Measurements of air flow patterns and temperatures in a 60'000 M3 industrial hall

A study was performed in an industrial hall heated by several propane radiant heaters located all around the hall at mid-height. The purpose of the study was to determine the advantages of this system when compared to convective heaters, and to determine its limits of application. For that purpose, a minimum instrumentation was installed in the building. This includes an automatic data logger, recording indoor temperatures, moisture content, and meteorological data on site. The energy consumption was manually recorded each week. C02 concentrations were also measured on a single day during and after working hours, and with heaters on and off. The interpretation of these measurements with an appropriate two zone model provided an estimate of internal and external air flow rates. Other measured data were used together with various simplified models to quantify various unknown quantities. In particular, the specific heat loss, the required peak power and important dynamic thermal characteristics of the hall are be directly deduced from the measurements. It is also shown that an important advantage of radiant heaters is that their heat is mainly transmitted to the floor during morning boost heating after night set back. This allows the comfort temperature to be reached earlier, with a lower air temperature, hence lower ventilation heat loss.