Natural ventilation systems in Mediterranean schools. A prototype experience in Andalusia as an alternative to mechanical ventilation

In high density occupation rooms, it is necessary to control indoor air quality (IAQ) combined with other comfort parameters. An adequate IAQ in classrooms enhances children learning and academic results are improved.
In the last decade, international technical regulations have increased air-tightness requirement in buildings in order to reduce heat losses. Following this trend, current Spanish regulations are based on mechanical ventilation systems to guarantee IAQ in no residential buildings. However, its use in schools presents several problems due to operational costs and maintenance needs. To solve these issues, Andalusian government is developing a research work to design alternative systems. In this way, natural ventilation systems already in use in UK school buildings, are tested in Andalusian schools, under the conditions of the Mediterranean mild climate and regional scholar schedule, with different operating conditions from those already tested in northern regions.
In this paper is presented an experimental Natural Ventilation System to guarantee IAQ conditions. It is designed combining cross ventilation and stack effect strategies in each classroom, calculated with computational simulations and compared with a mechanical ventilation system under current Spanish regulations. Main conclusion derived from simulations is the feasibility of using natural ventilation systems to guarantee Indoor Air Quality in classrooms and enhance the energy efficiency of the buildings of Andalusian schools. Based on this, a standard Natural Ventilation System model is proposed to be used for design criteria in new buildings to be constructed in coming years in Andalusia.
Previous simulations show that these natural ventilation systems are an alternative to comply with Spanish technical regulations. In addition, using these systems is possible to reduce investment costs between 8-10% and to avoid running problems during the use of the buildings, in addition to savings due to energy consumptions and CO2 emissions. Thus, this kind of systems could be used as passive actions to design Zero Energy Buildings.
This study will be extended with an experimental campaign in a new building located in the province of Seville, designed with both Natural and Mechanical Ventilation Systems and now under construction, is going to be used as a Test Building. It will be in use from September 2017 and a measure campaign is going to be developed during the whole scholar year, to analyse both natural and mechanical ventilation systems, comparing their operation, consumptions and users perception.