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Abstract: When modelling buildings, solar radiation has a large impact on the thermal balance because it usually heats the rooms. In radiant systems that are used for heating and cooling buildings, solar radiation has a large influence both on indoor temperatures and on the efficiency of the radiant system. Many analyses have already been carried out in order to study how beam and diffuse radiation can be distributed in a room. One of the most difficult issues, when modelling room thermal balance, is how to simulate the solar radiation when it enters the room, which in turn depends on the reflectance characteristics of the surface finishing elements. In this study, four different radiation models have been applied in order to solve an overall detailed, dynamic thermal balance in a room with pipes embedded in the floor. Two of the models are detailed; the other two consider the radiation entering the room to be diffuse radiation. As for the behaviour of the impinging solar radiation on the covering materials in a room, measurements have been carried out to determine the reflectance coefficients, which will be used in simulations for characteristic materials used in buildings. Results of the simulations show that a simplified model, which considers solar radiation as uniformly distributed in a room, cannot be used for a detailed comfort analysis; however, when looking at the cooling output of a radiant floor system at the design stage, a simplified model can predict energy transfer to a certain level of accuracy. Moreover, results coming from combined measurements and simulations show that the reflectance characteristic of the covering materials does not affect the cooling capacity of the radiant floor systems, since the most important parameter for cooling performance is the thermal conductivity of the covering layer. [Copyright &y& Elsevier]

Using of Double Skin Facade (DSF) became a very demanding trend in most kind of buildings, since it provides natural light, creates a connection between indoor inhabitants and the external environment without getting affected by harsh weather conditions. The verification of the balance equations to be used in a dynamic simulation software and the assessment of the active double-skin facade thermal performance in terms of energy recovery savings are the two main items of this study. For this purpose the software DIGITHON has been used. By comparing measured data of exit air temperature from a certain facade with calculated results, validation has been attained to use it in terms of buildings integrated with DSF. Highlighting benefits of using facade as a thermal energy recovery item during heating seasons on HVAC system is presented with respect to four European climatic zones for each orientation. Average pre-heat efficiency has been studied and illustrated on a seasonal scale. [ABSTRACT FROM AUTHOR]