# Improvement of the Chimney Effect in Stack Ventilation
## 6 Assessment of Methods for Improving the Gravity Ventilation System
### Chimney Cap  
There isa passive or active chimney cap with an additional electric drive. Passive chimney cows (e.g., rotating) are constructed in such a way that, at a low wind speed (>1 m/s), they generate negative pressure in the chimney outlet while maintaining the correct airflow direction. The effectiveness of the applied solution is presented in tabular form. Table 5. \begin{table}
\begin{tabular}{c c c} \hline \hline
**Factor** & **Comment** & **Assessment** \\ \hline \multirow{4}{*}{Availability of technology} & Typical, readily available building materials were used & \multirow{4}{*}{4} \\  & for the construction of the solar chimney. For the & \\  & construction of a transparent partition, colorless & \\  & plexiglass, 4 mm thick, cut to size was used. The joints & \\  & are made of 3 \(\times\) 3 cm wooden slats. & \\ \hline \multirow{4}{*}{Cost of materials and labor} & The purchased material cost PLN 320, while the cost of & \multirow{4}{*}{3} \\  & assembly and then assembly work was calculated at & \\  & PLN 250, which gives a total amount of PLN 570. & \\ \hline \multirow{2}{*}{Time of implementation} & The time to assemble the structure took two working & \multirow{2}{*}{3} \\  & days + one day for assembly. & \\ \hline \multirow{2}{*}{Aesthetic values} & In this case, the structure of the chimney lining was & \multirow{2}{*}{3} \\  & clearly visible from the street side. & \\ \hline \multicolumn{3}{c}{Total points:} & 13 \\ \hline \hline \end{tabular}
\end{table} 
Table 4: Self-assessment of the applied solution to strengthen the chimney draft. Looking at single-family buildings and collective housing, it was noticed that in the temperate climate zone typical of the Pomeranian Voivodeship, the most popular methods of improving gravity ventilation include the chimney cap. Based on the observations, it was found that the most popular chimney cap, used mainly in multi-family housing, is the fixed type (Figure 21a). This device is the simplest in terms of construction and the cheapest type of attachment. Among single-family housing, it happens often that residents decide to use a rotary type. Based on the observations, it is difficult to determine whether the attachment has an additional motor (Figure 21b). In the paper compares the effect of a chimney cap on the heating properties of a building. Based on the experimental tests, the efficiency of the device was checked by comparing the consumption of thermal energy in the building (Figure 22). The results were obtained by measurements. \begin{table}
\begin{tabular}{c c c} \hline \hline
**Factor** & **Comment** & **Assessment** \\ \hline \multirow{4}{*}{Availability of technology} & The chimney cowl is a generally available product on the market. Due to the quality, price and purpose, there are several dozen types of chimney cows. Without leaving your home, you can choose the right type of attachment by talking to a technical advisor. & 5 \\ \hline \multirow{4}{*}{Cost of materials and labor} & The cost of the attachment depends on the type: fixed attachments cost 60–250 PLN, self-adjusting attachments 170–450 PLN, and rotary ones 180–500 PLN. In this case, a rotating cowl was selected, the cost of which, including assembly, was PLN 480. & 5 \\ \hline Time of implementation & The element was delivered and installed within one day. & 5 \\ \hline \multirow{2}{*}{Aesthetic values} & In this case, from the side of the street, the attachment on the chimney was also clearly visible. & 3 \\ \hline \hline \end{tabular}
\end{table} 
Table 5: Assessment of the applied solution to strengthen the chimney draft. Figure 21: Multi-family housing in Gdärsk: (**a**) traditional chimney cap and (**b**) rotary type chimney cap. Based on the diagram (Figure 22), the effect of the chimney cap on the consumption of thermal energy for heating was compared. A total of 24 months were adopted for the analysis, where the first 12 months are the result without the chimney cap, and the next 12 months are the measurement with the chimney cap installed.