• SysInfo
• EnergySaving

This page has some ideas on Energy Saving. Unlike the ecobuilding page, it's a WiKi, so if you have any ideas, feel free to edit it (having logged in - please include a comment). Top tips for saving energy in a WGB office include:

• turn your PC and other electrical equipment off when not in use

• turn "up" the thermostat (towards RED / 5, away from BLUE / *)

• turning down the brightness on your LCD typically halves its power consumption

• don't use office lights unless needed. Consider a task lamp

To allow energy monitoring department is supplying power strips with builtin energy meters (see record and retrieve) for all desks, and also has more conventional monitoring adapters. We also have a few intelliplugs which allow desk furniture to be turned off when the PC shuts down.

results

Before starting on the details, here are some encouraging results to show what we have managed so far (13% so £22,498.24 for 2009-2010, and around 21% so £33K for 2010-2011). We need to keep it up.

The figures are based on meter readings and the proportion of the relevant building which we use, which changes each FY. The "William S Gates Building - W046" values for the were 93.42% of the actual meter readings, 1944075, for 2009-2010 and 2010-2011. For FY 2011-2012 our part of the WGB Target was reduced by 4.66% to 1853346 kW h, but as of 2011/02 we don't know what %age of the building is ours, but the suspicion is that as the RAM was not changed, it is still 93.42%.

• Target is the target up to the last recorded quarter.

• Variance is the amout by which the readings are below the Target.

• Estimated transfer is the Variance multiplied by the cost per kW h (8.4p if under Target, 16.8p if over).

(M039 stops being ours at the end of FY 2009-2010)

The quarters are 92, 92, 89 and 92 days respectively. Thus average kW usage for the quarters of 2009-2010 were 213, 175, 182, and 200 compared to the target 229kW.

kW h is the department's share of the WGB (e.g. 93.42%), kW is the average for the department. save is the percentage saving compared to the 2009-2010 target (1944075) up til 2009-2010, thereafter compared to the target (1853353) for 2010-2011.

(Aug 2010 was helped by 9hr, 1.2%, of power cuts and filer work just before the Bank Holiday.)

thermostat

The energy used by equipment in your office has to be dissipated. Sometimes this may just be a matter of pumping the hot air from the room, but at others it may involve using energy to drive a heat pump. The higher the thermostat setting (the red blob or '5' rather than blue blob or '*'), the greater chance that it'll be the former. Unless it's very hot or cold, if you turn it from one extreme to the other, you should be able to hear the chilled water shart and stop flowing. If you can hear it water flow all the time, the valve may be stuck, so contact building services.

lights

The fluorescent lights in your office consume power when on. Do not flick them on automatically - think about whether or not you really need them. Turn them off when you are not in. Most single offices have two pairs of tubes, each 58W, making a maximum of 232W, or three times the power of a PC and LCD. Large one person offices may have two sets of such lights, using up to 464W.

There are ambient light detectors on each fluorescent fitting. You can find them at one end of the fitting, protruding slightly down below the fitting. These automatically turn the lights down or off if sufficient light is coming in the windows. You can adjust the level at which they switch using the small variable resistor built into the light detector. Remember to turn the main switch off on your way out of the room, even if the lights appear to be off.

workstation

The largest consumer of energy in your office is likely to be your workstation. They typically use around 1-2W when "off", 50-60W when "idle", and around 130W when "busy".

turn it off

When leaving the machine for the day (and particularly several days) do consider turning it off. Many systems support hibernation ("save to disc") which attempts to reboot the machine to its previous state (network connections are likely to have timed out). Linux machine can be set to automatically shutdown when idle, and we hope to offer a similar facility for Windows in 2010. By only having the machine on for a 40 hour working week, 75% of the power consumption can be saved, or 400KW h/annum - or up to 1000KW h/annum if running a screen saver. To see how well a host is doing, look at its nagios derived summary.

For remote access, consider using the Time Sharing Systems.

HOWTO hibernate (Linux)

To hibernate ("save to disc") the machine needs to have some non volatile store to which to put the volatile information (RAM contents etc). Linux uses "the first swap partition" (so cannot use interleaved swap partitions with equal pri settings). It needs to be able to find it at the next boot, so (I think) has to be a partition (rather than a file). It has to be large enough to hold everything, so to make it reliable, it should be at least the size of the RAM (MemTotal in /proc/meminfo). It needs to be able to to find it on restart, either by an explicit "resume=/dev/sda11" on the boot line, or by mkinitrd auto detecting it).

