# Improvement of the Chimney Effect in Stack Ventilation
## 1 Introduction
Ventilation performance indicator's roleis to provide information concerning indoor air parameters in a room or a building. \[\mathbf{ACH}\left(\mathbf{t}\right)=\frac{\dot{\mathbf{V}}(\mathbf{t})*3600}{ \mathbf{V_{R}}} \tag{1}\]  
where:  
**ACH(t)**--stack ventilation times (ventilation efficiency), h\({}^{-1}\);  
**V(t)**--the amount of air leaving the ventilation system, m\({}^{3}\)/s;  
**V\({}_{\mathbf{R}}\)**--cubature of a ventilated room, m\({}^{3}\). Figure 1: Outside air temperature and wind velocity determined for the city of Elblag based on data from TMR. The process of air exchange during the measurement was adopted as a value independent of time. Therefore, the amount of air leaving the ventilation system **V(t)** and the stack ventilation times **ACH(t)** are assumed as constant values V and ACH. The following simplifications have been introduced to determine the stack ventilation multiplicity, which is to show the ventilation efficiency:  
* The air during measurements is thoroughly mixed;
* There are no gradients inside the room, meaning the air concentration is the same in the entire ventilation system. Information about realistic climate data of the local climate conditions is important, but usually not provided. In general terms, there are two different approaches to describe the climate data: Local Climate Station (LCS) and Typical Meteorological Year (TMY). In engineering, it is uncommon to consider the Local Climate Station (LCS). As we can see in the study [11], the most common practice is to use climate data from the TMY. However, [11] while based on climate data from the TMY, such values are usually slightly overestimated. In this paper, to determine the influence of passive energy on the stack ventilation system, in situ tests were carried out for a typical residential building located in Gdansk. The research was conducted in the summer and autumn periods from August to November. A single-family building was used for the research. The core of the research was to experimentally check the ACH value for the solution to improve the chimney effect in stack ventilation. In this case, two different ways to reinforce the chimney effect were used: the solar chimney and chimney cap. Therefore, a room with an air inlet and an outlet to the ventilation system was separated from the building. These limitations made it possible to obtain results mainly dependent on the external climate. During the experimental research, external climate research was carried out as well, based on its own climatic station in the vicinity of the building. The research was divided into three types. TYPE I consisted ofa test for the ventilation airflow in a traditional ventilation system, i.e., a room + ventilation duct made of solid ceramic brick. TYPE II consisted of enclosing a part of the chimney led out above the roof surface with a transparent wall. However, in TYPE III, a rotary-type chimney cap was used, which was installed on the traditional chimney described in TYPE I. During the research, the location of sensors was constant for the sensors inside the system and for the climate base.