back to article My home is bugged ... with temp sensors to save me cash

In the past, I've eulogised on the joy of metering and tuning my house, being money and carbon-neutral for gas and electricity at home, and my homegrown solar power. This time I scout out new tech, describe upgrading the insulation in my boy's bedroom with aerogel and how I'm monitoring its performance with spiffy iButtons, …


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  1. Anonymous Coward
    Anonymous Coward

    But what to do if

    Your partner insists on keeping an upstairs Window open two inches all the year round for "fresh air" and on keeping the bathroom window open for at least an hour after anyone has a shower because of condensation?

    AC because, well if she reads this...

    1. Anonymous Coward
      Anonymous Coward


      1) Extractor fan in the bathroom.

      2) It's not a problem having the windows open, if you don't have your heating on - Make a deal, if SWMBO (She Who Must Be Obayed) wants the windows open, get her to agree to switching the heating off - at least in that room - point out that you're just heating the street if the heating is on while the windows are open.

      1. Anonymous Coward
        Anonymous Coward

        > Make a deal, if SWMBO (She Who Must Be Obeyed) wants the windows open

        In this case its SWMAWBO (She who MUST and WILL be obeyed). Negotiation is not an option.

        1. Graham Dawson Silver badge

          Then the only solution:

          1. blazing row

          2. make-up sex


          4. You don't care any more (aka PROFIT!!!)

    2. James Hughes 1


      Turn the radiators off in those room and shut the door

      Get an extractor fan for the bathroom (if you don't have one you do need to keep the window open)

      Get windows with those little flappy vents at the top (for fresh air)

    3. NomNomNom


    4. Mips

      She is right you are wrong

      I have spent 40 years in this business. So believe me.

  2. Arrrggghh-otron

    iButton Model?

    Which iButton model did you use and is there a UK supplier?

    1. Arrrggghh-otron

      Don't worry...

      I found it...


      and a UK supplier...

      1. Anonymous Coward
        Anonymous Coward


        Oh good; at £23/each (min order 5) that sounds like just what I want! And then I still need a reader.

        Back in the real world, however, is there any sort of less expensive alternative? Except the batch of cheap digi thermometers and habit of regularly copying down the readings, that is.

        1. Allan George Dyer Silver badge

          Use the DS18S20 ...

          connect several of them to a microcontroller that sends the readings over your broadband connection and logs it on a convenient server. That's what I did:

          The DS18S20 is much cheaper, probably less than £2 each.

          The coat, please - airconditioning is too strong.

          1. Anonymous Coward
            Anonymous Coward

            You can get a lot of Dallas/Maxim parts

            for free as engineering samples from their website at Put in quantities just low enough to not have the order referred to a manager.

    2. Compact101

      I'm guessing he used this one

      Which has the nice little error msg at the top of the page "<--- Ummm, guys.. this is the WRONG WAY TO DO THINGS Each time you need to show an appnote you don't make a copy of an entire SQL query. The query should be centralized like somehwere under /includes/ and fed an ID number to query. Then it passes the data out as variables to your thermocron page, or whatever. ---> "

  3. Jim 59


    The author is obviously highly committed to this area, but uses too many abstruce references and concepts for a general Reg audience. Perhaps future articles could be written in a way more understndable to the outsider ?

    LED lightbulbs are super but aren't they still colossally expensive ? And in fact rather heavy on the juice ? seems well intentioned but isn't it offering little more than a charting service ?

    1. BristolBachelor Gold badge

      LED "bulbs"

      I recently found an LED GU10 "bulb" that would fit into my ceiling fan*/light and could be operated by the control in the fan (normal ones either blow-up or flash even when off). It looks quite nice, and is made by Philips so should be good. but costs 45€ WTF!!!

      *Yes ceiling fan because in the summer it costs a lot less to operate than air-con (see; I'm green!)

  4. gaz 7
    Thumb Up

    Interesting article, and mirrors what I am doing to an extent. My blog of how I set this up is here

    I am using 1-wire sensors, DS18S20s which I have built into RJ45 connectors, which are then plugged into my cat5 network, and then patched to a Debian running Pogplug via a iLinkusb connector, and a homemade hub.

