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Thread: Presence Conundrum...

  1. #1
    Automated Home Sr Member John Winter's Avatar
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    Default Presence Conundrum...

    Hello again folks.

    Hopefully some of the more adept Cortex people out there will have an answer to this one - or indeed there may be just a really obvious answer that I'm staring in the face! Please ridicule, or suggest complex solutions as appropriate....

    I have an HVAC object set up for the whole house - essentially I take the average temperature from a number of rooms and use that to control the on/off of my central heating. Even though it's a simple setup, it works very well in terms of maintaining correct room temperature and in saving energy.

    Trouble is, in the morning, the house is cold. I have to get out of bed for Cortex to realise I'm still in the house, infer my presence and then to switch on the heating.

    The HVAC object derives its presence input from the ground floor and first floor objects - their presence times out after the last room in them with movement has itself timed out. This time will be no more than 11 minutes, as for example the bedroom presence time out is 10 minutes , and the floor time out is one minute. So at that point, the HVAC will have no presence input, will run on for 10 minutes, then flick over to the unoccupied profile. The unoccupied profile is a much lower temperature setting than occupied, hence my house is a bit chilly in the morning.

    So you may say 'just use the house object to infer presence to the HVAC' - which of course has the ability to check external doors to see whether someone has actually left the house and is therefore much smarter than floor level presence.

    Here's the rub - I have external lighting, controled by PIR's that are within the house object. The occupied profile is correctly maintained overnight when using the house object, however if I leave the property via an external door and Cortex changes the house status to unoccuipied, then of course, an external movement detected by the lighting PIR's will result in an occupied state for the house - I don't want next door's cat controlling my heating! This is why I use the presence output at floor level for HVAC.

    So I've tried dragging and dropping my external 'rooms' to a location outside the house object, in the hope that presence would not then be inferred to the house (until very recently I didn't know you could do this...) but this seems to be not allowed by Cortex.

    I have an idea for a solution based on my alarm system's outputs forcing an occupied or unoccupied state to Cortex, but I'm not sure how to realise it. Essentially, I'm fairly security conscious, so always part set my alarm at night - which would be an ideal way of forcing Cortex to an occupied state. Also, I always full set my alarm when I leave the house, which would of course be an ideal way of forcing Cortex to unoccupied. This may solve my heating problem.

    So - answers on a postcard please......

    Cheers

    John
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    www.nodeone.blogspot.com

  2. #2
    Moderator Gumby's Avatar
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    Hi John,

    I think you have separate issues which are getting mixed up. In my opinion the first thing is to ensure that presence tracking is working well. Bedrooms are probably the trickiest for obvious reasons. I have a motion sensor above the bed and set the timeout longer than for other rooms. This seems to do a reasonable job of maintaining presence correctly.

    The next thing is that I have an HVAC object for each room. These drive "zone valve" objects, again for each room, since I have individual radiator valves. However, you can have multiple HVACs feeding fewer zones. This allows you to bind individual room presence to the profiles, even though your actual zoning may be coarser. Using this, you could set you unoccupied profile for the bedroom higher at night so that the correct demand temp is maintained even if presence tracking has lost occupancy. Of course, if your zoning is coarser, it does mean you will also heat other rooms, that is unavoidable in any control scheme where you don't have small zones.

    As for your external lighting - I don't currently have such lighting, so I have not worked through the best way to do this, but it is a topic I have been meaning to ask Vivian about for some time. Clearly it is a common requirement but the best approach is not obvious. In my mind it is better to have the external lights separated from house occupancy, for the reasons you have stated, but external doors ideally need to link into the subject areas to assist presence logic in those areas. This is the part I have not tried.

    There is almost a missing hierarchy level of "property" which can contain buildings with quite clear occupancy and open areas of less determinate occupancy due to animal life and multiple unmonitored exit routes. I am sure that you can get the effects you might want by having multiple "houses" and linking them for things like alarms, but it would be nice to make the user interface reflect the hierarchy.