If you run with a large first swap partition, you probably need do no more. There will be space, and mkinitrd will have found it. Save any state and test it.

Otherwise, you need to disable the existing swap partitions (if any), add a new partition which is large enough, and add a resume= key to the boot command line. Find a free partition (the Lab convention is that 0xff / BBT is used) using "cl-asuser fdisk -l" or some such, and change its type to 0x82 (cl-admin command does that). Create a swap partition on it with a suitable label, e.g. "cl-admin mkswap -L resume /dev/sda11". Tell the bootloader (e.g. GrUB2 or GrUB) to add "resume=/dev/sda11" to the command line by editing a file such as /etc/default/grub (Ubuntu using GrUB2: append to GRUB_CMDLINE_LINUX_DEFAULT) or /boot/grub/menu.lst (GrUB). Test it by saving all important state (in case it fails), adding the swap device ("cl-asuser swapon -L resume"), and asking it to hibernate ("cl-asuser pm-hibernate" or whatever your WM offers). Restart it (using the button, or the web page), check that the kernel command line looks right, and let it boot. Disable the swap partition ("cl-asuser swapoff -L resume").

You can now try using cl-isidle with the --halt flag - it will enable the resume swap partition, e.g. "cl-asuser cl-isidle --email $USER--isidle --halt". Call it with the -h flag to get help. It allows you to set various parameters, and can send email (to prod you to take a look). Sample uses are:

• on pool machines such as the MPhil machines, automatically halt if low LA and no (active) logged in users
• on a user WS to send email if it's idle, in case the user forgot to switch it off
• on Condor machines to shut them down when idle (Condor users can then resize and restart them as needed)

Sample systems. A "Swap" of "swap" means that it uses the available swap space, whereas "resume" means that a swap partition "resume" is added before hibernating.

turn it on remotely

With most systems it is possible to turn them on remotely using "Wake on Lan" (D865GLC, D875PBZ, D955XBKLKR, DQ965GFEKR, DG33TL, DQ35JO, DQ45CB, Dell OptiPlexGX280, HP dc5750), BMC controls (DQ965GFEKR, S3000AH, DQ35JO, DQ45CB, X2200/M2, X2500), etc. Email sys-admin@cl.cam.ac.uk for details about your workstation. If it cannot support WoL, we can almost certainly swap it for one which can.

Note that it may need to be turned on in the BIOS (the NIC LEDs should be on when most machines are "off", but not all), and the OS drivers need to enable it (check with e.g. "cl-asuser ethtool eth0 | grep -i Wake" that g (Wake on MagicPacket(tm)) is supported and enabled. If supported but not enabled, try adding the cl-wol-g package).

disable CPU wasters (e.g. 'screen saver')

It may well have fancy features to reduce its power consumption, but it is likely to use more energy when running CPU intensive jobs such as screen savers, upto 260% of the "idle" power consumption. Configure the machine to simply blank the screen.

use Time Sharing Systems (slogin-serv* and desktop)

The department has a number of Time Sharing Systems which are suitable for light remote use.

use shared servers (Condor)

For CPU intensive jobs, consider using the Lab's Condor Pool

use virtual servers

We can provide virtual servers which are likely to be more efficient than some old PC running in the concern of an office providing a small service.

Typical power usage

Below are some typical power usage figures. Numbers in brackets are independent core of threads (e.g. ignoring hyperthreading).

• "Off" is when the device is connected to the power, but turned off "at the front".

• "susp" is when it's at its lowest power setting. For a PC that would be suspended; for an LCD standby / suspend / off.

• "idle" is when it is running normally, but not working hard. For a PC that would be idle; for an LCD it's at its lowest readable brightness setting, with no USB devices attached, etc

• "avg" is 'typical' consumption for a device which has many phases (e.g. printers which keep the ink hot). It is averaged over many hours or days.

• "busy" is when running flat out. For a PC, this would be using all available cores, discs, etc; for an LCD it's at its brightest setting.

Numbers in ()s are the numbers of CPUs. an "H" suffix means that it also has hyperthreading.

