This section provides results from the analysis of the indoor climatic measurements inside the sample houses and in particular, examines how the indoor thermal temperatures compare to the ASHRAE Standard 55-2010 (ASHRAE 2010). Particular attention was paid to those occasions when the room was occupied. Therefore, any time between 0700 hrs and 2100 hrs was designated as occupied hours. A more specific marker of occupancy was also used, namely the occupant’s response on the smartphone questionnaire (see Section 3.8). Occupancy of bedrooms was deemed to occur after 2100 hrs and before 0700 hrs.
Table 3.5 presents a summary of the indoor and outdoor climate in Sydney during the 2012/13 summer season (between December 2012 and March 2013). The average temperature across the different types of room was 24.4°C, which was significantly higher than the outdoor temperature with an average daily mean of 22.7°C. The range of temperatures within each type of room was fairly consistent, ranging between 15°C and 37°C. Dining rooms recorded, on average, the coolest indoor temperatures. As shown in Figure 3.11, the majority (82.8%) of indoor temperatures recorded from the iButtons placed in the participants’ living rooms were within the range of 22–28°C, with an average of 25.0°C.
46 A Framework for Adaptation of Australian Households to Heat Waves
Table 3.5: Statistical summary of the indoor and outdoor climate measured across the sample of Sydney households between 1 December 2012 and 6 March 2013
Note: Temperatures within the living and dining rooms, study and kitchen were calculated between 0700 hrs and 2100 hrs and bedroom temperatures were calculated between 2100 and 0700 hrs.
Figure 3.11: Histogram of hourly living room temperatures in the sample of Sydney houses
Table 3.6 presents a summary of the indoor and outdoor climate for the sample of Adelaide houses between January and March 2012. The average temperature inside the living room with or without the air conditioner operating was approximately 2°C warmer than the mean outdoor temperature throughout the same period. As indicated in the responses from survey participants, bedroom temperatures were higher than the living room temperatures. Figure 3.12 shows the frequency distribution of the indoor temperatures in the living rooms between January and March 2012.
A Framework for Adaptation of Australian Households to Heat Waves 47 Table 3.6: Statistical summary of the indoor and outdoor climate measured
across the study in Adelaide between January and March 2012
Daily
Figure 3.12 Histogram of hourly living room temperatures in the sample of Adelaide houses
Table 3.7 presents a summary of the indoor and outdoor climate in Brisbane during both the 2011/12 and 2012/13 summer seasons. The average temperature (0700–
2100hrs) across all living rooms in the sample households was 26.5°C, about two degrees warmer than outdoor average temperatures during the same hours (24.4°C).
As shown in Figure 3.13, the majority (77.7%) of indoor temperatures recorded from iButtons placed in the participants’ living rooms were within the range of 23–28°C.
48 A Framework for Adaptation of Australian Households to Heat Waves
Table 3.7: Statistical summary of the indoor and outdoor climate measured across the sample of Brisbane households January–March 2012 and December 2012–March 2013
Daily Mean Outdoor
(°C)
7-Day Outdoor Running Mean (°C)
Living Room Temperature
(°C)
Bedroom Temperature
(°C)
Mean 24.4 24.4 26.5 NA
Min. 20.7 21.6 18.2 NA
Max. 29.6 26.8 41.5 NA
N 5,485 5,485 5,485 NA
SD 1.50 0.67 2.46 NA
Note: Temperatures within the living room were calculated between 0700–2100 hrs. Bedroom temperatures could not be calculated due to small sample size
Figure 3.13 Histogram of hourly living room temperatures in the sample of Brisbane houses
Differences between types of room
Figure 3.14 illustrates the distribution of indoor temperatures for each type of room within the Sydney sample during the 2012/13 summer season. The dining rooms’
temperature distribution appears to be displaced to be about 2°C cooler than the other types of rooms in the sample. The iButton data collected from the Brisbane study did not provide enough data to allow for a separate analysis by room. Since most houses studied in Adelaide had combined living and dining rooms and only a few had separate rooms used as a study, no analysis of the differences between rooms is shown here.
The statistics of the bedroom temperatures were presented above in Table 3.6.
A Framework for Adaptation of Australian Households to Heat Waves 49 Figure 3.14 Distribution of indoor temperature between room types during
occupied hours
Note: Living room, dining room, study and kitchen all for 0700–2100 hrs (bedrooms 2100–0700 hrs) in Sydney, normalised according to the number of observations per room type.
