Hygroscopic natural materials versus mechanical ventilation

Multi residential buildings, developed as highly energy-efficient and airtight are nowadays often fitted with mechanical Ventilation Systems as a way to overcome shortcomings and even defects tinked to indoor climate. The presented study investigates the potential of low-emitting. natural building materials with hygroscopic properties to contribute to a healthy and comfortable indoor environment, while reducing the need for mechanical Ventilation. A selection of natural building materials suitable for application as internal partition walls has been investigated with regards to their water vapour adsorption capacity. Special emphasis was placed on the investigation of modified earth plasters as well as wood-based materials, used as wall lining to provide increased adsorption capacities. In addition, tests on materials emissions (formaldehyde, VOCs, SVOCs and radon) as well as adsorption tests of airborne pollutants have been conducted in specially-designed fest chambers. All tests were performed at either the material or the component tevel. Overall results to date suggest that natural materials contribute to an improved indoor environment quality through an increased moisture-buffering capacity, low emissions and the potential to adsorb airborne pollutants, therefore reducing the need for mechanical Ventilation.