Data centers cooling loads may reach about 40% of their electricity demands. The number of that type of facility is continuously growing around worldwide and actions addressing energy saving are welcome to rationalize their operation. Free cooling appears as an effective solution to achieve energy savings, and the present work proposes a methodology for assessing data center free cooling operation based on the heat exchanger approach point. The methodology can be applied to both airside and waterside economizer modes. The proposed methodology is applied to fourteen Brazilian state capitals that represent all country climatic conditions. Free cooling environmental air temperature and humidity criteria are based on literature review and on ASHRAE thermal guidelines. Results show that cities such as Curitiba, São Paulo, Porto Alegre and Brasília can potentially operate in both airside and waterside economizer modes for more than 3000 h per year, even considering conservative data center thermal operating limits. Facilities placed on North and Northeast regions can only run under free cooling conditions if operational parameters are to be relaxed to consider more flexible operating limits. It is shown that indirect economizers are potentially more suitable to operate under ASHRAE recommended limits. The proposed methodology is shaped for evaluating free cooling hours during system conception.

数据中心的冷却负荷可能达到其电力需求的40％。在全球范围内，此类设施的数量正在不断增长，欢迎采取节能行动来合理化其运营。自然冷却似乎是实现节能的有效解决方案，目前的工作提出了一种基于热交换器进场点的数据中心自然冷却运行评估方法。该方法可以应用于空侧和水侧节能器模式。拟议的方法适用于代表所有国家气候条件的十四个巴西州首府。自然冷却的环境空气温度和湿度标准是基于文献综述和ASHRAE热指南。结果显示，诸如库里蒂巴，圣保罗，即使考虑到保守的数据中心热运行限制，阿雷格里港和巴西利亚港每年都可以在空侧和水侧节能器模式下运行3000小时以上。如果要放宽操作参数以考虑更灵活的操作限制，则位于北部和东北地区的设施只能在自然冷却条件下运行。结果表明，间接节能器可能更适合在ASHRAE建议的限值下运行。拟定的方法论旨在评估系统构想期间的自然冷却时间。如果要放宽操作参数以考虑更灵活的操作限制，则位于北部和东北地区的设施只能在自然冷却条件下运行。结果表明，间接节能器可能更适合在ASHRAE建议的限值下运行。拟定的方法论旨在评估系统构想期间的自然冷却时间。如果要放宽操作参数以考虑更灵活的操作限制，则位于北部和东北地区的设施只能在自然冷却条件下运行。结果表明，间接节能器可能更适合在ASHRAE建议的限值下运行。拟定的方法论旨在评估系统构想期间的自然冷却时间。