Healthy Buildings 2017 Europe July 2-5, 2017, Lublin, Poland. Experimental identification of thermal-moisture conditions in the indoor swimming pool

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1 Healthy Buildings 2017 Europe July 2-5, 2017, Lublin, Poland Paper ID 0261 ISBN: Experimental identification of thermal-moisture conditions in the indoor swimming pool Piotr Ciuman 1, Barbara Lipska 1 1 Silesian University of Technology, Gliwice, Poland *Corresponding piotr.ciuman@polsl.pl SUMMARY The aim of presented research was to evaluate thermal-moisture conditions in the ventilated actual school s indoor swimming pool in terms of occupants thermal comfort and building s envelope moistness. The research was carried out on the basis of long-time and short-time measurements of indoor air parameters: temperature, relative humidity, and speed, as well as, thermovision measurements of building s envelope temperature, for various states of outdoor air. Comparison of the experimental results with the air parameters values recommended by literature sources indicated a need to improve thermal-moisture conditions in the analyzed swimming pool. Methods of improvement by modernizing the ventilation system were provided. KEYWORDS natatorium, ventilation, air parameters, measurements, thermovision 1 INTRODUCTION In indoor swimming pools, substantial heat and moisture gains occur, which coupled with ventilation, shape air parameters distribution inside the facility. The particularly important parameter is relative air humidity, which too low value contributes to an increase of moisture gains in the swimming pool, as a result of more intense moisture evaporation, especially from a water surface. Whereas, too high value during a cold period causes moisture condensation on building s envelope, and during summer period leads to a feeling of sultriness by swimming pools occupants. Air parameters values should be selected in a way to ensure thermal comfort both for occupants (swimmers) and swimming pool s staff. Polish regulations do not uniformly specify the required values of these parameters. Therefore, their selection must be based on design guidelines from literature sources. In Table 1 suggested air parameters values in an indoor swimming pool of general use are presented according to various sources. In terms of thermal comfort, not only the values of individual air parameters are important, but also the relationship between them. It is represented, for example, by the Lancaster-Custens-Ruge sultriness curve (fig. 3), according to which in an indoor swimming pool specific air humidity should be kept lower than kg H2O/kg d.a. In the literature, only a few descriptions of experimental measurements in indoor swimming pools can be found. In the facility in Egypt (Abo Elazm and Shahata 2015) carried out measurements of indoor air temperature and relative humidity. For the swimming pool in

2 Canada (Lebon et al. 2016) carried out measurements of indoor air parameters, as well as building s partitions surface temperature. The aim of the research presented in this paper was the evaluation of thermal-moisture conditions in the ventilated actual indoor swimming pool for various outdoor air parameters, in terms of occupants thermal comfort and technical condition of the facility. It was carried out by the comparison of measurements results with the literature recommendations of these parameters. 2 EXAMINED INDOOR SWIMMING POOL The research was carried out in school s indoor swimming pool in Gliwice (fig. 1) of dimensions: length 17.6 m, width 11.7 m, average height 4.4 m, and therefore of a cubic capacity 906 m 3. Inside the facility was a pool of length 12.5 m and width 7 m. Fig. 1. View of the interior of school s swimming pool (tinyurl.com/pm5hyau) Internal heat sources in the facility were: people in the water and outside the pool, lighting, and radiators, while moisture sources were: people, pool water s surface, and wet floor. Thermalmoisture conditions inside the swimming pool were maintained with the use of a mechanical ventilation system. It was supplying variable ventilation airflow, depending on outdoor air parameters. During winter and spring periods, relative air humidity inside the swimming pool was kept on a stable, required level by mixing outdoor air with recirculating air at a right proportion in the mixing box. In order to maintain constant air temperature in the facility, it was necessary to heat the mixed air to a proper supply air temperature, with the use of heat recovery in the form of heat pipes and a heater. During the summer period, outdoor air was supplied directly, not subjected to thermal treatment. In the facility ventilation air was distributed as follows: the air was supplied by 12 slot diffusers along windows and 7 ceiling supply grilles on the opposite side above the occupied zone, the air was exhausted on both sides of the ceiling recess above the pool by 12 exhaust grilles. 3 RESEARCH METHODOLOGY Within the scope of experimental research, measurements identifying operating conditions of ventilation inside the swimming pool during winter, spring and summer periods were carried out. Distribution of air parameters in the occupied zone and above the water surface was determined as well. The risk of moisture condensation on the building s partitions was also

