Papers by Keyword: Wall Base Ventilation System

Abstract: Rising damp constitutes one of the main causes of monumental heritage and old buildings degradation, especially, its thick walls with heterogeneous composition. The LFC-FEUP has been developed important research in rising damp domain. In recent years, was validated and experimentally characterized the operation principle of a technique called "wall base ventilation system" for the treatment of rising damp in monumental heritage and ancient buildings consisting of circulating air at the base of the buildings walls with high thickness and heterogeneity in its constitution, with a saturation distant relative humidity. The studies previously developed allowed the interest and viability of the proposed system, taking time to develop a methodology for optimizes it. In this paper it is presented the optimization of the wall base ventilation system based on some important physical parameters. To optimize the system, it was developed a 2D evaporation model that describes the moisture transfer between the system and the wall as well as the water vapour transport throughout the system (Evaporation and Transport Model – ETM). It was also used and adapted another 2D model, to describe the rising damp phenomenon in buildings walls, considering the wall base ventilation system (Rising Damp and Evaporation Model – RDEM). Finally, the design model was developed, using both models (ETM and RDEM) and some experimental validation was done, which allowed the comparison between the levels archived by the wet front analytically and experimentally.

Abstract: Degradation in walls of Historical Building with rising damp is a complex problem to solve, due to the thickness and heterogeneity of those walls. The traditionally treatment techniques used (such as watertight barriers, injection of hydrofuge products, etc.) show, sometimes, to be ineffective or too expensive, justifying the need to find a new approach. Experimental studies validate the effectiveness of a new treatment technique applied to the walls of old buildings wall base ventilation system. Building Physics Laboratory (LFC) is developing a model of this technique. The sizing of the treatment system is based on knowledge of the characteristics of the wall, of the geometry of the ventilation system and of the building being dealt with. In this work it is described the moisture transfer process between the moving air flux, inside the system, and the wall. Experimental results were used to validate the mathematical solution and the values obtained are very similar.

Abstract: The treatment of rising damp in the walls of historical buildings is very complex, due to the thickness and heterogeneity of the walls. The techniques traditionally used for dealing with this problem (such as watertight barriers, injection of hydrofuge products, etc.) have sometimes proved ineffective, and that is why it is necessary to find a new approach. In recent years, the Building Physics Laboratory at the Faculty of Engineering, University of Porto has been conducting experimental research on the effectiveness of the wall base ventilation system, using natural or mechanical higro-regulate systems to reduce the level of the damp area. This experimental research and the simulations that were performed, clearly show that wall base ventilation is a system with potential. This paper presents the characterization of the hygro-regulated systems operation based on experimental studies developed in laboratory, which allowed the influence of the velocity of the air, condensation risk and the possibility of salt crystallization.