Modeling air leakage in buildings caused by the cyclic variation of the atmospheric pressure

Abstract

This article considers a new type of air infiltration through building envelopes caused by the barometric pressure variation. This process is independent from wind action or stack effect. A new building-atmosphere differential equation of air exchange is established. Based on the solution of the differential equation of air exchange, we propose the notion of pressure equilibration time 50 that characterizes the dynamic response of the building. Furthermore, experimental climatic data were processed using Fourier analysis methods in order to build an identification model based on the regular harmonics of external pressure oscillation. The barometric pressure reconstructed in its parameterized form was introduced in the differential equation of air exchange as a term that models the dynamics of the external action. The analytic solution of the differential equation of air exchange demonstrates that the indoor-outdoor pressure difference is insignificant at less than 10 À3 Pa for any harmonic of the external pressure variation. At the same time, it is concluded that the airtightness of the envelope has little influence on the process, as the indoor-outdoor pressure equilibration is almost instantaneous in a continuous regime of variation. The described mechanism of air infiltration explains the alternation of infiltration and exfiltration of air in buildings. For this, a mass balance of air exchange for the specific ranges of time is performed. We prove that the barometric pressure variation has an effect that accounts for 3.19% of the total quantity of air exchanged. The advances provided by this paper constitute a useful instrument for further studies concerning the stack effect in thermal dynamic conditions. Practical application: The paper proposes a novel methodology of determining the air exchange building-environment by considering a new component of infiltration and its cyclic variation: the barometric pressure. A new mechanism of natural air infiltration is determined and modeled and it should be added to the existing ones: wind action and stack effect. A complete methodology of analysis and extraction of

Quantifying airtightness in Brazilian residential buildings with focus on its contribution to thermal comfort

“…Nevertheless, it does not have the capacity of leak detection. The impact on airtightness of stack effect, wind, barometric pressure, or other conditions has been investigated (Kraniotis et al, 2014;Patrascu et al, 2018;M. H. Sherman, 1987M.…”

“…Despite the advances in the airtightness knowledge, its importance has progressed distinctively among countries, mostly due to their different climatic contexts, cultural influences and levels of development (Patrascu et al, 2018). It is common that countries of subtropical or tropical climates, such as Mexico and Brazil, overlook the concept and do not measure airtightness levels neither evaluate their impact on thermal comfort in buildings.…”

Evaluating methods for estimating whole house air infiltration rates in summer: implications for overheating and indoor air quality

“…The K-P "divide-by-20" method has drawn particular attention for being an inaccurate estimator (Keig et al, 2016;Johnston and Stafford, 2017;Vega Pasos et al 2019 and so is deemed appropriate only for low precision estimations of air infiltration (Ramos et al, 2015) during the heating season (Jones et al, 2016). Despite this, it is claimed that the K-P is the most used method (Patrascu et al, 2018).…”

“…2019, 2020) and so is deemed appropriate only for low precision estimations of air infiltration (Ramos et al , 2015) during the heating season (Jones et al , 2016). Despite this, it is claimed that the K–P is the most used method (Patrascu et al , 2018).…”