Home automation energy savings

[Andrew Gabriel]

As some of you know, I've been playing with home automation (mainly lighting and heating) for many years. I was not initially particularly concerned with energy efficiency, but as fuel prices increased, I did increasingly more in this area.

Anyway, I finally found time to go back and graph my gas usage over this period (or at least, the last 15 years which is the limit of my records). It seems that I have managed to reduce my gas consumption by 55% over that period. Note that no changes have been made to the house insulation over this period.

Graph here:

I really need to do a similar exercise for the electricity consumption, since it could simply be that that has increased by the same amount, although I think that's very unlikely. Up to 10 years ago, I had 4 always-on PC's, but that's down to just 1 now.

[Tim Watts]

I'm impressed you have data for that long!

[Tim Watts]

It stands to reason (to me anyway) that if you zone the CH and if you have 7 day timing, plus remote control to cope with aberrations of timings, that it ought to be a lot more efficient compared to the old way of "heat the whole house for fixed times".

My father used to run around turning TRVs (when he fitted TRVs to replace the basic on/off valves) up and down in bedrooms.

[cl]

My approach for the always-on PCs has been to work hard at reducing their power consumption. My desktop PC (which is always on because I use it remotely) now idles at only 18 watts even though it's an Intel I5 quad core processor with lots of memory and hard disk space. The other always on PC is a Raspberry Pi using only one or two watts.

[Andrew Gabriel]

This house is just a single zone (would love to zone it, but it requires pulling down the kitchen ceiling to get to the relevant pipework). It doesn't have TRVs either - I have twice bought a set to do it, but then used them in another house. The system is pretty much as originally installed in 1990 (not by me) and still using a Potterton Profile (non-condensing boiler). All I've done is take over the control of the heating and hot water from the basic timeswitch which was originally fitted.

The energy usage is now too low to justify replacing the boiler with a non-condensing one, unless/until the current boiler gets expensive to fix. With me servicing it, it hasn't needed any replacement parts in the last 15 years. (The only cost has been getting my flue gas analyser serviced/calibrated every 3 years.)

A significant part of the savings come from not using a timeswitch (although I still did run timed programmes like a timeswitch when I first moved it to home automation control). Heating and hot water are almost entirely now manually requested, but also automatically linked to occupancy, so they shut down when no one is there, or gone to bed. Hot water cylinder is only heated sufficiently for a bath or a shower, whichever is wanted at the time (I have some more work to do on this). As you say, remote operation is also a key part of it.

[Allan]

[snipping]

How have you been able to manage to pin down the figure of 18 watts. Like you, I have an always-on PC for remote working, and I'd like to be able to monitor the usage so I can see what effect various changes have on its consumption, and also get an accurate idea of what it is consuming when it's 'always-on' over a period of a week or so.

Thanks

[Tim Watts]

Stick the TRV valves in minus the heads and get a HeatGenius ZWave system. I've tried it out in a relatives flat and it has very much behaved itself over winter. I'm extremely impressed. I suspect payback of about 3 years which is fine. But the way the flat is occupied, it doesn't do to heat all the rooms all the time so it is probably not heating half the place for about half the boiler-on-times so quite a moderate saving.

[JimK]

how long do the batts last in the TRV heads, assuming reasonably sensible usage?

Jim K

[Clive Page]

How did you get past their awful website to find out anything about it?

Their main page consists mainly of a video (which I could not bring myself to waste time watching). Several levels down in their page structure I got to "How it works" and then "Products" and I still couldn't work out what they provide and how it works. It looks like they have motors that will attach to some the existing TRV bodies and be controlled remotely, but whether they are wired in or need batteries that need replacing regularly (running motors frequently must use a fair bit of juice) I can't tell. And whether they have a programmable timer, or use exclusively thermostats, or whether you have to continually monitor it by smartphone, I can't work out. Is this what it is, if so why the hell can't they explain it.

