Data center cooling costs can be a real pain for data center managers. On average, 40 percent of the total energy consumption in a data center goes towards keeping their IT equipment cool – which is comparable if not greater than the cost of powering their IT hardware! To add to the problem, new equipment is generating more heat within each data center cabinet, which means the CRAC must work harder than ever.
So, the question everyone is asking is: How do we reduce our data center cooling costs while also increasing the efficiency of cooling technology?
One answer could be to arrange data center racks in hot/cold aisle configurations, meaning the fronts of the racks in one row face the front of the racks in an adjacent row to avoid hot air exhausted from the back of the cabinets drawn into nearby equipment. The problem is even with this longstanding best practice; air mixing can still occur. Let’s look at another solution: aisle containment. Aisle containment systems can minimize hot and cold air mixing by effectively capturing the air within a given aisle. Chilled air within the cold aisle recirculates, while exhaust air in the hot aisle vents out of the data center environment. Utilizing an aisle containment strategy allows IT and data center managers to raise data center temperatures without harming equipment, resulting in significant energy savings. Let’s further break down hot and cold aisle containment systems.
A closer look at cold aisle containment systems
Cold aisle containment’s job is to keep in cold air. The cold row is capped at the tops of the cabinets and across the aisle, and doors are installed at the ends. This system aims to create a smaller area to cool and focus the cooling on the front of the systems. A cold aisle containment system is typically used in high-density data centers because it efficiently directs cold air onto densely populated racks rather than cool the entire room.
Although cold aisle containment systems do not require conventional raised floor cooling, it is often used in environments in which cold air is generated outside of the containment area and brought in through the floor. Most existing data centers employ this type of cooling system, which can be retrofitted for cold aisle containment with minimal impact on operations.
Cold aisle containment that uses an internal cooling system can be implemented on a raised floor or slab. The CRAC units are positioned within the containment area, enabling even more focused cool airflow and greater CRAC unit capacity and efficiency. For this configuration, less energy is required for air movement, and air temperatures can be set higher. Both types of cold aisle containment use the same design approach. It is usually more cost-effective to employ a cold aisle containment system, but hot aisle containment typically proves to be more operationally effective.
Hot aisle containment systems explained
With hot aisle containment, a physical barrier is constructed to prevent hot and cold air from mixing, trap exhaust air at its hottest point and direct exhaust airflow into the AC return. Hot aisle containment reduces energy costs by improving cooling efficiency. It also increases the cooling capacity of CRAC units. Hot aisle containment can be used with either external or internal cooling systems and with or without a raised floor, keeping in mind significant data center modifications may be required if a hot air plenum or ductwork does not already exist.
One drawback of this system is that the hot aisle can be unpleasant for data center personnel, but the remainder of the room can be set to a more comfortable temperature. This leaves the rest of the room available for other uses, making it an economically efficient solution.
Putting it all together
The benefits of hot aisle and cold aisle configurations can be enhanced with aisle containment systems that control air mixing, improve cooling efficiency and CRAC unit capacity and direct chilled air for equipment intake. Cold aisle containment aims to create a smaller area to cool and focus the cooling on the fronts of the systems, while hot aisle containment traps exhaust air at its hottest point and provides a direct path into the AC return.
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