Project Objectives

Given the importance of establishing building pathology assessment methods, it was important to create a reliable Building Pathology System (BPS), to provide easy access to the most relevant information available on building pathology. The implementation of such system, anchored on the partial systems developed at IST, puts into practice all the potential from existent building inspection systems. Available information on the pathology of non-structural elements was collected through intense literature surveys of international scientific publications. The steps proposed were:

A) Creation of an overall system based on normalized lists of defects, causes, diagnosis methods and repair techniques. First, by joint examination of the partial systems, matching the systemic pattern and nomenclature, and later by cross-checking the various systems. This joint analysis was a big challenge due to the great amount of information collected before. The reliability of each partial system was analysed and additional data was collected in situations requiring greater pathology characterization. Finally, the overall system was tested on a varied range case studies.

B) Development of a computer tool that describes the building and its elements. This tool includes: i) A database where relevant building information is stored; ii) An inspection module, allowing the standardization of inspections and the resulting reports; and iii) A decision-making module on the action to be carried out after inspection and diagnosis of any defect, dedicated to building maintenance operations. Using these attributes in the BPS, a relevant minimization of the subjectivity of inspections of buildings elements and of the dependence on the inspector’s experience is expected, which is one of the biggest challenges of the building pathology assessment methods. It is expected that the developed computerized inspection system has a range set of practical applications: i) Use in inspections; ii) Use in plans of proactive maintenance of buildings; iii) Decision-support in rehabilitation projects; iv) Preparation of devaluation reports of buildings; v) Use for official surveys (pre-intervention, effects of insurance policies; sale/rental); vi) Preparation of final diagnosis report with a standardized structure; and vii) Use as pre-normative basis of standardized inspections for buildings to be subjected to an officially recognized methodology.

Knowing the durability and service life of buildings/components at the design stage is extremely useful, with several practical applications, namely to evaluate the environmental and economic impact of buildings. This information (when the characteristics and the environmental conditions of the buildings are well known) is relevant to manufacturers to set warranty periods for materials and designers to select the most suitable material for a given application. Thus, models are needed to relate the service life of building components and the set of conditions that characterize and influence it. Using this type of information it is possible to develop maintenance strategies for existing buildings and at the design stage, estimating their remaining service life, which is essential for built heritage managers, insurers and users. There is an increasing demand for simple tools to estimate the service life of building components, thus enabling a more rational management of the built heritage.

The main aim of this project was to develop a risk-based building management system, which consists of a systemic evaluation of the performance of the building envelope. This assessment involves various stages of use of building components, from the definition and systematization of inspection and diagnosis systems to the definition of service life prediction (SLP) methods, allowing a more rational decision-making process in maintenance scheduling. Task 1 of the project consisted of the definition of a “degradation atlas”, which illustrates the various types of defects that affect the building envelope (coatings and roofs). These data are based on written and visual information obtained through expert-knowledge systems. In task 2, the project created a computational tool functioning as a guide to the technical inspection of the building envelope. This tool corresponds to the first Milestone of the project, functioning as an encyclopaedia of the building envelope’s pathology, giving the description of the defects that may affect the building components, examples of case studies whose overall degradation is represented by images and associated to specific degradation levels, possible causes associated with the defects detected and suggestions of diagnosis methods and repair techniques. Task 3 comprises the definition of a methodology to integrate inspection data in SLP methodologies. The data related to the building envelope’s pathology must be converted to an overall degradation index that depicts the global performance of any construction element. Based on this index, different methodologies for SLP will be proposed (task 4). At the beginning of the project, the existing methodologies for SLP tended to ignore the randomness associated with the degradation phenomena and the random errors associated with the predictions. There were more accurate and complex methods in the literature, but they were usually unintelligible to common users. This project overcame some of the limitations of the existing methodologies. A computational algorithm for SLP of the building envelope was developed (task 5). This algorithm represents the second Milestone of the project and can be used by any stakeholder in the construction sector. To apply the software, the user needs to define the type of envelope’s element whose service life is to be predicted. In the next stage, the decision-maker must define the target output and, consequently, the most adequate model. The software allows the user to decide whether to use a method in which service life is given by an absolute value, another in which it is given by a mean value associated with a set of dispersion measures or yet another in which it is represented by a probability distribution (with data related to the risk of failure of the element under analysis). The software is user-friendly, and the application of any of the models is equally simple. Thus, the user can obtain the service life of a particular element, provided the model knows the characteristics of the element under analysis. The software works as an artificial intelligence-based algorithm, learning from the patterns provided by the data acquired so far. Then the user needs to define the criteria adopted to establish the end of service life of the element, i.e. maximum acceptable degradation level. The values of service life of building components in the literature are always related to an unknown level of demand. This software overcomes the limitations of existing methodologies, providing the user with various examples of maximum degradation levels associated to the analysed element, with schematic figures and the pathology associated with each level. Thereby, the user can choose the level that best characterizes the users’ needs and the building context. The computational tool created will be supplemented by a procedure guide, which explains how to use the software and provides recommendations for the implementation of the models and their advantages and limitations and guidance related to the best use of the models for a given application (with examples).

The deliverables of the project can be used in various domains of construction: i) stochastic models provide useful information in the context of insurance policies, such as the most probable failure time of coatings according to their characteristics and the age when it is extremely unlikely that rupture of these elements occurs; ii) service life data crucial for life cycle assessment (LCA) and life cycle costs (LCC), allowing optimizing the costs and environmental impact of buildings during their life cycle; iii) information concerning the durability of building components to be used in the definition of combined maintenance strategies, involving various elements of the envelope, where an intervention in the building involves different rehabilitation actions.