# Applicability and sensitivity of the TAIL rating scheme using data from the French national school survey

Minh Tien Tran, Wenjuan Wei, Claire Dassonville, Corinne Mandin, Mickaël Derbez, Christophe Martinsons, Pascal Ducruet, Valérie Hequet, Pawel Wargocki

<figure><img src="image_1.png" /></figure>

## To cite this version:

Minh Tien Tran, Wenjuan Wei, Claire Dassonville, Corinne Mandin, Mickaël Derbez, et al.. Applicability and sensitivity of the TAIL rating scheme using data from the French national school survey. 43rd AIVC - 11th TightVent - 9th venticool Conference, Air Infiltration and Ventilation Centre, Oct 2023, Copenhagen, Denmark. hal-04813199

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Submitted on 2 Dec 2024

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# Applicability and sensitivity of the TAIL rating scheme
using data from the French national school survey

Minh Tien Tran¹, ², *, Wenjuan Wei¹, Claire Dassonville¹, Corinne Mandin¹,
Mickael Derbez¹, Christophe Martinsons¹, Pascal Ducruet¹, Valérie Héquet² and
Pawel Wargocki³

1 Scientific and Technical Center for Building
(CSTB), Health and Comfort Department, French
Indoor Air Quality Observatory (OQAI)
77420 Champs-sur-Marne, France
Presenting author: *Minh Tien Tran*

2 IMT Atlantique, CNRS, GEPEA, UMR 6144
CEDEX 3, 44307 Nantes, France

3 International Centre for Indoor Environment and
Energy, Department of Environmental and Resource
Engineering (DTU SUSTAIN), Technical University
of Denmark (DTU)
2800 Lyngby, Denmark

## ABSTRACT

The TAIL rating scheme for assessing the quality of Thermal, Acoustic, Indoor air, Luminous, and the overall environment was initially developed to assess indoor environmental quality (IEQ) in hotels and offices. To broaden the use of the TAIL rating scheme to other buildings, its applicability for schools was studied. Two additional parameters, i.e., reverberation time and nitrogen dioxide concentration, were included to account for the specificities of the building use and population. The TAIL rating scheme for schools was applied to the data collected through a national survey performed in France in 602 classrooms between 2013 and 2017 to examine the scheme's feasibility and sensitivity. The results show that using the scheme makes it possible to discriminate IEQ conditions in schools and helps identify problems that may lead to health risks or discomfort, such as insufficient ventilation or overheating during winter. It is concluded that the TAIL rating scheme adapted to schools allows tangible assessment of classroom IEQ and identification of problems requiring improvement, thus promoting a better school environment that eventually will support the proper development of children.

## KEYWORDS

Thermal, ventilation, acoustic, lighting, perception

## 1 INTRODUCTION

Nowadays, humans stay indoors more and more. Extreme climate change can further intensify this trend. Indoor environmental quality (IEQ) is thus an important parameter. IEQ comprises the thermal environment, the acoustic environment, the indoor air quality (IAQ), and the lighting environment. A substantial number of studies have demonstrated the influence of IEQ on occupants' health, comfort, and well-being. These effects are not only limited to adults but also to children in schools. Children are more susceptible to inadequate IEQ as their bodies are still under-development. It is, therefore, essential to create a rating scheme for assessing the quality of the school environment. With this vision in mind, the TAIL-rating scheme for schools was developed. Initially, the TAIL rating scheme was developed for hotels and offices as a part
of the European ALDREN project, promoting the in-depth energy renovation of buildings [1]; the TAIL rating for schools is an adaptation of the original TAIL rating scheme with additional parameters relevant to these environments. Reverberation time for the acoustic environment and nitrogen dioxide ($NO_2$) concentration for indoor air quality were added; updates were made to match the new World Health Organization (WHO) air quality guidelines. A feasibility and sensitivity analysis was performed using measurement data from the French National Schools' survey (2013-2017), coordinated by the Scientific and Technical Centre for Building (CSTB).

# 2 RESULTS AND DISCUSSION

Table 1 presents all parameters in the TAIL rating scheme for schools, with all threshold values for each quality category. The following section presents the results of the TAIL-rating scheme, with Table 2 presenting details of the TAIL classification for each component, and parameter individually.

