Cooling of computer rooms
in SME companies
Leaflet for company managers and computer managers in SME companies
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Program
Electricity
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26°C in computer rooms is a temperature without risk.
Air conditioning is not needed to achieve 26°C: Cooling by means of open
windows or with a ventilator are cost-effective alternatives..
Use the heat from the computer installation to heat neighbouring rooms.
26°C in server rooms
The requirements on the computer infrastructure
of an SME company increase continually, as well
as the performance and current consumption of
new servers. In the summer, this can lead to excessive temperatures in the computer room.
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excessive temperatures
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25
20
15
Jan Feb
May June
Jan March
Mrz Apr Mai
Jun July
Jul Aug
Aug Sept
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Okt Nov Dec
Dez
Fig. 1
Excessive temperature in a computer room
Various studies and pilot projects in large server
installations have shown that a room temperature
of up to 26 C is permissible. This temperature
does not lead to any impairment of the operation,
nor to a reduced service life of the computer installation.
Cooling with a ventilation system
A room temperature of 26 C can be guaranteed in
many cases without the use of air conditioning.
Cooling by means of a simple ventilation system
is efficient and cost-effective. The hot air is
sucked out of the computer room using a ventilator, while cool air flows in through an air vent.
The current consumption of the ventilator is extremely low, and you will save 70% of the electricity costs for the cooling. The service life and reliability are also much higher than for air conditioning systems.
Heating with the exhaust heat
During the complete heating period, you can use
the heat from the computer installation and blow
the hot air into a neighbouring room (corridor,
staircase). With 1'000 watts of waste heat you can
heat approximately 100 square metres of office
space and thereby save energy and money.
In the summer, it is essential to discharge the heat
into the open air. To do this, the waste air is diverted to the outside by means of a flap and a
second air duct.
Steps towards an efficient cooling system
1. Measure the temperature
Monitor the temperature in the computer room
over several weeks in the summer. If the temperature exceeds 26 °C for longer periods, you must
take measures.
2. Check the installation location
Is the computer installation located in a sensible
place? Would it be possible to move the installation, or parts of it, to a cooler place, for example,
to the basement?
Installation in an exterior room simplifies the implementation of the ventilation system considerably. Sufficient cooling could even be ensured by
opening a window.
3. Planning/executing the ventilation
If excessive temperatures occur even with an optimal installation and despite open windows, you
should arrange for a ventilation technician to draw
up an offer for room ventilation for you.
Fig. 2
Simple air ventilation plant in a computer
room
First determine the heat dissipated by the computer installation according to Table 1. This data
will serve as a basis for the dimensioning of the
ventilation for the ventilation technician.
Leaflet
– 2 –
Waste heat
Device
Server for small work groups
(up to 20 users)
per server
200 Watt
Server for larger workgroups
(more than 20 users)
per server
500 Watt
Switch, modem, firewall etc.
per unit
Non-interruptible power supply (UPS)
Tab. 1
20 Watt
100 Watt
Heat dissipation of various computer devices
Consider any possible extensions of the computer
infrastructure. For a room with windows, add
50 watts per square metre floor space.
The ventilation is planned as an exhaust air system and has two ventilation channels. One leads
to a neighbouring room (to assist the heating during the winter), while the other leads to the open
air. By means of a manually operated flap, you
can switch between the two modes of operation.
An air vent allows cooler air to flow in from the
building. The ventilator itself is controlled by a
thermostat.
During the planning, you should also take the
noise emissions from the computer installation
into consideration.
4. Operation of the ventilation
Set the thermostat to a temperature of 26 C. Provide any windows with shading, and switch off the
room heating.
Continue to monitor the temperature in the computer room (thermometers with a minimum/maximum indication are practical).
Use of an air conditioning system
With an unfavourable location of the computer
room, it is possible that the ventilation system will
be inadequate in the hottest periods, and that an
air conditioning system will have to be procured.
This should run as a supplement to the ventilation,
and will thereby achieve a considerably longer
service life than if used in continuous operation. In
this way, the ventilation system pays for itself
once again.
Energy label
When evaluating an air conditioning system, pay
attention to the energy label, and choose a unit
with Efficiency Class A.
For more information...
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Leaflet 26 Grad in EDV-Räumen - eine Temperatur
ohne Risiko (only in German)
Leaflet Power Management with Windows Server
2003 (only in German)
Federal Office for Energy, June 2006
Download: www.electricity-research.ch
Cooling of computer rooms in SME companies
The required cooling power results from the waste
heat of the computer installation that you determined for the dimensioning of the ventilation
(1,000 watts of dissipated heat corresponds to 1.0
kW cooling performance).
Summer/Winter operation
During the complete heating period, the ventilation
system can be used for cooling, and any air conditioning system can remain switched off. At the end
of the heating period, switch over to summer operation. As long as the external temperatures are
not too high, you can continue cooling with the
ventilation system, but the hot waste air must be
led outwards to the open air. In the hottest period,
you will have to put the air conditioning into operation where necessary.
Heating period:
• Ventilation system in operation
• Switch off any existing air conditioning
• Ventilator thermostat set to 26 C
• Air at 20 – 22 C is drawn in from a neighbouring room
• Exhaust air at 25 – 27 C is blown into the
neighbouring room
• Power consumption maximum 150 watts for
1'000 watts of waster heat
Transitional period:
• Ventilation system remains in operation
• Any air conditioning remains switched off
• Switch over the waste air flap, and divert the
air to the outside
High summer:
If the ventilation system is insufficient and you
have an air conditioning system available, put the
air conditioning system into operation during the
hottest period:
• Switch the air conditioning on, and set the
thermostat on 26 C
• Switch the ventilation system off
• Current consumption of 300 to 450 watts for
1,000 watts of waste heat
Optimizing the operational period
Switching the server off during the night, or putting
it into a sleep mode saves additional energy for
the server operation and for the cooling (see the
corresponding leaflets below).
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Leaflet Schalten von IT-Servern (only in German)
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Download: www.electricity-research.ch
Energy label for air conditioning systems:
www.energieetikette.ch
Prepared by Thomas Grieder (Encontrol GmbH, Niederrohrdorf)