Free cooling potential for Brazilian data centers based on approach point methodology

•The free cooling potential of data centers is assessed for Brazilian conditions.•A graphical methodology is presented for all economizer modes based on heat exchanger approach.•Free cooling hours are identified on a psychrometric chart.•Free cooling potential for 14 Brazilian cities are assessed. 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.