Home  5  Books  5  GBEzine  5  News  5  HelpDesk  5  Register  5  GreenBuilding.co.uk
Not signed in (Sign In)

Categories



Green Building Bible, Fourth Edition
Green Building Bible, fourth edition (both books)
These two books are the perfect starting place to help you get to grips with one of the most vitally important aspects of our society - our homes and living environment.

PLEASE NOTE: A download link for Volume 1 will be sent to you by email and Volume 2 will be sent to you by post as a book.

Buy individually or both books together. Delivery is free!


powered by Surfing Waves




Vanilla 1.0.3 is a product of Lussumo. More Information: Documentation, Community Support.

Welcome to new Forum Visitors
Join the forum now and benefit from discussions with thousands of other green building fans and discounts on Green Building Press publications: Apply now.




    • CommentAuthorDavidND
    • CommentTimeJul 2nd 2021 edited
     
    Controls before Replacement Systems

    The home heating industry is in turmoil. Alternative technologies silently vie for control of the wallets of homeowners. As you read this, yet more innocent homeowners are being conditioned to believe that nothing short of spending thousands upon thousands to replace what they already have can save our little blue planet… God help us!

    While we all need to act more responsibly, this feels to me more like scamming of innocent, caring homeowners. Govt ineptitude coupled with industry keeping its mouth shut for fear of killing the approaching golden goose.

    From where I sit, I see that we DO NOT NEED to change what’s already installed in homes to meet the immediate climate change targets. Households can both save money and meet said emissions targets almost overnight. How? By the controls industry FINALLY pulling their collective digits out & delivering homeowner-friendly controls. This dearth of truly homeowner-friendly controls has been a major root cause of our over consumption & hastened our pending disaster.

    The bimetallic strip thermostat was invented in the 1800s. It transitioned into homes in the 1960s with central heating. The 70s saw the awakening of environmentalism, as energy scarcity reared its head and costs rose, and that drove the market for electronic Building Management Systems for commerce. Manufacturers refused to consider the needs of homeowners. So-called Smart controls, which appeared around 2010, are really an adjunct to the late 70s home automation trend. Has their emergence into the mainstream meant a massive reduction in consumption? Heartbreakingly NO! Despite being so potentially capable, today’s controls remain, to the vast majority of homeowners, like the impenetrable forest in Sleeping Beauty.

    Konrad Adenauer, founding father of modern Germany, said, “One needs to look at things so deeply they become simple.” So, no matter what type of heating system homeowners install, it can only EVER be as good as a homeowners ability to use it – its controls.

    I recently bought controls from global manufacturers. Disturbingly I found them the antithesis of usable. My estimation is that poorly set up or in correctly used controls are responsible for approx. 1/3 of our excess energy consumption. Frankly, in usability terms, they are appalling. Instructions seem to have barely changed since the 80s. Manufacturers still DEMAND that users are fluent in ‘controls’ and see any failure to understand by users as ''user error'. How very disturbing. Without doubt, manufacturers try hard. They work hard to engage & they always explain / document every nuance. However, this is like shouting louder and louder to someone who's deaf!

    During my research, when homeowners were asked why they don’t consider ‘Smart controls’, many said their home, "...doesn't matter in the grand scheme of things.” Truth is, that's a sop, an easy, barely, socially acceptable answer. Further examination uncovered unexpressed fear of change, fear of increased costs, fear of failure (various including inability to master) as well as fear of ‘losing control’ of their home.

    It would be yet another environmental disaster to replace systems not currently being controlled properly with different systems not being controlled properly. Replacing existing controls with appropriately user-friendly controls so existing system efficiencies can be maximised would positively impact emissions almost overnight and vitally buy valuable time to not only properly assess alternative energy sources, but to get people properly trained and to configure housing stock so it become truly fir for lower energy sources.

    I have tried but I can find no case to be made for replacement without appropriate controls. We need to harness controls technology to support us fallible human beings. We need it TODAY to support and guide us through the impenetrable forest to deliver that all important kiss to awaken the Sleeping Beauty that is planet Earth.

