Effect of the exposed steel structure on the thermal performance of buildings

Depending on the building typology, the architectural characteristics and the materials used in a building, its interaction with the local climate can produce negative impacts on the energy consumption of the buildings. The presence of steel in the building structure characterizes a reduction in the thermal resistance of the building envelope, which causes an increase in energy costs for environment heating or cooling. In this context, simulation of the thermal performance of buildings using computer programs has generated several constructive advantages for the establishment of energy-efficient buildings. This paper's main purpose is to evaluate the influence of the exposed steel structure area on the thermal performance of naturally ventilated and artificially conditioned environments using computational simulations. The results showed that in the numerical simulation of naturally ventilated environments, there were increases of about 3.0% and 2.0% in the environment indoor temperatures during the winter and summer periods, respectively. Considering the winter period, the heat losses through the steel structure were up to 4.1 times larger concerning those made for walls without steel, and the heat gains about 4.2 times higher in the summer period. The effects of thermal bridging were more evident in the evaluation of artificially conditioned environments. There was a maximum increase of 4.8% in the environment total cooling thermal load and, as a consequence, a maximum variation of 4.9% in the building energy consumption, evidencing that the larger the exposed steel area in the building closure system, the larger the effect caused by this thermal bridge.