Thermal Optimization of Existing Buildings in the Cold Climates of Iran Using Trombe-Wall Characteristics

This research is aimed to find an energy optimization method for existing buildings in cold climate regions of Iran. In the proposed system, a secondary skin is installed against the unglazed surfaces of the southern wall, creating a Trombe-wall. The sun-facing wall is then painted in black, and covered with a transparent material like clear glass, leaving a closed air gap between them. The resultant unvented Trombe-wall increases the thermal resistance of the building envelope, and reduces heat loss while absorbing and storing solar energy at the same time. This can also cause a reduction in fluctuations of indoor air temperature. The simple way of construction, in addition to formal and spatial structure, and the materials used in building construction in cold regions make this system a feasible option to apply to urban and rural buildings. In order to assess the thermal performance of the proposed system, the basic model was simulated in three different configurations for the sun-facing wall: with the conventional wall, with the insulated wall, and with the proposed system. The simulation was done by EnergyPlus 8.0. The results of the simulation approved higher thermal performance of the proposed system as compared with the conventional wall and the insulated wall. Due to the need for providing thermal comfort conditions in buildings and preventing overheating, calculation of parameters such as dry-bulb and mean radiant temperature was done. This showed a decrease in the total heating period time, and improvement of indoor comfort in critical outdoor conditions. The proposed system was applied to an existing building in a cold climate region, and the real-time results fairly tallied with the predictions.