Proceedings of International Conference: Sustainable built environment in the tropics: New technology, new behaviour? School of Architecture, Tarumanagara University, Jakarta, Indonesia, 12-13 November 2012.
Healthy and Comfortable Dwellings for the Low-Income Settlements
in Surakarta
Y. Arsandrie¹², R.M.J. Bokel², A.C. van der Linden², S.R. Kurvers², J.J.M. Cauberg²³ ¹Department of Architecture, Faculty of Engineering, Muhammadiyah University of
Surakarta (UMS), Indonesia. Corresponding author: arsandrie@gmail.com
²Climate Design and Sustainability Group, Department of Building Technology, Faculty of Architecture, Delft University of Technology (TU Delft), the Netherlands ³Cauberg-Huygen, Raadgevende Ingenieurs BV, Maastricht, the Netherlands Abstract
Technology for the low-income group of people should be as simple as their daily life. Giving recommendations for simple dwelling design and changing people’s behaviour for a better living are the concerns of this research. A field-survey was conducted in November-December 2010 involving 426 respondents from four low-income kampongs in Surakarta Indonesia which has a tropical hot-humid climate. Thermal environment and indoor air pollutants was measured momentarily indoor and outdoor. The measured air temperatures in the field-survey were between 29.6 to 39.6°C. During the survey, respondents were interviewed and observations were done to obtain data of the people condition, thermal sensation and health status, as well as information about the condition of inhabitants’ dwellings. Data of the inhabitants’ health profile of Surakarta was obtained from the Health Department of Surakarta. The main severe illnesses found in Surakarta were asthma and other respiratory diseases. Statistical analysis were done using Binary Logistic, Cramer’s V, Spearman’s rho and Pearson Chi-Square to examine the association between variables of indoor air quality and thermal parameters with the health of the inhabitants and thermal comfort. Research found that cooking fuels and the kitchen design influence the health of the people. The amount of ventilation, vegetation, orientation of dwelling and the clothing adaptation are important to increase the health and thermal comfort for the low-income group of people. Recommendations are given in this paper. Photos of the existing dwellings are used as examples to be easily understood by the people for improving the thermal comfort and air quality in the dwellings. In addition, it is important to encourage inhabitants’ behaviours which can increase their feeling of comfort, health and quality of life.
Keywords: behaviour, health, indoor air quality, thermal comfort, tropics 1. Introduction
This research aims to investigate the dwellings of the low-income groups of people in Surakarta, Indonesia in the aspects of indoor air quality, health and thermal comfort so that the people who live in this group know how to obtain a better dwelling to live in. As a result, their living environment is expected to provide a healthier and more comfortable place in a broader sense (physically, mentally, and socially).
Indoor Air Pollution and Health
Activities which potentially cause indoor air pollution in the dwellings are cooking and smoking, especially the type of cooking fuels used and the tobacco smoke. Wood, coal and other biomass fuels (rice husks, jute, etc) are considered to be dirty cooking fuels while LPG
and kerosene are considered to be clean cooking fuels. Though natural gas and kerosene are far less pollution intensive than bio-fuels such as wood and dung, kerosene is irritating to the skin and mucous membranes [1]. Meanwhile, exposure to Environmental Tobacco Smoke (ETS) is associated with an increased risk of lung cancer and several other health effects, such as irritation of the eyes and cardiovascular diseases. Occasional smoking in the dwellings which produce 0.1-1 µg/m3 nicotine in the air will increase the prevalence of acute and chronic respiratory symptoms in children [2,3].
The amount of ventilation may influence the indoor air quality. In this research, dwelling ventilation is distinguished into two categories: sufficient (1) and not sufficient (0). The ‘sufficient’ ventilation is when the dwellings have cross circulation ventilation from two openings, while the ‘not sufficient’ ventilation is a condition when a dwelling only has one door as an opening. Dwellings which have small rooms are often a problem too; this is the case when women cook in the same room as in the bedroom or in the common room where their children are playing or where men smoke cigarettes among the other family members. According to Dasgupta [4], the amount of smoke in the kitchen and smoke leaking from the kitchen into other living spaces depends on the location of the kitchen, the ventilation, and the permeable nature of roof and walls materials in the kitchen.
