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Ideas to reduce electricty consumption at home

Just some quick thoughts on how to reduce electricity consumption at home. These figures are very rough-and-ready (but do come from 9 day's of monitoring with IAMs... but usage was a little unusual over the Christmas period):

  • 10 x 12V 50W halogen kitchen down-lights on TRIAC dimmer (currently 1kWh/day = £50/yr). These are the biggest single power draw in our house. I'm currently researching LED or CFL alternatives.
  • Central heating and hot water pumps (combined currently 0.6 kWh/day = £27 / year). Replace with energy efficient pumps (these cost about £100 IRC, so payback for 2 pumps would be ~9 years).
  • washing machine (currently 0.5 kWh/day = £22/yr) fit hot water feed with mixer. Heating water with a local gas boiler is more carbon efficient than using resistive heating.
  • dishwasher (currently 0.6kWh/day = £27 / year) fit hot water feed and disable hot air dryer somehow?
  • 34" CRT TV (currently 0.5 kWh/day = £22 / year) upgrade to LED LCD TV (32" LCD TVs use about 40W) (notes)
  • Dual-core Athlon HTPC circa 2006 (currently 0.6kWh/day = £27/year). Upgrade to 22nm Atom when it's available.

Raw consumption data from 9 days of usage after the break...

New year HTPC woes

(Happy new year!)

We have a home theatre PC dating back to about 2006 running Windows Vista and Windows Media Centre with a FreeView DTB card. It was working perfectly. But, for some reason, Microsoft have stopped providing electronic program guide (EPG) data from 1st Jan 2013. So we can't see the programme guide (hence we can't schedule recordings, which is one of the main functions of our HTPC). It's not clear if MS have decided to kill off the service deliberately (they seem to have gone off WMC) or if it's just a bug.

UPDATE 3/1/2013: MS have just fixed their EPG data. It's working again!

Here are some notes for alternatives I've tried:

Intel Atom notes

Current preferred spec

Case & PSU

  • Item: Cypher AK-ITX-04BK Mini-ITX from Akasa with 120W PSU VESA Mountable
  • Manufacturer: Akasa
  • Description: Small computer case
  • Supplier: scan
  • Supplier product code: LN45102
  • Web page: http://www.scan.co.uk/products/akasa-cypher-ultra-compact-mini-itx-case-black-with-120w-psu
  • Number required: one
  • Price (ex VAT): £44.98

This case has a "brick" PSU which should work with the 12V power input on the DN2800MT motherboard. Lovely small case. Has a hole for an RP-SMA connector (antenna). Just about enough space to mount a Nanode SMT inside.

The plug on the PSU which comes with the case is too big to fit the mobo. The mobo needs a "8 - 19 VDC external power supply though the DC jack on the back panel. This connector accepts dualbarrel plugs with an inner diameter (ID) of 2.5 mm and an outer diameter (OD) of 5.5 mm, where the inner contact is +8 (±10%) through +19 (±10%) VDC and the shell is GND. The maximum current rating for this connector is 8 A." (from p58 of the mobo manual.) So it's necessary to chop off the HUGE connector on the PSU (which has an outer diameter of about 7mm and an inner diameter of about 5mm) and replace it with:

  • Item: CONN PWR PLUG DC 2.5X5.5 8A MOD
  • Manufacturer: CUI Inc
  • Description: DC plug with 5.5mm OD, 2.5mm ID, 14mm length (and locking groove? TBC)
  • Supplier: Digi-Key
  • Supplier product code: CP3-002BH-ND
  • Web page: http://www.digikey.co.uk/scripts/DKSearch/dksus.dll?Detail&itemSeq=127910444&uq=634992759972123594
  • Number required: 6
  • Price (ex VAT): 1.30

Motherboard

  • Item: Intel DN2800MT Atom motherboard
  • Manufacturer: Intel
  • Description: mini-ITX motherboard with built-in Atom CPU
  • Supplier: Scan
  • Supplier product code: LN43166
  • Web page: http://www.scan.co.uk/products/intel-boxdn2800mt-mini-itx-intel-atom-n2800-motherboard-ddr3-1066-so-dimm
  • Number required:
  • Price (ex VAT): £66.28

(also available from Micom)

The N2800 Atom has enhanced speed step so should be capable of consuming just a few watts. It uses a PowerVR GPU which has virtually no Linux support. But that's not a problem because it'll be a headless data logger..

