The inherent barriers in air tightness analysis of heritage buildings

Abstract

The Energy Efficiency in buildings has been for years one of the most relevant lines of research. This goal is particularly challenging in the retrofit of historic buildings. In general, the main parameters involved in the passive behaviour of these buildings are two: heat losses and internal gains. With regard to heat losses, they can be distinguished between the thermal losses through the envelope and the losses though the indoor air renovation. The design of the envelope has been significantly improved in recent years by the degree of thermal insulation and the implementation of shading control, but many historic buildings are protected by heritage regulations that reduce the possibilities of intervention. Considering these limitations, the heat losses related to air renovation are not sufficiently considered. The control of ventilation gains and losses can be one of the bigger improvement rates of the energy efficiency, especially in historic buildings. Within the scope of ventilation, infiltration plays a major role in the building energy performance, but it also represents a relevant issue for user’s thermal comfort and the indoor air quality. To characterize the features of building ventilation two main types of tests are employed: the tracer gases method and the fan pressurization method. This study refers to the fan pressurization method that is also known as the blower door test or BDT. The present work shows the diverse complexity of particularities encountered during the determination of a campaign of 37 air tightness test conducted in historic buildings. The objective of the study is to define a methodology to anticipate and prevent the main problems that frequently arise when analyzing the air tightness of historic buildings. Additionally, some further improvements are given to fix some of problems that have been detected in the present Spanish and European regulation for BDT. The study shows the main barriers detected and introduces a checklist as a simplified tool that aims to help the technician during the testing process. Aspects like the imprecise regulation, the difficulties in the preparation of the sample, the transportation of the equipment, the difficulties to perform large-scale trials, or the quantification of the level of air tightness for every part, among other many problems. © 2016, University of Cantabria - Building Technology R&D Group. All rights reserved.