    What do you think?

    David
    • CommentAuthorHollyBush
    • CommentTimeJul 2nd 2021
     
    In summary you want better controls?

    Sounds like you think they are OK when set up and used properly, but most people are unwilling or unable to do so?

    I am reminded of a friend that was a building surveyor that authorised humidity detector fans be put in tenants bathrooms and kitchens, possibly other rooms where damp was a problem. This was because tenants were not opening windows and/or switching on the fans if manual. Obvious answer to take out the manual / user error and put automatic ones in.
    The problem was 90% of the fans got ripped out and sold, leaving a hole in the window or wall...
    • CommentAuthorRobL
    • CommentTimeJul 2nd 2021
     
    Our boiler controls are pretty basic; time and bimetallic strip temperature setting. I'm to be convinced you could beat it though given our current boiler's a bit dumb and only has manual control of its o/p water temperature.

    I accept that a more sophisticated boiler/heatpump could have weather compensation, either could show improved efficiency by running at a low power and low flow temperature. I worry though that weather compensation is something that only nerds are allowed to use.

    Air temperature isn't the whole story either - radiant imbalance has about as much impact as air temp on how warm people feel, so the thermostat should really try to measure that as well. It accounts for why people in c**p houses turn the heating up when it's cold outside and their walls are colder.
    • CommentAuthortony
    • CommentTimeJul 2nd 2021
     
    Cooling should not be needed in any well designed building.

    Heating control, where heating is needed are best as programmable ones that allow different times and different temperatures- chronostats, hive, nest or programmable room thermostats
    • CommentAuthorDavidND
    • CommentTimeJul 2nd 2021
     
    <blockquote><cite>Posted By: HollyBush</cite>In summary you want better controls?

    Sounds like you think they are OK when set up and used properly, but most people are unwilling or unable to do so?

    I am reminded of a friend that was a building surveyor that authorised humidity detector fans be put in tenants bathrooms and kitchens, possibly other rooms where damp was a problem. This was because tenants were not opening windows and/or switching on the fans if manual. Obvious answer to take out the manual / user error and put automatic ones in.
    The problem was 90% of the fans got ripped out and sold, leaving a hole in the window or wall...</blockquote>

    In summary, it's not really about what I want but more what the world NEEDS. Controls where they do the very best job that can be done with what you have installed. Controls where they use weather data, where they alter flow temp to minimise fuel used but hit the your comfort needs. Controls that work seamlessly, invisibly effectively.

    Think about cars. Before electronics in cars we had a manual choke. Through trial and error (waste in other words) we all eventually learned how far to open it dependant upon temperature etc. Today we have no idea what a choke is! We get in turn the key or push a button and it starts first time every time always. Considering the environmental controls cars also minimise fuel use but this is ALL invisible. No one, but no one gives anything a second thought. If the controls industry designed cars we'd all have to learn about pressurised systems to then set the fuel injection system each time we got in. We'd also have to understand turbo boost and how much is applicable in what circumstance. Truth is if we had to do that cars would now be doing 10mpg on a good day...

    Fact is, manufacturers understand it all. We COULD be soooo much more efficient but we are not simply because manufacturers cannot join up the dots and apply some customer empathy. Customers do not give a flying fig about HOW things do what they do so long as it works & works reliably.

    I am ashamed of the industry I once contributed to.
    • CommentAuthorDavidND
    • CommentTimeJul 2nd 2021
     
    <blockquote><cite>Posted By: tony</cite>Cooling should not be needed in any well designed building.

