Eco. Env. & Cons. 22 (4) : 2016; pp. (1647-1652) Copyright@ EM International ISSN 0971–765X
Relative humidity performance study as the basic of design evaluation in small type residences Erlina Laksmiani Wahjutami, 2Antariksa, 2Agung Murti Nugroho and 3Amin Setyo Leksono
1
Department of Environmental Science, University of Brawijaya, Malang, Indonesia Department of Architecture, University of Brawijaya, Malang, Indonesia 3 Department of Biology, University of Brawijaya, Malang, Indonesia 1 2
(Received 19 May, 2016; accepted 5 July, 2016)
ABSTRACT Indonesia is located in hot – humid climate area. Malang city becomes location of the research, which astronomically lays in 112.06o – 112.07o East Longitude and 7.06o – 8.02’o South Latitude. The requirements of buildings construction in the climate are the availability of natural lighting system and cross ventilation. Buildings on the limited land sometimes can not meet the requirements. On Small Type Residences (STR), buildings renovations are mostly maximized to meet rooms need. The issue of the research was high humidity level in renovated STR. The research aimed to find out relative humidity performance in humid rooms. The research method used 9 temperature and humidity sensor for 24 hours on plafond, mid-air, and floor area in the conditioned rooms. Based on the measurement, they showed high rooms humidity in general. The rooms relative humidity performance changed based on its time and level to the floor. The plafond area had the lowest level of humidity, while floor area had the highest one. The research results are used as the basis to evaluate STR design in order to meet the best thermal comfort.
Key words : Hot-humid, High humidity, Small type residence, Relative humidity performance
Introduction This research was held in Malang city, Indonesia. Astronomically, the city lies on 112.06o – 112.07o East Longitude and 7.06o – 8.02o South Latitude. In the development of indoor environmental control system, type of buildings, outdoor climate, and season, must be considered (Frontczak and Wargocki, 2011). The limitation of the research is small type residences (STR) in hot-humid climate. Hot-humid climate has a characteristic. Its relative humidity goes around 60-95% at temperatures of 22-33 °C. The discussed issue of the research is high humidity level in renovated STR. The purpose of the research is to find the cause of
high humidity level through descriptive research on STR floor plan, and to determine the relative humidity performance in conditioned rooms. Rooms in high humidity level can cause pneumonia to toddler (Mahalastri, 2014). They also can cause damage to the bulidings (Lourenco et al., 2006), mold growth and inhabitans’ health issue (Clarke, et al., 1999) and porosity to buliding material (Xu and Zhang, 2011). Humidity in buildings is unlikely to be perceived physically, in contrary to temperature. Basic design of buildings can be the cause of its humidity issue. According to (Mediastika, 2013) and (Karyono, 2010), unfavorable lighting and ventilation system will make inside of buildings humid. Basic principle of buildings design in the hot- humid climate is pas-
Corresponding author’s email :
[email protected] 1 P.G. Student
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sive cooling system. This system intended to reduce the thermal discomfort in buildings. Through natural lighting and ventilation system, plus continual air flow, hot-humid climate happening in outside will not affect condition inside buildings. Relative humidity values around 30-70% is the limit of thermal comfort. Humidity level under 30% or above 70% is the limit of thermal discomfort (Frick et al., 2008). The higher the temperature, the more the effect of air humidity on human body (Purnomo and Rizal, 2000). The correlation between the humidity level of rooms and temperature to comfort can be seen in Table 1 below:
tions as 5 houses faced west and the other 5 faced east. Temperature and relative humidity sensors were laid for a week in the rooms of the STR that was predicted to be the most humid. Besides temperature and humidity, light intensity and airspeed were also measured as a variable control. Bed rooms are more private, so they are often left closed more than the other rooms. A room area that usually belonged to humid category is bedrooms. Generally, the bedrooms area covers 7.5 – 9 m 2 . Based on that, area coverage of the rooms can be decided, with which used as representation of humid rooms.
