ASHRAE研究项目590“VAV系统中的外部空气和建筑物增压控制”于1988年9月1日正式启动，目标如下:开发一种方法，最好适用于手动计算和个人计算机计算，通过该方法比较运行成本，在变风量空调系统中，各种外部空气和回风/减压空气控制方式产生的通风量和建筑物增压，并评估和比较典型的代表性系统。由于问题的复杂性，不可能开发出完全手动的方法。然而，如本报告所述，一种非常通用的个人计算机技术已成功开发。 PC程序准确地模拟了七种基本类型的VAV控制系统，并且很容易扩展到这七种主要配置中的许多子类型。

ASHRAE Research Project 590, Control of Outside Air and Building Pressurization in VAV Systems, was officially begun on September 1,1988, with the following stated objective: To develop a methodology, preferably adaptable to manual calculation and to personal computer calculations, by which to compare operating cost, ventilation air quantity and building pressurization resulting from various means of outside air and return air/relief air control in variable volume air conditioning systems, and to evaluate and compare typical representative systems. Because of the complexity of the problem, it was not possible to develop a totally manual method. However, a very versatile personal computer technique was successfully developed as detailed in this report. The PC program accurately models seven basic types of VAV control systems and is easily extended to many sub-types within each of these seven major configurations.