And it seems to cost an awful lot too "Peter of Worcester Park spent £712" - that will take a huge saving to get a reasonable pay-back period. In principle I'd be interested in this, but not from a company who can't provide a decent explanation on their website.

[JimK]

"Wireless Radiator Valve 2 x AA 1 - 2 years, depending on use"

Jim K

[cl]

With a plug-in power meter, you can get them quite cheaply now on eBay etc. They're not perfectly accurate, especially with a non-sine load like a PC but tend to read high on such loads anyway. Mine is certainly pretty well spot on when tested with known loads such as incandescent lamp bulbs and even gives results in agreement with CFL lamp wattages.

In my experience the power consumption of a PC doesn't vary much with activity, unless you really hammer graphics intensive games. My previous system (which ran at a steady 40 watts or so when idle) never peaked at more than 80 watts. The current 18 watt system bubbles up to 30 or 40 watts if you really try hard but that's about all.

[Tim Streater]

Does your PC have any sort of Energy Saver Control Panel? I've got an oldish MacMini as a file server. I've configured it to go to sleep at

23.30 and wake up again at 08.00.

[Tim Watts]

Year or more apparently. I will be able to confirm that by next autumn! They only move the motor a few times a day at most, probably hardly at all in summer (although they to have a weekly exercise routine to prevent the valves sticking). The whole thing deep sleeps for about 10 mins or so between brief wakeups to ask the controller if it has any new settings (this makes it slightly laggy but as CH is laggy anyway, I certainly do not notice this).

[Tim Watts]

I read a few reviews, and read through some of their documentation. If you go to Quick Checkout you can see all the items they sell. These are rebadged components from other people except for their controller which is what they actually make and program.

Which is quite sensible IMO - they sell a system but they only have to worry about making one bit.

Updates and new features trickle out at a respectable but non alarming rate (ie they don't tend to break stuff, and they aim for a solid core before adding fluff).

Most of the cost are the Danfoss TRVs - they are not sold at a markup as far as I can see and at 60 a pop they add up fast.

Of course, you do not have to put them everywhere - I didn't. Just in the bedrooms in fact. This way the bedrooms can be "zoned out" in the day, and if the bedrooms are warm, you probably want the main rooms warm. And the bathroom and hall just act as shunts - we left regular TRVs on each set to the right temperature for those rooms.

It's also easy to buy an extra RF TRV plus a wall sensor and add zoning to a room if you change your mind later. Certainly seems very flexible.

[DJC]

I have the gas and lectric bills since I moved in 30 years ago, but only started keeping track when I replaced an electric shower with a gas combi in 2005. There were also some changes to the number of computers I have running.

but the cost graph is rather different

[newshound]

Oh come on, we DIYers keep *everything* on the grounds that it might come in useful some day....

[Dave Liquorice]

Meh, once you have an automated system that logs things it just happens. I have automatically:

Weather data from Aug 1999 (every few seconds) Mains Voltage from May 2008 (every 5 mins) Heating system from Sep 2012 (every 1 min) Electrical Power from Jan 2013 (every 1 min)

Oil Consumption from May 2000 (manual, weekly)

I'm surprised the mains voltage only goes back to 2008. That data comes from the UPS and that appeared around 2000/2001. Similarly for power, that data comes from a CurrentCost device which I'm pretty sure I have had for > 5 years.

[Robert]

What puts me off is that the Hub/controller does not appear to work in a standalone mode - e.g. with no internet connection to the HeatGenius server. Dont like being dependant on a 3rd party for this level of investment and such a critical system. Companies go bust, start introducing annual fees etc and you are tied in.

[Tim Watts]

I was told it does - but I am happy to go over and try that out at a convenient moment. Yes I share the same worry. However, there is nothing on the market with this level of functionality and ease of installation/management.

I portscanned it and it presents 3 TCP ports:

2 HTTP and one SSH.

The HTTP is not a website, but I suspect one is running an API over HTTP.

I should really wireshark it too while pointing the app at it.

Will report back in a week or so...