hot water storage

[Blackeagle]

Hi

I am enquiring the following for both Building compliance and EPC calculations

Would you please advise me how to determine or input hot water storage size information when dealing with an extension type of building in which hot water service is provided from the main building.

I only know size of the hot water storage vessel that serves the whole building.

I have already checked SBEM guide and EPC convention methods to ensure that i am following the right convention method to determine HWS cylinder size for the case of this project . no useful information found in the sbem manual, however EPC convention method says , instantaneous electric water heater (POU) should be used in the absence of available information and it forces to use 50% seasonal efficiency for the HWS generator , I am not entirely sure if this method is applicable for this case as I already know the main storage size , should i go down the route of using this approach ; It will lead higher carbon emission as a result of carbon factor of electricity and low efficiency of the system

I am wondering if one or both of the following could be more appropriate to be used instead ?

either pro-rating existing storage vessel size by the area served ( in relation to floor area ) , eg: if the whole building is 1000 m2 and the vessel size is 500 litre , the vessel size in the extension would be 125 litre ( extension area is 25% of the whole building)

or alteranatively , estimating appropriate storage vessel size to meet hot water demand occurred within the extension area

I would be appreciated if you can help me for the above enquiry.

Regards

[Terence]

I would say contact your accreditation scheme for advice as they will probably have came up against this scenario before.

If you have an approach for estimating the storage for the extension then send it to them and ask if it is suitable. if not they may be able to provide you with something better.

[PCully]

Hi Blackeagle,

Did you ever get any feedback on this? Is it something you'd be willing to share here in case it benefits someone in future?

Phil

[Wasted Energy]

I have this problem too.

Communal parts of apartment blocks that share the DHW (gas, chp, 800+ litres storage and 200+ metres DHW return) and need an SBEM.

These communal parts consist of 6 or 10 rooms and clearly if you assign all of the DHW used to serve some 100+ apartments to these rooms then the auxiliary energy and thermal losses for the whole DHW system are enormous relative to the room area included in the SBEM.

But what then should be assigned in terms of DHW?