ASHRAE 90.1.2010 and receptacle loads

The 25% minimum for process loads was never a requirement in LEED. The credit language was poorly written so it sounded that way but it was never the intent. Under v4 this part of the credit language was removed. The 25% is a remnant left over when LEED was originally written around an office building. It was based on energy use data that showed that the typical office building's plug load was about 25% of the total energy use. It was/is used as a guideline in reviews. If you were over 25% then you were usually OK, if under 25% you had to provide an explanation as to why you were under. What is most important is that you model the process loads (items that impact energy use but are not regulated by 90.1) as accurately as possible. An elementary school will be about 15%, an office 25%, a high rise office may be greater due to elevator use, add a restaurant to an office building and the percentage increases, etc.  High process load facilities like a refrigerated warehouse, data center, manufacturing plant, etc. will have 50% to 90% process. LEED requires that you model all energy use within and associated with the project. The higher the identical process as a percentage of the total, the lower the overall savings. So under estimating the process is not a conservative estimate of savings. As a rule when in doubt always produce a conservative estimate of savings. All process loads should be modeled based on the actual installed equipment or some reasonable data set like the 90.1-User's Manual or the COMcheck manual. So forget the 25%, model the process accurately and the reviewer will determine if you have done so in a reasonable manner.

Hi Marcus, I have a general query based on equipment loads as per ASHRAE 90.1 - somewhere we use the terminology "receptacle loads" while somewhere we use "plug and process loads".  When do we use which and what is to generally to be used as per ASHRAE 90.1?

All unregulated energy loads in 90.1 are process loads. Unregulated means that the standard does not address it.Receptacle and plug loads are the same thing. Energy loads that plug into a receptacle. Hardwired equipment that is not regulated is often lumped into the plug loads too depending upon the equipment. If that equipment is significant you generally want to separate it out in your models.