Özet:

Net zero-energy buildings are one of the most important steps towards reducing human energy consumption. In buildings, a significant amount of energy is used for heating and cooling purposes. In the buildings, the atmosphere and the heat transfers occur through surfaces. The difference between the exterior and the interior of the building determines the amount of heat to be transferred from the walls. The temperature of the building’s outer surface may vary according to environmental conditions such as wind, sun radiation, outer temperature and atmospheric border layer (AST) stability characteristics. With the help of HAD simulations, the building surface temperature change can be created as a heat map. The created heat map can help to design energy-efficient buildings. In this study, the front temperature map of a general building was simulated with ANSYS Fluent. Since the layer of AST changes the turbulence characteristics and the temperature in the vertical profile, the layer is given special attention during simulations. The length of Monin-Obukhov (M-O) determines different layer levels. RANS equations for simulations have been solved and the realizable k-ε model for turbulence modeling has been used. The limit conditions for the input, output and subpart for simulation are given according to the M-O similarity. The building modeled with its full dimensions has been given the heat flow values taken from literature. Three different wind speeds and three different layer conditions were analyzed and 9 scenarios were created as a result. In all the scenarios created, the ground temperature was taken at 27 degrees, and the heat flow produced by the buildings was taken from literature at 105 w/m2. Comparing the results of the 9 scenarios, the impact of layering on the front temperature of the building has been observed. As the wind speed increases, the impact of the layer on the front temperature increases.

Anahtar Kelimeler:

Özet:

The net-zero energy buildings are one of the most important steps towards decreasing the total energy consumption of humanity. In the buildings, a considerable amount of energy is used for heating and cooling purposes, and heat is transferred to the atmosphere via the façade of the buildings. The difference between the inside and outside temperature of the facade determine the heat flux through the walls. The temperature of the façade can vary with environmental conditions such as wind, solar radiation, outside temperature, and stability characteristics of the Atmospheric Boundary Layer (ABL). With the aid of CFD simulations, the temperature variation can be created as a heat map. The created heat map can help to design energy-efficient buildings. In this study, the façade temperature map of a generic building is simulated with ANSYS Fluent. Since the stratification changes the turbulence characteristics and temperature along with the vertical profile of ABL, special care is given to the stratification during the simulations. Different stratification levels are determined in line with the Monin-Obukhov (M-O) length. For the simulations, RANS equations are solved and the realizable k-ε model is used for the turbulence modeling. The boundary conditions at the inlet, outlet, and bottom are given in line with the M-O length. The building is explicitly modeled and heat flux values taken from the literature. Three different wind speed and three different stratification conditions are analyzed and as a result, 9 scenarios are created. The result of the 9 scenarios shows the effect of stratification on the facade temperature of the building. As the wind speed increases the effect of stratification on the facade temperature increases.