The Development of Nomographs Into Mathematical Functions

Abstract This study was initiated to develop a quick, accurate evaluation of the energy usage and demand of hospitals. The computer programs that were available to facilitate such energy studies required more time, accuracy and data than was available in the project scope (i.e. an industrial type of overall energy audit) to perform a long-term energy analysis. The thoroughness required of a comprehensive study of such a complex facility could not, however, be sacrificed for the sake of a quick, expedient solution. A compromise solution that is both accurate and quick was found in the series of nomographs produced by an exhaustive study by the Federal Programs Office of the U.S. Department of Energy. This report, dated June 1, 1979, is entitled, “Architects and Engineers Guide to Energy Conservation in Existing Buildings.” Pertinent nomographs from this report were converted into mathematical functions. These, in turn, were assimilated into a seamless stand alone database application, complete with data entry screens, pull down menus, help messages and data entry screening. The result is an effective, user friendly software program that is simple enough to be used by contractors, but with the accuracy and input variability required of professional energy auditors. The weather data bases includes over four hundred U.S. stations and several hundred international locations, to include bin analysis capabilities at each. The cumulative result of the equations itemized herein, when used for a building analysis, is a consistent match to actual metered energy usage data. This was proven on a dozen comprehensive hospital energy audits, for which over $10 million in actual energy conservation projects were proved. These were done for the Texas Loan Star program using oil overcharge money. There is strong confidence by users of this software that the values this application of nomographs produces are accurate and trustworthy. The calculations are performed quickly and easily enough that many iterations can be done — in the time taken to do a single run on competing software — to evaluation many interrelated project costs and paybacks.