研究表明，暖通空调风管系统是工业和商业建筑的主要能耗之一。管道系统的低效设计意味着能源被浪费和/或安装了过多的管道系统材料。风管系统优化提供了实现显著节能的机会。新的管道系统优化方法，称为T方法。是ASHRAE和福陆丹尼尔公司合作研究的结果[ASHRAE 1988]。本研究活动的目的是开发实用的管道优化程序，并以ASHRAE 1985手册中的示例为参考进行经济分析。选择寿命周期成本作为目标函数。约束条件包括压力平衡、标称风管尺寸、预选风管、风速和安装限制。T法风管设计包括三个串联步骤: 系统——冷凝、风机选择和系统扩展。论文“T法风管设计，第一部分和第二部分”介绍了该方法的理论、逐步计算程序、经济分析和示例[Tsal等人，1988]。对每一步的全面解释和许多例子证实了T方法的实用性。

Studies show that HVAC air duct systems are one of the major energy consumers in industrial and commercial buildings. Inefficient design of a duct system means that either energy is being wasted and/or excessive ductwork material is being installed. Duct system optimization offers the opportunity to realize significant owning and energy savings.The new duct system optimization method, called T-Method. was developed as a result of cooperative research between ASHRAE and Fluor Daniel Corporation [ASHRAE 1988]. The purpose of this research activity was to develop a practical duct optimization procedure and conduct an economic analysis using the example in the ASHRAE 1985 Handbook as a reference. Life cycle cost is selected as the objective function. Constraints are pressure balancing, nominal duct sizes, preselected ducts, air velocity, and installation limitations. The T-Method duct design consists of three steps performed in series: system•condensing, fan selection, and system expansion. The papers "T-Method Duct Design, Part I and Part II" presents the theory of the method, step-by-step calculation procedures, economic analysis, and examples [Tsal et al. 1988]. A comprehensive explanation of each step with many examples confirm the practicality of the T-method.