Part L Criterion 3

[jmcc]

Hi,

having difficulty with a few zones in a model in regard to Criterion 3. I have some very similar zones with the same layout, glazing, u values etc but one is exceeding the limits under BRUKL Criterion 3 and the other compliant. Is there any process to trace the error, would running suncast help even though i dont have any complex shading devices?

Help!

[Complex Potential]

Hi

If you have run the model already you can query the room inside VE Complaince and take a look at the solar energy comparison under the criterion 3 heading in terms of target energy and actual energy. This may give you more of a clue as to what is happening, especially if you compare against the compliant figures in the "similar" zone you refer to.

As a general rule I would run suncast since it should improve the accuracy of your model in all cases. This may inadvertently solve your problem.

Without seeing the model it is difficult to be more specific but... is the zone in question a mostly internal space? I ask because internal zones of open plan spaces which have a small sliver of external wall can sometimes throw up odd results under criterion 3 due to the rather convoluted way the methodology has to be applied by the software.

If the room is only failing by a small margin you could try adding blinds to the glazing construction (this may only work for DSM so if you are using SBEM you may not have the option); the Apache help file details the procedure. Other measures include using glass with a lower g value and adding external shading devices.

If you have no luck, give us some more details to work with and we may be able to help. Screenshots are always good.

CP

[PCully]

I genuinely find that understanding how the Criterion 3 check is applied in Apache and also how it can be complicated can really help to then problem solve against it, bit like most of the regs if you just boil problems down to their most simple form you can see what options you have.

try these Knowledge Base articles then review the rooms in question, tabular room data would let you plot the Crit 3 data for these rooms altogether for easy comparison

http://www.iesve.com/support/knowledgebase/faq/3016
http://www.iesve.com/support/knowledgebase/faq/2434

Phil

[veronica8a]

IS this also applicable for Part L2013? Your reference to the Crit3 benchmarks is from 2010... Also, can you take advantage of automated, external blinds to comply with Criterion 3? Can you model this as part of your Compliance model? I checked the NCM Modelling Guide 2013 and it doesn't mention any automated external blinds any ideas on whether or not we can take advantage of these for compliance? Thanks!!

[Complex Potential]

Yes it still applies to 2013 and yes you can use blinds to help with C3 compliance as long as you are using the dynamic simulation method.

[jm2000]

Is there a particular way the blinds are applied (ie through window constructions) so that the BRUKL adds "Yes" to the field regarding the blinds?

Thanks