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

Revision history [back]

click to hide/show revision 1
initial version

illogical heat transfer simulation

Hi, i'm new in the openstudio developing and i'm working with OS application. I made a simple box case with 3 stories, each one constitude with a two components envelope and a couple of simple windows. The envelope is composed of a low conductivity concrete in the outside and a mean conductivity concrete in the inside face (Both with 0.21 Btu/lb.R of specific heat, 0.9 on thermal alpha and 0.7 on solar alpha). No schedules, space types, internal loads or HVAC system was applied. It is only compose by single thermal zone.

When i run the simulation, the results is seems to be illogical: -> The interior temperature is attenuated throught-out the day and for all the year. The amplitude of the daily temperatures (comparing day and night) is less than one or two celsius degrees . I'm comparing outdoor drybulb temperature with zone mean radiant and air temperature (witch are the same).

-> Another issue i see is that the solar irradiated outside face temperature has peaks of twenty celsius degrees highers than the ambient temperature on the midday and then has also lowers temperatures than the outdoor on the night.

These circunstance doesn't match together, because the boundary conditions makes me think that the internal temperature must oscilate between peaks, and the manual/excel calculation of the heat transfer confirms me that.

I'm thinking on a hypotesis but i want to know first if i'm missing some important steps on the definition of the model and this is a trivial issue or not.

This is my first interaction on the forum so i don't know if it is possible to share the model and the EPW file. I thank you in advice.

illogical heat transfer simulation

Hi, i'm new in the openstudio developing and i'm working with OS application. I made a simple box case with 3 stories, each one constitude with a two components envelope and a couple of simple windows. The envelope is composed of a low conductivity concrete in the outside and a mean conductivity concrete in the inside face (Both with 0.21 Btu/lb.R of specific heat, 0.9 on thermal alpha and 0.7 on solar alpha). No schedules, space types, internal loads or HVAC system was applied. It is only compose by single thermal zone.

When i run the simulation, the results is seems to be illogical: ->

  • The interior temperature is attenuated throught-out the day and for all the year. The amplitude of the daily temperatures (comparing day and night) is less than one or two celsius degrees . I'm comparing outdoor drybulb temperature with zone mean radiant and air temperature (witch are the same).

    ->

  • Another issue i see is that the solar irradiated outside face temperature has peaks of twenty celsius degrees highers than the ambient temperature on the midday and then has also lowers temperatures than the outdoor on the night.

These circunstance doesn't match together, because the boundary conditions makes me think that the internal temperature must oscilate between peaks, and the manual/excel calculation of the heat transfer confirms me that.

I'm thinking on a hypotesis but i want to know first if i'm missing some important steps on the definition of the model and this is a trivial issue or not.

This is my first interaction on the forum so i don't know if it is possible to share the model and the EPW file. I thank you in advice.

illogical heat transfer simulation

Hi, i'm new in the openstudio developing and i'm working with OS application. I made a simple box case with 3 stories, each one constitude with a two components envelope and a couple of simple windows. The envelope is composed of a low conductivity concrete in the outside and a mean conductivity concrete in the inside face (Both with 0.21 Btu/lb.R of specific heat, 0.9 on thermal alpha and 0.7 on solar alpha). No schedules, space types, internal loads or HVAC system was applied. It is only compose by single thermal zone.

When i run the simulation, the results is seems to be illogical:

  • The interior temperature is attenuated throught-out the day and for all the year. The amplitude of the daily temperatures (comparing day and night) is less than one or two celsius degrees . I'm comparing outdoor drybulb temperature with zone mean radiant and air temperature (witch are the same).

  • Another issue i see is that the solar irradiated outside face temperature has peaks of twenty celsius degrees highers than the ambient temperature on the midday and then has also lowers temperatures than the outdoor on the night.

These circunstance doesn't match together, because the boundary conditions makes me think that the internal temperature must oscilate between peaks, and the manual/excel calculation of the heat transfer confirms me that.

I'm thinking on a hypotesis but i want to know first if i'm missing some important steps on the definition of the model and this is a trivial issue or not.

This is my first interaction on the forum so i don't know if it is possible to share the model and the EPW file. I thank you in advice.