3 examined. The experimental research encompassed: 1) long-time measurements (the period from January to June 2015 and 2016): outdoor air temperature and relative humidity at the weather station, indoor air temperature and relative humidity inside the swimming pool at the measuring points A1 A10 on the walls at the height of 1.7 m (fig. 2), 2) short-time measurements carried out in the absence of people on selected days of this period: supply air temperature and relative humidity inside ventilation duct, air velocity at supply grilles and slots, air temperature, relative humidity and speed at measuring axes P1 P6 at four levels (0.1 m, 0.6 m, 1.1 m, 1.7 m) above the floor around the pool (fig. 2), air temperature, relative humidity and speed at measuring points 1 7 at the height of 0.2 m above the water surface (fig. 2), pool s water temperature, 3) thermovision measurements carried out during the winter period (February 2016). Fig. 2. Distribution of measuring points and axes in the swimming pool Long-time measurements of air temperature and relative humidity inside the swimming pool, as well as short-time measurements of air relative humidity and temperature above the floor and water surface and supply air were carried out with the use of APAR AR235 temperature and relative humidity registers (apar.pl). Short-time measurements of air speed and temperature above the floor and water surface were carried out with the use of Sensor Electronic thermoanemometers with omnidirectional, spherical sensor HT-428 with the measuring system AirDistSys 5000 (sensor-electronic.pl). Supply air velocity was measured with the use of multifunctional measuring instrument TESTO with a vane probe with telescope handle (testo.com). Pool s water temperature was measured with the use of Sensor Electronic DRT-10 thermometer (sensor-electronic.pl). Thermovision measurements were carried out with the use of FLIR i50 and ThermaCAM E45 infrared cameras, and the results of measurements were

4 developed with the use of FLIR Tools software (flir.com). 4 RESULTS OF VENTILATION CONDITIONS AND WATER PARAMETERS MEASUREMENTS The measurements were carried out at different values of the outdoor air temperature: during the winter period from -1.3 C to 15.2 C, during spring season from -3.4 C to 27.9 C, during the summer period from 4.8 C to 37.6 C. Measured values of air supplied by slot diffusers were in a range from 0.41 m/s to 1.89 m/s and were lower than the recommended value (Kolaszewski 2003), which resulted in a significant decline in a range of supply air jet. Air velocity values at supply openings were used to determine volume flow rates of air supplied to the facility by ceiling grilles and slot diffusers along windows of defined, on the basis of stocktaking, effective surfaces. Calculated on this basis the number of air changes in the swimming pool was: in winter 2.70 h -1, in spring 1.77 h -1, in summer 1.48 h -1. These values were lower than recommended 3-6 h -1 (ASHRAE 2011; Recknagel et al. 1994). The measured average water pool temperature equaled to 31 C and was too high for pools for swimming lessons (VDI 2089; Jaskólski and Micewicz 2000; Kappler 1997). 5 EVALUATION OF THERMAL-MOISTURE CONDITIONS INSIDE THE SWIMMING POOL Table 1 shows the results of air temperature, relative humidity and speed measurements in the occupied zone inside the swimming pool. Measured values were compared with the ones recommended in the literature. Table 1. The results of air parameters measurements in the swimming pool Measured value Value for air Value for air above the floor above the water Recommended values Temperature ( o C) acc. (VDI 2089): t w + (2 4) - winter period acc. (ASHRAE 2011): spring period acc. (Jaskólski et al. 2000): 28 - summer period acc. (Kappler 1977): t w + (3 5) Relative humidity (%) acc. (VDI 2089): winter period spring period summer period Speed (m/s) - winter period spring period summer period where: t w pool water temperature acc. (ASHRAE 2011): acc. (Jaskólski et al. 2000): acc. (Kappler 1977): (< 70) acc. (Jaskólski et al. 2000): 0.1-0,15 acc. (Kappler 1977): The air temperature in the swimming pool was lower by up to approximately 5 o C than the pool water temperature, which was not in accordance with the recommendations (VDI 2089; Kappler 1977). It had a negative impact especially on swimmers, who while leaving the pool experienced organism cooling and thermal discomfort. Although, it should be noted, that the air temperature values were within the range of (ASHRAE 2011) recommendations. In the case of relative air humidity, the maximum values were higher on average by about 15-20% than recommended, and the minimum values, only for the winter period, were lower by 3-13% than recommended (VDI 2089; ASHRAE 2011; Jaskólski and Micewicz 2000; (Kappler 1977). Above the water surface, the values were in accordance with the recommendations (VDI 2089; Jaskólski and Micewicz 2000; Kappler 1977). Only for the