## 2.1 Thermal environment

Of the 305 schools where the thermal environment was assessed, the measurements in 237 schools were made in the heating season and 68 schools in the non-heating season. Figure 1 shows the distribution of all measurement instances for heating and non-heating seasons. While generally measured air temperatures in the non-heating season are higher than in the heating season, there were still occurrences in which recorded air temperatures from the heating season were as high as in the non-heating season. This suggests overheating in classrooms measured during the heating season. Closely examining the schools measured during the heating season, Figure 2 regroups and displays all measurement instances in the 237 schools during the heating season with colored horizontal lines corresponding to the quality level. The figure shows that a more significant variation was observed in schools having low quality according to the TAIL rating scheme. This could be due to low air temperature in the early morning and/or improper use of the heaters leading to high air temperature.

## 2.2 Acoustic environment

The acoustic environment was assessed using only the background noise level recorded during the school's standard period of occupation (09h00 to 17h00) but made on the weekend with no occupants. This choice is guided by the fact that the sound of the particle measurement device cannot be dissociated from the background noise level during measurements on weekdays. The results obtained show different quality levels. A Wilcoxon non-parametric test showed that compared to a school located close to medium to low traffic, schools located in high-traffic zones had a higher background noise level both on Saturdays (p-value = 7.6.10⁻⁴) and Sundays (p-value = 1.27.10⁻²).

## 2.3 Indoor air quality (IAQ)

IAQ was assessed using seven parameters: benzene, formaldehyde, visible mold $RH$, $CO_2$, $NO_2$, and $PM_{2.5}$. Figure 3 presents all $CO_2$ concentration measurements separated by measured season. Schools where measurements were made during the heating season, had higher $CO_2$ concentrations than schools measured during the non-heating season, as windows were probably less open. Figures 4 and 5 present two opposite trends in relative humidity measured during the heating and the non-heating season. From the quality category I (high) to IV (low), the measured relative humidity tended to decrease during the heating season and increase during the non-heating season. Figure 6 shows a map of all 307 schools where $NO_2$ concentration was
color-coded by their corresponding quality category. While most schools achieved the green-high (category I) quality level, schools located in highly populated areas achieved a lower quality level. Following the same principle, Figure 7 shows the map of the quality level of measured PM<sub>2.5</sub>. Compared to the NO<sub>2</sub> concentration, measured PM<sub>2.5</sub> quality were low but with no observed difference between urban and rural area. This resonated with previous findings, as PM<sub>2.5</sub> sources are a mix of both indoor and outdoor and from its ubiquitous nature [2].

## 2.4 Visual environment

The visual environment assessments focused solely on measuring artificial lighting levels at students' desks and on the writing boards. The overall results for each classroom were determined on the basis of the lowest recorded measurements.

## 2.5 Overall IEQ

303 out of 308 schools had the lowest (category IV) red quality category, and five schools had the next to the lowest orange quality category (category III). This result will urge schools to adopt a holistic approach to assessing the current state of IEQ. They also show the advantage of considering all four components simultaneously when making decisions for IEQ improvement, which is a fundamental principle of the TAIL rating scheme, with no compromise regarding ensuring optimal IEQ in educational institutions.