    The software I am using is HomeAutomation ( which is web-based and allows you to collect tempretures from 1-wire devices, as well as it's main function which is control remote control sockets (Home Easy etc) devices using a Telldus USB transmitter.

    Although I do not control the heating from the system, it does monitor the heating as I have a sensor strapped to one of the pipes, and I can sense when it comes on and off. The system sends a tweet when the heating comes on, and I have adjusted the system settings accordingly to reduce when the heating kicks in automatically.

    I also update iMeasure weekly, and have seen my electricity and gas bills fall since installing this system. So far it has enabled the hardware to pay for itself within a few months, and the savings continue.

    Next logical step would be to buy and hook up some like a currentcost meter to better record the used electricity, and allow the heating boiler to be directly controlled from the server.

    1. richard 7

      Been running this >4 years.

      Same chips, grouped in clusters then bridged to RS485 and fed along to an embedded ethernet controller (X-Jack from Lantronix) All works perfectly and was untill recently all online. We've been working with this stuff a lot and I have set on my bench the beginning of a a whole range of products aimed at doing just this quickly and easilly, Watch this space.

      It does make you realise quickly just how some bits of your house might be insulated slightly badly and you'll instantly see some serious gains. We dry-lined out outside walls and used the styrene sheet and although at the time it seemed horrednously expensive to do (£20 a roll) with the figures in front of you it makes you apreciate how much you've saved. Same with loft insulation et al. We expanded it a little over the years to give it per rad control and then started zoning and intelegent management of what gets heated when. Evenb on an 8 year old early Combi boiler it made a huge difference to the bill.

  5. yossarianuk

    What about people growing weed?

    This sounds like some grand conspiracy against cannabis growers...

    The LED lighting industry will have a boom...

    1. Anonymous Coward
      Anonymous Coward


      If you can get marine corals to live off LEDs, you can certainly grow weed with them.

      They aint cheap though.

    2. Anonymous Coward 15
      Black Helicopters

      And if you grow weed with LEDs

      The police chopper flying overhead will have less of a huge heat escape to spot.

  6. Tim #3

    LED bulbs

    Interesting stuff indeed. Has anyone tried any of the normal (bayonet) fitting 240v LED light bulbs that are appearing? I saw a 5w one in use last week & it was equivalent to a 40w incandescent bulb imho, I'd be interested to hear how good the brighter ones are in particular.

    1. This post has been deleted by its author

  7. dotdavid

    LED bulbs

    Not sure about the other energy saving techniques mentioned, but I had a look at that site selling LED bulbs and found that to replace the ten nasty halogens at home with LED equivilents would cost £22 a bulb!

    I'm not sure how long it would take to recoup £220-worth of investment in lower energy bills, but I'm thinking "a long time".

    I didn't mind replacing my old regular lightbulbs when the replacement bulbs are only a couple of quid each and tend to last longer anyway, but these LED things are going to have to get much cheaper to have much of an effect I think.

  8. Anonymous Coward
    Anonymous Coward

    I'd love to see your accounts for this

    How long will it take to cover costs? Including your time?

    1. Anonymous Coward
      Anonymous Coward

      it's not just about money

      It's about reducing your energy footprint.

      The financial bottom line, while certainly a consideration, isn't always the most important thing for everyone.

  9. Anonymous Coward
    Anonymous Coward

    Leak proof home = sweaty changing room

    Where does all the moisture in the air go from cooking, bathroom and sweating and breathing go ?

    1. Anonymous Coward
      Anonymous Coward


      Modern building regulations require cooker hoods in kitchens and extractor fans in bathrooms. Also trickle vents in various windows.

  10. Yet Another Commentard

    Old buildings

    You would be surprised what you can do with an old building (and enough cash). This one was done by a friend of my wife's, and is quite incredible. It's a Victorian terrace, all gutted, reworked, and has no heating at all.

    A tad extreme for a DIY thing, but just goes to show.

  11. The BigYin


    I've just have the bloody plastering done. Damn you to heck! :)

    I had some polystyrene-backed boarding used as was told that they did not qualify for any relief. Hey ho, at least my bills will be lower. I was aware of Areogel but the contractor had never heard of it and I struggled to find any products - now I know which names to use I might be able to find them the next time the plaster falls off.

