The invention relates to a method for determining the heat loss coefficient K of a premises, comprising the following steps: in the unoccupied premises, taking a series of measurements of at least one temperature inside the premises T ik at short time intervals over at least two successive time periods D k corresponding to different heating power values Ptot k for the premises; determining the temperature of the outside air T ek at the aforementioned short time intervals; for each period of time D k , based on the change T ik (t) in value T ik as a function of time, selecting a time interval ?t k for which the change T ik (t) is substantially linear, and, subsequently, over time interval ?t k , determining the slope a k of the tangent to the curb T ik (t) and deducing the value of the heat loss coefficient K of the premises on the basis of slopes a k .