<table><caption>Table 1: IEQ parameters included in the TAIL rating scheme for schools</caption><thead><tr><th>Parameter</th><th>Category I</th><th>Category II</th><th>Category III</th><th>Category IV</th></tr></thead><tbody><tr><td>Air temperature</td><td colspan="4">Quality of the thermal environment (T)</td></tr><tr><td></td><td colspan="4">Building with mechanical cooling</td></tr><tr><td></td><td>Heating season:<br>22 ± 1 °C</td><td>Heating season:<br>22 ± 2 °C</td><td>Heating season:<br>22 ± 3 °C</td><td>If other quality levels cannot be achieved</td></tr><tr><td></td><td>Non- heating<br>season: 24.5 ± 1 °C</td><td>Non- heating<br>season: 24.5 ± 1.5 °C</td><td>Non- heating<br>season: 24.5 ± 2.5 °C</td><td></td></tr><tr><td></td><td colspan="4">Building without mechanical cooling</td></tr><tr><td></td><td>Heating season:<br>22 ± 1 °C</td><td>Heating season:<br>22 ± 2 °C</td><td>Heating season:<br>22 ± 3 °C</td><td>If other quality levels cannot be achieved</td></tr><tr><td></td><td>Non- heating<br>season:<br>Upper limit:<br>0.33 θ<sub>rm</sub> + 18.8 +<br>2°C</td><td>Non- heating<br>season:<br>Upper limit:<br>0.33 θ<sub>rm</sub> + 18.8 +<br>3°C</td><td>Non- heating<br>season:<br>Upper limit:<br>0.33 θ<sub>rm</sub> + 18.8 +<br>4°C</td><td></td></tr><tr><td></td><td>Lower limit:<br>0.33 θ<sub>rm</sub> + 18.8 -<br>3°C</td><td>Lower limit:<br>0.33 θ<sub>rm</sub> + 18.8 -<br>4°C</td><td>Lower limit:<br>0.33 θ<sub>rm</sub> + 18.8 -<br>5°C</td><td></td></tr><tr><td></td><td colspan="4">θ<sub>rm</sub>: outdoor running mean temperature</td></tr><tr><td>Background noise level</td><td>≤ 30 dB(A)</td><td>≤ 34 dB(A)</td><td>≤ 38 dB(A)</td><td>If other quality levels cannot be achieved</td></tr><tr><td>Reverberation time</td><td>Classroom with volume < 250 m<sup>3</sup>:<br>0.4 - 0.6 s<br>Classroom with volume ≥ 250 m<sup>3</sup>:<br>0.6 - 0.8 s</td><td>Classroom with volume < 250 m<sup>3</sup>:<br>0.6 - 0.8 s<br>Classroom with volume ≥ 250 m<sup>3</sup>:<br>0.8 - 1.2 s</td><td>No criteria</td><td>If other quality levels cannot be achieved</td></tr></tbody></table>
<table><caption>Table 2: Summary of IEQ in schools using the data from the French National schools 'survey (308 schools in total)</caption><tbody><tr><td colspan="5">Quality of the indoor air quality (I)</td></tr><tr><td>Benzene concentration</td><td>&lt; 2 µg/m³</td><td>≥ 2 µg/m³</td><td>No criteria</td><td>≥ 5 µg/m³</td></tr><tr><td>CO₂ concentration</td><td>550 ppm above outdoor concentration</td><td>800 ppm above outdoor concentration</td><td>1350 ppm above outdoor concentration</td><td>If other quality levels cannot be achieved</td></tr><tr><td>Formaldehyde concentration</td><td>&lt; 30 µg/m³</td><td>≥ 30 µg/m³</td><td>No criteria</td><td>≥ 100 µg/m³</td></tr><tr><td>NO₂ concentration</td><td>&lt; 10 µg/m³</td><td>&lt; 20 µg/m³</td><td>No criteria</td><td>≥ 20 µg/m³</td></tr><tr><td>PM₂.₅ concentration</td><td>&lt; 5 µg/m³</td><td>≥ 5 µg/m³</td><td>No criteria</td><td>≥ 15 µg/m³</td></tr><tr><td>Radon concentration</td><td>&lt; 100 Bq/m³</td><td>≥ 100 Bq/m³</td><td>No criteria</td><td>≥ 300 Bq/m³</td></tr><tr><td>Relative humidity</td><td>30 – 50%</td><td>25 – 60%</td><td>20 – 70%</td><td>If other quality levels cannot be achieved</td></tr><tr><td>Ventilation rate</td><td>≥ (10 L/s/p + 2.0 L/s/m² floor)</td><td>≥ 7 L/s/p + 1.4 L/s/m² floor and &lt; 10 L/s/p + 2.0 L/s/m² floor</td><td>≥ 4 L/s/p + 0.8 L/s/m² floor and &lt; 7 L/s/p + 1.4 L/s/m² floor</td><td>If other quality levels cannot be achieved</td></tr><tr><td>Visible mold inspection</td><td>No visible sign</td><td>&lt; 400 cm²</td><td>&lt; 2500 cm²</td><td>≥ 2500 cm²</td></tr><tr><td colspan="5">Quality of the lighting environment (L)</td></tr><tr><td>Daylight factor</td><td>≥ 5.0%</td><td>≥ 3.3%</td><td>≥ 2.0%</td><td>If other quality levels cannot be achieved</td></tr><tr><td>Artificial illuminance (students' tables and writing board)</td><td>≥ 500 lux</td><td>≥ 300 lux</td><td>≥ 200 lux</td><td>If other quality levels cannot be achieved</td></tr></tbody></table>

