The cold aisles are physically enclosed with doors and a roof or panels. Cool air from the raised floor (or overhead ducts) is contained in this aisle. Servers pull in air at consistent, low temperatures. n is a best practice solution that separates hot and cold air streams. This method raises the temperature of the air returning to a Computer Room Air Con itioner (CRAC) unit, which allows the unit to operate more eficiently. Cold air is delivered into this aisle through: Servers pull this cold air into their front. Cold Aisle Containment isolates the cooled supply air from the cooling units within direct proximity of the air intake of critical equipment.