Thermal Environment
In the tropical climate of Indonesia, the thermal environment in naturally-ventilated dwellings is improved by ventilation. The large ventilation opening is a benefit when the air movement from outside brings the cool breeze and reduces the high humidity in the dwellings. The size of the east-west walls is recommended to be reduced, to minimize the solar radiation on the dwellings, and increase the north-south walls [5].
Trees bring many positive benefits as well. Besides improving thermal comfort and energy demand, they also remove carbon dioxide (CO2) from the air and decrease the air pollution. Trees cool the surrounding environment by keeping the air temperatures low and cooling the surface below them. Where trees do not fit because of the limited area of the land, the option is to grow vegetation such as vines which need less soil and space [6].
The simplest form of personal adaptation to a thermal environment is by changing clothing. The clothing adaptation is largely different between men and women, especially in Asia. Besides changing their clothes, people show personal adaptation by moving to other places to find a more comfortable place. When they find the weather is too warm for them, they move to a different place to find a cooler place.
2. Method
The field-survey was done in November-December 2010 involving as many as 426 respondents from four kampongs in Surakarta Indonesia, i.e.: Kampong Semanggi, Nusukan, Sewu and Sangkrah. The inhabitants of the four kampongs have a low-income and small dense dwellings located next to the big rivers in Surakarta, Bengawan Solo and River Pepe. The method used were momentarily indoor air quality and thermal measurements measured outdoors and inside of the dwellings, including CO2 concentration, air temperatures, globe temperatures, relative humidity, and air velocity measurements. Measurement of carbon
dioxide was done using a Carbon Dioxide Meter (CompuFlow TSI Alnor CF910) for 15 minutes of monitoring.
Figure 1. Indoor air quality and thermal comfort measurements
The air temperature and relative humidity measurements were done using a digital meter CEM DT-615, air velocity using AVM410, and globe temperatures using a digital thermometer and a black globe. Measurements were taken between 09.00 and 14.00 WIB. Information about the general health profile of the inhabitants in Surakarta was obtained from the Health Department in Surakarta [7]. During the field-survey people were asked to answer questions such as: type of cooking fuel, time and place of cooking, cigarette smoking in the family, availability of severe illnesses and common cold in the family. Information related to the dwelling and kitchen ventilation/openings was filled out by the supervisors.
For the thermal comfort assessment, four questions were asked, including the 7- point ASHRAE [8] thermal sensation scale from -3 (cold) to +3 (hot), the 5-point of thermal acceptance scale, 3-point McIntyre’s [9] thermal preference scale (want to have warmer, want no change, want to have colder) and a question about thermal problems. In addition, observation and checklist were done to see the amount of ventilation, dwelling orientations, personal adaptation and vegetation/trees in the surrounding environment.
3. Indoor Air Pollution, Health, and Thermal Environment in Surakarta
The indoor air problem of the low-income settlements in Surakarta is expected to be mainly caused by the use of ‘dirty’ cooking fuels (wood or coal), location of the settlements which is prone to frequent flooding, the bad habit of smoking cigarette in the dwellings, and outdoor pollutants from the traffic or other sources. Most of the respondents cook in their dwellings every day, normally in the morning or midday, while a small number of people do not cook at home. The frequency distribution showed that most of the people use LPG gas (210), followed by wood (46), kerosene (39), combination of LPG gas and wood (29), coal (17), combination of kerosene and wood (17) or LPG gas and kerosene (14); while other combination of cooking fuels are only used in less than 10 households.
For the closed question about smoking, the number of households in which at least one of their members smokes is 61.1% (usually men). The percentage of people who smoke in each kampong are high, over 50% of the surveyed population.
