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Abstract(s)
Atualmente, e face à ocorrência da pandemia global do novo coronavírus, existe uma forte preocupação na forma como os sistemas de AVAC devem ser sujeitos a adaptações. O contínuo funcionamento de edifícios de comércio e serviços durante um período de pandemia é fundamental para manter a economia global, podendo evitar efeitos negativos drásticos a nível de produção, de empregabilidade e de produtividade de um setor de atividade. Considerando que a maior parte dos casos de infeção de SARS-CoV-2 tiveram origem na partilha de espaços interiores, a correta avaliação da redução do risco de contágio obtida através de alterações dos sistemas de AVAC permite perceber se a utilização dos espaços dos edifícios deve ser efetuada com algumas restrições, ou, se é ser necessária a implementação de medidas drásticas, como o encerramento completo dos edifícios. Com este trabalho, pretende-se a avaliação da diminuição do risco de contágio de doenças infeciosas transmitidas pelo ar através da implementação de medidas de prevenção aplicáveis a sistemas de AVAC. De forma a calcular a probabilidade de infeção dos espaços, foi utilizado o modelo de Wells-Riley adaptado para o vírus SARSCoV-2. Através da implementação de estratégias de melhoria de filtragem e purificação do ar nos espaços interiores, foi possível obter uma redução da probabilidade de infeção de 47% relativamente à estratégia de aumento do caudal de ar novo para o dobro do valor mínimo regulamentar. Esta conclusão contraria as publicações mais recentes das maiores sociedades relevantes do AVAC relativas à situação de pandemia, que propõem o aumento do caudal de ar novo sem o aumento do nível de filtragem existente. As alterações dos sistemas de AVAC propostas neste trabalho traduzem-se num aumento do consumo elétrico global do edifício e, consequentemente, num aumento do custo de exploração anual. Foi definido um rácio entre o aumento do custo de exploração anual e a redução da probabilidade de infeção global do edifício em relação a um sistema de AVAC existente dimensionado para o caudal mínimo de ar novo regulamentar. O objetivo deste rácio é a avaliação da viabilidade das adaptações propostas. Verificou-se que, com a instalação de lâmpadas UV-C em unidades terminais de conduta, consegue-se o rácio mais baixo, tornando-se na melhor adaptação. Relativamente à instalação da Unidades Purificadores de Ar em espaços interiores, verificou-se um rácio superior à estratégia de instalação de lâmpadas UV-C. Quanto à estratégia de aumento do caudal de ar novo, verificou-se o maior rácio entre todas as soluções, tornando-se a pior adaptação do sistema de AVAC.
Currently, and given the occurrence of the global pandemic due to the new coronavirus, there is a strong concern in the way that HVAC systems should be subject to adaptations. The continuous operation of commercial and service buildings during a pandemic is essential to maintain the global economy and can avoid drastic negative effects on the levels of production, employability, and productivity of a complete sector of activity. Considering that most cases of SARS-CoV-2 infections originated from the sharing of indoor spaces, the correct assessment of the reduction of the infection risk obtained through changes in HVAC systems allows us to understand whether the use of these establishments should be carried out with some restrictions, or, if it is necessary to implement drastic measures, such as the complete closure of buildings. With this work, it is intended to evaluate the reduction of the infection risk of infectious diseases transmitted by air through the implementation of preventive measures applicable to HVAC systems. In order to calculate the probability of infection in indoor spaces, the Wells-Riley model calibrated for the SARS-CoV-2 virus was used. Through the implementation of strategies to improve filtering and air purification in indoor spaces, a reduction in the probability of infection of 47% was obtained comparatively to the strategy of increasing the outdoor air flow to twice the minimum regulatory value. This conclusion contradicts the most recent publications of the major relevant HVAC societies concerning the pandemic situation, which recommend increasing the outdoor air flow without increasing the existing filtration levels. The changes in the HVAC systems proposed in this work bring an increase to the building’s overall electrical consumption and, consequently, an increase in the annual operating costs. A ratio was defined between the increase in the annual operating costs and the reduction in the building’s overall probability of infection relative to an existing HVAC system sized for the minimum regulatory values of outdoor air flow. The purpose of this ratio is to assess the viability of the proposed adaptations. It was found that with the installation of UV-C lamps in ductable fancoil units, the lowest ratio is achieved, making it the best adaptation. Regarding the installation of portable air cleaners, a higher ratio than the UV-C lamp installation strategy was achieved. As for the strategy of increasing the outdoor air flow, the biggest ratio was obtained, making it the worst adaptation of HVAC systems relative to the others.
Currently, and given the occurrence of the global pandemic due to the new coronavirus, there is a strong concern in the way that HVAC systems should be subject to adaptations. The continuous operation of commercial and service buildings during a pandemic is essential to maintain the global economy and can avoid drastic negative effects on the levels of production, employability, and productivity of a complete sector of activity. Considering that most cases of SARS-CoV-2 infections originated from the sharing of indoor spaces, the correct assessment of the reduction of the infection risk obtained through changes in HVAC systems allows us to understand whether the use of these establishments should be carried out with some restrictions, or, if it is necessary to implement drastic measures, such as the complete closure of buildings. With this work, it is intended to evaluate the reduction of the infection risk of infectious diseases transmitted by air through the implementation of preventive measures applicable to HVAC systems. In order to calculate the probability of infection in indoor spaces, the Wells-Riley model calibrated for the SARS-CoV-2 virus was used. Through the implementation of strategies to improve filtering and air purification in indoor spaces, a reduction in the probability of infection of 47% was obtained comparatively to the strategy of increasing the outdoor air flow to twice the minimum regulatory value. This conclusion contradicts the most recent publications of the major relevant HVAC societies concerning the pandemic situation, which recommend increasing the outdoor air flow without increasing the existing filtration levels. The changes in the HVAC systems proposed in this work bring an increase to the building’s overall electrical consumption and, consequently, an increase in the annual operating costs. A ratio was defined between the increase in the annual operating costs and the reduction in the building’s overall probability of infection relative to an existing HVAC system sized for the minimum regulatory values of outdoor air flow. The purpose of this ratio is to assess the viability of the proposed adaptations. It was found that with the installation of UV-C lamps in ductable fancoil units, the lowest ratio is achieved, making it the best adaptation. Regarding the installation of portable air cleaners, a higher ratio than the UV-C lamp installation strategy was achieved. As for the strategy of increasing the outdoor air flow, the biggest ratio was obtained, making it the worst adaptation of HVAC systems relative to the others.
Description
Keywords
AVAC Ventilação Modelo de Wells-Riley Risco de infeção por via aérea Aerossóis Qualidade do ar interior HVAC Ventilation Wells-Riley model Airborne infection risk Aerosol Indoor air quality