# Effects of Night Ventilation on Indoor Air Quality in Educational Buildings--A Field Study
## 2 Materials and Methods
### Measured Kindergartens  
Kindergarten 1 was built in 2015. The playroom (37 m\({}^{2}\)) had a CAV mixing ventilation system at a corridor bulkhead (Figure 1g). The set values for the supply air temperature were from 22 to 17 \({}^{\circ}\)C and corresponded to the set values for the exhaust air temperature from 20 to 25 \({}^{\circ}\)C, respectively. The time program controlled the air handling units. The designed supply airflow rate was 110 L/s which was 3 L/s\(\cdot\)m\({}^{2}\) for the 10-20 individuals. Kindergarten 2 was built in 2003. The playroom (30 m\({}^{2}\)) had a corridor bulkhead CAV air distribution system (Figure 1h) with cascade control of the supply air temperature based on the exhaust air temperature. The air handling units in the other service areas had a shorter operating time than in the playroom. The designed supply airflow rate was 105 L/s which was 3.5 L/s\(\cdot\)m\({}^{2}\) for 5-15 individuals. Kindergarten 3 was built in 2012. The playroom (21 m\({}^{2}\)) had a corridor bulkhead CAV mixing air distribution system (Figure 1i). The system maintains constant static pressure in ductwork with frequency converter-driven fan motors and supply air temperature cascade control with room sensors. The control setting was either fast (1/1), slow (1/2), or stop. The \begin{table}
\begin{tabular}{c c c c} \hline \hline
**Primary School 1** & **Ventilation (VAV)** & **Weekdays** & **Weekend** \\ \hline built: 2013 & pre-started & mon 04–18, tue-fri 05–18 & 1 h per day \\ VAVmax: 3 L/s\(\cdot\)m\({}^{2}\) & continuous & 00–24 & 00–24 \\ floor: 40 m\({}^{2}\), occ: 10–20 & intermittent & as in case 1 + 20–22 + 00–02 & 02–05 + 10–13 + 18–21 \\ \hline
**Primary School 2** & **Ventilation (CAV)** & **Weekdays** & **Weekend** \\ \hline built: 2006, renov: 2012 & & mon 05–18, & 14–15 \\ CAVmax: 3 L/s\(\cdot\)m\({}^{2}\) & pre-started & tue-fri 06–18 & 00–24 \\ floor: 65 m\({}^{2}\) & continuous & 00–24 & 00–24 \\ occ: 20–30 person & intermittent & as in case 1 + 20–22 + 01–03 & 02–05 + 10–13 + 18–21 \\ \hline
**Primary School 3** & **Ventilation (CAV)** & **Weekdays** & **Weekend** \\ \hline built: 1953, renov: 2012 & & mon-tue 05:30–20:00, & 06:00–18:00 \\ CAVmax: 3 L/s\(\cdot\)m\({}^{2}\) & & wed-fri 05:30–18:00 & 06:00–18:00 \\ floor: 60 m\({}^{2}\) & continuous max & 00–24 & 00–24 \\ occ: 20–30 person & continuous min & as in case 1 + half power at night & as in case 1 + half power at night \\ \hline
**Primary School 4** & **Ventilation (VAV)** & **Weekdays** & **Weekend** \\ \hline built: 2012 & continuous & 00–24 & 00–24 \\ VAVmax: 3.5 L/s\(\cdot\)m\({}^{2}\) & intermittent & 05–18 + 20–22 + 01–03, & 02–05 + 10–13 + 18–21, \\ floor: 87.5 m\({}^{2}\), occ: 20–30 & & otherwise minimum & otherwise minimum \\ \hline
**Secondary School** & **Ventilation (VAV)** & **Weekdays** & **Weekend** \\ \hline built: 1975, renov: 2014, & pre-started & mon 05–17 tue-fri 06–17 & - \\ VAVmax: 3.6 L/s\(\cdot\)m\({}^{2}\) & continuous max & 00–24, max at night & 00–24, max \\ floor: 42 m\({}^{2}\), occ: 20–25 & continuous min & 00–24, min at night & 00–24, min \\ \hline
**University Building** & **Ventilation (VAV)** & **Weekdays** & **Weekend** \\ \hline built: 1964, renov: 2015, & pre-started & 06–17 & - \\ VAVmax: 4 L/s\(\cdot\)m\({}^{2}\) & continuous & 00–24 & 00–24 \\ floor: 39.5 m\({}^{2}\), occ: 3–5 & intermittent & 06–17 + 19–21 + 02–04 & 02–05 + 10–13 + 18–21 \\ \hline \hline \end{tabular}
\end{table} 
Table 1: The measured school buildings: occ denotes the usual number of occupants in the room, floor refers to the floor area in the room, CAVmax is the maximum airflow rate per floor square meter in a constant air volume system, and VAVmax is the corresponding airflow in a variable air volume system. exhaust air valves were at the corridor wall. The designed ventilation rate was 3 L/s\(\cdot\)m\({}^{2}\). The playroom was for 5-10 children. Kindergarten 4 was built in 2013.