Reconciling Indoor Air Quality and Energy Efficiency in Air-Conditioned Classrooms: Case Studies for Portugal and Macao

Abstract

Abstract-Growing awareness on the subject of classroom's indoor air quality and concerns regarding the probable link between indoor air quality, student's attendance and academic performance, support recent legislation limiting classroom's indoor pollutant concentrations. A consequence of this legislation is the generalized shift towards air-conditioned classrooms and increased budgets for schools energy running costs. According to the scientific literature, demand control ventilation systems are suited for classrooms, ensuring indoor air quality and thermal comfort with significant energy savings. Based on detailed building energy simulation this paper compares a demand control ventilation system and a (traditional) constant air volume system considering a typical classroom located in two distinct climatic regions: Portugal and Macao. Based on hourly results of classroom's indoor CO 2 concentrations and indoor air temperatures, and on annual air-conditioning energy consumptions, advantages of the demand control ventilation system are discussed.Index Terms-Classroom indoor air quality, demand control ventilation, energy efficiency, thermal comfort. I. INTRODUCTIONSeveral European governments have decided to invest in rebuilding and refurbishing their stock of existing public schools. According to Mumovic [1], UK's government is commited to a £45 billion program dedicated to the rebuilding of secondary schools in England and Wales. Gertis [2] states that during the current decade, Germany will invest €73 billion in the rebuilding and refurbishing of public school buildings. The Portuguese government has also invested in the rebuilding of over 100 existing secondary schools [3] and a trend that favors cyclic rebuilding instead of new construction is foreseeable in Europe, in the future.These large scale public investments take place at a time of growing awareness on the subject of classroom's indoor air quality (IAQ) [4], [5] and of concern regarding the probable link between IAQ and student attendance and academic performance [6] having different indoor air quality and green building labeling methods available.Traditionally, European classrooms were naturally ventilated; in warmer Mediterranean countries classrooms were often neither heated nor cooled. However, the need to ensure indoor pollutant concentrations below specific maxima imposes the use mechanical ventilation; therefore all rebuilt and refurbished schools now include heating and cooling systems, used to remove the fresh air thermal loads and remove the classroom thermal loads.These "new" retrofitted schools, with air-conditioned classrooms, represent a "paradigm shift" in Europe, especially for Mediterranean countries. An important consequence of this "shift" is being felt at school administration boards, which are now facing a significant increase in schools energy running costs. The use of energy efficient air-conditioned systems is essential to minimize the problems associated with excessive increase in energy running costs.Macao and southwest Asia...