Hi all,

I would like to confirm my understanding of the Canadian alternative compliance path for EAp2/c2. The first requirement in the ACP is to "comply with the mandatory requirements of ASHRAE 90.1-2010". I have two questions regarding this requirment:

1) Does it pertain only to the reference building or does it pertain to the proposed building as well? I am assuming that it pertains only to the reference and not the proposed, since the whole point of NECB section 8 is to allow some proposed building components to fall below code requirements and for other components that exceed code requirements to "make-up" for their performance.

2) I'm confused as to whether this sentence means that I must comply with the entirety of ASHRAE 90.1-2010 (i.e. all sections), or just the "Mandatory Provisions" sections (i.e. sections 5.4, 6.4, 7.4, 8.4, 9.4). My interpretation is that the reference building should only satisfy NECB 2011 requirements and the "X.4" sections of ASHRAE 90.1-2010 since the purpose of the Canada ACP is to make energy modelling more convenient for Canadian projects. However, a sentence further down says "In cases where ASHRAE and the NECBC reference requirements concerning the same item, the more stringent requirement shall be adhered to". This sentence seems to suggest that I should be comparing NECB and ASHRAE requirements side-by-side, which is why I am confused.

For example, I am working on a project that is located in climate zone 6 (for both NECB and ASHRAE). According to NECB 2011 Table, in the reference building, I need 1.2 m of horizontal underslab insulation with a USI value is 0.757 W/m2K, which corresponds to an imperial F-factor of 0.65 Btuh/ft-F. However, ASHRAE 90.1-2010 Table 5.5-6 says that for unheated slab-on-grade floors, the assembly maximum F-factor is F-0.54. This is what I am troubled with - if I only need to comply with the "Mandatory Provisions" sections of ASHRAE (i.e. the "X.4"), then I wouldn't have to comply with Table 5.5-6 and I would model F-0.65 for the reference building. However, if I have to comply with the entirety of ASHRAE, then I do need to follow Table 5.5-6, and consequently I would need to model F-0.54 for the reference building.

Could someone please help by clarifying?

Thank you so much,