Compliance of room temperatures with ASHRAE’s adaptive comfort ranges (ASHRAE 55-2010R)
Indoor temperatures recorded in each household’s living room during summer were plotted against a weighted, 7-day running mean of outdoor temperature recorded from the nearest BOM weather station. These observations represent the full records made by iButton monitors, regardless of the room’s occupancy status. Superimposed on the same scatter plot are the 80% and 90% ASHRAE adaptive thermal acceptability limits.
These limits define the warmest and coolest acceptable indoor temperatures (de Dear
& Brager 2002; ASHRAE 2010). Indoor temperatures outside these limits are deemed by ASHRAE 55-2010 to be unacceptable.
Results from the Sydney study
Figure 3.15 shows the indoor temperatures recorded between 0700 hrs and 2100 hrs (occupied hours) during summer in Sydney. As illustrated, the majority of indoor temperatures (ranging between 20–28°C) during the months of December, January and February were within the 80% and 90% ASHRAE acceptability limits suggesting that most participants would have felt comfortable during these times. It was found that 85.6% (18,779 hours) of the total number of hours of indoor living room temperatures were within the upper and lower 80% ASHRAE acceptability limits (between 20–23°C and 27–30°C). This suggests a high level of compliance with the adaptive comfort standard as proscribed in ASHRAE Standard 55-2010 (ASHRAE 2010).
50 A Framework for Adaptation of Australian Households to Heat Waves
Figure 3.15: Living room temperatures (0700–2100 hrs) during summer in Sydney compared to ASHRAE Standard 55-2010, with 80% (solid line) and 90% (dashed line) acceptability limits
Note: Each data point represents an hourly average of the indoor temperature.
With regard to indoor bedroom temperatures, the times in which these rooms would most likely be used were classified as being between the hours of 2100 hrs and 0700 hrs. Figure 3.16 shows the range of indoor temperatures recorded within all bedrooms within the Sydney sample households during the 2012/13 summer season.
As the times at which most people used their bedrooms corresponded to night-time temperatures, the bedroom temperatures appeared to be much cooler than those for the living rooms. Indoor temperatures within the bedrooms ranged from 20–28°C throughout the summer season. Hence, only 1,355 hours (16.3%) were outside the upper and lower 80% ASHRAE acceptability limits suggesting a wide range of acceptable temperatures.
Figure 3.16: Bedroom temperatures (2100–0700 hrs) during summer in Sydney compared to the ASHRAE Standard 55-2010 80% (solid line) and 90% (dashed line) acceptability limits
Note: Each data point represents an hourly average of the indoor temperature.
A Framework for Adaptation of Australian Households to Heat Waves 51 Results from the Adelaide study
Figure 3.17 shows the results of the monitored indoor temperatures of the living room in the apartment building for the summer period (January–March 2013). Most of the observed temperatures within the living rooms were within the ASHRAE 80%
acceptable limits, and were only outside the ASHRAE acceptable limits for 7.6% of the time spent. On the other hand, the bedrooms had a higher percentage of time spent outside the ASHRAE 80% acceptable limits, with 12% of the time spent above the upper threshold (Figure 3.18). Overall, the living rooms and bedrooms performed quite well considering the air conditioners were rarely used.
10 15 20 25 30 35
5 10 15 20 25 30 35 40
Indoor Temperature (C)
7 -Day Running Mean Outdoor Temperature (C)
Figure 3.17: Living room temperatures (0700-2100hrs) during summer in Adelaide compared to ASHRAE Standard 55-2010 80% (solid line) and 90%
(dashed line) acceptability limits
Note: Each data point represents an hourly average of the indoor temperature.
Figure 3.18: Indoor bedroom temperatures during summer in Adelaide compared to the ASHRAE Standard 55-2010 80% (solid line) and 90% (dashed line)
acceptability limits
Note: Each data point represents an hourly average of the indoor temperature.
52 A Framework for Adaptation of Australian Households to Heat Waves
Results from the Brisbane study
Figure 3.19 shows the indoor living room temperatures recorded between 0700 hrs and 2100 hrs (occupied hours) during summer in Brisbane. Compared to the range of temperatures recorded in the Adelaide and Sydney studies, the Brisbane living room temperatures had a greater scatter, with more frequent exceedences of the ASHRAE 55-2010 acceptability limits. Nevertheless, the majority (over 80%) of indoor temperature measurements within the living rooms fell within the 80% ASHRAE acceptability limits.
Figure 3.19: Living room temperatures (0700–2100 hrs) during summer in Brisbane compared to ASHRAE Standard 55-2010 80% (solid line) and 90%
(dashed line) acceptability limits
Note: Each data point represents an hourly average of the indoor temperature.