GN09 (main machine room) uses around 24kW (10kW of UPS, 3kW non UPS and 11kW A/C), as does SE18 (group machine room). Before all the lighting meters are connected, a guess at the lighting is around 16% or 30 kW. On the "private" side of the building, approx half the use is during "office hours". Around 24% is used for power in offices, and around 60% is used running the building, e.g. plant.

PC components

If getting a new PC or refitting an old one, do consider the components used

CPU

On most systems, the OS can greatly reduce the CPU power when it is "idle". The power used can normally be modelled as a fixed "idle" power, plus an amount for the CPU cycles. Low power CPUs have a low "idle" value, a low cost per CPU cycle, and often limit the maximum number of cycles by having fewer cores or threads.

The quoted thermal design power is a likely maximum, but usually significantly more than normal use. Some also have a quoted typical thermal power which may be more realistic.

The ratio of TDP to Core x Clock Speed Ratio (W/GHz/Core) is a useful metric if the CPUs are expected to run flat out all the time. See wikipedia for examples.

Disc

Discs are rated for "read/write" (or "active"), "idle", "standby" and "sleep".

• WD RE4-GP 3.5" 2TB uses 6.8/3.7W active/idle.

• WD AV-25 2.5" 5400RPM 500GB uses 1.6/0.65W active/idle.

Graphics

Normally on-chip or on-board graphics uses less power than a separate graphics card. Passive cooled cards tend to be designed to use less power, and are quieter. See a comparison of 73 cards to see what some use (up to 321W).

Memory

Some new "LP" DIMMs are appearing for server machines.

ideas

Below are some ideas. Feel free to add any, however potty they may sound. Others may chip in thoughts about them.

PV cells

There is a proposal to install (e.g.) 497 m2 of Polycrystalline PV giving a System Size of 71.44kWp, Annual Energy Yield of 59,068kWh and Annual CO2 Savings of 33,551kg. The cost may be split between the department and EMBS. The Feed-in Tariff scheme is due to pay a generation rate of 31.4p/kW h as it is 10-100 kWp for 25 years.

Reduce corridor lighting

Certain areas (e.g. the E end of SC) have two double bulbs per two ceiling panels, whereas others (e.g. the W end of SC) have one double bulb per four ceiling panels. As the latter seems sufficient, it would save a lot to use the same scheme in the former. Some corridors use more electricity on lighting than power.

shut (parts of) the building down outside office hours

By "shutting down" parts of the building (turning off network switches, and thus UTP connection and phones, also with switching off the Air Handler Units) we could save lots of energy.

open windows in machine rooms

(This is mainly here as an example of a whacky idea ....)
Machine rooms are not connected to the main building temperature control system, but use their own coolers. These do not have "free cooling" (GN09 has kit for it, but it's disabled), so using unconditioned air from outside may sometimes be plausible,
Can this be controlled? Is lack of conditioning a problem? Can some kit run warmer than it does?

use of recycled paper

We could use recycled paper in the printers as a default. Users can select better quality paper when they want it (e.g. from a different tray) but I suspect that recycled paper is sufficient for ordinary printing needs. -- John Wickerson (jpw48) Not really to do with energy saving. Mixing paper types in different trays of the same printer is, I think, too complicated for most people. We have had extensive paper trials - 100% recycled is very very poor quality and produces a lot of paper dust which would kill the printers. Partially recycled paper was used until the price rose over the course of 6 months from about 10% more than non-recycled paper to 80% more than non-recycled paper. Supply was also erratic. We gave up (with regret) -- ckh11

defaults

Defaults matter: any new machines (or other major changes such as a reinstall of a machine) should be set to default to hibernate overnight. Changing existing setups may be counter productive.

less vacuuming

The floors are vacuumed far too often relative to the apparent amount of dirt which builds up on them. This is both energy-wasteful and irritating.

less lighting in common areas

Why light the hallways during the day? Other areas (bike lock-up, bike shed) appear to be always on

cooling the hot water in toilets and kitchens

The hot water taps in the building are really really hot -- we could save energy by lowering the temperature of the boiler perhaps? -- John Wickerson (jpw48)
Note that there are Health and Safety concerns such as Legionnaires' disease. We need to run the HW ring above 50C (I'm told that the current target is 50-60). Look at the disabled toilet sinks' HW supply - it is pre-mixed down. So we may be able to make the water come out of the tap less hot, but the boiler needs to be set high - pb22

Footnotes