  • Item: 2GB (1x2GB) DDR3 1066Mhz Value Select SODIMM 204 Pin Notebook Memory Module
  • Manufacturer: Corsair
  • Description: Memory module
  • Supplier: BT Business Direct
  • Supplier product code: 5GK8QE00
  • Web page: www.businessdirect.bt.com/products/corsair-2gb--1x2gb--ddr3-1066mhz--value-select-sodimm--204-pin-notebook-memory-module-5GK8.html
  • Number required: one
  • Price (ex VAT): £6.66

WiFi

  • Item: U.FL-RPSMA BULKHEAD MOUNT, 200MM
  • Manufacturer: GIGATRONIX
  • Description: Antenna cable
  • Supplier: Farnell
  • Supplier product code: 1706348
  • Web page: http://uk.farnell.com/gigatronix/u-fl-rpsmabulk-200mm/u-fl-rpsma-bulkhead-mount-200mm/dp/1706348
  • Number required: one
  • Price (ex VAT): £6.42

Cheaper cables are available from Amazon but I need to use a college-approved supplier. Farnell 2143312 would also be a cheaper option (£3.50) but wasn't in stock when I ordered.

  • Item: RN-SMA4-RP - ANTENNA, 2.4GHZ, 4INCH W/ RPSMA
  • Manufacturer: MICROCHIP
  • Description: WiFi antenna
  • Supplier: Farnell
  • Supplier product code: 2143322
  • Web page: http://uk.farnell.com/microchip/rn-sma4-rp/antenna-2-4ghz-4inch-w-rpsma/dp/2143322?Ntt=2143322
  • Number required: one
  • Price (ex VAT): £4.08

  • Item: Centrino Wireless-N 2230

  • Manufacturer: Intel
  • Description: mini PCIe wireless network card
  • Supplier: Micom
  • Supplier product code: 2230BN.HMWWB
  • Web page: http://www.micom.co.uk/intel-centrino-wireless-n-2230
  • Number required: 5
  • Price (ex VAT): £11.65

This plugs into the motherboard. It's designed to use two antennae but it seems to work fine with one antenna on my 802.11g network. There are lots of Intel miniPCIe adapters. Some have draft-N support only. Some have Bluetooth (which I don't need). Cheaper adapters can be found on Google but this 6230 adapter is fairly cheap and comes from an approved supplier; plus Intel WiFi adapters should have good support on Linux. Insight also do the WiFi Link 1000 and Wireless-N 1030 (both for £9.99 ex VAT) but these are "order upon request".

Hard drive

  • Item: Seagate Momentus 320GB 5400.5 2.5" Notebook Hard Drive
  • Manufacturer: Seagate
  • Description: Hard disk drive
  • Supplier: Scan
  • Supplier product code: LN26698
  • Web page: http://www.scan.co.uk/products/320gb-seagate-st9320325as-momentus-54005-25-95-mm-sata-3gb-s-5400rpm-8mb-cache-14ms-ncq
  • Number required: one
  • Price (ex VAT): £28.32

The system draws ~14W while logging (but with a power factor of only about 0.35)

Build order:

  • Take top off case
  • Remove HDD bracket
  • Fit back plate
  • Fit motherboard
  • Fit WiFi aerial cable
  • Fit WiFi mini PCIe card & connect to aerial cable
  • Fit cables from case to motherboard
  • Fit HDD to bracket and install in case and fit cables

Additional notes

Electronics

  • Item: HEADER, RIGHT ANGLE, 6WAY
  • Manufacturer: TE CONNECTIVITY / AMP
  • Description:
  • Supplier: Farnell
  • Supplier product code: 1248172
  • Web page: http://uk.farnell.com/te-connectivity-amp/826947-6/header-right-angle-6way/dp/1248172
  • Number required: six
  • Price (ex VAT): £0.199

The header is required because the header supplied on the NanodeRF SMT isn't right-angled, so the FTDI adapter sits at right angles to the Nanode, and this configuration won't fit in the tiny Atom case. So we need to replace the straight header with a right-angled header.

  • Item:
  • Manufacturer:
  • Description:
  • Supplier:
  • Supplier product code:
  • Web page:
  • Number required:
  • Price (ex VAT):

Motherboards

D945GSE

  • Tech specs PDF
  • Min power draw = 12.28 W
  • Max power draw = 42.01 W
  • Audio is ICH7-M with ALC662 audio codec
  • "Front panel audio header with support for Intel High Def Audio"
  • NO LINE IN (see table 4 on p21 of tech spec PDF)
  • N270 (2.5W TDP)

continued...

Update: building meters

Just a very quick update. Recent work has been focussed on getting the energy meters ready for the MSc group who will be doing a project on "VIsualisation and Analysis of Domestic Electrical Energy Consumption" next term. Specifically, I've been working to get the Open Energy Monitor EmonTX talking to my rfm_edf_ecomanager Nanode code and discussing ways to eak as much accuracy from the measurement hardware as possible. And trying to find a way to measure reactive power for students who won't be able to measure mains voltage and phase angle directly (this is discussed in depth here).

