As an integral component of the Climate Change Framework for Built Environment set by the Hong Kong Green Building Council, the Zero-Carbon-Ready Building Scheme has exemplified a collective dedication to mitigating carbon emissions in the building sector. This initiative marked a significant stride towards fostering a greener and sustainable built environment. With such a momentum on decarbonisation, building owners and developers are provided with myriad trade-offs in optimising cost and value to meet the life cycle carbon emissions reduction goals.

A holistic design trade-offs strategy requires a comprehensive analysis of the specific context, project goals, and local conditions as a prerequisite for informing decisions that align with the objectives of the Scheme. Striking a balance between embodied construction and operational carbon emissions over the life cycle appears to be a crucial aspect of realising the most building value. The design trade-offs strategy shall be particularly axed on the building envelope, since the envelope components are long-lasting and among the costliest of all building systems. It shall also focus on outsized impacts on energy consumption and operational carbon emissions over the buildings’ life for regulating heating and cooling loads, and enabling the integration of advanced systems required for optimal electrification.

Concretely, the strategy consists of integrating human comfort, well-being and all sustainability objectives that involve a series of innovations associated with the core trade-offs, including climate adaptability versus cost, air quality versus energy performance, shared spaces versus building floorplate efficiency, design-phase innovation versus long-term operations and maintenance, thermal performance versus embodied carbon, technological advancements and low-carbon material choices versus cost-effectiveness, and window-to-wall ratios versus operation emissions. The trade-offs drive critical design decisions that impact the building sustainability and offer frameworks for considering total carbon emissions over the life cycle.

Ultimately, the design trade-offs strategy helps identify the life-cycle carbon “sweet spots” in line with the Scheme. However, there are no optimal solutions applicable to all projects. Solutions are highly contextual, responding to constraints specific to geographic location, built environment, immediate site, occupant characteristics, existing regulatory system, and resource availability.

This article is contributed by Ir Dr Alex Gbaguidi with the coordination of the Environmental Division.