Ventilation System Economic Calculator

Here is a simple tool you can use to evaluate & compare economic performance between two different ventilation systems. The program accepts basic building, site, and system operation information as input, and shows the difference in operating cost between the two systems as output. The program uses simplified energy use calculations only, and does not account for possible differences in ventilation system effectiveness, variations in natural ventilation rate, occupant lifestyle, maintenance (or lack thereof), etc., etc. The calculated operating costs are useful for cost comparison purposes only, but, as stated on new car EPA stickers: "Actual mileage may vary".

To use the program, click on any of the highlighted cells with blue text, change the value, and instantly see how your changes affect the bottom line. Note that the default values in the spreadsheet are provided as examples only.

Program Notes/Usage


Building Information: Enter overall building length, width & height. Program calculates floor area and enclosed volume. Multiplying by ACH (entered below) yields total amount of air exchanged.

Temperature Data: Enter monthly or annual Heating Degree Days for your location. Program calculates average outdoor temperature by dividing HDD by number of days and subtracting the result from base 65. If a monthly value (i.e. in the range 0-2,500) is entered, program divides by 30 days. If a value in the range 8,000-20,000 is entered, program assumes Annual value and divides by 365.

Energy Information: Enter energy Information, local costs and estimated efficiency (AFUE) of your heating equipment. Program uses this information to determine costs.

Vent System Data: CFM, Supply air temp (SAT) and Temperature Difference (TD) are calculated from user entered values as follows:
  CFM = Volume * ACH / 60