Wendes Systems, Inc. was founded by Herbert C. Wendes PE who authored an estimating instructional manual designed to assist HVAC Sheet Metal Estimators in the methodology for preparing thorough and accurate HVAC sheet metal labor and material cost estimates.The manual contained a logical step-by-step approach for producing HVAC sheet metal estimates.The detailed unit labor cost data contained in his manual was derived from more than twenty five years of labor studies conducted by Herbert C.Wendes during his career in the HVAC industry. The studies included the various steps in the process for manufacturing and installing HVAC sheet metal ductwork in commercial buildings.Herbert C. Wendes was invited by trade associations and independent companies to conduct workshops throughout North America instructing estimators in the principles detailed in the instructional manual.
During 1980 many of the labor calculations and formulas contained in the instructional manual were converted to program language for use with a hand calculator. With the introduction of the IBM XT computer the mathematical formulas for producing labor and material cost were then programed for the DOS operating system and have become more detailed and sophisticated with advancements in computer technology.