This paper focuses on the study and quantifications of pathologies in solar energy, gas, cooling, heating and ventilation installations, based on complaints filed in the courts by the owners of a large number of houses in which errors appeared in those installations. The relevant complaints filed across all of Spain were studied, in what is an important contribution to forensic engineering, given that access to the outcome of civil court cases is seldom obtained. The representativeness of the data is not partial but total, since the entirety of cases existing in the period under study was part of the sample, enabling us to consider this to be a general exposition on the epidemiology of construction pathologies in installations in houses in Spain. It should be noted that the Spanish construction sector is one of the most problematic ones, due to the dissatisfaction generated in homeowners, and as it is one of the ones leading to the highest number of complaints filed with consumer protection bureaus and in the courts. In the investigation, results have been obtained for each of the installations (183 cases in total), according to the type of anomaly (the most important are dysfunctions, leaks and humidity), the pathological origin (poorly arranged encounters, omissions of elements, among others) and the type of construction where it is produced (especially in block dwellings).