The main severe illnesses people have in the four kampongs which were surveyed in Surakarta is asthma and other respiratory diseases (36.3%), followed by chronic pulmonary
and heart diseases (nearly 10% on each). Asthma and other respiratory diseases are the main severe illness found in the four kampongs.
From the field-survey, a measured air temperature outdoors and indoors from 29.6 to 39.6°C was found, the relative humidity outdoors and indoors was 35.3-70.7% and 32.8- 71.1% respectively. Meanwhile the maximum air velocity outdoors was at 3.2 m/s and indoors 0.9 m/s. The globe temperatures measured during the field-survey were at the similar range as the outdoor and indoor air temperature.
4. Results and Discussion
Cooking Fuels, Smoking and Health
Data from the Health Department of Surakarta and the interview of the inhabitants’ health status found that the main illnesses of people in Surakarta were asthma and other respiratory diseases. Survey of the health in the households found that one of the main causes of death in infants (0-11 months) and children less than 5 years old is acute respiratory infection. The prevalence of asthma or other respiratory diseases and chronic pulmonary diseases (CPD) is higher when the households use wood and coal for cooking (20.6%) compared to the use of other cooking fuels (8.0%). The binary logistic [10] is conducted to assess whether the use of wood and coal significantly predicts whether or not the inhabitants suffer from asthma or other respiratory diseases and chronic pulmonary diseases. The result of this test is presented below:
Table 1. Binary logistic of the use of ‘dirty’ cooking fuels and the diseases
Variable β SE Odds ratio p
Wood and coal 1.1 0.37 2.99 0.003
Constant -2.4 0.19 0.09 0.000
It is shown in Table 1 above that wood and coal significantly predict whether or not the people will suffer from asthma, other respiratory diseases and CPD, χ² = 7.99, df = 1, N= 426, p < 0.01. The presence of people who suffer from asthma or other respiratory diseases as well as chronic pulmonary diseases are significantly associated (p < 0.01) with the activities of cooking by using wood or coal (odds ratio = 3.0) as it is shown in the binary logistic statistic test.
Meanwhile the relationship between the prevalence of asthma and chronic pulmonary diseases and the availability of family members who smoke was investigated by using the Pearson Chi-Square test which indicates no significant association between those two variables which is shown by p > 0.05 (p = 0.16).
Kitchen Condition, Indoor Air Pollutants and Health
The poor condition of the kitchen may create a bad indoor air quality as well. A kitchen is defined as a poor kitchen when the ventilation in the kitchen is minimal, when the inhabitants use open stoves, or when the room layout of the dwelling is not good, i.e. when people perform the cooking activities close to the living room or bedroom. A kitchen is defined as a good kitchen when there is sufficient ventilation close to the cooking area to remove smoke, when people use stoves in a good setting, and when the kitchen is separated from the other
rooms. A poor kitchen may increase the indoor air pollutants such as CO2. In Figure 2, the CO2 concentration of the two different kitchen conditions is presented.
Figure 2. Maximum CO2 concentration in the different kitchen conditions
The figure shows that the CO2 concentration in the poor kitchen is slightly higher than the good kitchen (± 20 ppm). Figure 2 shows that using ‘dirty’ fuels for cooking and having a poor condition of the kitchen contributes to the quality of indoor air in the low-income settlements.
The ventilation in the kitchen was observed to see if the opening is sufficient to remove smoke from cooking. The kitchen openings are distinguished by a code of 0 to 3, from 0=no opening, 1=less opening, i.e. only small opening from a window or a hole in the wall or roof, 2=enough opening, if there is opening from the door, and 3=large opening, when there are openings from a door and window or when a kitchen is located outdoors.
