About the Free-Cooling Estimated Savings


	This web calculator is designed to assist a data center manager in determining the potential energy and cost savings as a result of using FREE-AIR COOLING or EVAPORATIVE COOLING. The two cooling systems are calculated independently and are not considered to be directly correlated to each other, therefore their values are not necessarily directly additive in savings.

HOW TO USE THIS APPLICATION:
The user is required to enter several weather criteria parameters, as well as the power consumption of the data center.

	DRY BULB TEMPERATURE:	Temperature of the air (user can enter a MAXIMUM and MINIMUM threshold)

	DEWPOINT TEMPERATURE:	Measure of the humidity in the air. Represents temperature at which water will condense. (user can enter a MAXIMUM and MINIMUM threshold)

	RELATIVE HUMIDITY:	Measure of the humidity in the air. Represents the relative amount of moisture in the air at a given temperature.

	WETBULB TEMPERATURE:	Measure of the humidity in the air. Represents the temperature to which air will cool due to evaporation.

	REQUIRED WETBULB DEPRESSION:	Represents the spread between the WETBULB TEMPERATURE THRESHOLD and the recommended WETBULB temperature for efficient use.

METHODOLOGY:
The database used in these calculations contains approximately 2186 weather stations scattered throughout the United States and Canada. The database consists of all hourly observations taken during the period extending from 1999 through 2008. Upon a user request for a particular location, and provided the data center environmental criteria, a count will be performed of all hours meeting that criteria over the period 1999 through 2008. This count of hours is then divided by 10 (total years of data) in order to provide a result of the "normal" number of occurrences during a given year. The total number of hours will always range from 0 to 8760 hours.


	-FREE-AIR COOLING: Calculation is based on DRYBULB TEMPERATURE (deg), DEWPOINT TEMPERATURE (deg), and RELATIVE HUMIDITY (%).

	-EVAPORATIVE COOLING: Calculation is based simply on the WETBULB TEMPERATURE (deg), and the required WETBULB TEMPERATURE DEPRESSION.


	COST SAVINGS ESTIMATION: The cost savings are based on a simple model which consists of a multiple of the total number of hours which meet the environmental criteria, the number of kilowatt-hours consumed, and the provided electric rate.