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Hello everyone,

I'm new to building simulation, so I'd appreciate you help. I'm using openstudio to model a 12 floor office building, in which, 9 floors are the same, so I'm using a multiplier. The building is located in Brazil and it has a massive window wall.

The HVAC system is VRF with air return, so we don't use exclusively outdoor air. I've set the air loop to represent both outdoor air and return air by the "Fan Variable Volume". I set the VRF system changing only schedules, total capacity and COP. In the VRF terminal everything's autosized, excepr for schedules.

I'm using schedules for commercial times in Brazil, which is around 8a.m. to 18:30p.m. on weekdays and no use in weekends. I set the HVAC system to start one hour before occupation times. Even though I've already checked and changed schedules, design/operational heating and cooling temperatures, increased the sizing factor to 2F, the model keeps presenting around 150 unmet hours for cooling and 1300 umet hours for heating, mostly in office spaces.

It is hard to believe that the problem is the HVAC system's capacity, cause it's been designed (overestimated) for a occupation of 30 people in office spaces and I'm using only 11 people (following ASHRAE) in my model.

I plotted the Unmet hours Troubleshooting, that shows me a really variable air temperature trhoughout time in conditioned zones. The following picture is for the floors with the multiplier, those are the ones that show the higher value for unmet hours. Besides that, air loop node temperatures point that the air leaves the thermal zone with a higher temperature than when it went in.

C:\fakepath\unmet 3.JPG C:\fakepath\unmet.png C:\fakepath\unmet 2.png

Truth is, I've ben trying to solve this for a while and I'm not sure what to look for here. I'd be very thankful if you could help me solving this problem.

Hello everyone,

I'm new to building simulation, so I'd appreciate you help. I'm using openstudio to model a 12 floor office building, in which, 9 floors are the same, so I'm using a multiplier. The building is located in Brazil and it has a massive window wall.

The HVAC system is VRF with air return, so we don't use exclusively outdoor air. I've set the air loop to represent both outdoor air and return air by the "Fan Variable Volume". I set the VRF system changing only schedules, total capacity and COP. In the VRF terminal everything's autosized, excepr for schedules.

I'm using schedules for commercial times in Brazil, which is around 8a.m. to 18:30p.m. on weekdays and no use in weekends. I set the HVAC system to start one hour before occupation times. Even though I've already checked and changed schedules, design/operational heating and cooling temperatures, increased the sizing factor to 2F, the model keeps presenting around 150 300 unmet hours for cooling heating and 1300 umet hours for heating, cooling, mostly in office spaces.

It is hard to believe that the problem is the HVAC system's capacity, cause it's been designed (overestimated) for a occupation of 30 people in office spaces and I'm using only 11 people (following ASHRAE) in my model.

I plotted the Unmet hours Troubleshooting, that shows me a really variable air temperature trhoughout time in conditioned zones. The following picture is for the floors with the multiplier, those are the ones that show the higher value for unmet hours. Besides that, air loop node temperatures point that the air leaves the thermal zone with a higher temperature than when it went in.

C:\fakepath\unmet 3.JPG C:\fakepath\unmet 4.JPG C:\fakepath\unmet.png C:\fakepath\unmet 2.png

Truth is, I've ben trying to solve this for a while and I'm not sure what to look for here. I'd be very thankful if you could help me solving this problem.

Hello everyone,

I'm new to building simulation, so I'd appreciate you your help. I'm using openstudio to model a 12 floor office building, in which, 9 floors are the same, so I'm using a multiplier. The building is located in Brazil and it has a massive window wall.

The HVAC system is VRF with air return, so we don't use exclusively outdoor air. I've set the air loop to represent both outdoor air and return air by the "Fan Variable Volume". I set the VRF system changing only schedules, total capacity and COP. In the VRF terminal everything's autosized, excepr for schedules.

I'm using schedules for commercial times in Brazil, which is around 8a.m. to 18:30p.m. on weekdays and no use in weekends. I set the HVAC system to start one hour before occupation times. Even though I've already checked and changed schedules, design/operational heating and cooling temperatures, increased the sizing factor to 2F, the model keeps presenting around 300 unmet hours for heating and 1300 umet hours for cooling, mostly in office spaces.

It is hard to believe that the problem is the HVAC system's capacity, cause it's been designed (overestimated) for a occupation of 30 people in office spaces and I'm using only 11 people (following ASHRAE) in my model.

I plotted the Unmet hours Troubleshooting, that shows me a really variable air temperature trhoughout time in conditioned zones. The following picture is for the floors with the multiplier, those are the ones that show the higher value for unmet hours. Besides that, air loop node temperatures point that the air leaves the thermal zone with a higher temperature than when it went in.

