The terms ‘sustainability’, ‘energy efficiency’, ‘green building’ and ‘carbon footprint’, appear in most articles and publications of late dealing with the building and construction industries. The Green Building Council has been formed (the Steel Construction Industry is represented by Dr Hennie de Clercq), and SANS 204 ‘Energy efficiency in naturally ventilated buildings’ is being finalised and will be published before the end of the year. A number of local and overseas seminars and conferences are focussed on these topics. It is clear that sustainability will be a fundamental consideration and design requirement in the very near future – and not in a fuzzy ‘tree hugging’ sense, but rather to comply with specific requirements of the National Building Regulations – the building law of the country. Sustainability with regard to buildings is essentially based on three criteria: social acceptability, affordability and energy efficiency.