Heat transfer is the transfer of energy between two regions due to a difference in temperature or heat flows down the gradient of temperature i.e. when two zones at different temperatures are placed in thermal contact with each other, there is a flow of heat from the hotter zone to the colder zone until they reach the same temperature. This heat transfer is reported as Internal Conduction gain or loss.

Heat transfer rate (q) between two zones at different temperatures formulated as:

q = U * A * (ts1 - ts2)

Where,

U = Overall heat transfer coefficient

A = Area of the surface in consideration

ts1 = Temperature of surface 1

ts2 = Temperature of surface 2

Within the drawing.tool, the U-value (SI) / R-value (IP) of the internal wall can be easily edited to include the impact of internal heat transfer between different zones.

This feature is incredibly helpful when analyzing the heat flow between the adjoining zones at drastically different temperatures. For example, the laboratory and the storage room would have a higher amount of inter-zone heat transfer compared to a couple of adjoining offices. Other common examples of heat transfer between zones are server or IT rooms to adjacent offices which are set to different temperatures.