This paper describes an experimental study of the buoyancy-driven flow and the associated energy transfer within a closed, halfscale stairwell model. It provides new data on the velocity, temperature, volume and mass flow rates of the air circulating between the upper and lower storeys. The results are presented for various heat input rates from the heater, located in the lower floor. For most of the data presented, heat transfer to the surrounding atmosphere takes place through the side walls. However, the case of insulated side walls is also included and the effects on the parameters of interest are discussed. The velocities were measured using hot-wire anemometers of a temperature compensated type, and the temperatures were measured using platinum resistance thermometers. These measurements were supported by flow visualisation using smoke. The paper also provides data on the rate of leakage through the stairwell joints, measured using a concentration decay method.