IES-VE User Forum

Hi,

We have just been working on a school that needs to comply with Part L 2010. The model has been updated from IES 2013 to 2014.

Previously (with IES 2013) the classrooms were allowed to be allocated absence detection (MAN-ON-AUTO-OFF). Now in IES 2014 (with the regs set to 2010) this is not an option.

It is only possible in teaching spaces <30m2 as this is now associated with local manual switching.

I believe that as the NCM database changed from version 4 to version 5, the settings for NCM teaching space changed.

Can we confirm which version of the NCM database IES 2014 with 2010 regs is using?

If it is using version 5, then I don't believe this complies with the 2010 edition of the modelling guide which references version 4.


As a separate issue, why with the new database (5.2d) is absence detection no longer an option for large classrooms?
Is this type of control ineffective on larger rooms? Should lighting designers be using presence detection?

If the room has absence detection do we have to enter presence detection as the best match?


Some development on lighting controls and zoning etc. could make complying with the modelling guide so much easier. Especially if floor area is going to dictate which type of controls are allowable.

We seem to be moving backwards with this methodology sometimes.

Ross

Hi, I queried something similar a little while ago and got the response that:

“Following a ruling from the approval body, local manual lighting switching should only apply to rooms of 30m2 floor area or less (despite the fact that SBEM doesn't apply this rule)”

This has then been interpreted that if you can't have a local manual switch, you can't have Man-On-Auto-Off absence detection control.

It doesn't make any sense to me as we regularly design rooms of >30m² floor area with manual switching and absence detection. IES say they are just following the guidance provided by the various bodies, which is fair enough.

There are now large parts of the NCM that make so little sense to me I'm seriously questioning the abilities and experience of whoever is developing the methodology. I'd love to sit down with them and discuss all of the industry's concerns with the NCM but they show no interest in engaging with the non-domestic modelling community.

Hi All,

I also queried this to IES and got the same response as John.

I think that subdividing the spaces to match the room's lighting control strategy ensures that the absence sensors can still be assigned correctly. Subdivision in this case can be completed with the electrical engineer's advice.
I hope this helps.

Regards,

Eleni

JohnLloyd wrote:There are now large parts of the NCM that make so little sense to me I'm seriously questioning the abilities and experience of whoever is developing the methodology. I'd love to sit down with them and discuss all of the industry's concerns with the NCM but they show no interest in engaging with the non-domestic modelling community.

I don't even know who these shadowy people are.

Perhaps the NCM is created by manatees dropping balls into a random number generator? (see South Park: Cartoon Wars)

I have also had the same discussion with IES Technical support, I was forward extracts of correspondence between IES and the approval body. It is clear that IES have followed the advice they were given i.e.

For rooms displaying the message ‘Local manual switching - is NOT permitted by room activity and geometry’, the settings for ‘Occupancy sensing’ should be limited to those which don’t involve manual control, namely:
AUTO-ON-DIMMED
AUTO-ON-OFF
NONE

However if you download iSBEM_v5.2.d (freely available from the NCM website) and run a couple of experiments you can get a saving from applying man on - auto off to rooms over 30m2.

Using the example building that comes with iSBEM i selected zone Z1/01 Centre, a large open plan office with floor area of 614m2. Clearly >30m2 and an activity type that allows absence detection.

This Zone (Z1/01 Centre) has no occupancy control assigned. (no changes)
Running iSBEM gives a BER of 41.56KgCO2/m2/yr and lighting energy figure of 30.72KWh/m2/yr

Assign occupancy control of Auto on/off and parasitic power of 0.1W/m2
Running iSBEM gives a BER of 41.5KgCO2/m2/yr and lighting energy figure of 30.64KWh/m2/yr

Assign occupancy control of Man-on/ Auto-off and parasitic power of 0.1W/m2
Running iSBEM gives a BER of 41.39KgCO2/m2/yr and lighting energy figure of 30.44KWh/m2/yr

iSBEM gives a saving by applying the absence detection. This would suggest that the advice IES have been given above is not correct or out of context. There are some additional rules that apply to activity types.