  12. petur

    I'm currently using a Flukso ( to monitor 3 AC circuits and solar (pulse), looking at capturing the gas meter via an additional pulse input. Limited graphs but enough to be useful in monitoring your consumption

  13. DJ Smiley
    IT Angle

    Mould... mositure

    Won't your house go mouldy if you seal up all these gaps, or is it a case of you'll never fully seal it, so don't worry about it?

    1. Anonymous Coward
      Anonymous Coward


      (i) a dehumidifier

      (ii) a heat exchanging ventilation system

  14. johnnytruant

    LED lighting ftw.

    I moved house just as my local $supermarket had Philips Econic bulbs at 75% off, so as the previous owners had taken all the bulbs with them, I took the opportunity to install LED lighting throughout.

    Even given that I have 22 GU10 spots in the house, the entire house tops out at 110W total for all lights, and it cost less than fitting CFLs. Modern LED bulbs are bright and warm enough to light any room - I have whiter "sunlight" TP24 bulbs in the kitchen and bathroom and warmer Econic ones in the front and bedrooms.

  15. Anonymous Coward
    Anonymous Coward

    Upstairs downstairs?

    I put a few extra inches of subsidised Space Blanket in the loft earlier in the year (ordinary one and two halves bedrooms twenty year old semi).

    Since doing that, upstairs is consistently two or three degrees warmer than downstairs, and if I turn the downstairs CH thermostat (digital programmable thing) up over 16C, bedrooms end up at 21C in the evening which is uncomfortable. It's not a complete surprise (hot air rising, etc) but it isn't the obvious way to run a house - bedrooms are supposed to be cooler than living areas, aren't they?

    Forced air ventilation and/or heat recovery seems a bit OTT.

    Is this a common situation or is it just me?

    1. The BigYin


      Turn the rads in the bedrooms down/off?

      Or look at increasing the insulation between the floor?

      Or close a few doors?

      Hard to say without knowing the layout of the house.

    2. Samuel Williams

      If you haven't got them, you really need thermostatic radiator valves (TRVs) upstairs at least (or ideally anywhere away from the main roomstat). Made a huge difference when we put them in - upstairs is now cooler than downstairs. If that's not an option, you could try balancing the radiators. This means using the valves to restrict flow to make sure each radiator is heating up at the same rate and you really need thermometer(s) and patience to do it properly.

      1. Anonymous Coward
        Anonymous Coward

        thanks to TheBigYin and Samuel Williams. Anyone else?

        AC 13:17 here again, all input gratefully received.

        "Turn the rads in the bedrooms down/off?"

        Upstairs rads already all set to off, thanks, apart from small radiator in small bathroom (in small house).

        "look at increasing the insulation between the floor"

        I'm guessing it'd go up the stairs instead. Not really room for a door. I semi-seriously considered one of these dangly-shop-door-curtain things (sorry, dunno what they're really called).

        "Or close a few doors?"

        Then I keep walking into the doors.

        Less facetiously, the only downstairs radiator that is on anything other than very very low is the small rad in the small hall (opposite the digital CH thermostat, and the main reason it's on at all is so the stat gets warmed up a bit when the CH runs).

        I s'pose I could leave various doors closed on a trial basis just to see what happens.

        "you really need thermostatic radiator valves (TRVs) upstairs at least" and

        "try balancing the radiators."

        In principle, fine ideas. In practice, for me, because upstairs gets too hot anyway, all the radiators except the bathroom and the hall are already set to "off" as described above.

        "upstairs is now cooler than downstairs"

        Just what you need, but if things are properly insulated, how can it be, given that heat rises? For that to happen, surely upstairs must be losing heat more rapidly through walls, Windows and (upstairs) ceiling than it is gaining from the floor below (and from any upstairs radiators). Not good from an efficiency point of view, surely, even if it's good from a comfort point of view?

        There is ventilation upstairs where I am (windows are original wooden frames, not double glazed, not big windows admittedly as it's a small house, opened on trickle ventilation setting on half the windows).

        I take it this isn't a common problem then?

        Again, thanks for all input so far, more will be gratefully received.