C:\fakepath\unmet 3.JPG C:\fakepath\unmet 4.JPG C:\fakepath\unmet.png C:\fakepath\unmet 2.png

Truth is, I've ben trying to solve this for a while and I'm not sure what to look for here. I'd be very thankful if you could help me solving this problem.

Hello everyone,

I'm new to building simulation, so I'd appreciate your help. I'm using openstudio to model a 12 floor office building, in which, 9 floors are the same, so I'm using a multiplier. The building is located in Brazil and it has a massive window wall.

The HVAC system is VRF with air return, so we don't use exclusively outdoor air. I've set the air loop to represent both outdoor air and return air by the "Fan Variable Volume". I set the VRF system changing only schedules, total capacity and COP. In the VRF terminal everything's autosized, excepr for schedules.

I'm using schedules for commercial times in Brazil, which is around 8a.m. to 18:30p.m. on weekdays and no use in weekends. I set the HVAC system to start one hour before occupation times. Even though I've already checked and changed schedules, design/operational heating and cooling temperatures, increased the sizing factor to 2F, the model keeps presenting around 300 unmet hours for heating and 1300 umet unmet hours for cooling, mostly in office spaces.

It is hard to believe that the problem is the HVAC system's capacity, cause it's been designed (overestimated) for a occupation of 30 people in office spaces and I'm using only 11 people (following ASHRAE) in my model.

I plotted the Unmet hours Troubleshooting, that shows me a really variable air temperature trhoughout time in conditioned zones. The following picture is for the floors with the multiplier, those are the ones that show the higher value for unmet hours. Besides that, air loop node temperatures point that the air leaves the thermal zone with a higher temperature than when it went in.

C:\fakepath\unmet 3.JPG C:\fakepath\unmet 4.JPG C:\fakepath\unmet.png C:\fakepath\unmet 2.png

Truth is, I've ben trying to solve this for a while and I'm not sure what to look for here. I'd be very thankful if you could help me solving this problem.

Hello everyone,

I'm new to building simulation, so I'd appreciate your help. I'm using openstudio to model a 12 floor office building, in which, 9 floors are the same, so same. For the first time I'm using a multiplier. The building is located in Brazil and it has a massive window wall.thermal zone multiplier.

The HVAC system I'd like to know if the correct approach is VRF with air return, so we don't use exclusively outdoor air. I've set the air loop to represent both outdoor air and return air by the "Fan Variable Volume". I set multiply the VRF system changing only schedules, total capacity and COP. In OA/return air flow to meet with the VRF terminal everything's autosized, excepr for schedules.

I'm using schedules for commercial times in Brazil, which is around 8a.m. multiplied floors. OpenStudio doesn't do that by itself, right? At first, I was not multiplying capacity and ir flow accordingly to 18:30p.m. on weekdays the multiplier and no use in weekends. I set the HVAC system to start one hour before occupation times. Even though model presented a lot of unmet hours. Now that I've already checked and changed schedules, design/operational heating and cooling temperatures, increased the sizing factor to 2F, input on VRF and air flow, the model keeps presenting around 300 unmet hours for heating and 1300 unmet hours for cooling, are mostly in office spaces.

It is hard to believe that the problem is the HVAC system's capacity, cause it's been designed (overestimated) for a occupation of 30 people in office spaces and I'm using only 11 people (following ASHRAE) in my model.gone.

I plotted the Unmet hours Troubleshooting, that shows me a really variable air temperature trhoughout time in conditioned zones. The following picture is for the floors with the multiplier, those are the ones that show the higher value for unmet hours. Besides that, air loop node temperatures point that the air leaves the thermal zone with a higher temperature than when it went in.

C:\fakepath\unmet 3.JPG C:\fakepath\unmet 4.JPG C:\fakepath\unmet.png C:\fakepath\unmet 2.png

Truth is, I've ben trying to solve this for a while and I'm not sure what to look for here. I'd be very thankful if you could help me solving this problem.appreciate your help.

Hello everyone,

I'm using openstudio to model a 12 floor office building, in which, 9 floors are the same. For the first time I'm using a thermal zone multiplier.

I'd like to know if the correct approach is to multiply the VRF capacity and OA/return air flow to meet with the multiplied floors. OpenStudio doesn't do that by itself, right? At first, I was not multiplying capacity and ir flow accordingly to the multiplier and the model presented a lot of unmet hours. Now that I've increased the input on VRF and air flow, the hours are mostly gone.

I appreciate your help.