Table 1. The effect of humidity on a comfortable temperature in the room Humidity
0-30% 30-50% 50-70% 70-100%
Day’s Thermal Comfort
Night’s Thermal Comfort
22-30oC 22-29oC 22-28oC 22-27oC
20-27oC 20-26oC 20-26oC 20-25oC
Source: Gut, Ackerknecht in (Frick et al., 2008)
In the context of climatic design, the term “comfortable” refers to the conditions that humans can work efficiently and sleep well so their body will completely recover from tiredness after working (Mauro and Widhiningsih, 1979). Natural ventilation setting in hot-humid climate with high airspeed will raise thermal comfort (Candido et al., 2010). Combination of value of air flow and heat reception are: at range of 24-27 oC minimum airspeed goes 0,4 m/s; at 27-29 oC goes 0,41-0.8 m/s, and at 29-31 o C goes > 0,81 m/s (Candido et al., 2011). In the end, natural ventilation setting is energy free consuming that is important for efficieny of energy using in builidngs (Yin et al., 2010).
Materials and Methods The first step to do was descriptive research on renovated STR floor plan, view the sections in Sawojajar residences. A renovated STR floor plan (fig. 2) was compared to a basic floor plan (fig. 1) in order to spot the changes that caused its humidity level to go high. There were 10 STR buildings used as samples of the research. They shared 2 composi-
Fig. 1. Original STR floor plan before renovation.
The rooms that was second observation, was conditioned as similar as humid rooms condition in the first observation. Room area was 3x3 m 2 with plafond level standing at 3 m (Fig. 3). Temperature and relative humidity measurement were also run for a particular aim. It was to figure out relative humidity performance in the rooms, especially at plafonds, middle rooms, and floors area. Measurement of relative humidity performance ran for 3 days. The instruments used were 9 HOBO relative humidity and temperature data logger. They were set at a distance of the same wall in the room, as shown in figure 3. Measurement ran for 24 hours in the condition of tightly closed windows and no light and airflow at all. Light intensity in the rooms was conditioned into 0 lux and 0 m/second airspeed. Light intensity in the amount of 0 lux showed that the rooms were relatively dark if there were no artificial lighting. Natural lighting did not go through into the rooms at all. Airspeed, which rates at 0 m/second, showed that the rooms were hardly had any airflow. Those were based on gen-
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1649 the room). On the second day, they were laid 150 cm away from the floors (in the mid–air level of rooms) while on the third day, they were laid 10 cm away from the floors (on the bottom).
Results
STR Facing West
STR Facing East
Fig. 2. STR after renovation
Fig. 3. The room that was conditioned as representation of humid rooms in STR.
eral result of measurement in the rooms of the STR that were observed; nearly no natural light and temperature setting in the humid rooms. On the first day, the 9 instruments were laid 10 cm away from the plafonds (at the upper level of
Based on the comparison of the STR original floor plan and the one after renovated, it could be seen that the fact of limited land pushed inhabitants to renovate their house maximally in order to meet limited rooms demand. From the Figure 2, it showed that expansion of house area decrease percentage of green opening area on the site, especially the backyard. It caused lack of natural light and airflow supply to the houses. Function of their windows as access for natural light and fresh air went poor. Light intensity going into the rooms greatly decreased and cross ventilation process hardly occurred inside. According to the conditions of healthy buildings in hot-humid climate, where the natural light and cross ventilation as its major, the rooms allegedly would have high humidity. It could be proven by the result of humidity and temperature measurement in the rooms (Fig. 4). Generally, it showed that temperature and humidity movements in the both samples went nearly similar. Whether STR faced East or West, both of them had high humidity level. The measurement show that STR facing west had combination of humidity and temperature by 60% - 34oC at the lowest humidity, and by 76% - 30.4oC at the highest humidity in the day. In night time, it went 80% - 31.4oC and 84% - 27.8 oC. STR facing east had a combination around 58% 31.5oC and 81% - 28oC in day time. In night time, it went 74% - 29.5oC and 81% - 27.2oC. Based on Table 1, the combination between the humidity and temperature above belonged to the category that caused thermal discomfort to inhabitants. From the results of relative humidity performance measurement in the conditioned room (Fig. 5-6-7), it appears there is a significant difference. As we note, the result of measurement in the first one hour, whether on plafonds, mid rooms or floors area, were
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omitted. The omission occurred because during that time, measurement just begun so that the relative humidity were not stable yet. Humidity in the rooms always moved and changed following time. On the plafond area, the relative humidity went around 75-82%, middle area of the rooms went around 76-82%, and the floors area went around 80-85%. In day time, humidity level tended to be lower than it did in the night time. Room level positions also affected humidity level. The humidity level on the plafonds area was lower than in the mid-air area (Fig. 6) or even the floor area (fig. 7). During 24 hours, relative humidity on the floors area tended to be higher but lack of change. This could be noticed on the different color shift that occurred.
