The Carbon Value Engineering project aims to maximise the reduction of embodied carbon in the built environment. Rather than proposing a new process for these reductions, it adapts the industry-standard practice of value engineering (VE) for integrated carbon and cost minimisation. The project set out to answer two research questions:
- What is the impact of value engineering in its current form on building embodied carbon, and life-cycle carbon emissions?
- To what extent can the process of value engineering be adapted to maximise the reduction of embodied and life-cycle carbon emissions early in the design phase while also securing economic value?
In the first stage of this research (Embodied Carbon and Capital Cost Impact of Current Value Engineering Practices: A Case Study) the authors determined that the traditional VE processes driven only by cost can reduce building embodied carbon emissions through dematerialisation. However, such reductions were small, with VE strategies applied to a case study building reducing material costs by 0.72%, and initial embodied carbon by 1.26% (6.67 kgCO2-e/m2) within a cradle-to-gate framework.
In this final report, the authors demonstrate how considering cost and carbon simultaneously during VE can yield significant carbon and cost reductions at a late design stage, without fundamentally changing the building design (form, orientation, planning, etc).
The research presents a Carbon Value Engineering framework. This is a quantitative value analysis method, which not only estimates cost but also considers the carbon impact of alternative design solutions. It is primarily concerned with reducing cost and carbon impacts of developed design projects; that is, projects where the design is already a completed to a stage where a Bill of Quantity (BoQ) is available, material quantities are known, and technical understanding of the building is developed.
This framework is tested by exploring the same case study building as before. This time, a number of alternative design solutions are tested and their embodied carbon and capital cost calculated. This research demonstrates that adopting this integrated carbon and cost method was able to reduce embodied carbon emissions by 63-267 kgCO2-e/m2 (8-36%) when maintaining a concrete frame, and 72-427 kgCO2-e/m2 (10-57%) when switching to a more novel whole timber frame. With a GFA of 43,229 m2 these savings equate to an overall reduction of embodied carbon in the order of 2,723 – 18,459 tonnes of CO2-e. Costs savings for both alternatives were in the order of $127/m2 which equates to a 10% reduction in capital cost.
For comparison purposes the case study was also tested with a high-performance façade. This reduced lifecycle carbon emissions in the order of 255 kgCO2-e/m2, over 50 years, but at an additional capital cost, due to the extra materials. What this means is strategies to reduce embodied carbon even late in the design stage can provide carbon savings comparable, and even greater than, more traditional strategies to reduce operational emissions over a building’s effective life.