    Heating control, where heating is needed are best as programmable ones that allow different times and different temperatures- chronostats, hive, nest or programmable room thermostats</blockquote>

    Fact is, NO smart control is yet properly integrated. No smart TRVs react appropriately as many internally transfer heat due to construction issues so cycling.
    • CommentAuthorHollyBush
    • CommentTimeJul 2nd 2021
     
    When I first read this I thought it was a bit of a rant, which I guess it is, but it is certainly not just a rant - looking at a few recent threads, in particular:

    http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17046&page=1#Item_6

    and the link

    https://www.theheatinghub.co.uk/why-our-condensing-boilers-do-not-condense


    I understand better - partly it's about configuration of the system, that initial setup and then partly appropriate control, which can be complex, but it appears rare that both are done well. I am sure there are other issues too, but it is difficult for normal people to get their heads around all the concepts and issues, especially when many manufacturers and installers don't join the dots too.

    I hope thread gets more attention.
  1.  
    Posted By: DavidNDI am reminded of a friend that was a building surveyor that authorised humidity detector fans be put in tenants bathrooms and kitchens, possibly other rooms where damp was a problem. This was because tenants were not opening windows and/or switching on the fans if manual. Obvious answer to take out the manual / user error and put automatic ones in.
    The problem was 90% of the fans got ripped out and sold, leaving a hole in the window or wall...


    In summary, it's not really about what I want but more what the world NEEDS. Controls where they do the very best job that can be done with what you have installed. Controls where they use weather data, where they alter flow temp to minimise fuel used but hit the your comfort needs. Controls that work seamlessly, invisibly effectively.

    I have some tenants, a family of 3 (ages 50 to 26) and a central heating system with a standard nothing special 7 day programmable heating controller with manufactures instructions. 2 issues relevant to this thread, 1 they asked me to program the controller because they couldn't cope and 2 they wanted me to set the temp to 26 deg for when they were at home. When I queried this they said they liked to sit in shorts and tee shirts whilst watching TV but don't worry they will pay for the heating.

    All the smart controls in the world won't help with attitudes as above.
    •  
      CommentAuthordjh
    • CommentTimeJul 3rd 2021
     
    Posted By: Peter_in_HungaryAll the smart controls in the world won't help with attitudes as above.

    Indeed.

    And it's probably worth pointing out that a lot of the reason that cars are simpler to use and more fuel efficient than they were is thanks to legislation requiring car manufacturers to do that, not due to them somehow being better than heating manufacturers. It doesn't do anything for ease of repair or cost of servicing either.

    But domestic heating equipment is part of the same broken legislative environment as building control et al. Fire safety results kept secret because they are 'commercial'????
    • CommentAuthorowlman
    • CommentTimeJul 3rd 2021
     
    It all reminds me of my "F" gas aircon engineer friend. He gets exasperated after call-outs to heat pump systems where the client keeps switching the whole thing off and on, buggering up the programme, which they then can't re-set, despite him originally setting it on auto, with temp and time of day set backs etc. All the clowns need to do is use the remote control to make minor temporary adjustments but leaving the main programme on auto.

    This unwillingness to use simple controls if fairly endemic and puts the lie to the general assumption that Smart Meter installation and subsequent electricity monitoring will save households money, - perhaps in theory, but that's about as far as it goes, and is another story.
    •  
      CommentAuthordjh
    • CommentTimeJul 3rd 2021
     
    Posted By: owlmanIt all reminds me of my "F" gas aircon engineer friend. He gets exasperated after call-outs to heat pump systems where the client keeps switching the whole thing off and on, buggering up the programme, which they then can't re-set, despite him originally setting it on auto, with temp and time of day set backs etc. All the clowns need to do is use the remote control to make minor temporary adjustments but leaving the main programme on auto.

    This unwillingness to use simple controls if fairly endemic

    One could argue that the fault is with the designers who apparently made the main on/off switch very accessible and either didn't provide or didn't make accessible an adjacent equivalent of the controls on the remote.
    • CommentAuthorjms452
    • CommentTimeJul 3rd 2021 edited
     
    Posted By: DavidNDwe DO NOT NEED to change what’s already installed in homes to meet the immediate climate change targets


    This is clearly true and I'd guess that there's 10-20% to be gained here which might help us meet targets for a year or two.

