CPD PROGRAMME
Professional development
The CIBSE Journal CPD Programme
Members of the Chartered Institution of Building Services Engineers (CIBSE) and other professional bodies are required to maintain their professional competence throughout their careers.
Continuing professional development (CPD) means the systematic maintenance, improvement and broadening of your knowledge and skills, and is therefore a long-term commitment to enhancing your competence. CPD is a requirement of both CIBSE and the Register of the Engineering Council (UK).
CIBSE Journal is pleased to offer this module in its CPD programme. The programme is free and can be used by any reader. This module will help you to meet CIBSE’s requirement for CPD. It will equally assist members of other institutions, who should record CPD activities in accordance with their institution’s guidance.
Simply study the module and complete the questionnaire on the fi nal page, following the instructions for its submission. Modules will be available online at
www.cibsejournal.com/cpd while the information they contain remains current.
You can also complete the questionnaire online, and receive your results by return email. Cooling options for data centres
This module considers the low energy cooling options currently available to help reduce the energy consumption and carbon footprint of data centres
The challenge to reduce mechanical cooling and carbon footprint has led to further developments in free cooling and adiabatic cooling. This article specifi cally looks at high energy use data centres, and at the evolving recommendations to reduce their energy consumption both by the use of free cooling equipment on mechanical cooling systems and by the introduction of adiabatic cooling equipment. The article follows a previous CPD in the July 2010 Journal, titled Evaporative cooling enhancement on air cooled chillers. However, one of the driving forces to develop lower energy consumption cooling systems has been the white paper prepared by the ASHRAE Technical Committee 9.9, 2011 Thermal Guidelines for Data Processing Environments1
. The principal elements of
this paper will be considered, followed by the low energy cooling options that are currently available to meet the recommendations of the white paper.
ASHRAE TC 9.9, 2011 Thermal Guidelines for Data Processing Environments The fi rst edition in 2004 sought to bring some recommendations for data centre environmental conditions. It was upgraded in 2008, with the aim of producing an environmental envelope that would lead to high reliability and energy effi ciency, and then further upgraded in 2011. The main
www.cibsejournal.com 0 0 10 20 30 Figure 1: ASHRAE environmental classes for data centres
emphasis of the latest edition is to extend the recommended envelope to provide more options for the type and use of data centre server equipment, and to take into account the effects of different environmental conditions on server equipment. For example, the higher the selected room temperature, the greater power is required to operate the server equipment and the lower its reliability. This has to be balanced
against the requirement for smaller size cooling equipment, free cooling and/or adiabatic cooling enhancement. Figure 1 shows the recommended envelope and the allowable envelopes for the different data centre classes developed. The ‘allowable’ limits expressed in Figure
1 are described as being acceptable to operate at for short periods of time, without affecting the overall reliability and operation
April 2012 CIBSE Journal 51 40 Dry bulb temperature (C) 50 60 30 Psychrometric chart
SI metric units, sea level barometric pressure – 101.3 kPa
A3 A2 A1 10
Recommended Envelope
A4 20
30
20 0 10
10%
20%
40% 60%
Relative humidity
80%
Wet bulb or saturation temperature (C)
Moisture content, g/kg dry air Humidity ratio, kg/kg dry air – moisture content / 1,000
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