In designs and ASHRAE code documents, we are now striving to maximize the performance of the building's HVAC systems. This means going beyond equipment efficiency to systems' operational efficiency. The target of these improvements is the lowering of pump and fan energy usage and optimization of plant control. When modeling these operational improvements,the saying certainly applies, "if you can't measure it, you can't count it."

In this paper, the author explores water-side design and its' effect on pumping energy. Three of the major computer simulation programs used by design engineers are reviewed and compared with lab tests and building data. None of these programs currently offer a way to model improvements to the pumping system operation. This paper draws from previous ASHRAE papers and articles concerning low delta-t and control valve selection to present a method of using the models to measure system improvement, thus allowing us to count the savings.