Hello.
Actually, you don't have to model 200 zones. Consider doing the following: build your model for only one story. For a ceiling surface of a particular zone, in the outside boundary condition, specify "surface" and enter in the object field the corresponding floor for that same zone. And vice-versa for the floor. This will give a good estimation for the intermediate stories. You can then use the zone multiplier to get the energy results for the sum of all stories, except the bottom and top one. This aproximation is acceptable if the zones are conditioned and the temperature won't be floating around too much.
Special attention should be given for the bottom floor and the top floor. The first one most likely has a very different layout, due to the entrance hall and other eventual differences. The top one, though might be equal to a regular story, it will have sun incidence on the top, so the ceiling must be given an outside condition boundary (and the ceiling eventually will have a different construction from the rest of the stories).
Also, you should look at the layout of a single story and lump together similar zones (with similar schedules for loads and occupation) facing the same facade, into one single zone. When dealing with the HVAC system, put on each of these lumped zones the total number of terminal and zone units that you need and the results should come out fine. These simplifying methods can be found in the getting started manual, take a look for more detailed information.
For a final note, consider shadowing effects from the building itself and from outside surfaces. They might compromise these simplifications, so some caution is needed when deciding what to simplify.
Pedro.
On 21-10-2011 16:50, jvd2pe wrote:
Dear Forum,
Assuming:
- 10 story hotel with 200 guest rooms facing all compass directions
- Each guest room has HVAC and outdoor air from a through-the-wall heat pump
How can I create a simple modeling scheme and schedules which will reflect normal occupancy variations?
As I think about it, the reality of operation is quite different than a central HVAC unit, because random individual rooms can be completely off, while others are on. Room temperature, ventilation and fan power are all affected. There will be no predictable pattern for which rooms are unused or unoccupied. ASHRAE does have some typical use patterns in their 90.1 User Manual but, for example, they assume 100% on time for fans. That's too coarse for my taste, and will overestimate energy substantially.
I REALLY don't want to model 200 individual zones with varying schedules! I know that I'm not the first one to wrestle with this idea, so I am hoping for some creative insight from you.
Thanks in advance!
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