Question-and-Answer Resource for the Building Energy Modeling Community
 | 1 | initial version |
This is my understanding about the OA setup in eQuest:
1, OA setup can be defined in either zone level (ex: Flow per Area, Flow per Person) or system level (Minimum Outside Air ratio). Usually zone level definition will overide system, but not always. We should be very careful when we had inputs in both levels. 2, If we input 1.00 into "Minimum Outside Air" of "Outside Air and Economizer" tab in system level, at the same time we input OA in the zone level "Flow per Area", actual OA ratio varies in different situations. If the OA defined in zone level is more than the system design supply air flow rate (could be defined by system or autosized based on load), result would be 100% OA. If the OA required by zone is less than the system design supply air flow rate, OA ratio would be "OA required by zone/supply air flow rate" which is less than 1. An interesting example is DOAS in eQuest. If we define a DOAS on a small zone, many other zones use OA from this system, the OA required by zones would be a very large number and definitely larger than the supply air flow rate of the small zone. In this case, OA ratio would be 1. 3, If we only defind OA in system level, input system air flow rate and minimum outside air ratio as 1.00. The results would be absolutely 100% OA.
| | 2 | No.2 Revision |
This is my understanding about the OA setup in eQuest:
1, OA setup can be defined in either zone level (ex: Flow per Area, Flow per Person) or system level (Minimum Outside Air ratio). Usually zone level definition will overide system, but not always. We should be very careful when we had inputs in both levels.
levels.
2, If we input 1.00 into "Minimum Outside Air" of "Outside Air and Economizer" tab in system level, at the same time we input OA in the zone level "Flow per Area", actual OA ratio varies in different situations. If the OA defined in zone level is more than the system design supply air flow rate (could be defined by system or autosized based on load), result would be 100% OA. If the OA required by zone is less than the system design supply air flow rate, OA ratio would be "OA required by zone/supply air flow rate" which is less than 1. An interesting example is DOAS in eQuest. If we define a DOAS on a small zone, many other zones use OA from this system, the OA required by zones would be a very large number and definitely larger than the supply air flow rate of the small zone. In this case, OA ratio would be 1.
1.
3, If we only defind OA in system level, input system air flow rate and minimum outside air ratio as 1.00. The results would be absolutely 100% OA.
| | 3 | No.3 Revision |
This is my understanding about the OA setup in eQuest:
1, OA setup can be defined in either zone level (ex: Flow per Area, Flow per Person) or system level (Minimum Outside Air ratio). Usually zone level definition will overide system, but not always. We should be very careful when we had inputs in both levels.
2, If we input 1.00 into "Minimum Outside Air" of "Outside Air and Economizer" tab in system level, at the same time we input OA in the zone level "Flow per Area", actual OA ratio varies in different situations. If the OA defined in zone level is more than the system design supply air flow rate (could be defined by system or autosized based on load), result would be 100% OA. If the OA required by zone is less than the system design supply air flow rate, OA ratio would be "OA required by zone/supply air flow rate" which is less than 1. An interesting example is DOAS in eQuest. If we define a DOAS on a small zone, many other zones use OA from this system, the OA required by zones would be a very large number and definitely larger than the supply air flow rate of the small zone. In this case, OA ratio would be 1.
3, If we only defind OA in system level, input system air flow rate and minimum outside air ratio as 1.00. 1.00 and NO INPUTS in ZONE LEVELS! The results would be absolutely 100% OA.
