Influence of Single and Double Membrane Roofs on Thermal Behaviour of Enclosed Space

Even though membrane structures have been increasingly used in the world, their energy efficiency is very unfavourable due to poor thermal properties. This causes relatively high consumption of heating energy in the winter, as well energy consumed for the operation of air-conditioning during the summer, that is, under circumstances which require thermal comfort. Since thermal comfort depends on the air temperature and temperature of the interior surfaces of the envelope, this paper presents a study of the measurement and comparison of temperatures of single and double membrane structures in the summer period. Data collection was accomplished by measuring two adjacent structures, one covered with single and the other covered by a double membrane. Verification of the measured data was performed by comparing it with the official measured temperatures in the same period. The air temperatures were measured in all the separate air compartments and particular surfaces of each membrane. By analysing the measured data and their classification based on daylight and night-time periods, certain conclusions were drawn about the influence of an additional layer of membrane on the temperature of the air inside a covered structure

The Thermal Behaviour of a Cylindrical Air Layer Enclosed between Double Fabric Roof Membranes

Objects covered by fabric roof membranes are specific in terms of energy consumption, primarily because of the negligible thickness of the material and its good thermal conduction properties. One of the ways of improving the energy efficiency of these objects is the implementation of a double fabric roof membrane structure with an enclosed non ventilated air layer. This paper analyzes the thermal-insulation behaviour of the air layer enclosed between tensile fabric roof membranes which are used for structural purposes. The compilation of the necessary data was carried out by measuring a real object covered by a double fabric roof membrane, semi-cylindrical in shape. The surface temperatures of each membrane were measured, as were the outside and inside air temperature and the air temperature between the membranes during the summer months. In addition, the solar irradiance during the same period was also measured. The analysis of the measured data took into consideration all the present forms of energy transmittance (convection, conduction and radiation), as well as the shape of the air layer and the thermal-physical specific features of border surfaces. The results of the study indicate that thermal behaviour of a closed semi-cylindrical air layer depends on the real outer conditions in the summer months. A methodological approach to the thermal modelling of these structures has accordingly been proposed