Measurements of ventilation rates and internal temperatures have been recorded in a naturallyventilated auditorium with high intermittent heat gains for a wide range of weather conditionsat a UK site. Satisfactory internal temperatures and high ventilation rates have been found forwinter, mid-season and summer external conditions.Simple ventilation and thermal models have been derived from experimental data whichallow the prediction of ventilation rates and internal temperatures within the auditoriumdespite the complex natures of the flow regimes and heat transfer mechanisms present. Theventilation model assumes that flowrates are driven by the buoyancy effect. The thermalmodels have been derived assuming there is one dominating effect driving internaltemperatures in the space (i.e. the heating system in winter and external temperatures insummer).Good correlations have been found between predicted flowrates and internal temperaturesand those actually measured in the auditorium. The models could be used to estimateflowrates and internal temperatures in similar naturally ventilated enclosures.