IES-VE User Forum

After doing a remodel I am now failing the overheating check on the brukl PDF.

To me I shouldn't be failing as the room has cooling and very little glass.

Really losing my patience, you fix one problem and run right off the cliff into another

First off i'd like to point out that Criterion 3 is a solar gain check and not purely overheating. This is described in detail in the NCM modelling guide.

Basically what happens is a benchmark solar gain is calculated for each space following the guidance in paragraphs 114-116 . It is important to note that the benchmark is not the solar gain for the space in the Notional building. This benchmark is then compared against the solar gain for the same space in the actual building. If the solar gain for the space in the actual building is higher than the calculated benchmark then you fail the criterion 3 check for that room.

As you are using SBEM it is very difficult to troubleshoot this issue as it is SBEM itself which calculates both the solar gain in the actual building and the benchmark. If you feel it is incorrect then all I can recommend is sending your project input file to the sbem helpline sbem@bre.co.uk and ask them to have a look.

To find the input file select Building Compliance and then View Results folder.



The input file will have the building name and the extension .inp (eg. examplebuilding.inp). You can ignore the BRUKL and notional building input files.

Great...

The fact that your room has cooling does not exempt it from Criterion 3 since Criterion 3 is about limiting solar energy, not overheating. In fact, having cooling actually increases the chances that your room will be subject to the check.

I have noticed that one of the quirks with the way in which the C3 methdology is described means it will throw up a fail for a room which has walls which are mostly internal but with a sliver of external wall somewhere. Does your room fit this description? If it does you could try redefining the geometry to get rid of the external bit.

Also, as Terence says, SBEM is massively restrictive in terms of how you can model and what you can interrogate. If you can, try to move into using DSM instead and things will begin to make more sense I think.

Modelling for Part L in general can be quite frustrating but try to keep in mind that most of the wierd things that seem to happen actually make sense once you have a detailed enough knowledge of the NCM Modelling Guide and the SBEM Manual. I would highly recommend reading through them or at least having both on hand for reference as you go along.

CP

Thanks CP. I have read the guides.

Does anyone know how to view the benchmark when using SBEM?

I don't know if there is anywhere that you can get extra details of the SBEM outputs but if you check in your SBEM results folder (under regs) then you can see all the output files. If you look at the .sim file it gives solar gains and solar limit for each room so that should be what's used in the BRUKL

Phil