The built environment accounts for 39% of global energy related CO₂ emissions, and construction generates 13% of global GDP. Recent success in reducing operational energy and the introduction of strict targets for near-zero energy buildings mean that embodied energy is becoming the dominant component of whole life energy consumption in buildings. One strategy that may be key to achieving emissions reductions is to use materials as efficiently as possible. Yet research has shown that real buildings use structural material inefficiently, with wastage in the order of 50% being common. Two plausible mechanisms are 1) that some engineers hold individual misconceptions, or 2) that inefficiency is a cultural phenomenon, whereby engineers automatically and unquestioningly repeat previous methods without assessing their true suitability. This paper presents a survey of 129 engineering practitioners that examined both culture and practice in design relating to material efficiency. The results reveal wide variations and uncertainty in both regulated and cultural behaviours. For the first time, we demonstrate that embodied energy efficiency is not a high priority, with habitual over-design resulting in more expensive buildings that consume more of our material resource than necessary. We show wide variability in measures that engineers should agree on and propose research through which these culture and individual issues might fruitfully be tackled within the timeframes required by climate science.