Operational Stories

New HKUST Building Aims for Less than 500 kgCO2 per Square Meter 

We typically think of building electricity consumption as the primary source of greenhouse emissions, but in fact, the construction phase itself can be responsible for up to half of the overall emissions during a building’s lifespan. This is because concrete and steel – two primary materials in buildings – emit significant amounts of carbon as they are manufactured. These emissions are referred to as embodied carbon.  

Embodied carbon is under Scope 3 of Greenhouse Gas Protocol framework. This relates to life cycle assessment (LCA) stages A1 to A5 from raw material extraction of building materials to on-site construction activities.  

As part of the Hong Kong Green Building Council’s Climate Change Framework for Built Environment, the “Upfront Embodied Carbon Certification” will benchmark embodied carbon by using an intensity metric (kg of embodied carbon for every square meter of space) for different building types. Documentation will be verified for compliance to either a self-determined embodied carbon baseline or absolute embodied carbon baseline referencing international baselines and local examples, with a reduction target of 40% by 2030 and zero upfront embodied carbon by 2050. LCA stages A1 to A5 of superstructure should be inclusive.  

For HKUST, embodied carbon relates to our scope 3 carbon emissions under capital goods. In the new Martin Ka Shing Lee Innovation Building under construction, steel reinforcement bar or rebar is expected to contribute 50 to 60% of the embodied carbon. These emissions can be reduced significantly by investing in the use of recycled steel for Rebar produced in electric arc furnaces (instead of coal-powered blast furnaces), which cuts emissions roughly in half.  This green procurement practice meets the building’s technical performance, complies with regulations and has no timeline implications. 

While more expensive, this green rebar actually saves money for the university. How is this? To align with the University’s Net-Zero commitment, the Innovation Building will require an accompanying purchase of Carbon Offsets to neutralize the carbon dioxide emitted in the production of materials and construction of the building (embodied carbon). The additional cost of green rebar is actually less than the cost of purchasing carbon offsets to cover the emissions of “brown” rebar.  

Together with green concrete which makes up 30 to 35% of embodied carbon, the Innovation Building is expected to be one of Hong Kong’s lowest embodied carbon buildings at less than 500 kg CO2-e/m2 for the raw material supply, transport and manufacturing portion of the building constructed above the ground level or otherwise defined as the product stage of superstructure works. This is more than 30% less than the Hong Kong Green Building Council’s absolute embodied carbon baseline for non-residential buildings.  

Scheduled for completion in 2025, the project is expected to continue to track and refine its embodied carbon calculations during the construction stage.