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
the value, and instantly see how your changes affect the bottom line.
Note that the default values in the spreadsheet are provided as examples
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.
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.
Information, local costs and estimated efficiency (AFUE) of
your heating equipment. Program uses this information to determine
CFM, Supply air temp (SAT) and Temperature Difference (TD) are calculated
from user entered values as follows:
= Volume * ACH / 60
SAT = OAT+((IAT-OAT)*SRE)
TD = IAT-SAT