Table 2. Prevalence of Asthma and Chronic Pulmonary Diseases (CPD) and the Sufficiency of the Kitchen Ventilation
Kitchen Opening Severe Illness Total
No asthma/CPD Asthma/CPD 0 1 50.0% 1 50.0% 2 1 48 92.3% 4 7.7% 52 2 168 89.8% 19 10.2% 187 3 37 97.4% 1 2.6% 38 Total 254 91.0% 25 9.0% 279 100% 0 = no opening
1 = less opening if only a small opening from a window or a hole in the wall or roof 2 = enough opening, if there is opening from the door
3 = large opening, when there are openings from a door and window or when the kitchen is located outdoor Ventilation and Indoor Thermal Comfort
Ventilation in dwellings is distinguished into two categories based on the sufficiency of the ventilation. The first category where there is only one door in the dwellings is called ‘less’ (ventilation) and the second category is called ‘sufficient’ defined when there is not only one door but there are two doors or a door and window(s) as well as some other small openings. The dwellings with sufficient ventilation were significantly different from the dwellings with less ventilation on the aspect of indoor air temperature (p = 0.013). Inspection of the two
group-means indicates that the average measured indoor air temperature level in the dwellings with sufficient ventilation (32.9°C) is lower than in the dwelling with less ventilation (33.3°C), see Figure 3. When there is sufficient ventilation, the mean indoor air temperature decreases about 0.4°C compared to the condition of less ventilation in the dwellings.
Figure 3. Relationship between ventilation and the measured indoor air temperature The Cramer’s V and Pearson Chi-Square were used to examine the relationship between the sufficiency of dwelling ventilation and the subjective thermal assessments. Cramer’s V analysis indicates a statistically significant association between ventilation and all of the subjective thermal assessments variables: thermal vote (Cramer’s V = 0.18, p < 0.05), thermal acceptance (Cramer’s V = 0.19, p < 0.01), thermal preference (Cramer’s V = 0.16, p < 0.05), and thermal problem (Phi value = -0.12, p < 0.05).
Orientation and Indoor Thermal Comfort
Orientation is defined by the main entrance of the dwelling. Some dwellings have only one access (for examples in Kampong Nusukan and Sangkrah) because the dwellings are attached to each other. Dwellings in these two kampongs are set in a row which faces the north. Most of the dwellings in Kampong Sangkrah face the Pepe River while the ones in Kampong Nusukan have the view of the Pepe River on the backside.
Cramer’s V analysis indicates a statistically significant association between the orientation of the dwelling and the indoor air temperature which is shown in Cramer’s V value = 0.44, p < 0.05. The effect size is medium [11]. A north orientation gives the lowest indoor air temperature, followed by south, east, and west (see Figure 4 below). The same statistical analysis indicates a statistically significant association between dwelling orientation and thermal vote (Cramer’s V value = 0.17, p < 0.01), thermal acceptance (Cramer’s V value = 0.15, p < 0.01), thermal preference (Cramer’s V value = 0.15, p < 0.05), and thermal problem (Cramer’s V value = 0.20, p < 0.01). Ventilation 34.0 33.5 33.0 32.5 32.0 less sufficient M ea n indo or a ir t em pe ra tur e (° C)
Figure 4. Indoor air temperature on the different orientation
Respondents more frequently voted for neutral and slightly warm when the dwellings are facing north, while for the other orientations they voted slightly warm to warm. From the statistical tests it can be concluded that the better dwelling orientation in the area is the north-south orientation compared to the east-west orientation.
Vegetation/Trees for Improving Indoor Air Quality and Thermal Comfort
The surrounding trees seem to influence the condition of the air pollution. It is known that Kampong Nusukan and Sewu have a higher percentage of trees near the surrounding dwellings, 69% and 77% respectively, compared to Kampong Semanggi (60%) and Sangkrah (8%). The percentage of trees in the surrounding area, which is high in Kampong Semanggi is also a good filter for reducing the outdoor pollution.
The categories of vegetation from the field-survey are simplified into two categories of ‘no tree’ and ‘with tree/s’. The surrounding environment with trees was significantly different from the surrounding environment without trees for the outdoor air temperature (p = 0.047). Inspection of the mean indoor air temperature in the two groups (with trees and without trees) indicates that the outdoor air temperature level in the surrounding environment with trees (33.0°C) is lower than the surrounding environment without trees (33.3°C). The effect size d = 0.20 is small. This test shows that if there are some surrounding trees, the indoor air temperature in the dwelling tends to be slightly lower than when there are no trees in the surrounding environment.