        1. Samuel Williams

          *Heat* itself doesn't rise - it transfers from a hot place to a cold place. But, *hot air* rises because it is less dense than cold air, which is most likely what's to blame for heat transfer in the house. Our hallway is kept a little cool (with TRV) - the main thermostat is now in the lounge. Overly heating the hallway will probably send the hot air up the stairs. Thermostats were very often installed in hallways (as was ours), which makes no sense really - why optimise the temperature in a room you only walk through? A wireless jobby put a stop to that.

  16. Anonymous Coward
    Anonymous Coward

    Underfloor air circulation!!!

    "I have one button under the floor (which immediately showed up a huge draught coming in through the exterior wall below floor level)"

    You really need to have air circulation from outside under your floor, this stops it getting damp and rotting. The back room of my place had to have its wooden floor removed by the previous occupants because they blocked up the air bricks to stop the draughts and this knackered the floor. They then compounded their idiocy by replacing the floor with a concrete plug. No rear cellar extension for me...

    What I have done in one room is put a tongue and groove floating floor over the top of the mis-matched draughty floorboards, this is a pretty effective insulation and looks nice too. In another room with all the original Victorian floorboards, I used marine caulking (black polyeurothane) between the gaps and sanded and used a wax/varnish hybrid on the boards. You can, of course, just put a carpet over sealed floorboards.

    I'd be interested to know if you have any ideas for insulating a Victorian terrace with solid walls. I've replaced all the windows with double glazing, the chimneys are blocked during the Winter (when not in use!) with chimney balloons and draughts from floors have been stopped as mentioned above. I just can't really think of anything else to improve it. Loft insulation is present, but lacking in volume, however as we're going to have the loft converted soon that's not really an option.

    I monitor my energy use and temperature with a combination of CurrentCost meter and home-brew arduino logging into a RRDB. I like your idea for monitoring each individual room, but I'd like to do it real-time if possible.

    1. James Hughes 1

      Solid walls!

      I've got solid walls on a lot of the house, the modern extension with is way warmer than rest of house. Not sure what to do except line the walls on the inside which is a major building job.

    2. David Pollard

      Victorian terrace with solid walls

      An internal insulated lining would work ... but what about the joists? In most of these properties, built before joist hangers were invented, they were supported on one brick's worth of the wall with only a single brick on the outside to keep them dry.

      The insulation manufacturers suggest leaving the gap between the downstairs ceiling and the floor above uninsulated. Although this allows circulation, it leaves a severe heat bridge; and there may still be enhanced tracking of condensation towards the cold wall.

  17. BristolBachelor Gold badge

    Thermal bridges

    Aren't they the metal screws that you use to feed the warmth from the room straight through the insulation into the wall? :)

  18. John Smith 19 Gold badge

    Some kind of IR draught finder would be a great idea.

    I think some kind of thermistor pair wired in a bridge and mounted in a tube with partition running longways in it. Ideally each would have some kind of indicator so the colder one points you in the direction of the draught.

    I've done this with a wet finger and it's astonishing how fast the air flow is when the actual hole seems to be little more than a pin prick.

  19. Anonymous Coward
    Anonymous Coward

    Point of order: LED "bulbs" and colour

    Basically all available now high output "white" leds are blue at the heart. Not just the warm ones; all convert some portion of the blue to red or green, or why, yellow. "Warm" ones just lose more to try and fill in some of that sometimes rather huge gap between blue and green-down-to-red with some yellow. Apparently we don't have the efficient phosphor mixes to make a truly "white" light; there's always a blue spike of some size and maybe a dip, sometimes quite deep. It's why things in led torchlight tend to look off. So when testing these things, please obtain spectrum charts!

    1. Anonymous Coward
      Anonymous Coward


      The "blue LEDs" use IR to excite a yellow phosphor and also have a blue LED, this is what gives the slightly odd colour to the light.

      That is from memory, a couple of years back, it may have changed by now.

      1. Anonymous Coward
        Anonymous Coward

        "The "blue LEDs" use IR to excite a yellow phosphor"

        Surely that would be "use UV to excite a (something) phosphor"?

        Phosphors, afaik, can only make the light wavelength longer. IR is already longer than visible, therefore you can't get visible light from exciting a phosphor with IR.

