Energy-efficiency classes provide coarse but easy-to-process information designed to help complex decisions. However, they are multi-attribute indices, imprecisely related to the running costs of graded products. Here we evaluate the impact of adding simple but accurate yearly or lifetime energy cost information to the European Union energy label. We conduct a field experiment with an online retailer of energy-using durables, measuring customers’ (n = 126,614) search and purchases of refrigerators. Providing precise energy costs leads to purchasing products with lower prices and in lower energy-efficiency classes, but with similar overall energy and total costs. Furthermore, information provision lengthens product search among buyers, with more attention paid to low energy class products. These results highlight that the use of energy classes involves a trade-off between short-term economic savings and higher search cost. By drawing attention away from energy costs, energy-efficiency classes might not be adequate in the context of a fair and transparent climate transition.

能效等级提供粗略但易于处理的信息，旨在帮助做出复杂的决策。然而，它们是多属性指数，与分级产品的运行成本不精确相关。在这里，我们评估了在欧盟能源标签中添加简单但准确的年度或终生能源成本信息的影响。我们与一家能源耐用品在线零售商进行了现场实验，测量客户的 ( n = 126,614) 搜索和购买冰箱。提供精确的能源成本会导致购买价格更低、能效等级更低的产品，但总体能源和总成本相似。此外，信息提供延长了买家对产品的搜索，更多地关注低能耗产品。这些结果突出表明，能源类别的使用涉及短期经济节约和更高搜索成本之间的权衡。通过将注意力从能源成本上转移开，在公平和透明的气候转型背景下，能源效率等级可能不够。