IES-VE User Forum

Hi All

Does anyone have experience in modelling a block of flats (100+). How would you use the profiles what gains would you consider and what profiles for them?

Several works been carried out to estimate combined gain of about 5W/m2 for flats. That includes gains from people, lighting, cooking, consumer electronics, lighting etc.

I can assume this should be used for always on type of gain, however I would expect some sort of profile for it. In case of all electric flats the combined gain would be assumed as electrical power (with error, as human or livestock activity is not electrical).

Could anyone share alternative approach and how do you deal with ventilation requirements for this sort of buildings? We can assume something in order of 10l/s/p, would this be always on continuous profile though?

Has anyone ever compared such simulation result with actual data measured?

I would advise going to Building Template Manager, then Import Templates, navigate to NCM and apply the NCM room templates for dwellings. The NCM templates are created by the BRE and although exaggerated, contain all the profiles you are asking for. Occ, Vent, Small power, lighting, everything plus theyre diversified figures. Its a validated template. To create your own would require you explaining and confirming your assumptions which will result in arguments. You cant argue the NCM as theyre a recognised standard and are applied to all Part L SAP/SBEM's etc.

I apply these for all energy strategies for both domestic and commercial unless I have data, which we never have because everything in our industry is arse about face.

Best way to model it is actually using NCM/ASHRAE profiles which are readily available as templates in VE.

We don't actually encourage the use of NCM Templates.

See the following PDF: http://bit.ly/VEtemplates

Thanks for your hints. I could not fully utilise NCM profiles as I modelled each flat as one space and used profiles based on measured data for most of the things (lighting, electricity, occupancy). Measured data was for whole apartment rather than each room, therefore that was an easier approach.

I have tried to derive missing profiles from the NCM ones as looking at apartment in general. The things I struggle the most is the ventilation. Regulations say minimum of 0.3 l/s should be available, in my case it gives something in order of 6.6 l/s/person which is less than minimum of 8 l/s but the number of occupants may vary. Theory is that if more occupants present than more heat gain and increased ventilation rate will be compensated by activity hence not so much impact on the loads.

Idea was to try to model airflow through trickle ventilators realistically to work out the total heating load for each apartment (to size central DH plant appropriately). Block in consideration is a conversion and hence to achieve compliance only u-values have to meet criteria. I am more interested in efficient central plant operation, so trying to get loads closest to realistic ones and offset as much as possible by renewables.

Does anyone has some experiences on similar thing or perhaps could you share some figures to benchmark my results?

Thanks

P

Terence wrote:We don't actually encourage the use of NCM Templates.

See the following PDF: http://bit.ly/VEtemplates

This man speaks wisely. Be wary of the NCM outside of compliance modelling. As a method for estimating true energy in use, it leaves much to be desired.

Then perhaps IES can provide a set of diversified profiles for every single type of room you will ever encounter. Which is recognised outside compliance without argument. Furthermore this set of profiles will be required to be based upon real data, which as you are all aware is somewhat lacking at our stage of analysis. Until then you have only the NCM or ones you create yourself. The self created ones will be subject to QA to the nth degree and can be argued for and against with equal validity and much going round in circles will ensue. Of course in a perfect world we would have all the information we need. I agree the NCM is exaggerated and you can only really agree with the trends they highlight and not the quantified data. If you are after real world data then yes you must pursue data from the client and I wish you all the luck in the world with that. The NCM, although not perfect, can be adjusted and provides a good foundation for self created data sets.