    However, it's a false choice - There's no way to introduce a step function change in home heating, it has to happen over at least a decade, fitters need to be trained and the transition should align with the replacement cycle of gas boilers.

    So is the proposal not to start ramping up heat pump installs whatsoever and invest all the effort/funding in better controls?

    If so that would seem rather short sighted. In a few years when all the gains from better controls are realised all the armchair commentators (me included :wink:) will be asking why the **** weren't there any efforts to kick start the heat pump installer infrastructure earlier.

    edited for typos
  2.  
    I shared a house with an electronics student, who was the only one out of us who could program the VCR (remember them?)

    Another of our housemates was a psychology student who couldn't understand how anyone could design VCRs to be so difficult for most humans to interact with.

    20 years later, they are now married, with kids who have no idea what VCRs were or how difficult they were to use, they all watch TikTok which 'just works' intuitively.

    Most time/temperature controllers seem to be based on the VCR generation of programming techniques, and so are inaccessible to most humans. They need to be replaced with TikTok style controllers.
    • CommentAuthorbhommels
    • CommentTimeJul 4th 2021
     
    Having gone over the years from a bi-metal thermostat to an electronic one to a Nest to a weather compensation controller (with the Nest now repurposed as a zone controller) I can confirm that there are savings to be had by having better controls but perhaps not as much as the OP thinks, and certainly not enough to meet any sort of CO2 reduction goal. I am with jms452: focusing on controls now is a distraction from the real task at hand.
    • CommentAuthorEd Davies
    • CommentTimeJul 4th 2021
     
    I've done my own “smart” heating control. If anything, my oil use has gone up slightly but there are a lot of confounding factors, not least the probable sludging up of my radiators [¹] but also increased comfort. Still, I suspect that to have got the increased comfort with the simple thermostat would have needed burning even more oil.

    Posted By: DavidNDMy estimation is that poorly set up or in correctly used controls are responsible for approx. 1/3 of our excess energy consumption.
    What do you mean by “excess” energy consumption? What accounts for the other 2/3rds of it? How did you come to this estimation? (I'd not be surprised if that was a reasonable figure, depending on what you mean by “excess”, but still it'd be nice to understand where it came from.)

    [¹] http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17038
  3.  
    On the usual internet theme of 'recommend what you've got', I never need to touch our heating system controls. Storage combi (which heats water 5am to 10pm covering the widest range of times we might want hot water), Weather compensating heating control (no internal thermostats) running 4am to 10pm with very low temperature UFH. Heating switches off entirely when external temp is above 12C. The heating part of our energy consumption is low enough that it's not an issue.

    If you've a badly insulated house that relies on high temperature emitters to rapidly increase the room temperature for the rooms you're in when you're in them the issue really Controls are a sticking plaster. The issue is poorly insulated/airtighted homes.

    BUT, I do quite like the 'learning' aspect of the Nest stat - you manually adjust the temperature as you want it, and it learns what you do and does it automatically over time. Using those with multiple zones (and a hard upper/lower limit programmed into the amount of user adjustment) seems pretty foolproof. That's what I've done for my mother (who has Alzheimers). I also left the old school timer/programmer connected to the mains but with no output so she could still switch that on and off without it doing anything.....
  4.  
    The thing that seems to be missing from so many heating control systems is the ability to control different zones/rooms independently.

    When I last looked into all this (5-7 years ago?), things like Nest didn't offer this - but has that changed now?

    I ended up going for a Honeywell system that has a central controller and then a TRV on each radiator that can communicate by RF with the central controller. It just about works but is a bit of a constant hassle partly because of the controls - they are a bit clunky in general but there are also certain things you have to remember how to do - for example, how to re-pair a radiator controller with the main unit if you replace it or the battery runs out or whatever. The instructions for these things are bad, and the methods not entirely intuitive. There are all sorts of aspects of how it works that are not really clearly explained (things like whether individual radiator controllers over-ride central commands or vice versa) and I have to keep a notes document for myself so that I can remember how to sort stuff out from one winter to the next.

