Cooling
Every watt the IT equipment and the UPS draw ends up as heat that the cooling system has to remove. This section starts from that heat, including the part the UPS adds, and works through the equipment that removes it, the airflow that delivers it, the limits of air at high density, and the maintenance that keeps it running.
For three reasons: the UPS adds heat, its batteries suffer from heat, and a cooling failure lands on it. Schneider Electric's cooling-load paper counts UPS losses as part of the room's heat, 13% of the total in its typical example. ASHRAE's paper on power equipment says the life of UPS batteries is very sensitive to temperature, and gives the rule of thumb that lead-acid life halves for every 8 to 10 °C above 25 °C. The same paper notes that during an HVAC failure the IT equipment draws more power as its fans speed up, so the UPS carries more load just as the room heats.
That is why the pages in this section treat the UPS room as part of the cooled space, not as an afterthought.
Enough for the IT load, the UPS and power distribution losses, lighting and people, plus margins. The server room cooling sizing guide walks through Schneider Electric's worksheet, including the UPS term, and its rule of thumb of 1.3 times the IT load for small rooms.
Most rooms use either a CRAC, with its own compressor, or a CRAH, fed with chilled water from a chiller plant. The CRAC vs CRAH comparison sets out the differences, and the precision vs comfort cooling guide explains why office air conditioning is a poor fit for IT and UPS rooms.
By deciding whether cold air reaches the equipment inlets or mixes with hot exhaust on the way. Schneider Electric's paper on cooling architectures finds traditional uncontained room cooling effective at around 1-2 kW per rack, and says that at 20 kW per rack or more it no longer works without containment. See hot and cold aisle containment and in-row and liquid cooling for high-density racks.
Regular maintenance by people who know precision equipment. Vertiv points out that precision cooling has very different service needs from building air conditioning. The cooling maintenance guide lists what a visit covers for CRAC and CRAH units. Cooling design, installation and maintenance are delivered through specialist cooling subcontractors.
Yes. Its losses are part of the room's heat load, UPS modules are cooled by forced air, and its batteries age faster when warm. ASHRAE puts the ideal for lead-acid batteries at 25 °C.
ASHRAE recommends 18 to 27 °C at the IT equipment inlet. Battery rooms need the narrower range the battery maker specifies.
Poorly. Vertiv notes that precision cooling puts about 95% of its capacity into the dry heat electronics produce; comfort systems spend much more on removing moisture.
Cooling design, installation and maintenance are delivered through specialist cooling subcontractors.
Sources, checked 2026-10-04:
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