The main conclusions of an analysis of low-CO 2 , eco-efficient cement-based materials, carried out by a multi-stakeholder working group initiated by the United Nations Environment Program Sustainable Building and Climate Initiative (UNEP-SBCI) are presented, based on the white papers published in this special issue.

We believe that Portland-based cement approaches will dominate in the near future due to economies of scale, levels of process optimisation, availability of raw materials and market confidence. Two product-based approaches can deliver substantial additional reductions in their global CO 2 emissions, reducing the need for costly investment in carbon capture and storage (CCS) over the next 20–30 years:

1. Increased use of low-CO 2 supplements (SCMs) as partial replacements for Portland cement clinker. 2. More efficient use of Portland cement clinker in mortars and concretes.

However, other emerging technologies could also play an important role in emissions mitigation in the longer term, and thus merit further investigation.