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RE: [EnergyPlus_Support] Compuer Load
Yes, use the meter. Preferably on all (or a large % sample) computers.
Differing CPUs and video cards not to mention different software running and
widely different power supply efficiencies will make the power usage quite
variable.
The dates on ASHRAE references are all old. Computers have changed and
generally use more power (I don't think the 530 W is on a desktop computer,
perhaps a large server).
Donald Fast
Building Insight Technologies Inc.
Suite 1, 3661 West 4th Ave.
Vancouver, BC V6R 1P2
*new* Tel (604)629-8300 ext 315
*new* Direct (604)629-8315
Fax (604) 732-9238
donald@xxxxxxxxxxxxxxxxxxx
> -----Original Message-----
> From: Khizir Mahmud [mailto:mahmud_khizir@xxxxxxxxx]
> Sent: September 27, 2004 7:24 PM
> To: EnergyPlus_Support@xxxxxxxxxxxxxxx
> Subject: RE: [EnergyPlus_Support] Compuer Load
>
>
> Thanks all for providing suggestions and documents. I have gone
> through these and found that there are variations among them.
>
> Computer Load :
> ---------------------------------------------
> ASHRAE (page 28.14, Fundamental 1997) recommended 90W-530W for
> size 16 to 640 kbyte.
>
> Theaker (43W, 1991)
> Wilkins (73W, 1991)
> Warden Engineering (67W,1999)
>
> Monitor :
> --------------------------------------------------
> ASHRAE : 78W (1997, Fundamental)
> Theaker (30W, 1991)
> Wilkins (45W, 1991)
> Warden Engineering (32W,1999)
>
> And i didnt understand about the size as ASHRAE recommended for
> 16 to 640 kbye. What does this size mean ?
>
> I have a three phase watthour meter connected to my computer . So
> if i calculate from the power consumption for typical load
> condition , will it be ok ?
>
> Thank you all
>
>
> Donald Fast <donald@xxxxxxxxxxxxxxxxxxx> wrote:
>
> The most accurate is to use the power meter for each computer,
> under typical
> load conditions.
>
> If this is not practical:
>
> Here is an excerpt from http://silentpcreview.com/article28-page2.html --
> ...
> How Much Power is Enough?
>
> Typical 300W models have replaced 230W and 250W models as baseline units
> since the introduction of the AMD Athlon. They feature a fan (or
> two) rated
> for 35~40 cubic feet per minute (CFM) airflow. Presumably, this level of
> airflow is required for adequate cooling at full power output to
> pass safety
> approvals under UL, CSA, CE and other regulations.
>
> Our own experience shows idle AC power consumption of 60~90W, and about
> 110~130W at 100% CPU utilization in several fairly representative mid-line
> test systems. Given the typical 65~70% effiiciency of a PSU, the DC power
> delivered is 40~60W at idle and 80~90W maximum. In other words, the amount
> of power actually required by typical desktop systems is about 30% of the
> capacity of the typical 300W power supply. Although some headroom
> is always
> good to have, most of us are paying for power capacity that is never used.
> One of the nasty side effects is the fan noise of high airflow required to
> keep the PSU adequately cooled when delivering maximum power.
>
> Why this state of affairs exists is a matter of marketing and technical
> obfuscation, probably more by accident than any massive conspiracy. With
> relatively low current requirements prior to the Athlon, the
> aforementioned
> 230W and 250W were perfectly adequate for PC systems, even if the power
> supplies didn't deliver full rated performance. That changed with
> the Athlon
> and then the P4. PSU makers were quick to introduce higher rated
> models said
> to be required for the new power hungry processors. It was a good
> marketing
> opportunity. Rather than "Our 250W PSU is better than theirs," it
> is easier
> to sell the message "Our 300W PSU is better than their 250W PSU."
> Bigger is
> always better, isn't it? It also allowed higher prices to be charged.
>
> A counterpoint is AMD's system builder's guide, which suggests higher
> numbers: up to ~180W for a typical system and ~250W for a high performance
> system, but these numbers are obtained by adding the maximum power rating
> for each component, then taking 20% off to account for real-world
> conditions. It is actually difficult to get 80% of maximum power draw; how
> many applications can actually demand 80% power from every
> component in a PC
> simultaneously? Intel's PSU recommendations are similar. Suffice it to say
> that as manufacturers, both AMD and Intel are looking at worst-case
> secenarios. As custom builders, enthusiasts and system
> integrators can make
> choices based on real needs and applications.
> ...
>
> Donald Fast
> Building Insight Technologies Inc.
> Suite 1, 3661 West 4th Ave.
> Vancouver, BC V6R 1P2
> *new* Tel (604)629-8300 ext 315
> *new* Direct (604)629-8315
> Fax (604) 732-9238
> donald@xxxxxxxxxxxxxxxxxxx
>
> > -----Original Message-----
> > From: mahmud_khizir [mailto:mahmud_khizir@xxxxxxxxx]
> > Sent: September 25, 2004 7:14 PM
> > To: EnergyPlus_Support@xxxxxxxxxxxxxxx
> > Subject: [EnergyPlus_Support] Compuer Load
> >
> >
> > Dear All
> >
> > Recenlty i am simulating a office room load in Energyplus. In my
> > simulation model there is a computer. Now i am facing problem about
> > the heat generated by a computer. Is there any standard value or is
> > there any procedure to calculate the heat load?
> >
> > If i calculate the heat load of the computer from a watthour meter
> > consumes by a computer will it be ok ?
> >
> > Thank you all
> >
> >
> >
> >
> > The primary EnergyPlus web site is found at:
> > http://www.energyplus.gov
> >
> > The group web site is:
> > http://groups.yahoo.com/group/EnergyPlus_Support/
> >
> > Attachments are not allowed -- please post any files to the
> > appropriate folder in the Files area of the Support Web Site.
> >
> > Yahoo! Groups Links
> >
> >
> >
> >
> >
> >
>
>
>
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