Emerson Liebert Economizer Solutions Fiche De Données

The effect of ambient conditions in representative cities on economization hours and resultant energy savings, using different 
economization methods (assumes cold aisle temperature 71°–80° F; CRAC return temperature 85° F). Cooling tower calculations were 
made with Liebert chilled water-based precision cooling products. Drycooler calculations were based on Liebert precision cooling products 
equipped with GLYCOOL option. Air economizer calculations based on 41.9° F dew point limitation.

Comparative hours of economizer operations through varying CRAC supply and return temperatures in three cities representing distinct ambient conditions 
(partial economizer operation = outside ambient used to precool or assist in cooling of data center return air).

3

Fluid-Side vs. Air-Side Economization Comparison

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 Compatible with moderate climates

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 More operating hours than fluid-side economizers, if 

humidification is added

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 Can be used on systems that don’t use water for heat rejection

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 Lower initial capital costs

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 Uses less water than fluid-side economizers

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 Compatible with Liebert DS and Liebert CW precision cooling 

products (downflow only)

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 Ductwork required to get air into IT space

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 Narrower range of effective hours of operation if used without 

humidification

■

 Dust and pollen sensors are required to minimize filter 

maintenance; humidity control can be costly and challenging

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 Need proven, intelligent controls to ensure proper temperature 

and humidity

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 High-density applications may require more localized cooling

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 Mildew minimization actions required

Liebert Precision Cooling Economization 

In accordance with ASHRAE’s guidance, and in keeping with our position as the industry’s power and cooling leader, Emerson Network 
Power provides effective, efficient economizer solutions. Emerson Network Power offers fluid-side economization solutions and an air-side 
economizer – and Liebert technologies are well suited to work with economization solutions from third-party providers.

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 Can be used in any climate cold enough to provide effective hours 

of economization; Glycol-based systems operate effectively at 
the widest range of outdoor ambient temperatures

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 Wider operating range results in 2x–3x more effective hours than 

air economizer systems in most climates

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 No outside air is introduced to the data center, so the filtration 

and humidification functions of the CRAC unit operate normally 
to ensure optimal air quality and relative humidity

■

 Service requirements and complexities are reduced compared 

to air-side economizers; less filter changing and maintenance are 
required

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 Compatible with Liebert DS, Liebert CW, Liebert Challenger 3000 

and Liebert XD precision cooling systems (downflow and upflow)

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 Indirect piping and control are more complex

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 Higher initial capital costs

■

 Added water use for cooling tower

Atlanta

Chicago

Seattle 

25%

17%

18%

48%

41%

14%

39%

23%

27%

52%

34%

33%

39%

28%

22%

61%

61%

15%

51%

36%

34%

67%

58%

25%

70%

49%

34%

No economizer

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Full economizer

■

■

Partial economizer

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Potential dependant on dew point