Analysis of IAQ Based on Modeling of Building Envelope Coupled with CFD&HT Room Airflow

Buildings represent a major part of the world energy requirement. The simulation of combined heat, air and moisture (HAM) and pollutant transfer in this context is important to predict the indoor air quality (IAQ), along with the thermal comfort inside the buildings. Moreover, it is important to have appropriate levels of indoor humidity along with the room temperature as movement of water vapor through the building envelope causes a lot of harm to the building structure and reduces the quality of its thermal insulation leading to higher energy demand. In modern houses people is exposed to a big amount of building materials, many of which release pollutants, many of them are volatile organic compounds (VOCs) that degrade the IAQ. The knowledge of the peak loads, temperatures, humidity levels, pollutant dispersion can help to optimize the design of new buildings or existing buildings that need to be refurbished and therefore results in energy efficient buildings. In this work a modular object-oriented building simulation tool (NEST) with CFD&HT code Termofluids, capable of coupling different levels of simulation models, allowing the simulation of heat, air, moisture and pollutant distribution (multizone model, envelope model, room analysis and HVAC system) and VOC is presented. The modular approach gives flexibility of choosing a model for each element and to have different levels of modeling for different elements in the system. Special attention has been focused on: the large eddy simulation turbulence models used for the room air dynamics and pollutants distribution transport and high performance parallel software. Parallelization of the building simulation is necessary if some critical processes/zones need to be modeled with more detail for reducing computational time. The main focus of this article is to couple the HAM and pollutants models for the building envelope with CFD&HT models with heat, moisture and pollutant transfer models for room airflow. An analysis of the effect of different materials on the IAQ of the buildings will be performed.