<table><thead><tr><th>Parameter</th><th>Category I</th><th>Category II</th><th>Category III</th><th>Category IV</th><th>Missing data</th></tr></thead><tbody><tr><td>Overall classification (TAIL)</td><td>0</td><td>0</td><td>5</td><td>303</td><td>0</td></tr><tr><td>Thermal environment (T)</td><td>13</td><td>32</td><td>102</td><td>158</td><td>3</td></tr><tr><td>Air temperature</td><td>13</td><td>32</td><td>102</td><td>158</td><td>3</td></tr><tr><td>Acoustic environment (A)</td><td>89</td><td>99</td><td>57</td><td>49</td><td>14</td></tr><tr><td>Background noise level</td><td>89</td><td>99</td><td>57</td><td>49</td><td>14</td></tr><tr><td>Indoor air quality (I)</td><td>0</td><td>5</td><td>16</td><td>287</td><td>0</td></tr><tr><td>Relative humidity</td><td>44</td><td>155</td><td>87</td><td>19</td><td>3</td></tr><tr><td>CO₂</td><td>3</td><td>25</td><td>67</td><td>213</td><td>0</td></tr><tr><td>Benzene</td><td>247</td><td>53</td><td>0</td><td>3</td><td>5</td></tr><tr><td>Formaldehyde</td><td>237</td><td>71</td><td>0</td><td>0</td><td>0</td></tr><tr><td>PM₂.₅</td><td>1</td><td>68</td><td>0</td><td>233</td><td>6</td></tr><tr><td>NO₂</td><td>200</td><td>67</td><td>0</td><td>40</td><td>1</td></tr><tr><td>Visible mould</td><td>290</td><td>17</td><td>0</td><td>0</td><td>1</td></tr><tr><td>Lighting environment (L)</td><td>1</td><td>56</td><td>97</td><td>151</td><td>3</td></tr><tr><td>Artificial lighting</td><td>1</td><td>56</td><td>97</td><td>151</td><td>3</td></tr></tbody></table>
<figure><img src="image_2.png" /><figcaption>Figure 1: Distribution of the measured air temperatures in schools during the heating season (237 schools) and non-heating season (68 schools)</figcaption></figure>
<figure><img src="image_3.png" /><figcaption>Figure 2: Distribution of measured air temperature during the heating season (237 schools) depending on the categories defined in the TAIL rating scheme</figcaption></figure>

<figure><img src="image_4.png" /><figcaption>Figure 3: Distribution of measured CO₂ concentrations in schools during the heating season (238 schools) and non-heating season (70 schools)</figcaption></figure>
<figure><img src="image_5.png" /><figcaption>Figure 4: Distribution of measured relative humidity in schools during the heating season (237 schools) depending on the categories defined in the TAIL rating scheme</figcaption></figure>

<figure><img src="image_6.png" /><figcaption>Figure 5: Distribution of the measured relative humidity in schools during the non-heating season (68 schools)</figcaption></figure>
<figure><img src="image_7.png" /><figcaption>Figure 6: Schools and their corresponding color quality of the measured NO₂ concentration</figcaption></figure>
<figure><img src="image_8.png" /><figcaption>Figure 7: Schools and their corresponding colored quality of the measured PM<sub>2.5</sub> concentration</figcaption></figure>

## 3 CONCLUSIONS

The article presents the application of the TAIL rating scheme for schools using the French national survey data. From its initial development for hotels and offices, two new parameters have been added to the scheme: RT and NO<sub>2</sub> concentration. The reference values for different quality levels were also updated following the new AQ Guidelines by WHO. The rating scheme was shown to discriminate schools based on their overall IEQ level and specific level corresponding to the thermal, acoustic, visual environment, and indoor air quality Analyses underlined trends, which can aid the decisions made by schools' administrations regarding IEQ improvement. There is clear evidence that the current state of IEQ is unsatisfactory. The TAIL also shows that to achieve high IEQ, no compromises should be made regarding quality levels of parameters defying IEQ. Further analyses will examine the relationship between the obtained IEQ levels defined by TAIL, building characteristics, and occupants' perceptions. A diagnostic plan can then be established, and as a result, further aiding schools in improving IEQ on their premises.

## 4 REFERENCES

[1] P. Wargocki et al., "TAIL, a new scheme for rating indoor environmental quality in offices and hotels undergoing deep energy renovation (EU ALDREN project)," *Energy Build.*, vol. 244, 2021, doi: 10.1016/j.enbuild.2021.111029.

[2] F. Amato et al., "Sources of indoor and outdoor PM2.5 concentrations in primary schools," *Sci. Total Environ.*, vol. 490, pp. 757-765, 2014, doi: 10.1016/j.scitotenv.2014.05.051.