Question-and-Answer Resource for the Building Energy Modeling Community
Get started with the Help page

# Revision history [back]

### Mismatch of Air heat balance and inside heat balance.

Hello Everyone!

This question is derived from one of my previous question. I divided one thermal zone into two new thermal zones vertically by adding a middle floor. And using the ideal loads air system, it is found that the total cooling loads of the two new zones are higher than the original one. ( For the building description, you can imagine a box with high glazing ratio on the north and west side).

Receiving suggestions from user:MJWitte, I check the all the zone air balance outputs.(like:Zone Air Heat Balance Internal Convective Heat Gain Rate, etc)

And I found that the new model has higher Surface Convection Rate. ( although I have the internal convective heat gain, their values are same in both of new and original model). And Then I went to check the inside surface heat transfer. According to the engineering reference:

However, when I check the report of the inside surface, I met two problems: 1. the total convection heat gain of surface doesn't match the air balance convective heat gain. ( I take the window into account). SO, I'm wondering, what is the heat source of Zone Air Heat Balance Surface Convection Rate?

2.When I add up inside face solar radiation heat gain of all surfaces, I found the new model has lower solar radiation heat gain. In my mind, because of more surfaces in the new model, the solar radiation should increase. Why are there more surfaces in the model, the lower solar radiation heat gain? How can a surface have lower solar radiation heat gain but higher convective heat transfer? Did I miss something?

### Mismatch of Air heat balance and inside heat balance.

Hello Everyone!

This question is derived from one of my previous question. I divided one thermal zone into two new thermal zones vertically by adding a middle floor. And using the ideal loads air system, it is found that the total cooling loads of the two new zones are higher than the original one. ( For the building description, you can imagine a box with high glazing ratio on the north and west side).

Receiving suggestions from user:MJWitte, I check the all the zone air balance outputs.(like:Zone Air Heat Balance Internal Convective Heat Gain Rate, etc)

And I found that the new model has higher Surface Convection Rate. ( although I have the internal convective heat gain, their values are same in both of new and original model). And Then I went to check the inside surface heat transfer. According to the engineering reference:

However, when I check the report of the inside surface, I met two problems: 1. the total convection heat gain of surface inside surfaces doesn't match the air balance convective heat gain. ( I take the window windows into account). account by using Surface Inside Face Convection Heat Gain Rate). SO, I'm wondering, what is the heat source of Zone Air Heat Balance Surface Convection Rate? Because the Zone Air Heat Balance Surface Convection Rate does not match Surface Inside Face Convection Heat Gain Rate.

2.When I add up inside face solar radiation heat gain of all surfaces, surfaces(Surface Inside Face Solar Radiation Heat Gain Rate), I found the new model has lower solar radiation heat gain. In my mind, because of more surfaces in the new model, the solar radiation should increase. Why are there more surfaces in the model, the lower solar radiation heat gain? How can a Does the Surface Inside Face Solar Radiation Heat Gain Rate mean all the solar radiation heat gain on the surface have lower solar radiation heat gain but higher convective heat transfer?including beam solar and diffuse solar? Did I miss something?

Does anyone know the relationship of all heat balance in the thermal zone?

### Mismatch of Air heat balance and inside heat balance.

Hello Everyone!

This question is derived from one of my previous question. I divided one thermal zone into two new thermal zones vertically by adding a middle floor. And using the ideal loads air system, it is found that the total cooling loads of the two new zones are higher than the original one. ( For the building description, you can imagine a box with high glazing ratio on the north and west side).

Receiving suggestions from user:MJWitte, I check the all the zone air balance outputs.(like:Zone Air Heat Balance Internal Convective Heat Gain Rate, etc)

And I found that the new model has higher Surface Convection Rate. ( although I have the internal convective heat gain, their values are same in both of new and original model). And Then I went to check the inside surface heat transfer. According to the engineering reference:

However, when I check the report of the inside surface, I met two problems: 1. the total convection heat gain of inside surfaces doesn't match the air balance convective heat gain. ( I take the windows into account by using Surface Inside Face Convection Heat Gain Rate). SO, I'm wondering, what is the heat source of Zone Air Heat Balance Surface Convection Rate? Because the Zone Air Heat Balance Surface Convection Rate does not match Surface Inside Face Convection Heat Gain Rate.

2.When I add up inside face solar radiation heat gain of all surfaces(Surface Inside Face Solar Radiation Heat Gain Rate), I found the new model has lower solar radiation heat gain. In my mind, because of more surfaces in the new model, the solar radiation should increase. Why are there more surfaces in the model, the lower solar radiation heat gain? Does the Surface Inside Face Solar Radiation Heat Gain Rate mean all the solar radiation heat gain on the surface including beam solar and diffuse solar?

Does anyone know the relationship of all heat balance in the thermal zone?zone? Thanks for your help in advance. This is the fileThe energyplus file