Characterization of natural ventilation in the São Cristóvão church in Lisbon - numerical modeling

• Autor(a) principal: Alcobia, João Eduardo Menezes Garrett
• Data de Publicação: 2021
• Tipo de documento: Dissertação
• Idioma: eng
• Título da fonte: Repositório Científico de Acesso Aberto de Portugal (Repositórios Cientìficos)
• Texto Completo: http://hdl.handle.net/10362/139251
• topic: Indoor Air Quality; CONTAM; sustainability; ACH; historical building; CO2; Domínio/Área Científica::Engenharia e Tecnologia::Engenharia Civil

Visitors have a relevant impact on indoor climate of buildings housing works of art, the link between the number of visitors, the indoor air quality, and the safeguarding of art pieces that are exposed without protective equipment is an important factor in the overall study of the indoor climate of historical buildings without mechanical ventilation or the possibility of its implementation. Regarding this concern and, simultaneously, the lack of studies on natural ventilation in historic buildings, this dissertation intends to analyse the performance of natural ventilation of São Cristóvão Church in Lisbon. For the preparation of this study, an analysis of the natural ventilation of this church was carried out by creating a model in the CONTAM software and the indoor air quality was analyzed by applying different international standards and guidelines for carbon dioxide levels and airflow rates. Estimating the current ventilation strategy, an average ACH of 0.75 (about 1100m3/h) was detected during the time the church is open, and during the time the doors were closed, a ACH value of 0.15 was recorded. In a year-long analysis, an average ACH of 0.30 was obtained. These indoor air replacement values guarantee an EN-15251 category I air quality for 72% of the year, and a category II air quality of 18%. Given the advanced state of degradation of some spans and the fact that masses, an occasional situation in which there is a high number of occupants, are always held just before the church closes, guarantees that the levels of carbon dioxide never exceed the limit of 350ppm above the outside values, imposed by EN-13779, registering a maximum of 291ppm. Different ventilation strategies were analyzed; three scenarios exploring different cross-ventilation tactics; a scenario that assumes the church is closed all year round; and a scenario which, estimating an increase in the number of users, gives a notion of human pollutants variations and possible consequences.