Optimising sustainable investments for CO₂ reduction in construction : a decision-making model for Hegeman Holding

This research was conducted at Hegeman Holding in collaboration with CAPE and the ECOLOGIC research project. The study aims to support Hegeman in developing a cost-effective investment strategy to reduce 50% of its scope 1 and 2 CO₂ emissions by 2030, in line with the requirements from the CO₂ Performance Ladder certification and the Corporate Sustainability Reporting Directive (CSRD). A stochastic Mixed Integer Linear Programming (MILP) model was developed, combining Monte Carlo methods (MCM) and Chance Constrained Programming (CCP) to determine the optimal investment mix and timing under uncertainty. The model was applied to a case study at Hegeman, revealing that the 50% reduction target was infeasible given the current investment options, but a 45% reduction was achievable at minimal cost. The model, validated by experts, significantly outperformed simplistic approaches such as the Marginal Abatement Cost curve and heuristic methods, with cost reductions of 65.7% and 88.9%, respectively. This research contributes practically through a decision-support tool for Hegeman. The scientific contribution is the novelty of the combination of a MILP with MCM and CCP within the context of investment decision-making in the construction sector.