urban densification. By analysing façade design and parametric architectural strategies, the study aims to identify sustainable solutions that minimize environmental impact while complying with regulatory standards.

A combination of literature review and computational simulations was used to evaluate different façade typologies. The literature review identified common façade systems and their carbon footprints, while a case study applied this knowledge to a realistic scenario. Using parametric modelling tools such as Grasshopper, energy simulations were conducted to assess carbon impacts. An optimization process then identified the most sustainable façade configurations, highlighting key trends and design considerations.

The findings reveal that material selection, façade design, and energy efficiency significantly impact the total carbon footprint of buildings. Among the façade types analysed, aluminium unitized façades have the highest embodied carbon emissions due to the carbon-intensive nature of aluminium production. In contrast, prefabricated timber façades have the lowest embodied emissions, benefiting from a lower carbon footprint and carbon sequestration potential. Concrete façades fall in between, with their high weight contributing to greater embodied carbon despite lower emissions per kilogram. The relationship between window-to-wall ratio (WWR) and embodied carbon varies by material; a higher WWR increases emissions for aluminium and timber façades, whereas for concrete façades, it reduces embodied carbon as glass replaces carbon-intensive concrete elements.

Operational carbon emissions are highly dependent on façade orientation. North-facing façades require the most heating due to limited solar exposure, while south-facing façades benefit from passive solar heating but require more cooling. The most effective way to reduce operational carbon is by improving glazing insulation (lowering U-values), especially in colder orientations. Increasing the Rc-value of insulation has only a minor effect when WWR is high, as window heat transfer dominates. With an assumed 2% annual improvement in energy efficiency and grid decarbonization over a 75-year lifespan, operational carbon emissions are expected to decrease by 50%, making embodied carbon an increasingly dominant factor.

Considering both embodied and operational emissions, timber façades emerge as the most sustainable option, particularly when paired with optimized glazing and insulation values. Aluminium façades have the highest total carbon footprint, with embodied emissions accounting for nearly half of the total impact even in efficient configurations. Concrete façades present a unique trend, where reducing WWR can sometimes increase total emissions due to the high embodied carbon of concrete relative to glazing. These results emphasize the need for an integrated approach to façade design, balancing material selection, insulation levels, glazing performance, and orientation to minimize total carbon impact.

This study acknowledges several limitations, including reliance on a single simulation program, uncertainties in future energy grid decarbonization, and a limited range of material and façade options. Future research should explore additional materials, occupant behaviour models, and renewable energy integration to enhance sustainability assessments. Further validation using multiple simulation methods, diverse climate models, and broader material databases would improve reliability and deepen understanding of façade performance across different environmental contexts.