To me local manual switching and occupancy control are two separate issues. Absence detection can be successfully applied to areas larger than 30m2. Reading the iSBEM technical manual the limits of occupancy sensing are on activity type

Thought I would provide a brief history of this issue to users.

First thing you should all know is that for Part L 2013 the DCLG completely changed the approval process for DSM software. Before Part L 2013 all DSM's had to do was follow the NCM Modelling Guide to the letter and self validate (which sounds simple but actually involved quite a lot of back and forth emails with the approval body where we sought clarifications and had to show them everything from the modelling guide was implemented correctly).

For Part L 2013 this was changed so that DSM's had to follow the modelling guide as well as match results from iSBEM for 21 buildings of certain configurations. After some protest this was changed from matching results exactly to being within a certain percentage.

When running through the 21 approval models there were a few models where we had real difficulty in getting close to the results produced by iSBEM. After some further investigation we noticed the main reason for this was that the version of iSBEM used for approval tests (at that time) did not follow the paragraph 72 of the 2013 NCM modelling guide.
What we found was that iSBEM was only applying manual occupancy sensing in the rooms that where eligible for local manual switching. This put us at a disadvantage as our developers were strictly following the modelling guide and were applying "Manual-on-Auto-off" occupancy sensing systems for all rooms in the Notional Building (as per the modelling guide instructions). This made it impossible to get close to the approval test case results produced by iSBEM.

We raised this with the approval body and after they found the same behaviour from iSBEM their stance was for us to ignore the modelling guide and implement what iSBEM was doing. It was agreed this was to be done with a hotfix which was VE 2014 Hotfix 1. After we made this change we got close to the results from iSBEM and our DSM was approved was Part L 2013.

This is why the options for manual control do not appear in the current version unless a room is eligible for local manual switching.

It was then brought to our attention from users a few weeks later that the updated version of iSBEM appeared to have corrected this issue (i.e iSBEM was now following paragraph 72 of the NCM Modelling Guide). This was reported to our developers. Once it has been confirmed SBEM is following Paragraph 72 then our developers will re-instate the code they initially had for ApacheSim DSM.

I could be wrong but I suspect that even with recent updates from SBEM this has not changed and SBEM is still not following the modelling guide with regards to local manual switching and occupancy controls. We will confirm this with our own testing and raise it with the BRE if that is the case.

It would have been a lot easier if the old approval process was in place as if we didn't have to match SBEM results then we wouldn't have needed to make a decision to deliberately not follow the 2013 NCM modelling guide. Guess we just have to crack on with it though!

Terence, thanks for the information. At least we now know the reasoning behind the decision to remove the facility.

Could you perhaps direct us to a mailbox / person / phone number at DCLG or BRE who makes these decisions and develops iSBEM? Perhaps a raft of feedback from the end users could help get some changes made and more sensible outcomes?

Thanks,
John.

JohnLloyd wrote:Terence, thanks for the information. At least we now know the reasoning behind the decision to remove the facility.

Could you perhaps direct us to a mailbox / person / phone number at DCLG or BRE who makes these decisions and develops iSBEM? Perhaps a raft of feedback from the end users could help get some changes made and more sensible outcomes?

Thanks,
John.

I'll bet you a pint that information is "confidential".

JohnLloyd wrote:Terence, thanks for the information. At least we now know the reasoning behind the decision to remove the facility.

Could you perhaps direct us to a mailbox / person / phone number at DCLG or BRE who makes these decisions and develops iSBEM? Perhaps a raft of feedback from the end users could help get some changes made and more sensible outcomes?

Thanks,
John.

+1 For this. DCLG seem very keen that EPC assessors etc. are constantly audited to make sure the work is accurate, but there are so many grey areas in the NCM you could legitimately provide very different results for the exact same building! A few clarifications would go a long way.