Discussion Generally, direction of the STR facing east or west either was not significant to affect level of humidity. Tight building in sequence was practiced on the STR. This made almost no open space between one of the building to another. In other word, the buildings were close one another. The fact that there was no sufficient open space for access of light and airflow provoked the high level of humidity in the rooms. Therefore, inhabitants’ comprehension of hot-humid characteristic is important to understand condition of their buildings design. The result of measurement on the STR showed that humidity level on the STR in general was beyond normal limitation 70%. Combination of humidity and temperature indicates thermal discom-
STR Facing West
STR Facing East Fig. 4. Graphic result of measurement humidity and temperature.
WAHJUTAMI ET AL fort as being referred to Table 1, either in day or night time. According to Purnomo and Rizal (2000), the higher the temperature, the more effect of humidity does to human body. It is experienced by the inhabitants as well. Feeling of stuffy and hot, or even sultry became the issues, even though some of them have adjusted and adapted to that condition. The result of the relative humidity performance on the conditioned rooms showed that during 24 hours, the humidity made unique movements patterns (Figure 5-6-7). The relative humidity performance in the rooms always moved and changed following time. In day time, it tended to decrease, and in night time, it tended to increase. Position level of the instruments to the floors affected movement patterns into differences. With a comparison relative humidity value on plafonds, mid-air, and floors area by 75-82%, 76-82%, and 8085%, it could be seen that plafonds area had the lowest value of relative humidity, while the floor area had the highest one in overall.
Fig. 5. Image of relative humidity performance on plafond
1651 After all, high humidity level in rooms can make an issue for their inhabitants’ health, even damage on buildings. The fact that generally humid rooms had light intensity by 0 lux and airspeed by 0 m/ second, they needs artificial light and temperature setting support to meet room comfort. It will be more energy consuming though. It is true that natural light and temperature setting were free energy consuming. They are important for energy efficiency on buildings.
Conclusion On the basis of the research above, the renovated STR had less attention to opening factors (windows) as the important part of the building to get natural lighting and ventilation. As the result, relative humidity went high. The finding of relative humidity performance in the conditioned rooms said that their relative humidity level was above 70%. The number always
Fig. 6. Image of relative humidity performance in the mid-air area of the rooms.
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Eco. Env. & Cons. 22 (4) : 2016 Brawijaya University, Malang, Indonesia. Thus, the writer thanks them who make this journal possible.
References
Fig. 7. Image of relative humidity performance on the floors area.
changed, based on time and level upon the floors. In day time, the humidity level would be down while it would rise in night time. The lowest humidity level occured on plafond area, while the highest occured on floor area. The humidity level on floor always tended to be high and did not change a lot in 24 hours. Therefore, the building design in hot–humid climate should solve the issue of elimination systems against high temperature and humidity. It is for reaching healthy thermal and indoor comfort for the inhabitants.
Acknowledgment The journal writer was supported by a National Postgraduate Scholarship from Research, Technology, and Higher Education during study process in Doctoral Program Enviromental Science of
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