5 summer period, they were higher by 4% than recommendations (ASHRAE 2011). In the most of the occupied zone, the minimum air speed criterion was not met, and the air speed value was lower by up to 0.07 m/s than recommended (Jaskólski and Micewicz 2000). It resulted in a feeling of sultriness experienced by swimming pool s occupants. Higher air speed values than in the rest of the zone occurred mainly in the region of ceiling air supply. On the h-x chart (fig. 3) the area of identified air parameters conditions in the swimming pool during the measurements was marked. It was found that the substantial part of them exceeded the area limited by sultriness curve for indoor swimming pools. It resulted in thermal discomfort experienced by swimming pool s occupants. Moreover, it was a confirmation of subjective evaluation of thermal-moisture conditions by people who were carrying out the measurements, during which they experienced excessive sultriness, dizziness, organism weakness and drowsiness. It was also a result of the aforementioned too small number of air changes in the swimming pool. Infrared images were taken at the outdoor air temperature 0.2 C, indoor air temperature 27.4 C and indoor relative air humidity 56%. On their basis, it was found that the measured value of a surface temperature, minimum for all windows and other external partitions was 18.4 C and was higher than the dew point temperature 17.9 C. The risk of moisture condensation on windows and buildings partitions was evaluated at the design outdoor air temperature in the III climate zone -20 C (PN-EN 12831). At the same indoor air parameters, the minimum temperature of window s internal surface would be 11.5 C, and therefore the risk of moisture condensation on its surface would occur. In the case of other partitions, there is no risk of moisture condensation on their surfaces. Fig. 3. The h-x chart with the area of air parameters conditions inside the swimming pool during the measurements and sultriness curve for indoor swimming pools 6 CONCLUSIONS

6 1. As a result of air parameters measurements carried out inside the indoor swimming pool, it was found that in large part of the occupied zone thermal-moisture conditions and air speed values deviated from the literature recommendations. 2. On the basis of infrared measurements of building s partitions surface temperature, it was evaluated that at low outdoor air temperatures the risk of moisture condensations on windows indoor surfaces occurs. 3. In order to ensure thermal comfort conditions for occupants: swimmers in the pool and the staff, it is required to improve thermal-moisture conditions inside the swimming pool. This can be achieved by increasing supply air volume flow rate, velocity of air supplied by slot grilles and air temperature in the facility. 4. To find out about the impact of proposed changes on thermal-moisture conditions in the swimming pool, before modernizing its ventilation system, it is advised to carry out numerical calculations of air, heat, and moisture with the use of the CFD method. For such simulations, the results of measurements presented in this paper can be used to develop boundary conditions and for validation of calculations results. 7 ACKNOWLEDGEMENT The paper was prepared within the Statutory Work No. 08/010/BKM_16/0020, funded by the Ministry of Science and Higher Education. 8 REFERENCES Abo Elazm M. M. and Shahata A. I Numerical and field study of the effect of air velocity and evaporation rate on indoor air quality in enclosed swimming pools. International Review of Mechanical Engineering (I.RE.M.E.), 9(1), , ASHRAE ASHRAE Handbook HVAC Applications. Atlanta: American Society of Heating, Refrigerating, and Air-Conditioning Engineers, Inc. Jaskólski M. and Micewicz Z Wentylacja i klimatyzacja krytych pływalni. Gdańsk: IPPU MASTA sp. z o. o. Kappler H. P Baseny Kąpielowe. Warszawa: Arkady. Kolaszewski A Nawiew powietrza do hal basenowych przez nawiewne szyny szczelinowe. Chłodnictwo i Klimatyzacja, 7, Lebon M., Fellouah H., Galanis N., Limane A. and Guerfala N Numerical analysis and field measurements of the airflow patterns and thermal comfort in an indoor swimming pool: a case study. Energy Efficiency, online, pp PN-EN Instalacje ogrzewcze w budynkach. Metoda obliczania projektowego obciążenia cieplnego. Recknagel, Sprenger, Hönmann and Schramek Ogrzewanie i klimatyzacja - poradnik. Gdańsk: EWFE VDI 2089 Blatt 1 Technische Gebäudeausrüstung von Schwimmbädern Hallenbäder