ASHRAE 90.1-20xx Chapter 11 Dx Notes

In 90.1-2010 Table 11.3.2A Systems 10 and 11 are both listed with Cooling Type: 'Direct Expansion' - but without Note "C" below the table. Other systems (3,4,6,8,9) are all also DX but have a reference to Note 'C'. I cannot determine why systems 10 & 11 do not. The User Manual offers no insight either. This holds true in the corresponding tables in 90.1-2013 & 2016. Can any one shed some light on this logic or reasoning?

I would guess it was not intentional to leave off Note "c" for the cooling system column for systems 10 and 11 but that said, it is not present. Almost all DX systems use electricity for cooling and if your DX system is electric I would use electric for the baseline. Since 10 and 11 are for packaged terminal cooling, the likelihood of them using something other than electricity for cooling is very unlikely. If your proposed packaged terminal DX system uses gas or some other fuel for cooling, and you want to assume the same for the baseline, to be safe, I would ask for a formal interpretation by following the instructions here.

This response is my personal opinion and should not be viewed as an official interpretation from ASHRAE.

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JasonGlazer

answered 2018-11-14 09:01:10 -0500

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@JasonGlazer - thanks for the response. This is in line with what I would assume. It was one that a co-worker pointed out to me and I didn't have a good 'why' as to the cause. Do I need to submit this for formal interpretation to get it included in 90.1-2019? (WHOA....2019)