A room is 5x5x5=125 m3 and holds a temp of 30C. On the other side of all the walls the air is 20C. I measure that the room temperature drops about 0.001C per second. If I now use this equation...(adsbygoogle = window.adsbygoogle || []).push({});

[tex]

\dot Q = V \cdot C_P \cdot \rho \cdot \dot T

[/tex]

...I get the amount of heat that needs to be added in order for the room to keep this temperature (I think), and it's about 144W. What I don't get is that if I now calculate how much heat goes through the walls using the following equation...

[tex]

\dot Q = U \cdot A \cdot \Delta T

[/tex]

...this comes to 300W, but that means that I'm actually losing 300-144=156 Watts more than the first equation tells me!

Am I getting something all wrong here?! This really confuses me, and all attempts to explain this to me will be appreciated.

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# A room's heat loss

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