Simulation of FtX ventilation technique in a typical Swedish house

Abstract: This project discusses the effect of reducing the amount of fresh air supplied mechanically to a typical Swedish house, remaining constant the amount of air removed from the building. The new ventilation technique studied through this project is used by the so-called FtX ventilation systems, whose main difference comparing to FTX ones is that the supply airflow rate is reduced. This reduction of the supply airflow rate is simulated by means of commercial software called IDA Indoor Climate and Energy, which provides the energy consumption in the dwelling so as the temperature in the building and the different airflows. Firstly, the model of the house is built in IDA taking into account the regulations established by the Swedish Building Code and the materials and size of a typical construction in Scandinavian region. The building is located in Bromma, near Stockholm. The reason to situate the building in this place is that IDA ́s database contains the meteorological data registered in this location during a whole year, so yearly simulations can be carried out using real meteorological data. After simulating every model, results are gathered and compared. On the one hand, an energy study is carried out for a whole year in order to determine the optimal quotient between the supply airflow rate and the exhaust airflow rate which minimizes the energy consumption. This study indicates that when the supply airflow rate is 0.95 times the exhaust airflow rate, the energy consumed by the building is minimal. On the other hand, an economical study is done. To calculate the economical cost of the energy purchased by the building, the tariffs of a company which sells district heating and electricity in Stockholm are used. Considering these data and the energy consumption for the whole year, it is calculated the economical cost in each case. The optimal ventilation rate, in monetary terms, is (Qs/Qe) ≅0.9. In this case, the energy cost amounts to 13,880 SEK.