Perimeter Zones Requirements for Warehouse

The baseline must be modelled as per ASHRAE 90.1-2007 app. G. Therein it tells you how to divide the perimeter into virtual zones. You should do this for the proposed model as well as it is good practice (most of the time, there could be situations where it is not depending on the radiation infall from outdoors). As a good rule of thumb...whereever there is a thermostat, model the zone that thermostat is suposed to control. Again, check the standard...there are some good tips in there.

To be honest, this is a modelling issue. The thing is that a zone is considered "well mixed" in most programs and does not take into account temperature variation across the zone as would occure in real life. To make sure the thermostats and systems respond "semi-realistically" it is usually a good idea to seperate these as suggested. However, it is situational and geometry together with air movement, both thermally induced and mechanically induced are really what should influence your judgement calls.

Does that make sense?

In a warehouse you would not typically see any perimeter zoning except maybe by the loading docks. All things being equal in each of the 4 areas you could probably combine them into one thermal block without much of an impact on energy use. Combining areas into fewer thermal blocks in my experience is typically done to simplify the model. As Jean suggests this is a judgement call on the part of the modeler. Like all judgement calls you should be able to defend the actions you take as thermodynamically similar enough to only minimally affect the energy use.

I agree and would point out that Marcus says "loading docks", but basically think of other "zones" that may experience other dissimilar thermal loading as well.

For example near a fully glazed wall or near a hot machine. The type of thermostat may also be a consideration. I'm in Europe and just this minute there's a project where we use radiative ceiling elements for heating combined with operative temperature thermostates. Here I would think about hot or cold radiative surfaces as well which may influence the thermostat and drive the heating surface temperatures of the radiative panels. In that case adding additional "virtual" surface to split zones may even negatively effect the thermostat reading, so I need to be careful. At the same time, large spaces (especially high ones) could show some stratification. My software can handle this by using a "non-well mixed" room air model to capture some of these effects without splitting the zone. I've not started this job, but these would be some of the thoughts that would go through my mind to consider.

These kind of impacts start really mattering if the systems are ramping up and down and negatively effect efficiencies which is especially prevelant in radiant systems. Air systems tend to "well mix" better and not suffer from these control symtoms as much.

For LEED Table G3.1-7 tells you what you have to do. The exception for combining blocks will need to apply in order to combine zones into a single block. If all of the exception criteria apply then you can combine them. Jean has been trying to let you know the thinking that needs to go behind the combining of multiple zones into a single block.

I would divide the large open space into core and perimeter zones at a minimum. Since the the spaces are open to one another, I would make the partitions to be 100% hole.