The relationship between the effects of the surrounding environment with trees/without trees and the subjective thermal assessments indicates a statistically significant association between the surrounding environment with trees and without trees on all the subjective thermal assessments variables: thermal vote (Cramer’s V value = 0.22, p = 0.003), thermal acceptance (Cramer’s V value = 0.166, p = 0.021), thermal preference (Cramer’s V value = 0.26, p = 0.000), and thermal problem (Phi value = -0.133, p = 0.006), see Figure 5.
Orientation
North East South West 35.0 34.0 33.0 32.0 31.0 M ea n Ind oor Ai r Tem pe ra tur e (⁰ C)
Clothing as Thermal Adaptation
The clothing index of the occupants in the four kampongs varied from 0.18 to 0.55 clo for men and 0.21 to 0.81 clo for women, with the average clothing index being 0.35 clo (see Table 3). Most women wear a light dress (clothing index of 0.27 clo) to avoid high insulation of their bodies.
Table 3. Clothing index worn by men and women in the four kampongs
Clothing Index (clo)
Min. Max. Average
Kampong Semanggi 0.18 0.81 0.35
Kampong Nusukan 0.20 0.55 0.35
Kampong Sewu 0.24 0.55 0.36
Kampong Sangkrah 0.24 0.55 0.34
The Spearman’s rho shows a statistically significant correlation between clothing index and thermal vote (p< 0.05, small effect size) in a negative direction. This means that when people vote ‘warm/hot’, they are likely to wear fewer clothes and vice versa. Changing clothes or wearing fewer clothes is part of personal adaptation to achieve comfort.
5. Design and Behaviour Recommendation
Recommendations are given with respect to the indoor/outdoor thermal environment and indoor air quality to improve the existing dwellings. The figures from the existing dwellings are given as the examples with the values of good (√) and bad (X), see Figures 6 - 9.
Based on the discussion above, some recommendations related to the indoor air quality and thermal comfort is proposed. The investigation of cooking fuels, kitchen and dwelling design, vegetation and human behaviour leads to the following recommendations:
Figure 5. Relationship between trees and thermal vote
+3 +2 +1 0 -1 -2 -3 M ea n Th er m al V ot e
Figure 6. Recommendation to provide cross ventilation in the dwellings
Figure 7. Recommendation to use clean fuels for cooking
Figure 8. Recommendation to separate kitchen from other rooms
Figure 9. Recommendation to provide trees/vegetation in the surrounding environment When the dwelling area is too small and planting tree is not possible, people can grow vines which need less soil and space to reduce heat exposure on the dwelling surface and to remove the air pollutants from their dwelling environment.
X
√
X
√
X
√
Recommendations are also given for human behaviour. The habit of people to smoke cigarettes anywhere is recommended to be changed. The inhabitants do not have a special place for smoking, so they usually smoke in their dwellings or outside. This habit can increase the tobacco smoke in the dwellings which can cause asthma or other long-term lung problems. Clothing adaptation, which is done by people to achieve thermal comfort, is a smart behaviour to be maintained. People who live in the low-income settlements in Surakarta should feel a freedom to wear less clothing especially when they work at home. It is useful to reduce the feeling of thermal discomfort when modifications to the dwellings have been done but the temperature and humidity remain high.
5. Conclusions
Recommendations which are given in this paper are not new, but they are still important because the low-income people obviously have not put them into practice everywhere. The recommendations in this research are the simple steps expected to help the low-income group of people in Surakarta Indonesia to improve their own dwellings and to pay attention to their behaviour which can increase their quality of life.
Although the statistical analysis in this research showed no association of smoking habit of people who like to smoke cigarette in the dwellings and the diseases, however, the potential pollutants of smoking activity is important to be considered. Therefore, only smoking outside should be encouraged and a special area for smoking should be planned.
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