    Once it's all set up, it's kind-of usable by anyone (at least the individual radiator controls are) but relies on me keeping an eye on it and doing quite a lot of fiddling around. I think many people would have just given up on it by now.

    Maybe the latest versions of 'smart' systems can now do zoned heating with more user-friendly control?

    My parents had an air source heat pump system put in last year, and I was a bit surprised that it was just installed with the longstanding conventional control arrangement of a single central thermostat and then TRVs in each room. I don't think we should be installing that kind of control system in 2021. We should have systems that allow you to programme timed sequences for each room/zone independently, and turn off/on individual rooms easily from the central controller, using an intuitive and user friendly interface.

    So I agree with quite a lot of the OP.
    • CommentAuthorbhommels
    • CommentTimeJul 8th 2021
     
    My take on the desire for room-by-room controls is that the insulation is not good enough (yet). Either that or the house is huge.
    • CommentAuthorJonti
    • CommentTimeJul 9th 2021
     
    Posted By: bhommelsMy take on the desire for room-by-room controls is that the insulation is not good enough (yet). Either that or the house is huge.


    +1.

    Also, my experience of people is that one day they are warm enough at 20C and the next cold at 21C so unless a 'smart' system can actually cope with this it still isn't going to work in the real world. I wonder if we are simply over thinking this one. :confused:
    • CommentAuthorphiledge
    • CommentTimeJul 9th 2021
     
    Whats needed is a smart implant that triggers menopause like symptoms when theres the mere mention of it being a bit chilly😁
    •  
      CommentAuthordjh
    • CommentTimeJul 9th 2021
     
    Or a woolly jumper.
  5.  
    *another* jumper.

    An internal partition wall or intermediate floor with acoustic wool in it, has a U-value about 0.5, which is well able to maintain a temperature difference of say 3 degrees between say a lounge and a bedroom, given that the external walls can maintain a difference of up to 25deg from inside to outside.

    I like a bedroom to be say 21deg in the evening, maybe 15-17deg overnight, and about 19deg when I wake up. I like a lounge to be unheated overnight and through the day, and perhaps 21deg in the evening. By tweaking the timing of the different zones, I can just about do this, but it needs luck and lots of tweaking. Shouldn't be difficult for controllers to just do this, don't know why they don't. Most cars can organise different temperatures for the driver and passenger.
    • CommentAuthorbhommels
    • CommentTimeJul 10th 2021 edited
     
    Posted By: WillInAberdeen*another* jumper.

    An internal partition wall or intermediate floor with acoustic wool in it, has a U-value about 0.5, which is well able to maintain a temperature difference of say 3 degrees between say a lounge and a bedroom, given that the external walls can maintain a difference of up to 25deg from inside to outside.

    ...assuming no heat exchange through air movement and/or thermal bridging, everybody staying where they are and keeping the doors shut....

    I like a bedroom to be say 21deg in the evening, maybe 15-17deg overnight, and about 19deg when I wake up. I like a lounge to be unheated overnight and through the day, and perhaps 21deg in the evening. By tweaking the timing of the different zones, I can just about do this, but it needs luck and lots of tweaking. Shouldn't be difficult for controllers to just do this, don't know why they don't. Most cars can organise different temperatures for the driver and passenger.

    This is temperature profiling (in time), which as you say is well possible with today's controllers. As you well know it will only work if all time constants in the system are small, and temperature profiling is achievable with a boiler feeding radiators in a lossy house with low solar gain. Not something to aim for (and neither is the car analogy) I would think.
  6.  
    Well no - if a bedroom in a passiv haus has similar area of internal (U=0.5) and external (U=0.1) walls/floors/ceilings, it will be losing heat to the cold outside during heating season, faster than it is gaining heat from adjacent warmer rooms, so it can be cooled or heated at different times. Likewise it will lose heat through its windows (U>>0.5) faster than it gains heat through its internal doors.

