[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

RE: [EnergyPlus_Support] Indoor air temperature LOWER than ambient temperature

When you say ambient temperature, I assume that you are referring to the outdoor dry bulb temperature.
The dew point has a lower temperature.  The building surface ground may have a lower temerature, and assumed to be 18°C, if you did not not enter a set for the bulding.
The radiation component always acts faster than the covection component.  The exterior surfaces are facing the sky temperature, which is also lower than the ODT..

The ODT is usually the lowest at around 5 am.  The building will follow this with a delay.
Therefore, there are many possiblilities.
After sun rise, the indoor temerature can still be lower, because of ground cooling through the floor. So list the variable for floor temperature ro confirm.  If it is due to the low building surface ground temperature  (18°C), increasing the temperature will raise the indoor temperature by a similar amount..
 Dr. Li  


To: EnergyPlus_Support@xxxxxxxxxxxxxxx
From: azianzheep@xxxxxxxxx
Date: Fri, 17 Aug 2012 07:47:37 +0000
Subject: [EnergyPlus_Support] Indoor air temperature LOWER than ambient temperature


I've been doing E+ simulation for over half a year now and feel like I have a good grasp of it. But one thing I can't figure out is why I sometimes get results of indoor temperature being lower than ambient temperature. This often occurs during the early morning, 3am-9am. In reality this is impossible so I'm very confused by this result.

Can someone please explain to me why E+ produces this result?

If requested, I can attach additional information such as .idf or excel graph.

Many thanks,



Primary EnergyPlus support is found at:
http://energyplus.helpserve.com or send a message to energyplus-support@xxxxxxxx

The primary EnergyPlus web site is found at:

The group web site is:

Attachments are currently allowed but be mindful that not everyone has a high speed connection.  Limit attachments to small files.

EnergyPlus Documentation is searchable.  Open EPlusMainMenu.pdf under the Documentation link and press the "search" button.

Your email settings: Individual Email|Traditional
Change settings via the Web (Yahoo! ID required)
Change settings via email: Switch delivery to Daily Digest | Switch to Fully Featured
Visit Your Group | Yahoo! Groups Terms of Use | Unsubscribe