也许自世纪之交以来，推动美国工业快速增长和高生活水平的最大因素是丰富的低成本能源。能源消耗巨大，未来的需求将继续巨大。事实上，据预测，使用量将每十年翻一番，但我们再也负担不起能源的低效浪费。为了提高使用效率，保护现在是良好规划的一个组成部分，并且被认为在经济和技术上都是可行的。 因此，节能可能很快成为强制性措施。提高能源利用效率的可能方法的数量，以及关于这一主题的论文数量，都同样巨大。有些建议是从井口或矿井开始的，其他建议是基本的——比如晚上把恒温器调慢或离开房间时关灯；其他人再次推荐非常复杂的技术。本文讨论了一个重要领域:如何通过在废气被丢弃之前回收能量，在加热和冷却设备、燃料、维护和其他运行成本方面实现可观的节约。 引文:研讨会，ASHRAE交易，第80卷，第一部分，加利福尼亚州洛杉矶

Perhaps the greatest factor contributing since the turn of the Century to rapid industrial growth and high standard of living in the U.S. has been the availability of abundant low cost energy. Consumption of energy has been enormous, and future requirements will continue to be immense. In fact, it has been predicted that usage will double each decade, but we no longer can afford the inefficient waste of our energy resources.Conservation is now an integral part of good planning, for efficiency of usage, and is being recognized as economically and technically feasible. Energy conservation may therefore soon become compulsory. The number of possible ways to increase efficient energy use, and the number of papers on the subject, are equally large. Some proposals start at the well head or mine shaft, others are basic--like setting back the thermostat at night or turning off lights when leaving a room; others again recommend techniques of great sophistication. This paper discusses one important area: how to realize appreciable savings in heating and cooling equipment, fuel, maintenance, and other operating costs by recovering energy from exhaust air before it is thrown away.