    The MHRV blows air into the bedroom cooler than it extracts it from the bathroom - this is exactly the principle of car climate control. The direction of airflow should have been set in the correct direction to avoid heat transfer from warmer rooms.

    So it's quite possible to have different rooms at different temperatures at different times, if the house has been well designed, around its occupants needs.

    If the house cannot meet its occupants needs for comfort because it has excessive thermal mass, perhaps because of design choices around underfloor heating, or to compensate for too-big windows, then that's poor design in my book, cart before horse. Some people like the same temperature 24/7 which is fine, the house should work with their preferences..

    I am yet to see a time/temperature controller that "just does this" - they need programming like VCRs (see above).
    •  
      CommentAuthordjh
    • CommentTimeJul 10th 2021
     
    I don't think your picture of the heat flows in a passivhaus is very accurate and is probably misleading.

    One major omission is solar gains through the windows which should be quite large in winter. The south side of our house is always a degree or two warmer than the north side.

    Another omission is that even with all the doors closed (which is very far from normal in our house, and probably most houses) there will still be airflow under or over the doors between rooms and lobbies etc.

    And of course the air flow may carry the main heating input.

    The time constant is likely to be measured in days, or at least tens of hours.

    I suggest trying one before pooh-poohing the idea.
  7.  
    Posted By: WillInAberdeenAn internal partition wall or intermediate floor with acoustic wool in it, has a U-value about 0.5, which is well able to maintain a temperature difference of say 3 degrees


    Posted By: djhThe south side of our house is always a degree or two warmer than the north side.


    Indeed, the temperature in a well insulated house does not have to be the same in every room - hence individual room temperature controls are not limited to 'lossy' houses.

    Solar gain works well for a bedroom, to make it warm in the evening and allow it to cool overnight, however I would not want a heavy floor slab for a bedroom so would set up window size/shading accordingly if building new.

    We have teenagers so everyone's bedroom doors are kept firmly shut. The bedrooms open off a separate corridor from the living rooms.

    When I get round to it, the bedrooms will be on separate MHRV units from the living rooms, so with a different supply and extract temperature profile, and airflow direction from the MHRV supply through the bedrooms and outward round their doors to the corridor, not inward from the corridor.

    A U=0.1 construction of plasterboard/stud, wool/foam, sheath/cladding has a time constant around 3 hours (strictly the phase delay on a 24h cycle, but that's what we are interested in - the 'time constant' that you are thinking of, is how long it would take to cool to approach external ambient - instead we need to think how long to cool to the desired setback temperature). A heavier construction has a longer response time.

    Your taste may differ and that's fine, you have mentioned choosing a concrete slab, strawbales and a single centrally-post-heated air supply to all rooms, though not sure if that includes bedrooms, but that would not meet our needs for bedrooms. Would suit us better for living rooms.

    (Edited to expand)
    • CommentAuthorbhommels
    • CommentTimeJul 11th 2021
     
    @WiA: How do you arrive at a time delay of only 3 hours while having U=0.1? Or does the 3hrs apply to the internal walls?

    When I put a lightweight lay-up of wood cladding, 300mm mineral wool and plasterboard (U=0.1) into the onilne calculator of ubakus.com, I get a phase shift of almost 9 hours, which is line with what I would expect from my experience with my house (EWI'ed brick: U=0.14 and t=14 hrs).

    I don't know where you live but in my neck of the woods the external temperature is rarely constant for 9 hours, nevermind 14. With these time constants it is practically impossible to temperature profile my house, except perhaps when it is really cold outside and there is no solar gain to speak of, and we have not invited a load of warm bodies in.
    BTW the 14h delay made the task of tuning the weather compensation heating curve really difficult, especially when considering the in-screed UFH having a reaction time of 3h in addition.

