Utility Calculator Help

Heat Load

Heat Load is the total amount of of heat generated by electronic equipment within the site. It can be calculated by multiplying DC current and DC float voltage, both obtained from the rectifier. Example: 200A current at 54VDC float voltage gives 10.8 kW.

 

Cooling Setpoint

When indoor temperature exceed this set point, cooling is provided by the HVAC. This must be higher than the heating setpoint.

 

Heating Setpoint

When indoor temperature drops below this set point, heating is provided by the HVAC. This must be lower than the cooling setpoint.

 

Minimum Supply Temperature

Some HVAC can mix outdoor air with return air to provide minimum supply air temperature during colder months to prevent cold shock on electric equipment. This is typically set to 50 degrees F. If the HVAC does not have this capability, enter 0.

 

Lighting

Energy used for indoor lights that are always on. Enter 0 if no permanent lighting.

 

Passive Ventilation

Any ventilation system in the building that are not apart of the HVAC system in calculation. Example: exhaust dampers/fans.

 

Insulation R Value

Thermal Insulation R Value in sqft*F*h/Btu. Depending on material and thickness, the R value can range from 9 to 40. Leave at default (12) if unsure.

 

Model

Enter the model number of the outdoor units. If unsure of the exact model, generic model can be used as input, example: “5Ton 8EER”.

 

Free Cooling Type

If no free cooling (economizer) is available, select “none”. A conventional free cooling economizer delivers roughly 50% of the rated air volume while a full flow economizer delivers 100% of rated air volume.

 

Free Cooling Control

Older (2013 and before) or retrofit economizer uses a enthalpy controller to control humidity. Leave as blank if unsure of exact configuration. Newer economizer uses outdoor or indoor relative humidity to control humidity.

 

Free Cooling Setpoint

Free cooling (economizer) uses colder outdoor air to cool the site. This parameter sets a maximum outdoor temperature that the free cooling can occur. Must be set below cooling setpoint.

 

Supply Fan type

Most HVAC system use AC supply fan. EC brushless drives are more efficient at lower RPM but much more expansive.

 

Fan CFM

Air volume of the supply fan in cubic meter per second. Obtained from product specification sheet (use dry coil if specification differences wet/dry coil).

 

Mechanical Cooling (DX) performance.

Obtained from product specification sheet. Mechanical cooling performance per AHRI 390 testing criteria.