Material efficiency is not currently a common driver of building design. Indeed, in previous studies, we estimated that 12% of the mass of steel used in structural frames would be saved by more accurate specification of steel members. However, this inefficiency is not the main reason structural frames are light or heavy. We show here for the case of steel structures that it is the layout of the grid and the choice of the decking which have the largest impact on the embodied carbon of frames. Using a database of real designs, associated to a generative design model, we quantify the impact of grid and decking selections. Using our model, we find that real designs are relatively efficient economically, but less so environmentally: the typical building frame could have 40–60% less embodied carbon, and be approximately 10–20% cheaper with the right selection. We show how more complex frames have higher embodied carbon than simpler grids. From our findings, we establish a list of design considerations that architects and structural engineers should account for when creating an initial design to lower the embodied carbon: the complexity of the layout, the optimisation of the design and the choice of the decking technology.

材料效率目前不是建筑设计的常见推动力。确实，在以前的研究中，我们估计通过更精确的钢构件规格可以节省结构框架中所用钢重量的12％。但是，这种低效率不是结构框架轻或重的主要原因。对于钢结构，我们在这里表明，网格的布局和铺面的选择对框架的含碳量影响最大。使用与生成设计模型相关的实际设计数据库，我们可以量化网格和面板选择的影响。使用我们的模型，我们发现真实的设计在经济上是相对有效的，但在环境上却不那么有效：典型的建筑框架可以减少40–60％的含碳量，正确选择价格大约便宜10–20％。我们展示了更复杂的框架比简单的栅格具有更高的具体化碳。根据我们的发现，我们建立了一系列设计考虑因素，建筑师和结构工程师在创建初始设计以降低包含的碳时应考虑的事项：布局的复杂性，设计的优化以及铺面技术的选择。