Abstract
Software for numerical simulation of various types of energy used in buildings, i.e. building energy simulation (BES), have become an essential tool for recent research pertaining to building physics. TRNSYS is a well-known BES used in both academia and the construction industry for a wide range of simulations, such as the design and performance evaluation of buildings and related facilities for heating, cooling, and ventilation. TRNSYS has a modular structure comprising various components, and each component is interconnected and compiled through a common interface using a FORTRAN compiler. Its modular structure enables interactions with various external numerical simulation tools, such as MATLAB, Python, and ESP-r. For ordinary simulations of building energy load using TRNSYS, the generic module Type 56 is usually recommended, which provides detailed physics modelling of building thermal behaviours based on unsteady energy conservation equations and Fourier’s law for each building material. However, Type 56 explicitly depends on the transfer function method to discretise the original differential equations; therefore, it cannot model nonlinear phenomena, such as latent heat and moisture transfer between a building surface and ambient air. In other words, the current TRNSYS cannot be used to estimate the effectiveness of evaporation during cooling, which is a typical passive design method. Hence, the authors developed a MATLAB/TRNSYS integration scheme, in which TRNSYS was modified to model simultaneous heat and moisture transfer from the wet roof surface of a building. This scheme enabled TRNSYS to calculate the rate of evaporative heat and moisture transfer dynamically from the roof surface, assuming a control volume approximation of the roof surface. Finally, the effect of evaporative cooling on the thermal performance of an Indian building was estimated using the modified model.
Highlights
In recent years, several building energy simulation (BES) tools have become popular for evaluating the energy performance of new and existing buildings along with the increasing importance of energy saving and emission reduction in the building sector
In the scheme we developed, this feature was used to model heat and moisture transfer from a wet roof using TRNSYS
The water content of building materials are important for the evaporative cooling of buildings
Summary
Several building energy simulation (BES) tools have become popular for evaluating the energy performance of new and existing buildings along with the increasing importance of energy saving and emission reduction in the building sector. Spanaky et al [15] investigated the passive cooling effect of a ventilated roof pond protected with a reflecting layer and presented its numerical modelling using TRNSYS They utilised module Type 344b in TRNSYS, which was originally designed for outdoor swimming pools, and modified it to simulate a roof pond using Type 67. Their modelling presented good agreement with experimental data this approach cannot be directly applied for the modelling of evaporation from a wet roof or a roof with intermittent water spray. The evaporative cooling effect reproduced by this model under the climatic condition of New Delhi, India are presented
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