Savings and Costs
- During water-side economizer operation, costs of a chilled water plant are reduced by up to 70%.46
- Water-side economizer retrofits in California have shown one- to four-year paybacks.47
- Water side economizer retrofits can sometimes be costly. Two ENERGY STAR certified data centers – BNY Mellon and Target – examined water-side economizers and found unfavorable paybacks. See their case studies and public service announcements recognizing them as Low Carbon IT Champions.
- Water-side economizers can be integrated with the chiller or non-integrated. Integrated water-side economizers are the better option because they can pre-cool water before it reaches the chiller. Non-integrated water-side economizers run in place of the chiller when conditions allow.
- A variable speed drive should be used on the fan motor in the free cooling tower.
- Like air-side economizers, this technology depends on design and controls to work optimally.
- Data centers that use containment, along with a cold aisle or hot aisle configuration, usually have much higher server inlet temperatures. These higher temperatures can be produced using a higher chilled water set point. With intermixing eliminated, data center operators may be able to achieve their desired server inlet temperature with a 55°F or warmer chilled water supply. With these higher temperatures, water-side economizers can be used more often.
- Physical space is a major concern. Oracle attempted a retrofit and concluded that the additional parts—new "pipes, valves, and controls"—required physical space that existing facilities simply did not have.48
Top Twelve Data Center Energy Efficiency Strategies
Airflow Management Strategies