No Difference in indoor air temperature even after changing building materials in EnergyPlus

asked 2021-06-16 05:45:03 -0600

updated 2021-06-22 10:29:54 -0600

I'm working on finding out best suitable building material (brick) for semi-arid climate of India. The building that I'm simulating using EnergyPlus is a multi-storey builidng located in a dense urban setting. I tried changing building material with their respective thermal properties like thermal conductivity, density and specific heat. The output of respective scenarios didn't showed noticeable difference as it should be. Like, the building low thermal conductivity and higher specific heat should have lower air temperature than the building having material of high thermal conductivity and low specific heat. What could be the probable reason ? Attached are the images showing variation in indoor air temperature of different materials with time and the thermal properties of the materials used. C:\fakepath\plot_1.JPG C:\fakepath\plot_2.JPG C:\fakepath\material properties.JPG

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@hardik_gajjar what simulation tool are you using? Please mention the tool in your post's title, body, or tags so that others can provide better help. Also, it would help to include a screenshot image or other figure of the results that "didn't show noticeable difference".

Aaron Boranian ( 2021-06-16 09:25:37 -0600 )edit

Hi! Aaron. I've edited the post as suggested. Thanks

hardik_gajjar ( 2021-06-18 01:29:34 -0600 )edit

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answered 2021-06-18 07:44:17 -0600

Jim Dirkes
3544 ●27 ●16

updated 2021-06-21 05:46:12 -0600

You don't mention whether you have an HVAC system, but the image suggests that you do not. If you DO, then it is expected to have stable temperatures. If NOT, then the solar influence, including shading from adjacent buildings may affect interior temperature. Also, the mass difference between mud bricks with rice husk is probably very similar to mud bricks alone, making the lag in temperature conductance small. I don't know, however, what insulation difference exists... Hmmm... 1 air change per hour is significant, but not a "hurricane". It will, however, make mitigate temperature changes. I read the abstract and see that it refers to thermal properties, but does not mention the impact on the interior of a building (which is what you are doing).Just because a building has better insulation does not tell you a lot about the impact on interior temperature, particularly over the span of multiple solar cycles. In the case of mud bricks, the mass and thermal lag will also have an impact. All in all, I think I'd confirm in every way you can that the model has proper inputs, then carefully review performance differences to understand why the insulation has lower impact than expected - such as lower density due to increased insulation... Enjoy the investigation!

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Hi James. Thanks for your prompt response. I would like to clarify about missing information from my side. 1. HVAC system is kept OFF in the model. But I've kept natural ventilation ON for 24 hour with Air change of 1 l/hr. 2. Building is standalone, no surrounding buildings are modeled. 3. Solar data (direct sol. rad.) is provided as input data along with the other weather data.

hardik_gajjar ( 2021-06-19 20:40:52 -0600 )edit

A significant difference was observed by the authors who have developed these bricks in thermal transmittance and thermal admittance values between the bricks due to their difference of thermal properties. So in that context, there should be some difference in indoor air temperature between both the cases at peak time (12:00 to 16:00).

Provided is the link to the referred research article. https://link.springer.com/article/10....

hardik_gajjar ( 2021-06-19 20:42:00 -0600 )edit

Thank you so much James for providing me a hint to carry our further simulations. I'll try changing the density and others of a material and observe the indoor air temperature variation. However, can you cross-check my idf file for input parameters? I can send it by e-mail, as here it is not possible to attach other files than image files.

hardik_gajjar ( 2021-06-22 23:10:11 -0600 )edit

I'll be happy to take a look at your IDF.