Indoor Environmental Quality Trisha Parekh
Aim To establish an understanding of how indoor air temperature effects human comfort, satisfaction and productivity.
Methodology This research experiment was conducted using a UA-002-64 pendant sensor which measured the ambient temperature over 4 days from 20th Nov 2018 to 23rd Nov 2018. Simultaneously, the researcher recorded the thermal sensation, satisfaction, activity level and clothing level at various times of the day on the above dates. The date and time were noted on a spreadsheet so that the pendant readings could be coincided later. The qualitative analysis was recorded in detail, covering aspects related to researcher’s clothing and activity level, perceived productivity level, outside temperature and how cold or hot the researcher felt at that moment. A -3 to +3 score scale was adopted to record the subjective analysis.
Observation
VERY DISSATISFIED <-----THERMAL SATISFACTION -----> VERY SATISFIED
Thermal satisfaction (+3 to -3) 4 3 2 1 0 -1
-3 -3 -3 -3 -2 -2 -2 -2 -1 -1 -1 -1 0 0 0 1 1 1 1 1 1 2 2 2 2 2 2 2 3
-2 -3 -4
COLD <----THERMAL SENSATION ----> HOT
Fig.1. Thermal sensation and satisfaction
In the research duration, the indoor temperature readings as per the UA-002-64 pendant sensor ranged from 47.2oF to 90.3oF. Since the researcher was unaware of the actual indoor temperature at the time of conducting the qualitative analysis on herself, a ‘thermal sensation’ value was noted on a scale of -3 to +3 being too cold to too hot. It was observed that the researcher felt most satisfied in the thermal range of -1 to 1 (slightly cool to slightly warm). The researcher felt neutral in some of the warmer temperatures and was most dissatisfied when the inside temperature was either too hot or too cold. Additionally, the dissatisfaction was more in colder temperatures compared to a higher tolerance in case of hotter temperatures.
This is a simple analysis and does not consider the researcher’s activity and clothing level at that time. Below is a graph (Fig.2) that talks in detail about these two aspects related to thermal comfort, which are in fact a human body’s two best strategies to cope with external temperature fluctuations.
4 3 2 1 0 -1 -2 -3 -4
Indoor Temperature Thermal satisfaction (+3 to -3)
Thermal sensation (+3 to -3)
Met score
Clo factor
Fig.2. A comparison of thermal sensation to satisfaction, activity level and clothing
High activity levels like running/brisk walking are associated with high metabolism and lead the body to generate a lot of heat. This can help a body to stay warm when it is very cold outside. Wearing thick woolen clothes and jackets cause the body to retain its own heat within the thick layers of clothing and is the easiest way for a body to stay warm. In this exercise, a generic -3 to 3 scale was applied on activity level (met score) and clothing level (clo factor) to form a relation between these aspects to thermal satisfaction.
It can be observed that metabolism and clothing have a very important role to play in thermal sensation and satisfaction.
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The maximum satisfaction was recorded when the indoor temperature readings were 60F to 70F. However, a few anomalies can be observed even within this comfort range.
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At reading no.10, when the indoor temperature is a comfortable 61F, the researcher feels dissatisfied due to the very low met score (sleeping).
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On a lower temperature, the same day (60F), the level of satisfaction was very high due to the high metabolic rate and clothing factor.
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As the temperature goes higher, the researcher reduces her clothing levels. The metabolism remains lightly active and the comfort level drops gradually.
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At 76F, the researcher is involved in a form of high-level physical activity (running) and copes with this by reducing the clo factor drastically. She now feels warm and slightly dissatisfied instead of feeling very warm and dissatisfied.
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At extreme temperatures, comfort is best regulated by using both coping mechanisms, clothing level and metabolism rate. (Putting on extra layers when cold, removing them when hot; walking around/jumping when too cold and resting when too hot).
Conclusion Human satisfaction and productivity are very sensitive to the external temperature conditions. Although we humans can survive in wide ranges of temperature, we like our indoor environments to be conditioned in a certain way. Anything above or below that comfortable range can disrupt the satisfaction and productivity of an individual.
Productivity 3.5 3 2.5 2 1.5 1 0.5 0 -3 -3 -3 -3 -3 -2 -2 -2 -1 -1 -1 -1 -1 -1 -1 -1 0
0
2
2
2
2
2
3
3
3
3
3
3
Thermal Satisfaction Productivity
Fig.2. A comparison of thermal satisfaction and productivity
During this research, I learned how strongly my thermal comfort influences my productivity. Most importantly, I try to regulate my thermal sensation by increasing or decreasing my clothing levels and activity. I use this mechanism, involuntarily, all the time and only noticed my behavioral pattern to be working so effectively every single time.