On the Solution of Energy Balance Equation System to Predict Temperature Distribution in the Building Elements With Ventilated Air Gap

Abstract

The article presents the solution of heat balance equation system, describing heat exchange processes in ventilated envelopes, which was applied to derive formulas for the calculation of temperatures in the ventilated layers of the envelopes. The accurateness of the formulas was assessed by experimental research and analysis of the calculation results. During the process of heat exchange balance equation solution, the equations were simplified by introducing the following restriction into the derived formulas: they may only be applied for the ventilated envelopes with steel or similar coatings as their external layers, i.e. coatings having small heat capacity and minor difference between the external and internal surface temperatures. The derived formulas enable the calculation of the temperatures of the ventilated envelopes in the distance which does not exceed a half of the ventilated air gap length measuring from the air entrance into the gap. However, this restriction does not impede the estimation of the average thermal indicators of the ventilated envelopes.

Thermal Technical Analysis of Lightweight Timber-Based External Wall Structures with Ventilated Air Gap

“…Susanti et al demonstrate that due to various heat exchange process the temperatures of gaps may not be equated to the exterior temperature, especially in the case of double-skin roof [25]. The results of experimental research [26] demonstrated that the absolute error in the calculations of the average daily temperature of the ventilated air gap and external surface of the thermal insulation layer does not exceed the limits of 1.21 • C and 2.71 • C. The influence of doubleskinned structures on the energy performance of buildings is dealt with by experts all over the world, and some research is focused on climatic areas with temperate climates [27][28][29]. In this research, results of experimental heat measurements within the compositions of the monitored structures and the parameters of the internal and external environment were used in order to evaluate the influence of ventilated air gaps on the thermal technical behavior of lightweight timber-based cladding.…”