This paper describes a dynamic test method for determining transfer function coefficients (TFCs) for a wall specimen using a calibrated hot box (CHB). In this method, a wall specimen is installed between the climatic and metering chambers of a CHB. After a steady specimen heat transfer rate is attained, the air temperature in the climatic chamber is quickly ramped from an initial to a final temperature level in a linear manner. The final temperature level is maintained until a new steady specimen heat transfer rate is attained. The metering chamber is maintained at a steady indoor condition and is used as a calorimeter. The transient heat transfer rate at the inside surface of the wall specimen is determined at hourly time steps from an energy balance of the metering chamber. The poles and residues for a ramp analytical solution are derived by analyzing the measured specimen heat transfer response. The ramp analytical solution is subsequently used to form a triangular pulse from which TFCs are derived.
The dynamic test method was conducted on a masonry wall. Empirical TFCs derived by the test method predicted the diurnal performance of the wall specimen with good agreement. In fact, the results predicted by empirical TFCs tracked the measured results as closely as an analytical model.