Part L 2010 Criterion 3 & Daylight zoning

[olly h]

Hi,

Can someone please confirm the NCM daylight zoning requirements?

The NCM FAQ (link below) suggests that although spaces must be zoned according to daylight, this can be done automatically by SBEM and so the user doesn't need to enter these additional virtual partitions (ie 6m from the wall). I know you do need to be careful using the daylight dimming options in these situations.
http://www.ncm.bre.co.uk/page.jsp?id=9#a34

This has a big impact on 2010 Criterion 3 Solar gain checks as if you can maintain large zones you can average the solar gains over a larger floor area and it is much easier to comply.

How do energy assessors generally approach this, and what is the correct approach?

Thanks,
Olly

[bootsam]

Forgive me if i have misunderstood. I thought PartL2006 criteria 3 was based upon w/m2 whereas 2010 is now energy through the window.

However I draw daylight zones myself based upon the old 4m deep x 6m wide zones around the windowed periphery. This is mainly as I use the same file to calculate loads and each of those zone is a FCU for me. So on an open plan office I would have external windowed zones and internal zones.

[Complex Potential]

Olly

First off it's probably worth noting that only criterion 1 is mandatory for compliance. Criterion 2, 3, 4 and 5 are all recommendations but failure to follow them does not mean an automatic fail, especially where criterion 3 is concerned.

Putting that to one side, criterion 3 under 2010 now compares the total solar gains into your (applicable) room against a reference room which is defined within ADL2A 2010 section 4.44 and has nothing to do with your floor areas or zoning since the reference building will match them anyway.

In most cases a separate, overheating study using a bespoke apache model is a better way of demontrating to building control that the internal comfort conditions will be met.

CP