Application of Cold Radiant Surfaces in the Buildings Development in Summer Conditions

Abstract

This paper presents a numerical study of sustainable energy application in the buildings construction using cold radiant surfaces in summer conditions. The study is made in a University building and the proposed technology is used to improve the internal thermal comfort conditions in summer conditions. This numerical study uses a software that simulates the whole Building Dynamic Response with complex topology in transient conditions. The numerical model is founded on the balance of energy and mass integral equations. The energy balance integral equations are taken for the indoor air of the compartments, the transparent (windows) bodies of the building, the interior and surroundings bodies of the building and the opaque (walls and doors) bodies of the building. The mass balance integral equations, taken into consideration for the water vapor and the air contaminants, are developed for the spaces of the buildings and the solid matrix (opaque and interior bodies). The software is used to assess the human thermal comfort and indoor air quality levels, the cold radiant system, indoor thermal variables, and other parameters. The building analyzed in this work has 107 compartments, of which 33 are for classes. The radiant system is based on the use of subterraneous cold water. Three situations were analyzed: without cold radiant surfaces, with horizontal cold radiant surfaces and with all compartment cold radiant surfaces. The thermal comfort level, using the Predicted Mean Vote (PMV) index, and the indoor air quality, using the carbon dioxide concentration, are evaluated. The results demonstrate that the implemented Heated Ventilation and Air Conditioned system, working in Ventilation and Radiant methodology, with the use of all surfaces equipped with a cold radiant system, allows to guarantee, in the morning, acceptable, and, in the afternoon, near acceptable levels of thermal comfort by PMV index values according to category C of the standard ISO 7730. During occupancy, the indoor air quality levels obtained in the compartments are near the acceptable limit provided by the ASHRAE 62.1 standard.