    One take home thing from your post is that it would be nice to have MVHR with variable efficiency/bypass function so that it could let in colder air when desired, and possible, instead of leaving it to the occupants to open windows or such like. I could see a system of room-thermostat-controlled-variable-bypass-MVHR work for airtight, well insulated homes. It would be limited in what it can achieve though.
  8.  
    Hi Bhommels,
    I had a long boring lockdown so I started with the Fourier equation and worked from there to a sinusoidal internal temperature profile T=To.{Aexp[kx+ikx-iwt] + Bexp[-kx-ikx+iwt]} with 2π/w=24h as a root frequency, and similar heating profile and outside temperature profile and outside heat loss/gain profile. Add harmonics to make the profiles non-sinusoidal. This perhaps reveals too much about my personality :sad:

    The phase offset between the heating cycle and the internal temperature cycle is only a few hours for a light construction. So when the heat supply is reduced, the internal temperature reduces, a few hours later.

    However the phase offset between the internal and external temperature/heatflow cycles is longer, many hours. Some people call that the decrement delay.

    There's a different number again for the hypothetical case that you turn the sources of heat off and wait for the house to cool to ambient. That would be days.

    There are spreadsheet calculators round the web for this, but beware most are more interested in solar heat cycles, with solar heat flowing only in the 'inward' direction, so only one out of the A and B terms. We need both because both internal and external temperature/heat are varying in the real world, as you mentioned, and we need clarity whether the phase that is quoted is between the inside, outside, temperature or heat cycles.


    For simplicity, forget the frequency stuff and wildly approximate that most of the (thermal) mass in the lightweight room is the plasterboard. Per m2: 8kg, heat capacity ~8kJ/K. If this loses heat through say U=0.1 x DT=20degC , Q= 2W, then to cool the plasterboard by 1deg takes 8000/2 = 4000s, about an hour. To cool from say 21deg to 17deg takes about 4 hours. Our loft conversion worked like this.

    If you have brick and screed inside your insulation envelope then the thermal mass is much greater, so the response time will be longer as you mentioned.

    Some people like stable temperature, others like control, it should be possible to design efficient housing for both.


    We are looking at several smaller MHRV units for our current project rather than one big one, for different reasons (another thread), but this does allow different air temperature profiles for different parts of the house. It might allow different air flow profiles too, ventilate the bedrooms more overnight than during the day, hadn't thought about that. Similar to the car driver/passenger getting different climates!
    • CommentAuthorbhommels
    • CommentTimeJul 12th 2021
     
    @WiA: Frequentist approach to heating cycles, very clever. I hope that in practice the disturbances (weather, people, solar gain, etc) are small compared to the temperature cycles so it does not get all messed up! I guess you could design it such that you have the periodic cycles as a baseline and then have something more interactive to act on the deviations/disturbances?

    What I would like to see is predictive controls where an online weather forecast is used to anticipate what is going to happen and act accordingly. Not so useful perhaps in the middle of winter, it would mostly prevent over- and undershoots in the shoulder months (the more insulation, the more shoulder months). It would require careful tuning to the particular situation, though perhaps a self learning controller could do this for you.
  9.  
    Yes, that's exactly what I was thinking when I was frustrated by the VCR style of programming of typical heating controllers. VCRs have thankfully been replaced by apps which learn what you like to watch, and look at what's coming up in the next days, and have it all ready for you before you have thought about it. Why not heating controllers? Maybe the newer ones are heading that way.

    Edit: assuming widespread moves from gas to ASHP heating, the controller should also be looking at upcoming electricity prices and running the ASHP(s) and MHRV(s) at the right time of day (weather dependent) so each part of the house is just-warm-enough with minimum cost, considering the temperature efficiency of the ASHP and the response time of each part of the house. Shouldn't be too difficult...:confused: Oh and heat enough DHW at the right time too.

    Lightweight constructions are easier to control the heating, but less flexible for pre-heating and more susceptible to disturbances, so swings/roundabouts I guess.
   
The Ecobuilding Buzz
Site Map    |   Home    |   View Cart    |   Pressroom   |   Business   |   Links   
Logout    

© Green Building Press