Thermal sensitivity and adaptive comfort in mixed-mode office buildings in humid subtropical climate

Figures & data

Table 1. Summary of the characteristics of the three studied buildings adapted from (Khoshbakht et al., 2019).

ID	Green building certificate	Location	Climate	Year of built	GFA (m2)	HVAC	Interior	Air distribution	Orientation
B1	5 Green Star	Brisbane	Humid subtropical	2014	18,000	Zoned variable-air-volume	Mostly open plan	Desk vents	North South
B2	6 Green Star	Brisbane	Humid subtropical	2013	3,865	Evaporative cooling	Mostly open plan	Desk vents	North-East South-West
B3	6 Green Star	Gold Coast	Humid subtropical	2007	1,400	Split units	Mostly cellular	Overhead	North-West South-East

Table 2. Scale and response options of the real time thermal comfort survey adapted from (Khoshbakht et al., 2019).

Scale	Temperature
3	Hot
2	Warm
1	Slightly warm
0	Neutral
−1	Slightly cool
−2	Cool
−3	Cold

Table 3. Rating scales for preference questions in the survey questionnaire.

Scale	Temperature preference
−1	Cooler
0	No change
1	Warmer

Table 4. Summary of investigated rooms and subjective evaluations.

Demographic Information	Male	Female	Total
No. of participants	537	281	884
Average clothing insulation (clo)	0.5	0.5	0.5
Average age	34.7	35.4	35.0
Average metabolic rate (met)	1.1	1.1	1.1

Figure 1. An illustration of the location of the measurement tools on building plans, (a) B1, (b) B2 and (c) B3, adapted from (Khoshbakht et al., 2019).

Table 5. Instruments used for indoor environmental quality measurements (Khoshbakht et al., 2019).

Parameter	Instrument / sensor	Trade name	Time interval	Accuracy / calibration	Resolution / range
Air temperature (Ta)	Air Thermometer	Hux Connect	Continuous – every 5 min	±0.5 °C	5–60 °C
Globe temperature (Tg)	Globe thermometer	Hux Connect	Continuous – every 5 min	±0.5 °C	−25–85 °C
Air velocity (Va)	Handheld anemometer	Digitech	At the time of survey	±0.05 m/s	0–30.0 m/s
Relative humidity (RH)	Hygrometer	Hux Connect	Continuous – every 5 min	±2%	10–70%

Table 6. Environmental characteristics of the three mixed-mode buildings.

Variables	Min	Max	Average	Standard deviation
Air velocity (m/s)	0.3	0.6	0.3	0.1
Ta	19.8	33.2	25.3	1.8
Ta(out)	16.7	31.9	24.0	3.5
Top	20.3	33.6	25.8	1.9
Tpma(out)	13.4	26.1	20.8	3.8
Tn	21.9	25.9	24.3	1.2
TSV	−3	+3	−0.3	1.0
Tcomf	16.5	32.1	26.0	2.2

T_a = Indoor air temperature.

T_a(_out)= Mean daily outdoor air temperature.

T_op= Indoor operative temperature calculated using: T_op = (MRT + T_a) / 2 where MRT is mean radiant temperature.

T_pma(out)= Prevailing mean outdoor air temperature.

T_n= Neutral temperature calculated with ASHRAE 55’s adaptive model using: T_n = 0.31 T_pma(out)+ 17.8.

TSV = Thermal sensation vote.

T_comf = Comfort temperature using Griffith method T_comf = T_op – TSV/ G with G = 0.5.

Table 7. Distribution of the indoor operative temperature according to ASHRAE 55-2020 (ASHRAE Standards, 2020) adaptive thermal comfort of 80% and 90% acceptability limits during the survey periods.

ASHRAE 55-2020	Below	Within	Above
80% acceptability	<1%	89%	10%
90% acceptability	0%	97%	3%

Figure 2. Binned outdoor temperatures and TSV under NV and AC modes.

Figure 3. Thermal sensation votes regressed with temperature offset from neutrality, T_diff= T_op -T_n.

Figure 4. Participants’ thermal preferences have changed in response to thermal sensation. The lines show separate probit regression models that were fitted to the respondents’ ‘want cooler’ and ‘want warmer’ preferences.

Figure 5. Probit regression of participants’ thermal preference (TP) against the temperature offsets from Neutral temperature (T_diff).

Figure 6. The percentage of dissatisfaction in relation to temperature offsets from neutral temperatures (T_diff).

Figure 7. The correlation between indoor comfort temperature (T_comf) and prevailing mean outdoor temperature T_pma(out).

Figure 8. Comparison of the 80% temperature acceptability range of ASHRAE 55’s Adaptive model and the current study.

Khoshbakht, M., Gou, Z., & Zhang, F. (2019). A pilot study of thermal comfort in subtropical mixed-mode higher education office buildings with different change-over control strategies. Energy and Buildings, 196, 194–205. https://doi.org/10.1016/j.enbuild.2019.05.030

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ASHRAE Standards. (2020). Ansi/ASHRAE 55-2020: Thermal environmental conditions for human occupancy. American National Standards Institute, American Society of Heating, Refrigerating and Air-Conditioning Engineers.

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