Cheapest way to heat detached garage room

Discussion in 'Eco Talk' started by DC84, Dec 3, 2020.

  1. DC84

    DC84 Member

    I have a recently converted detached garage at the back of my garden. Unfortunately the cowboy builders didn't follow building regs and only put 25mm celotex insulation between the brick and the plasterboard. Only 75mm insulation on the ceiling if I recall (wasn't around when they did the work).

    Now in the winter months it gets very very cold, meaning I have to use 2 x electric radiators (1 1100w and 1 1400w, plus 1 2500w oil filled one to top up. This is working out quite expensive to run as I have to put them on for at least an hour to warm up the room properly, then keep them on for the duration I'm in the room (though I do switch to low power mode on the electric ones once the room nears comfortable temperature before eventually switching them off).

    Its a pretty large room (6m x 4.5m) so will take a lot to keep warm. The floor hasn't been insulated but I don't think that's where most of the heat loss will go. I'm not in the room 10 hours per day 7 days per week, but I will have to use it often.

    I've been trying to think about cheaper heating alternatives, as I don't think messing with the plasterboard putting more insulation over is an option right now.

    There's no gas supply to the garage only electric. I've thought about a wooden burner thing, but is this safe? What about air conditioning which is meant to be cheap to run (4p per hour apparently) and will keep the room at a stable temperature. Underfloor heating?

    Any suggestions or advice would be appreciated.
     
  2. rogerk101

    rogerk101 Screwfix Select

    You know the answer to your question ... you just don't like it.
    If you have insufficient insulation then you have excessive heat loss, and you need to use more energy to compensate for that heat loss. It's basic GCSE level physics ... or even earlier than that.
    Do the right thing and install the correct amount of insulation. It's a one-off upfront cost that reduces operating costs every year forever after.
    You know you're going to have to do it some time, so why put off the inevitable?
     
    RolandK and ElecCEng like this.
  3. DC84

    DC84 Member

    I forgot to add the conversion was only done about 2 years ago so pretty much new. This is why I don't want to rip the whole thing apart and start again so soon, and if I have to replaster over its going to cost well over £1500 plus I'll have to remount the electric sockets. I don't think I can make that money back in materials.
     
  4. rogerk101

    rogerk101 Screwfix Select

    Within a lot less than 10 years you will have paid out more in electricity to heat it than if you just bit the bullet and did it correctly now.
    Do you really think things are going to get any better/cheaper/easier in the future, because if you do, then you're more optimistic than you are wise.
     
  5. DC84

    DC84 Member

    This is largely dependent on if I can source the materials for a sensible cost then find a mate who can help me out. That would save costs if I can do it and it works.
     
  6. jonathanc

    jonathanc Guest

    What did you specify with the builders? That is in terms of insulation standards. Building reg standards etc?
     
  7. DC84

    DC84 Member

    I didn't know much about building regs back then esp for insulation, I think they just put in the bare minimum as they assumed it'd be shed type insulation just to stop frost. So I didn't specify anything back then.
     
  8. Please could you post a link to the air conditioning system you refer to that could heat your garage for 4p per hour.
     
  9. jonathanc

    jonathanc Guest

    or put it another way; 4p an hour is one third of a unit of electricity which means 300w heater. If there is no insulation that isn’t going to work

    As to the builders being cowboys? If there was no heating being installed then there is no requirement for insulation to be used under BR. If they built what you asked them, it’s pretty unfair to call them cowboys
     
    JayCee2020 likes this.
  10. furious_customer

    furious_customer Screwfix Select

    Using that logic Roger, I sincerely hope you have a Tesla Model 3 sitting on the driveway.
    For most people, cost *is* a factor.
     
  11. ElecCEng

    ElecCEng Screwfix Select

    At the moment insulation products have gone down in price. A few sheets of insulated plasterboard won’t set you back a vast amount. Just overlay your current ceiling, tape and joint, then paint. You could achieve that easily with decent DIY skills. Get a spark in to drop the lights, will be cheaper than you think. Lay/relay some insulated underlay under your floor. That will address a lot of your heat loss.

    A couple of electric radiators will be cheaper than an AC unit or extending GCH. Heat the room to a constant 15-16 deg C, then up it to 19-20 when you’re in the room. That costs a lot less than heating from 10-12 deg C to 20 whenever you use the room.



     
  12. rogerk101

    rogerk101 Screwfix Select

    Indeed, which is why my recurring response to those who try and skimp on materials is to look at the Total Cost of Ownership, rather than just the upfront Capital Cost.

    Total Cost of Ownership = Capital Cost + (Annual Operating Cost x Number of Years) - Selling Price

    Capital Costs can vary in that lower costs will fund a shoddy job of insulation, while spending more will provide a better insulated home, which is not just cheaper to heat, it's more comfortable to live in.
    Annual Operating Costs as we all know are dramatically reduced by better insulation.
    Number Of Years we don't know for the individual but we do know that insulation tends not to deteriorate much over time, so will still be pretty effective in 50 years time.
    Selling Price will be higher if you can provide the buyer with an EPC and/or heating bills showing that the house is cheaper to heat than the other houses the buyer is looking at.
     
    ElecCEng likes this.
  13. High Jonathan, please could you post a link to the energy supplier currently charging 12p/unit!! :)
     
  14. jonathanc

    jonathanc Guest

    Average is 14 to 15 p. So proves my point. If you want to find a lower rate look for economy 7 off peak. Anyway. Can’t heat an uninsulated garage for 4p an hour
     
  15. Hans_25

    Hans_25 Screwfix Select

    The cheapest way of heating the garage is with a gas heater, about one fifth the cost of electrickery.
     
  16. Alex0908

    Alex0908 New Member

    Thank you for sharing it
     
  17. furious_customer

    furious_customer Screwfix Select

    The point the OP is making here though is that the capital cost is out of his reach.
    That is why I mentioned the Tesla - it is significantly more efficient than the Nissan leaf - so why is there a market for the Nissan Leaf? How do they manage to even sell a single one? It is because the capital cost is less than half of the Tesla.
    So Capital cost matters to most people unfortunately.
     
  18. furious_customer

    furious_customer Screwfix Select

    If the wood-burner is installed correctly and is permitted in your area then it will certainly be safe.
    If you have a ready supply of wood even better.

    If you need to buy wood to burn in it then it is probably a similar running cost to gas.
     
  19. stevie22

    stevie22 Screwfix Select

    This is false logic. It will be QUICKER to get from 16 to 20 but the higher the temperature of the garage, the more energy will be lost. Hold it at 16 and there will be a constant loss of heat energy which you replace. Let the temperature go down to 12 (taking that as external temperature in your figures) and there is no energy used.

    I agree about the electric rads as being easiest. I'd probably go for 1 with a fan heater for a quick warm up. I'd also wear a sweater!!
     
    Hans_25 likes this.
  20. ElecCEng

    ElecCEng Screwfix Select

    I’ve back and forthed this for years, In well and badly insulated houses. This method always uses less in terms of kWh. 16 degrees C will generally keep moisture flowing out wards (inner fabric drier and a flow away from the VCL). I’m way over simplifying but my personal experience is it works. Once up to 16-17 it doesn’t take much to keep it there. Add the otherwise constant heating and cooling for the building fabric, it’s less energy.


     

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