HVAC accounts for about 45% of the data center’s total energy cost, which is too high. For this percentage to be reduced, it is essential that there is a good cooling system. The HVAC system in a data center has 3 main functions:
Temperature control: the servers and other active equipment in the data center increase the temperature a lot during its use, with the risk of failing or burning, which can cause an unscheduled stop in the data center and interrupt critical services. According to current best practices, the ideal operating temperature for a data center is around 25 degrees, but the power dissipation caused by active equipment can easily reach 50 degrees, causing irreversible damage to equipment and components. The HVAC system is the “key element” to help maintain a stable temperature in the data center.
Control of air quality: to have quality in the air, it is necessary to ensure that the data center is free of solid and contaminated particles, suspended or circulating. If there is particles or dust in the air, system operation can be impaired and cause unexpected downtime. The filtering system in the cooling units must be inspected frequently (through maintenance routines).
Humidity control: the equipment that makes up the data center is very sensitive to this characteristic. A reduced relative humidity content in the data center air can generate electrostatic charge, a phenomenon often associated with the failure of electronic components (typically short-circuit) of the mentioned active equipment (servers, among others). A high content can cause water to condense inside the servers. Any deviation or variation in the ideal temperature can lead to the proliferation of bacteria and it is therefore advisable to maintain the relative humidity values close to 50%.
HVAC equipment (Close Control) is the one that consumes the most energy in the data center in addition to the servers. For this reason, it is essential to take some special care during the design of the data center, in order to increase the efficiency of the HVAC system and, consequently, reduce energy costs, that is, reduce the PUE index to the maximum.
There are currently best cooling practices that should be adopted, regardless of the type of structure that we are setting up for the data center:
– The cooling (Close Control) must be placed as close as possible to the servers, so as to avoid unnecessary energy costs with air movement;
– Use of “free cooling” technology: use the external air of the environment to cool the interior of the data center, thus optimizing the consumption of electrical energy;
– Order the racks in naming aisles (cold and hot) with one or more rows and close them with front and rear doors (creation of CAC – Cold Corridor Containment);
– Provide, whenever possible, cooling with load modeling (modeling compressors) and ventilation speed variation (e.g. EC FAN) to adjust, at each moment, the production of cold air;
– Ensure that the cooling works without failures and/or interruptions. For this, it is very important to use rescued energy (typically from the Generator Set) to ensure the supply of critical loads, during the period of failure, cut or absence of power from the grid (EDP or other).