    In my experience the drag and drop doesn't always do what you might expect and because of that I never use it. IMHO it should be disabled so that it can't be "discovered".

    In general I try to avoid "working against" the logic of Cortex. If I find I am trying to "force" something, it often means that I've taken the wrong approach somewhere and there is another way of doing it. Cortex has been designed in an incredibly flexible way, but has been grounded in many real installations so there is usually a way of doing "normal" things.

    Hope that helps, I'm sure we are going to have an interesting discussion on this one.
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  3. #3
    Automated Home Legend chris_j_hunter's Avatar
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    how about feeding an alarm-clock function into the mix - ie: so you can push a button or speak when you go to bed, to tell Cortex when you want to get up, so it knows more clearly when to change profile & when to have things, including the heating, ready for when you want to get going ?
    Last edited by chris_j_hunter; 5th December 2010 at 04:30 PM.

  4. #4
    Moderator Gumby's Avatar
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    I quite like the idea of a "profile offset" feature which would allow you to advance or retard the heating profile. If you could link it to alarm time then even better.

    Since my wife works on varying shift pattern I have always been looking for ways that automation can be unlinked from strict observance to clock time.
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  5. #5
    Automated Home Legend chris_j_hunter's Avatar
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    profile offset - our current CH programmer has buttons for over-ride & over-ride for just an hour, one each for heating & hot-water ...

    often think an alarm should have (a smart alarm would have) several options - ie: wake me at a specific time, wake me after so many hours, wake me when such-n-such happens, wake in-time (to get ready) for something that has to happen, wake me for work, for day-off, for day-shift, for night-shift ... ie: setting an alarm perhaps shouldn't need us to be working-out / calculating just when we want it to do its bit !
    Last edited by chris_j_hunter; 5th December 2010 at 07:22 PM.

  6. #6
    Automated Home Ninja Viv's Avatar
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    The HVAC object has two presence run-on periods.
    When a room looses presence the HVAC will continute to use the occupied profile for a user defined period.
    On well sensed properties Cortex will track you around the property. To prevent lots of switching between occupied and unoccupied profiles as you move around the house the HVAC has a run-on period (similarly the lights).
    In the HVAC object the run-on period can switch between two possible values dependant on what time of day it is.
    The rational is that if you detect presence say in a bedroom after say 10pm then you set the run on period to be eight or ten hours. This will allow the HVAC to maintain an occupied profile even though no motion senses are detected when people are asleep.
    In the morning you switch to a shorter period so that it requires greater detection to maintain the occupied profile.

    Regarding external lighting.
    For external lights and PIR's a more conventional approach may be better.
    The external PIR's do NOT connect to a notional external room.
    The external Lights are NOT connected to a room.
    The external lights can still use an external light sensor and Operating period.
    Set the external light to use presence and external light level or other suitable mode which uses the timer. See the lights 'Conditional states required to turn a light on' so that the
    'or Timer' graphic is present.
    Make the external PIR trigger the Lights - Timer start connection.
    The light will then go on provided its dark for the 'Lights on duration timer'.
    This way the room, floor and house presence are un-affected.
    It can still also use a rooms presence if required for more complex operation.

    Viv.

  7. #7
    Automated Home Sr Member John Winter's Avatar
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    Thanks for the responses, folks - interesting comments...

    Quote Originally Posted by Gumby View Post
    I think you have separate issues which are getting mixed up. In my opinion the first thing is to ensure that presence tracking is working well. Bedrooms are probably the trickiest for obvious reasons. I have a motion sensor above the bed and set the timeout longer than for other rooms. This seems to do a reasonable job of maintaining presence correctly.
    The tracking does work well - I can walk around the house with my laptop connected to the server via RDP and watch the room presence indicators follow me around. One difference in my setup to yours is that I've strategically masked off the bed area of the room PIR sensors to stop the lights coming back on if I go to bed before the lights on period ends, I'll push a button on one of the lightswitches that's programmed to turn the lights off, and they then stay off. Perhaps I should look at re evaluating how I do this, looking more closely at the timeouts - unfortunately they only go on up to an hour, so I can't simply just increase the bedroom presence timeouts to say 8 hours..