Size of Arduino number types

The size (in bytes) of some number types on an Arduino (some of these are obvious):

char1
byte1
int2
size_t2
unsigned int2
short int2
long int4
long long int8
unsigned long int4
float4
double4

How accurate is an EDF individual appliance monitor?

To try to get a feel for how accurate the EDF transmitter plug is, I simultaneously recorded our washing machine using a WattsUp meter, an EDF transmitter plug and an EDF whole-house transmitter. The WattsUp samples once a second, the EDF devices sample about once every 6 seconds. (data was collected from the EDF devices using my Nanode code and my logging script). Here are the results (click on the image for a larger version):

Watts Up versus EDF IAM versus whole house

And here's the same data but this time the EDF IAM and WattsUp are laid on top of each other. I'm happy that the EDF device is of comparable accuracy to the WattsUp, at least in this experiment:

Watts Up versus EDF IAM

One thing I need to investigate a little more is that occasionally the EDF IAM appears to give a reading which is above the theoretical max wattage an appliance can draw (13 amps x 230 volts = 2990 watts). This doesn't appear to be an RF corruption issue (because the checksum is OK). I guess it's possible that our washing machine does sometimes draw too much (but for a short enough time to mean the fuse doesn't blow). I was hoping to capture an "overload" event in the data capture I did for the graphs above but unfortunately it didn't occur. If I get time I might try recording more WattsUp signals from our washing machine.

I've just ordered another 10 EDF IAMs. When these arrive (in about 10 days) I will have a total of 14 EDF IAMs. I'll run these for a week or so. If these check out OK then I'll probably order another 15 to get to a total of 30 to monitor every appliance in my home.

Group MSc project on "Visualisation and Analysis of Domestic Electrical Energy Consumption"

I'm hoping to organise a Computer Science MSc group project on "Visualisation and Analysis of Domestic Electrical Energy Consumption". One aim of the project is to produce an open-source app tol help people save energy by producing useful and interesting visualisations (pretty graphs) of their energy usage. The ultimate aim is to produce something a bit like Google Powermeter. But better ;)! The full spec of the group project is available here.

I'd be really eager to hear any comments / suggestions at this (very) early stage to try to make the project both lots of fun for the students and also useful to the community. Some specific questions might be:

  • Do you currently use a tool to visualise your energy use? (Such as Current Cost's website or Cosm or open.sen.se or something similar?)
  • Are there any specific statistics / visualisations that you'd be particularly interested in?
  • Would you be interested in being able to share details of your energy use with select friends to compare progress?

(To give a bit of context: Group projects run for the duration of the spring term (11 weeks starting Jan 2013). I'm a PhD student in the computing department so I'll be supervising the project but the detailed design is up to the MSc students. Groups usually consist of 5-6 MSc students. There are no guarantees that a group will actually want to do the project, of course!)

Ensuring the fan runs on my HP ProBook 6450b laptop

I have an HP ProBook 6450b laptop which runs Ubuntu 12.10 and Windows 7. It had a tedious and potentially expensive problem: when running Linux, the CPU fan would fail to turn on until the CPU temperature reached 105℃. This was dangerously hot. I wrote about the problem in detail on the Ubuntu Forum, including links to my conversations on the linux-acpi kernel list.

After spending about a month trying to find a software fix for this problem, I decided it was time to get the soldering iron out to fix the problem. Here's what I did:

Insulating our bedrooms

Back in February, we insulated the two bedrooms in our end-of-terrace Victorian solid-walled house. This blog post attempts to document the process, including lots of photos. The detailed plans for this project (including some CO2 calculations and a complete shopping list) are described in a previous blog post. A quick re-cap of the plans:

  • Our upstairs walls are not damp so we can just attach the insulation directly to the plastered wall, we didn't bother with wooden battens.
  • Use Fermacell instead of plasterboard. Fermacell is much stronger than plasterboard, so it should be possible to hang shelves directly from the Fermacell.
  • 65mm insulation + 12.5mm Fermacell
  • Use 160mm "frame-fixing" screws to mechanically secure the Fermacell to the brick. These come with their own wall plugs. To use, just drill straight through the Fermacell + insulation + brick, then hammer the wall plugs into place and screw in the long screws (i.e. you don't need to pre-drill the wall and then try to align holes in the insulation with holes in the wall).

In total it took about three weekends to install the insulation for both our bedrooms, MUCH less time than it took to insulate our living room. (This time does not include the time taken to plaster and decorate, which we had done by some excellent local decorators - I just installed the insulation & Fermacell.)

On to the details...

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