Abstract
Designing ventilation systems involves considerable computational effort which may be reduced via the use of a microcomputer. This article demonstrates how, by replacing the traditional row-column worksheet, a spreadsheet program may be utilized easily to perform ventilation system design. The article contains the equations and correlations necessary to define the mathematical relationships used to design a ventilation system. The equations and correlations are in forms which may be directly applied to most spreadsheet programs and may be used to develop a general ventilation template. Once this general ventilation template has been developed, it may be quickly adapted to any specific ventilation design problem.
The approach taken is to use the “velocity pressure” method of design. However, the basic concepts are applicable to use of the “equivalent foot” method. The equations are designed to minimize the manual use of psychrometric charts and tabular or graphical data. A design approach is outlined. How a spreadsheet functions is described. A sample design problem is discussed; the system layout, audit sheet, and ventilation template are included.
The use of a spreadsheet to perform ventilation system design calculations was validated in two studies. First, the results predicted by the spreadsheet model were compared to hand-calculated results given in textbook examples: on a scatter-plot, the points fell on a diagonal line of unit slope with the average error in the predicted values of -0.5 percent. Second, predicted static pressure values were compared to actual duct static pressure measurements: the average error in the predicted values was plus four percent.