Tuesday, October 31, 2006

MythTV energy costs

...between £165-£330 per year!

I'm increasingly disturbed by the energy consumption within my home and some time ago, bought a little plug-in power monitor to see where all of those KWh were going. The monitor plugs in to a wall socket and the kit plugs in to the monitor, either directly or indirectly via a PDU.

It was quite useful in showing me that my cable-box consumed 100% power while on standby and my MythTV server and slave frontend consumed around 150W.

I have a lot of kit that currently runs 24x7. Different parts of it are needed for recording shows, for watching shows, for when people are in the house or for remote access. There's a Venn diagram in there somewhere but here's the list:
  • MythTV Slave/frontend inc. ATA disk, PVR350, USB-serial convertor, homebrew serial-IR sender
  • MythTV backend inc. 2x ATA disk, DVB-T card, USB2 card
  • External USB2-ATA enclosure and disk
  • USB2 media card reader
  • USB2 webcam (currently off)
  • NTL cable-TV box
  • RGB-SVideo convertor
  • 100Mb switch
  • Airport Express
  • Broadband router
  • NTL cable-broadband box
  • Subwoofer (in auto-standby mode)
  • AV amp (in standby)
The rest of my AV kit (DVD player, Plasma screen, VCR) is controlled indirectly by my AV Amp via a special relay-controlled PDU. If the Amp is off or in standby, the PDU cuts power to the AV kit.

A lot has changed since I first looked at the power consumption of my Myth setup. Due to varying size/noise/location requirements, it used to be spread out around the house but now almost everything resides in the same location, in the cupboard under the stairs. This should make consolidation and power control somewhat easier & cheaper.

I now have an Electrisave. It's a device that can monitor the power consumption of individual power-circuits or an entire home by electromagnetic current sensing. Mine is clamped on my house feed and reads a steady 0.25Kw when the house is quiescent, ie. with no heating, cooling, lighting or domestic appliances running. That's 2190 KWh, 2 Tons of CO2 or about £250 per annum.

Not all of this is down to the PVR subsystem. I have a bunch of devices on standby; clock-radios, a stereo and the microwave. There are also a handful of other devices drawing power such as a wireless phone base-station/holder and electric toothbrush charger.

I'm determined to get to the bottom of this 250W; my short-term goal is to halve it and this will definitely need me to completely re-think my current MythTV setup...


Blogger Floppy said...

Bloody hell, that's a lot. I've got a similar device for measuring power, but I've not got around to plugging it into my Myth setup to find out what it draws. Might have to now though, you've scared me. Have you ever tried using the auto power-off and wake-up functionality? Also, do you know of any way to send a remote command when a recording ends, for instance to turn off the video source?

5:53 pm  
Blogger Floppy said...

Of course, you can solve the CO2 aspect of your usage by switching to a 100% renewable provider like Good Energy (www.good-energy.co.uk)...

5:55 pm  
Blogger Mezzanine said...

I spent a few hours last night familiarising myself with and testing nvram-wakeup. It works really well on the GX150 but as we'd expect, there are issues with it on the Shuttle. First off, I still can't get the Shuttle to boot reliably. If I perform a warm reboot it always come back up ok. However, if I shut it down for any length of time, it often takes several power cycles to get the POST to complete. This is an age-old hardware problem I've had that never really bothers me as the Shuttle is always on... Ah, ooops.

Secondly, there doesn't appear to be a way to enable/disable the BIOS wakeup by poking the nvram. You can set the wakeup time but can only switch it on or off in the BIOS. This may not be fatal.

Anyway, I need to move my PVR350 over to the GX150 and make it my dedicated BE. I can then start using Myth's builtin sleep/wake functionality. The Shuttle will become a dedicated FE. Both boxes seem to support WOL (with the Shuttle also claiming to support WO-USB and WO-keypress amongst others). Perhaps by moving the Hauppauge card, I might even get the Shuttle to boot consistently...

However, actually reconfiguring as above is about a weeks worth of tinkering due to all of the existing dependencies and interactions within my system.

9:49 am  
Blogger Floppy said...

I had the same POST problems with my Zen originally, but I think I got round them by underclocking it. Not sure if that helps you at all?

10:54 pm  
Blogger Mezzanine said...

Underclocking it helps but doesn't cure it. Actually I undervolted and hardcoded some FSB and memory timings a year ago. Before that, it wouldn't even warm-reboot reliably. I have a feeling the cold boot might be power-related as warm-booting doesn't require a disk drive start power surge. Hence, removing the PVR350 might cure the problem.

9:05 am  
Anonymous Anonymous said...

Hi I've been looking for something like your electricity usage meter in the UK for a while now, but all I could find US versions of the same.

If you don't mind me asking, what is it called and where did you get it from?

3:42 pm  
Blogger Mezzanine said...

I bought the Electrisave from Ethical Superstore. The plug-in energy meter is from Maplin, Code L61AQ.

4:16 pm  

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