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Electric boilers - effect on power demand of a block of flats

donf
Hello there.


I would like to  know if anyone on the forum has done a study of or knows about an existing study of the impact on power demand of introducing electric boilers to block of flats. 


I have been tasked with estimating the impact of a gradual migration to electric boilers for central and water heating in a modern block of flats. Nearly all of the flats currently use gas fired combi boilers.


I then have to present this information to UK Power Networks so that they can asses whether or not an increase in capacity to the building supply might be needed in future.  Finally I need to put any recommendations to the owners' management board.


Clearly electric boilers will have some impact on power demand.


I can start with an estimate of current power demand (worst case) for a typical flat.  To that end, I'll be doing a survey of about 25% of the flats to come up with a figure.


I can then apply the IET Electrical Installation Design Guide diversity calculations for a typical flat and then the building as a whole using figure 3.4 (IET Electrical Design Guide Nov 2008 page 33).


I can then do a second power consumption exercise adding the demand of a typical electric boiler per flat and then the whole building.


However, it's not clear to me if this approach will be suitable for a massive migration to electric boilers.  I need to be sure of my ground if I approach UK Power Networks with a demand figure.


If we look at the usual peak use of heating demand (morning and evening) a building full of electric boilers, to me, could add a significant load to existing street fuses and possibly even cable capacity.


I would be grateful for any suggestions and experience people could bring.


Kind regards


donf










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  • 0
    Hi to you all,


    Many thanks indeed for your comments so far.

    This study is trying to look 4-5 years down the road so technology may have changed/improved by then.

    As for broadgauge I would expect a large increase in building load if people used electric boilers for on-demand heating of water for radiators and hot water.

    Thank you Amanda, it will be a good idea to check in with the DNO which I plan to do.  Just to clarify, does that 3.4kWatt apply for dwellings with space heaters?  In the case of an electric boiler, I’d probably have to add quite a bit more for peak demand.

    Agreed Mike, electric boilers won’t be better than heat pumps.  However their installation cost and the architectural impact of the exterior condensers would likely be vetoed by the building management committee.  From what I lifted from a brief Internet search, 13kWatt is a typical example of the instantaneous consumption of an electric boiler, confirming your observation that they have about half the heating capacity of a gas boiler.  (Not sure about efficiency without further reading)

    Andy, the building heat loss should be low.  The building is modern and all windows and exterior doors are double-glazed. The loft is well insulated and only the perimeter flats would have a slightly higher heat transfer to the exterior.

    On the subject of how the boilers will be used, from a behavioural point of view, most of the residents are retired people who like to stay warm. Their daily habits appear to be regular so I would expect instantaneous heating demand to peak in the mornings and evenings.  

    At this point, then I have to return to the point that if, at any time, we had more or less simultaneous switch-on of a number of electric boilers (in this case, 12 flats per building, each building with its own supply cables and fuses) we are likely to see much greater peak demand than for a standard flat scenario.

    As wallywombat mentions, there won’t be much diversity in those peaks.

    I remain open to further debate!



    donf
Reply
  • 0
    Hi to you all,


    Many thanks indeed for your comments so far.

    This study is trying to look 4-5 years down the road so technology may have changed/improved by then.

    As for broadgauge I would expect a large increase in building load if people used electric boilers for on-demand heating of water for radiators and hot water.

    Thank you Amanda, it will be a good idea to check in with the DNO which I plan to do.  Just to clarify, does that 3.4kWatt apply for dwellings with space heaters?  In the case of an electric boiler, I’d probably have to add quite a bit more for peak demand.

    Agreed Mike, electric boilers won’t be better than heat pumps.  However their installation cost and the architectural impact of the exterior condensers would likely be vetoed by the building management committee.  From what I lifted from a brief Internet search, 13kWatt is a typical example of the instantaneous consumption of an electric boiler, confirming your observation that they have about half the heating capacity of a gas boiler.  (Not sure about efficiency without further reading)

    Andy, the building heat loss should be low.  The building is modern and all windows and exterior doors are double-glazed. The loft is well insulated and only the perimeter flats would have a slightly higher heat transfer to the exterior.

    On the subject of how the boilers will be used, from a behavioural point of view, most of the residents are retired people who like to stay warm. Their daily habits appear to be regular so I would expect instantaneous heating demand to peak in the mornings and evenings.  

    At this point, then I have to return to the point that if, at any time, we had more or less simultaneous switch-on of a number of electric boilers (in this case, 12 flats per building, each building with its own supply cables and fuses) we are likely to see much greater peak demand than for a standard flat scenario.

    As wallywombat mentions, there won’t be much diversity in those peaks.

    I remain open to further debate!



    donf
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