Optimization of Thermal Insulation Parameters for Vertical Perimeters in Buildings with Single-Layer Walls

This article presents the results of a study on the impact of selected parameters of a building’s ground-floor zone (the junction of the external and foundation walls, the ground floor slab, and the ground itself) on the temperature field within the external envelope. This study aims to analyze the influence and optimize the parameters of vertical perimeter insulation in the ground-floor zone of the building. Mathematical modeling was selected as the research method. This paper analyzes the relationships between the temperature ϑimg on the inner surface of the wall at the analyzed node and the linear thermal transmittance coefficient ψim of the thermal bridge occurring in this location, as influenced by the following parameters: dp—thickness of the insulation layer in the ground floor slab; df—thickness of the vertical perimeter insulation layer in the foundation wall; t—location of the insulation layer in the ground floor slab relative to the “external wall-foundation wall” contact surface; r—location of the vertical perimeter insulation layer in the foundation wall; and λs—thermal conductivity of the single-layer external wall material. The analysis was conducted under the climatic conditions of Białystok, Poland. Using THERM 7.6 software for computational experiments, data were obtained to develop deterministic mathematical models of these relationships. The models enabled the assessment of the degree and nature of the influence of the studied factors on ϑimg and ψim, optimization of selected parameters, and mathematical description of safe operating conditions for external walls in the ground-floor zone of heated buildings. It was found that the parameters dp, df, and r have favorable effects, increasing ϑimg by 2.57%, 2.51%, and 4.17%, respectively, when varying from their minimum to maximum levels. Conversely, the parameters t and λs negatively impact ϑimg, contributing reductions of −12.01% and −4.66%, respectively, with a cumulative effect of −16.67%. Optimal parameter values were determined based on energy efficiency criteria. This information may be useful for researchers, designers, engineers, and decision-makers when making informed decisions during the design phase of heated buildings.