economizer standards and data center impacts1

Economizer Standards and Data Center Impacts: 

Economizer Standards and Data Center Impacts The new 2001 Seattle Energy Code requires the application of economizer (free cooling) cycles for computer rooms and data centers. Other energy codes may adopt similar language. 2000 Washington State Energy Code 2001 Seattle Energy Code Effective March 1, 2002

Code Applicability: 

Code Applicability The current Washington State Energy Code does not specifically include data centers in the economizer requirements. Some building officials recognize the extreme difficulty in meeting the exact letter of the current code with respect to economizer capacity and may accept partial economizer capacity or treat these loads as process loads with special humidity considerations and not apply the economizer requirements to data centers. Applicability may vary with each jurisdiction.

2000 Washington State Energy Code: 

2000 Washington State Energy Code 1433 Economizers: Economizers meeting the requirements of Section 1413 shall be installed on the following systems, single package unitary fan-cooling units with a supply capacity of greater than 1,900 cfm or a total cooling capacity greater than 54,000 Btu/h…. The total capacity of all units without economizers shall not exceed 240,000 Btu/h per building, or 10% of its aggregate cooling (economizer) capacity, whichever is greater… EXCEPTIONS: The use of outdoor air cooling affects the operation of other systems (such as humidification, dehumidification, and supermarket refrigeration systems) so as to increase the overall building energy consumption. 3. A water economizer system, which is capable of cooling supply air by indirect evaporation. Such a system shall be designed and capable of being controlled to provide 100% of the expected system cooling load at outside air temperatures of 50°F dry-bulb / 45°F wet-bulb and below. For this calculation, all factors including solar and internal load shall be the same as those used for peak load calculations, except for the outside air temperatures…

2001 Seattle Energy Code: 

2001 Seattle Energy Code 1433 Economizers: Economizers meeting the requirements of Section 1413 shall be installed on the following systems, including those serving computer server rooms, electronic equipment, radio equipment, telephone switchgear… EXCEPTIONS: 3. A water economizer system, which is capable of cooling supply air without the operation of mechanical refrigeration equipment. Such a system shall be designed and capable to be controlled to provide the following: a. Design economizer cooling capacity: The calculated system cooling load served by all terminal equipment without airside economizer at 45°F db/40°F wb, with solar and internal loads the same as those calculated for peak cooling load except for outside air temperature… b. Design economizer fluid supply temperature: The design fluid supply temperature delivered to the terminal cooling coils when in economizer operation at 45°F db/40°F wb…

Data Center Impact: 

Data Center Impact The primary impact to Data Centers is the requirement for evaporative heat rejection to achieve lower fluid temperatures which allows a more effective water-side economizer cooling cycle. There are (3) basic types of heat rejection equipment. Dry Coolers Open Cooling Towers Closed Circuit Fluid Coolers

Dry Cooler: 

Dry Cooler Capacity is dependent on ambient dry-bulb temperature. Low fluid temperatures are hard to achieve. Air is drawn over “dry” coils.

Open & Closed Cooling Towers: 

Open & Closed Cooling Towers Air comes into contact with water (directly or indirectly). Capacity is dependent on ambient wet-bulb temperature.

Open & Closed Towers: 

Open & Closed Towers Open Cooling Tower

Open & Closed Towers: 

Open & Closed Towers Open Cooling Tower Open Tower w/ Heat Exchanger

Open & Closed Towers: 

Open & Closed Towers Open Cooling Tower Open Tower w/ Heat Exchanger Closed Tower (Fluid Cooler)

Chilled Water SystemNo Economizer: 

Chilled Water System No Economizer CRAC and Supplemental Cooling Equipment

Chilled Water Systemwith Water-Side Economizer: 

Chilled Water System with Water-Side Economizer

Condenser Water SystemWater-Side Economizer Operation: 

Condenser Water System Water-Side Economizer Operation

Condenser Water SystemCombined Operation: 

Condenser Water System Combined Operation

Condenser Water SystemMechanical Cooling: 

Condenser Water System Mechanical Cooling

Conclusion: 

Conclusion Many building codes now expect full capacity air or water economizers for data centers. Verify expectations with building officials. Allow for additional space, weight, and other impacts for additional heat rejection equipment required to provide water-side economizers.