        Classic fluorescent lights come in various colours and tones, all excited by a gas discharge which gives off UV light to excite a phosphor (or mixture of phosphors).

        Why doesn't the same phosphor mixing principle apply to "white" LEDs (yet)?

        1. PsYcHoTiC_MaDmAn

          not quite.

          fluorescents use UV to excite the phosphors, however due to "safety concerns" regarding the potential for UV to escape the bulb, white LEDs utilize blue light (450nm ~ish if I remember correctly) to excite the phosphors instead,

          this means that theres been a lot of development with regards blue LED efficiency (which is good if your into marine corals), but it does mean that the white LEDs have a large skew towards the blue spectrum.

          unfortunately theres a lot less development at the red end of the scale (the only 680nm LEDs I've found are the 3-5mm ones which have pathetic lumens/watt) so plant growth isn't as good (not specifically referring to pot, I was looking to build an array for a freshwater planted tank)

          on the effective lumens, I'm wondering if this refers to the fact that the light is sent out in one direction, and isn't reabsorbed by the bulb (CCFLs and their loops, or reflectors on the inside of halogens etc)

  20. dark1here

    Under your floor, assuming it is supended floor there should b airbricks to ensure the circulation of air, to prevent the decay in the floorboard and joists. Block these bricks at your peril.

    If you feel the need to insulate, you need mineral wool bats or similar between the floor joists. I used flame retardent polystyrene

  21. All names Taken


    Ditch the sensors > get used to the cold > invest in warm clothing that is easy to wash n dry.

    Perhaps the boss indoors is from a colder clime or outdoor way of life?

  22. Anonymous Coward
    Anonymous Coward

    Solid walls and similar problems... and solutions?

    There is information available for you, much of which comes from real experience.

    Have a look at e.g. - I'm sure there is better available, but that will have to do for now.

  23. Mips

    This article should come with a health warning


    There was a time when you could not get a mortgage for a timber frame house (that may still be the case). The reason for this is because of an inherent fault.

    The ancient form of timber frame building had lots of ventilation, they had no windows and the roof let the smoke out through the thatch, later chimneys and windows were added. Insulation was non-existent, heating was poor and very little water was used in the house.

    Modern living is completely different and a challenge for a timber frame or for that matter any type of house. We put huge amounts of water into the air and have very little ventilation. There is pressure on the structure to pass this moisture to outside and in winter this moisture as it cools will condense at some point within the structure. The condensation point is critical as if it occurs too far in you will get dampness and in the case of timber frames increased risk of timber decay. The condensation point is controlled by internal humidity and the level of insulation: the condensation point moves towards the warm side of the insulation as it is increased.

    It is possible to control the flow of moisture through a structure using vapour barriers: vapour will still get through but not in sufficient amounts to cause a problem, they are prone to being damaged which is why timber frame has a bad reputation.

    Another technique is to conduct the water back to the warm side by wicking and evaporate it off on the inside. This requires very strict control and is where a certain amount of snake oil might appear. Water in the insulation reduces its efficiency, evaporating the water takes energy and reduces the inside surface temperature and water has to evaporate and you cannot use conventional finishes. In the end you still have the water in the house and additional ventilation is needed.

    Basically I do not like dry lining, external cladding is better if you can afford it and if it can be accommodated. Breathable buildings are fine but will not deal with lots of moisture and are very specialist. Of course you could use air conditioning, but that rather defeats the point.

    LED lighting

    I believe that LED lighting is the future and we are getting there, but there are still a lot of snake oil salesmen out there.

    Don’t expect to get more than 80lm/W for white light and for warm white 60lm/W. The prices I see are still high, don’t expect to get good prices from stores and DIY outlets. Go for a reputable manufacturer. Spotlights are good, replacement GSL and fluorescent tubes are questionable, modular luminaires: ouch!

    I would not pay £20 for a spotlight, £13 is about right at the moment.

    I have been using LED lighting for about 12 months but only for specific application with PIR switching where a fast response is an advantage.

  24. All names Taken

    Seems a shame that those longlife incandescent replacing lightbulbs fail by their second winter.

    Either completely or by throwing out a horrible dingy light.

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