Ability of simplified approach of indoor humidity simulation

Abstract

Indoor air relative humidity is an important parameter influencing the hygro-thermal performance of building structures and the indoor climate as well. In order to predict the resultant indoor humidity in the zone for the designed indoor surfaces and moisture production/ventilation regime and to suggest possible improvements, a sufficiently accurate dynamic model is necessary. The computational codes simulating the interaction between indoor air and interior hygroscopic materials can be divided roughly into two groups: codes using simple lumped models and codes using a detailed description of the heat and mass transfer phenomena in the building structures. Ability of one of simplified models – model based on EMPD concept was evaluated in case that the main EPMD approach assumption – the limited thickness of hygroscopic material – is fulfilled. In practise the assumption of limited penetration depth is fulfilled in case when most of hygroscopic surfaces are represented by room equipment (carpets, furniture) or by the structures with water vapour barrier under the indoor hygroscopic layer. The evaluation of EMPD model was done by comparison of the indoor humidity simulation results by complex computational code NPI and simplified code PenDepth based on EMPD concept. On the base of the comparison the reliability of the EMPD model for different moisture production/ventilation regimes, outdoor weather changes and indoor temperature changes was determined.