The Hot and Cold Passage

 Server racks and relay racks are the storage cabinet. They are integral pieces of hardware equipments in a data center. A server rack is considered to house, protect and organize a variety of computer equipment. Keeping racks and relays cool is an essential undertaking, which require hot/cold aisles. A lot of energy is wasted when cold air that comes into the room is mixed with the hot air passing out. To conserve energy, hot aisles and cold aisles are separated and are staunched from interacting with one another.

Hot/ cold aisle is a plan design for server racks and other computing tools in a data center. They are a familiar consideration for data center architects, engineers, and end users. The idea was perhaps conceived by Robert Sullivan of the Uptime Institute. The design requires air conditioners, fans, and raised floors as a cooling infrastructure. It also necessitates on separation of the inlet cold air and the exhaust hot air.

In enclosures of cabinet space at the data center, heat is produced significantly. As heat increases within the cabinet space, the threat of overheating and damaging the equipment increases. To control such danger, hot/cold aisle is used. Hot/cold aisle is the most sought after concept promoted by thermal managers in recent times. The layout eliminates the direct transfer of hot exhaust air from one system into the intake air of another system in contemporary design. In this system, cold air is pumped directly into a cold aisle. This is supremely separated by curtains which prevents any progress of air into other parts of the data center. The air in the cold aisle is sucked by the fans in the tool on both sides of the aisle. This action is supported by  the equipment that is rightly positioned. Further, air is blown out of the equipment into the hot aisles on both sides of the cold aisles. The hot aisles are detached, which likely extent fire regulations and expediency permit. The air is then passed straight into the return plenum. Both hot-air and cold-air can improve the predictability and efficiency of traditional data center cooling systems.

Both cold/hot aisle approaches reduce the mixing of hot and cold air. However, there are practical dissimilarities in performance and operation that have major consequences on work environment conditions and economize hours. The preference of hot-aisle containment over cold-aisle containment can save up to 38% in annual cooling system energy cost, corresponding to a 13% reduction in annualized Power Usage Effectiveness.

Hot/cold have their advantages and disadvantages. Let us have a look at some of them.


  1. Cooling is proficient – less air is pumped and hence, lower energy is cosumed saving on costs.
  2. The average heat level of the computer room can be raised, which lowers energy costs even more (consistent temperature is important, not cold temperature)
  3. Is self sufficient. It can pay for itself in weeks, if cooling ability in the data center is set up
  4. Can be qualified for a utility reimbursement
  5. The home coming air is hotter. This makes it easier to utilize outside air which is more competent and more hours/year. Hence, lessening energy costs


  1. The air blows tough on IT workers in the cold aisle –This can be chilly and cause discomfort for the workers.
  2. It is much hotter in the hot aisle for IT employees
  3. Changes are often opposed by IT workers, regarding fire regulators

For obvious, above mentioned reasons, it is important to have Aisle Containment. Containment systems began as physical barriers that merely separated the hot and cold aisles with vinyl plastic sheeting or Plexiglas covers. At present, vendors propose plenums and other commercial options that mingle containment by variable fan drives to avoid cold air and hot air from mixing. Curtains (Aisle Containment curtains) can be very useful in managing airflow in the data center. They are easy to configure and setup.

 There are a few finest practices for hot aisle/cold aisle containment. This includes:

  • Hoisting the floor 1.5 feet so that air being pushed by air conditioning tool can pass through.
  • Establishing automatic doors in the data center.
  •  Installing soaring cubic feet per minute (CFM) rack grills which has output in the range of 600 CFM.
  •  Positioning devices that have side or top exhausts in their own part of the data center.

There are three most valuable ways to reduce budget and save energy costs in the data center. They are:

  1. Utilizing outside air for cooling purpose
  2. Advancing air movement. Lastly,
  3.  Virtualization

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