    Quote Originally Posted by Gumby View Post
    The next thing is that I have an HVAC object for each room. These drive "zone valve" objects, again for each room, since I have individual radiator valves.
    Until Karam develops some z wave controllers compatible with these -

    http://www.automatedhome.co.uk/New-P...hermostat.html

    then I'll have to go with the 'whole house' concept of heating.... SWMBO will not take kindly to me chopping out the walls for thermostat control cables!

    I do seem to remember some time back we touched on external lighting and how it can be achieved without screwing with house presence but I do agree with your comments regards an intermediate level of hierarchy - perhaps just a connection to a 'virtual' house (with the ability to monitor external doors), for example would be adequate for my particular issue.


    Quote Originally Posted by Gumby View Post
    In my experience the drag and drop doesn't always do what you might expect and because of that I never use it. IMHO it should be disabled so that it can't be "discovered".
    Yes - it really didn't seem to work properly - the icons changed, connections were lost, and some objects disappeared altogether.

    Quote Originally Posted by Gumby View Post
    In general I try to avoid "working against" the logic of Cortex. If I find I am trying to "force" something, it often means that I've taken the wrong approach somewhere and there is another way of doing it. Cortex has been designed in an incredibly flexible way, but has been grounded in many real installations so there is usually a way of doing "normal" things.
    Agreed, but you could look at my suggestion as just adding additional inputs to Cortex to ensure it's behaving in a more efficient manner - if for example you leave the house and set the alarm at the same time, you might as well have all the internal lights switch off straight away, ignoring the timeouts. No harm in that.

    I do like the idea of a 'time shift' for heating - similar in function to the HVAC temperature compensation feature, but changing turn on times dependant on external factors as opposed to set point temperatures.

    Quote Originally Posted by Viv View Post
    The HVAC object has two presence run-on periods.
    When a room looses presence the HVAC will continute to use the occupied profile for a user defined period.
    On well sensed properties Cortex will track you around the property. To prevent lots of switching between occupied and unoccupied profiles as you move around the house the HVAC has a run-on period (similarly the lights).
    In the HVAC object the run-on period can switch between two possible values dependant on what time of day it is.
    The rational is that if you detect presence say in a bedroom after say 10pm then you set the run on period to be eight or ten hours. This will allow the HVAC to maintain an occupied profile even though no motion senses are detected when people are asleep.
    In the morning you switch to a shorter period so that it requires greater detection to maintain the occupied profile.

    Regarding external lighting.
    For external lights and PIR's a more conventional approach may be better.
    The external PIR's do NOT connect to a notional external room.
    The external Lights are NOT connected to a room.
    The external lights can still use an external light sensor and Operating period.
    Set the external light to use presence and external light level or other suitable mode which uses the timer. See the lights 'Conditional states required to turn a light on' so that the
    'or Timer' graphic is present.
    Make the external PIR trigger the Lights - Timer start connection.
    The light will then go on provided its dark for the 'Lights on duration timer'.
    This way the room, floor and house presence are un-affected.
    It can still also use a rooms presence if required for more complex operation.

    Viv.
    Viv - the variable run on periods seem perfect for what I need, and I hadn't actually realised that that's what they're for. I've changed them now, and will hopefully have a nice warm house tomorrow morning....

    Also - the suggestion you've made for external lighting seems sound. I just now need to start removing my external rooms and resetting connections for the orphaned objects. I'm assuming camera record triggers should be unaffected?

    Many thanks

    John
    --------------------------

    www.nodeone.blogspot.com

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