Why consider the EcoCooling CREC (Computer Room Evaporative Cooler)?
- To save energy
- To release power
- To increase airflow
- To reduce noise
- To reduce cap ex
- To save internal space
- To meet externally imposed targets
- As a marketing tool
The use of electricity in the IT sector has both financial and environmental significance.
Many data centres consume as much electricity in their cooling systems as in their servers. This has both cost and power availability implications.
It is believed the IT sector has a bigger carbon footprint than air travel and consumes over 5% of the developed world's electricity. Many operators want to reduce their impact on the environment by consuming less energy.
An EcoCooling CREC system can reduce your cooling cost by 95%, comply with ASHRAE 9.9 and produce a PUE (Power Usage Effectiveness) of under 1.1. Click here to see what PUE is.
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What Is Direct Evaporative Cooling?
Evaporative cooling is a very simple method of cooling air without using refrigerants. A direct evaporative cooler, using wetted filter pads, cools air by bringing it into contact with water. Water evaporates into the air stream and cools it. The amount of cooling is dependent upon the temperature and relative humidity of the air. In the UK the maximum theoretical air off temperature is 22°C. In practice the actual temperatures achieved using evaporative coolers in UK data centres can approach 24°C on the very warmest days. This allows full compliance with ASHRAE temperature standards.
How does the EcoCooling CREC system work?
The EcoCooling CREC system is a ventilation system carefully sized to provide a constant flow of fresh air to the IT equipment. A patented attemperation system maintains a constant temperature supply to the IT equipment. The hot air is mixed with ambient, or evaporatively cooled air, using a single damper. When the external temperature rises over a set point the evaporative cooling is enabled to ensure either the typical target air supply temperature of 18.5°C is achieved most of the time rising only during the very hottest periods. A standard EcoCooler CREC module will supply ~3 cubic meters per second which can support over 35kW of IT load.
The CRECs are controlled by Schneider Crouzet control systems designed by EcoCooling which control the evaporative coolers, vary the speed of fans and position dampers. Links to fire systems and refrigeration backup are also incorporated into a single control system which has appropriate levels of redundancy. The latest control systems incorporate network communications
Please see control section for more detail on this
What has changed to make Fresh Air Cooling Systems possible?
Modern IT is equipment is far more robust than older equipment. For example most manufacturers specify a 10°C to 35°C operating temperature. Relative humidity is not so critical now tape to tape and paper systems are no longer used. This has been exploited to a limited degree with the use of air economisers or free air cooling systems. Until now these still required a backup refrigeration system to accommodate the times of the year when ambient temperatures exceed 25°C. EcoCooling evaporative cooling systems (CRECs) remove the need for refrigeration completely by providing a constant flow of cooled air under 22°C – even during the warmest periods.
For a summary of the 9.9 guidelines and more details on how EcoCooling evaporative cooling complies with these guidelines see the environmental standards.
What are the savings?
To understand the savings we need to look at the energy used by a traditional CRAC system
The performance of a traditional refrigeration based CRAC system varies according to the design and the utilisation. A CRAC uses electricity for the refrigeration circuit, the air distribution fan, the condenser fan and a small amount for the control systems.
The most efficient CRACs, with variable speed fans and the facility for free cooling will have a Coefficient of Performance (CoP) of 3.7. This means that 3.7kW of cooling will be produced for every 1kW of electricity consumed. This does not include the cost of humidification. An EcoCooler CREC consumes 1.5kW of electricity to support a load of 35kW. This is equivalent to a CoP of 23.8 giving a saving of 85%.
In practice most CRACs are not fitted with the energy saving options and have a CoP of 2. In many cases this is not achieved and the true operating CoP is closer to 1 meaning that the same amount of energy is put into the cooling system as is taken by the IT equipment. The table below shows the typical savings for a 100kW server room using various cooling solutions based on 8p/kWhr and 0.53702 kg/CO2 per kWhr.
|EcoCooler||CRAC with free cooling||Standard CRAC||Typical CRAC|
|Power Consumed kW||4.2||27.0||50.0||100.0|
|Annual Electricity Use kWhr||36,792||236,757||438,000||876,000|
|Electricity Saving kWhr||n/a||199,965||401,208||839,208|
|Electricity Cost Saving||n/a||£15,997||£32,097||£67,137|
|Carbon Saving Tonnes||n/a||107||215||450|
Note that the water usage would be approximately 160 cubic meters per year for a 100kW coCooling CREC system.
PUE is a common measure of the efficiency of a data centre. It is the ratio of the total data centre power and that used by the IT equipment. The lower the PUE the better the efficiency – EcoCooling CRECs can regulary achieve PUEs of less than 1.1. For more information on evaporative cooling and the effect on PUE click here
What happens if my data centre is under populated – how will this affect the PUE ?
The CREC system can produce PUE's of less than 1.1 even for partly populated data centres
Where can CRECs be used and do I have to get rid of my existing fridge kit?
CRECs can be easily retrofitted into existing data centres or installed as part of a new build. They can be fitted both external to the building and within plant rooms. Existing fridge kit can be kept and used as a backup system. See examples of Data Center Installations.
1 – EcoCooling evaporative coolers are externally fixed (or internally fitted within a plant room using a louver to allow fresh air in)
2 – Modular systems provide simple compliance with tiered redundancy levels
3 – Existing CRAC systems can be retained
4 – Air is supplied to the underside of the raised floor or directly into the cold aisle.
5 – Standby generators only have to support 10% of the electricity consumption of the CRAC systems.
6 – UPS rooms are cooled with simple ventilation systems utilising evaporative cooling
7 – EcoCoolers are linked to all fire systems for controlled shutdowns.
8 – Typical roof mounted EcoCooler.
How do I understand what I would require for my data centre?
CRECs are normally installed as 35kW , 70kW or 100kW modules - these enable total flexibility for population of the data centre and can reflect the density.
We would recommend hot and cold aisle containment - some data centres use raised floors for air distribution but many designs now use above floor techniques for air distribution click here for installation examples ,schematics and design principles
How do you control the system and the environment?
Data centre and server rooms can be complex operations . The EcoCooling CREC controller provides local control of cooling equipment and is fully integrated with fire systems. Key environmental parameters are continuously monitored and the PLC then sets damper positions and fan speeds to control temperature and optimise performance.
For more information on control please press here.
How is Air Quality Mantained?
Local air quality and internal standards are carefully considered during the design process. In areas where the air is very contaminated great care should be taken before using any fresh air system. EcoCooling has developed a range of installation solutions to provide prefiltering and G4 standard final filtration
Click here for Cambridge university case study
Comparison with Air Conditioning
The key benefits of using EcoCoolers compared with conventional refrigeration based air conditioning are:
- Over 90% reduction in electricity usage
- Lower capital costs
- Lower maintenance costs
- EcoCoolers qualify for Salix schemes.
- Energy use is typically 3% of installed capacity
- Low cost spare parts holding
- Can provide ASHRAE and manufacturing compliant conditions
- Uses low energy axial fan technology
- Dynamic control of air supply temperature creates 100% ASHRAE RH Compliance
- No F gas compliance costs
- Simple technology
- Ability to cope with very hot days
- Allows release of available power for other activities
- Hot and cold aisle arrangements are ideal for EcoCooling systems
- External access for maintenance.
- No internal space used
- Modular system achieves required redundancy
- Simple expansion through modular design
- No refrigerants
- Less than 10% of the carbon footprint of conventional air conditioning
Can fit into Carbon Reduction Commitment energy