Hot Object In a Cooler Space How would you calculate the heat given by an object that is hotter than its surroundings? I know there's Newton's Cooling Law, but what about any heat given off by radiation? Are these additive quantities? 
 A: It comes down to the calculated load to heat the total area in cubic feet of the space to 72 degrees. Then add the additional heat to overcome heat loss from walls, windows, doors, floors etc. Then minus the heat gain from people, equipment, solar etc. Finally you design for peak condition like the coldest day of the year. As for the fire places 18 sq foot heat source you would convert that to BTUs and compare to your load calculations. Too many missing factors to answer your question directly.
A: Just use Newton's cooling Law to calculate heat transfer:
$$\frac{dQ}{dt}=hA(T-T_0)$$
where:


*

*$\frac{dQ}{dt}$ is the heat transferred from the glass to the room.

*$A$ is the total surface area of the glass.

*$T$ and $T_0$ are the temperatures of the glass and the room respectively.


$h$ is the overall heat transfer coefficient and can be found on various engineering sites, for various materials and temperature ranges.
Make sure your calculation is dimensionally consistent (use compatible measuring units).
