Guaranteeing high indoor air quality and high degree of user satisfaction at the same time is one of the challenges when improving the energy efficiency of a building. Current non-residential buildings mainly use mechanical ventilation systems to ensure high air quality. Mechanical ventilation systems are known for minimising heat losses but at the same time lead to higher installation, operating and maintenance costs. Furthermore, mechanically conditioned rooms may lead to the sick building syndrome caused by the lack of operable windows. Natural ventilation being more accepted by users has the potential to guarantee energy efficiency of buildings in conjunction with people satisfaction.
Present natural ventilated buildings pose the risk of higher energy demand and less indoor air quality due to user’s behaviour. Controlled natural ventilation based on indoor CO2-concentration and room air temperature is needed. However, the efficiency of a control strategy highly depends on climate zone and control parameters. This paper aims to explore the impact of different control strategies on the energy efficiency of an operable louver window. The most efficient strategy is then compared to a mechanical ventilation system
In a simulation four window opening strategies based on CO2 concentration were tested in Mediterranean, subtropical and moderate climate zone. Only at very cold and very warm conditions a difference in the different natural ventilation strategies was observed. When comparing the natural ventilation conditions to mechanical ventilation major differences were found. In almost all climate conditions natural ventilation outperformed the mechanical ventilation. In several climatic conditions energy consumption by the natural ventilation system was 10 fold lower than by mechanical ventilation, conflicting the common view that mechanical ventilation is the more efficient system.