Hello all,

I have some difficulties understanding the thermal zones concept. It is clear to me that a zone might be a space or a group of spaces which have similar thermal loads and are served by the same system, but do these spaces have to be on the same floor? I have a three-storey building that has an outside air system, serving several spaces and each of them is on a different floor. Can I combine these spaces into one thermal zone? What would you do in such case?

Thank you!

Kristina

In many cases, it is okay to combine rooms from different floors into thermal zones. But in your case - you shouldn't combine them into one thermal zones (since it would adversely affect your energy calculations).

Unfortunately, I can't tell you how to model DOA in eplus, but the solution is not to combine the entire system into one thermal zone. Sometimes people create a "dummy" space that has no loads and is set to use ALL of the OA, so that the DOA can effectively be counted for by simply separating the ventilation.

Hope that is somewhat helpful

You can find a criterion for defining thermal zone in the standard ISO 13790.

In particular you have not to dived a space in more thermal zone if:

1. Set-point temperatures for heating/cooling of the spaces differ by no more than 4 K;

2. The spaces is serviced by the same heating systeme (if any) and the same cooling system (if any);

3. At least 80% of the floor area are serviced by the same ventilation system;

4. The ammount of ventilation (in cubic metre per square metre of floor area per second) differs by not more than a factor of 4 within 80% of the floor area.