Purpose: The purpose of this paper is to identify and compare cost and carbon critical elements of two office buildings, and to help achieve an optimum balance between the capital cost (CC) and embodied carbon (EC) of buildings. Design/methodology/approach: Case study approach was employed to study cost and carbon critical elements of two office buildings as it allows an in-depth and holistic investigation. Elemental estimates of CC and EC were prepared from BoQs of the two buildings by obtaining rates from the UK Building Blackbook. Pareto principle (80:20 rule) was used to identify carbon and cost critical elements of the two buildings, and the significance hierarchies of building elements were compared. Findings: Substructure, frame and services were identified as both carbon and cost critical elements responsible for more than 70 per cent of the total CC and EC of both buildings. Stairs and ramps, internal doors and fittings, furnishings and equipment were identified to be the least carbon- and cost-significant elements contributing less than 2 per cent of total CC and EC in both buildings. The hierarchy of cost and carbon significance varies between buildings due to the difference in the specification and design. Originality/value: The increasing significance of dual currency (cost and carbon) demands cost and carbon management during the early stages of projects. Hence, this paper suggests that focusing on carbon and cost-intensive building elements is a way forward to keep both cost and carbon under control during the early stages of projects.