Trigger temperature for air conditioning on cooling mode (during summer)
The preceding analyses detailed the indoor temperature of the living rooms in the sample households for Sydney, Adelaide and Brisbane between the hours of 0700 and 2100. From these results, it is possible to calculate the room temperature at which participants started to use their air conditioner units for cooling purposes. This was deemed to be when a difference > 5°C was observed between the supply air of the air conditioner unit and the occupied zone of the living room. The graph in Figure 3.20 illustrates those excerpts from the total iButton records of living room temperatures recorded when the air conditioner was operating in cooling mode. The graph illustrates that the majority (90%) of indoor temperatures when the air conditioner was on fell within the ASHRAE 80% acceptability limits. From this analysis, it was estimated that the average Sydney living room trigger temperature for the air conditioner in cooling mode was about 26°C.
A Framework for Adaptation of Australian Households to Heat Waves 53 Figure 3.20: Indoor living room temperatures (0700–2100 hrs) during summer in Sydney when the living room A/C unit was operating in cooling mode compared to ASHRAE Standard 55-2010 80% (solid line) and 90% (dashed) acceptability limits
Note: Each data point represents an hourly average of the indoor temperature.
Figure 3.21 presents a similar analysis of indoor bedroom temperatures during the times in which participants were using their air conditioner unit for the Sydney sample.
While the sample size was smaller than for the living room analysis above, the graph indicates that over 60% of air-conditioned bedroom occupied hours during Sydney’s summer were cooler than the lower 80% ASHRAE acceptable temperature limit. The adaptive model contained no bedroom data and these observations indicate that, in its current format, it should probably not be applied to sleeping quarters. Figure 3.21 also illustrates that participants frequently left their bedroom air conditioner unit running while they slept, because the average room temperature was 17°C.
Figure 3.21: Indoor bedroom temperatures (2100–0700hrs) during summer in Sydney when the bedroom A/C unit was operating in cooling mode compared to ASHRAE Standard 55-2010 80% (solid line) and 90% (dashed line) acceptability limits
54 A Framework for Adaptation of Australian Households to Heat Waves
Note: Each data point represents an hourly average of the bedroom temperature.
Results from the Brisbane study
Figure 3.22 illustrates that the range of indoor living room temperatures within the Brisbane households was quite different to those from Sydney (as was shown in Figure 3.20). It should be noted that there were less data available for the Brisbane study (the Sydney study had a total of 1,052 hours of data whereas the Brisbane study only had 230 hours). The average living room temperature of 24°C in Brisbane’s summer during air conditioner operation was 2°C cooler than that observed in the Sydney sample.
Figure 3.22: Indoor living room temperatures (0700–2100 hrs) during summer in Brisbane when the living room A/C unit was operating in cooling mode
compared to ASHRAE Standard 55-2010 80% (solid line) and 90% (dashed line) acceptability limits
Note: Each data point represents an hourly average of the indoor temperature.
Indoor temperature versus ASHRAE Standard
To understand how the participants’ indoor thermal environment at the time of answering the questionnaire compared to the adaptive comfort model in ASHRAE Standard 55-2010 (ASHRAE 2010), the data were plotted against a running 7-day mean of the outdoor temperature. Figures 3.23, 3.24 and 3.25 show the range of indoor temperatures experienced by the participants at the time they answered the survey in Sydney, Adelaide and Brisbane respectively. In all locations, the majority of indoor temperatures (above 80%) fell between the upper and lower limit of acceptable temperatures (20–30°C in Sydney, 19–30°C in Adelaide, and 21–30°C in Brisbane) as defined by ASHRAE Standard 55-2010.
A Framework for Adaptation of Australian Households to Heat Waves 55 Figure 3.23: Concurrent indoor temperature for the Sydney study at the time of answering the comfort questionnaire plotted against 7-day running mean outdoor temperature compared to ASHRAE Standard 55-2010 80% and 90%
acceptability limits
Figure 3.24: Concurrent indoor temperature for the Adelaide study at the time of the comfort questionnaire plotted against 7-day running mean outdoor
temperature compared to ASHRAE Standard 55-2010 80% and 90% acceptability limits
Notwithstanding the small sample size and short duration of the Brisbane study, Figure 3.25 indicates that about three-quarters (72%) of the data points for occupied hours during air conditioner operation in living rooms were within the 80% ASHRAE acceptability limits: the remaining quarter of the observations fell above the upper threshold (28–30°C).
80% ASHRAE Lower
56 A Framework for Adaptation of Australian Households to Heat Waves
Figure 3.25: Concurrent indoor temperature for the Brisbane study at the time of the comfort questionnaire plotted against 7-day running mean outdoor
temperature compared to ASHRAE Standard 55-2010 80% and 90% acceptability limits