Previous Upgrades Assessment

During the summers of 2008, 2009 and 2010, the Facilities Management Division (FMD) at UOW received a high number of complaints due to thermal discomfort from the occupants located mainly in the first floor (4.109-4.109a, which are labelled as air- conditioning upgrade conducted in 2010 in Figure 7.3) and north facing offices in the east wing of Building 4. Occupants’ complaints triggered FMD actions to assess the indoor environmental quality in office 4.109, 4.109a and 4.109b. Hence, during summer 2009-2010, specifically from 14/12/2009 to 17/12/2009 for offices 4.109 and 4.109a, and from 5/03/2010 to 12/03/2010 for office 4.109b, indoor air temperature and relative humidity monitoring along with air quality spot check measurements, principally CO2 and CO, were conducted. Results showed that monitored indoor temperatures fluctuated, but most of the time exceeded the acceptable temperature range of 20°C- 26°C. Mean temperatures were 26.1°C for 4.109-4.109a and 25.8°C for 4.109b, reaching a maximum temperature of 29.3°C and 27.3°C, respectively. Based on these results, air-conditioned was installed in these offices. In regards to air quality, the readings were below the maximum limit from ASHRAE Standard 62.1 (2007). However, no measurements were taken for the first floor north-facing offices located in the east wing, where also numerous occupants complained due to thermal discomfort. Therefore, one of the occupants located in this area, specifically in 4.129, set-up thermocouples (Figure 7.3 shows the location of the thermocouples measurements) to monitor indoor air temperatures over summer 2010, from 1st November 2010 to 28th February 2011, in three offices deemed as uncomfortable, i.e. 4.129, 4.130 and 4.G34. The mean and maximum indoor air temperature recorded during the monitored period is described in Table 7.3.

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Table 7.3 Monitored mean indoor air temperature and maximum indoor temperature

from 1st November 2010 to 28th February 2011 for offices located in the east wing of Building 4.

Office Indoor mean

temperature (°C) Indoor maximum temperature (°C) Standard deviation (°C) 4.130 26.3 34.4 2.2 4.129 25.8 34 2.6 4.G34 25.5 33.5 1.6

The high indoor temperature readings over summer 2010 were provided to FMD as evidence of the overheating issues. The data shows that temperatures consistently above 26ºC were reached in the first floor offices, with maximum indoor temperature over 34ºC. Complaints reached a crescendo leading to the Deputy Vice-Chancellor (Operations) meeting with the affected staff to try to resolve the problem. This, in turn, prompted a decision by senior management and FMD to install a 23-kW Daikin air- conditioning system servicing the first floor north facing offices of the east wing in January 2012 (specified as air-conditioning upgrade implemented in 2011 in Figure 7.3). The assessment of alternative retrofit measures that potentially could have avoided the installation of the air-conditioning system is presented in §7.4.

Building 4 Energy Signature Assessment

Energy consumption data was acquired and analysed from the 1st November to the 15th December for each of the years 2011, 2012, and 2013, both before and after the air- conditioning system upgrade. Similarly, the ambient hourly dry bulb temperature was extracted from the Bureau of Meteorology’s Bellambi weather station dataset for the years 2011 and 2012 and from the roof-top weather station on Building 4 (installed by the present author) for 2013. The resultant energy signatures, constructed with the total energy consumption monitored for these periods, is shown in Figure 7.5. The parameters of linear best fit, i.e. coefficient of determination and the slope of the linear regression are presented in Table 7.4.

The energy signatures showed lower daily energy consumption for given outside air temperature for 2013 as compared to 2011 and 2012. This could be attributed to changing the air-conditioning set-point in some parts of the building (for instance increasing the temperature set-point of the air-conditioning) or lower internal loads, e.g. lower lighting consumption due to a few inoperable light fittings or occupant behaviour. A slight difference in slopes was also observed. The lower slope in 2011 was likely to

171 be primarily due to the lower demand for cooling because of the air-conditioning upgrades in early January 2012.

Figure 7.5 Energy Signature for Building 4 comparing the period 1st November-15th December 2011, 2012 and 2013. Each point represents the daily energy intensity (8.00am to 5.00pm) against the daily average air temperature for weekdays.

Table 7.4 Slope and coefficient of the determination for the linear best fit of the

different energy signatures.

Year Energy Signature Slope (kWh/m2 °C) R2

2011 0.00425 0.73

2012 0.00556 0.52

2013 0.00501 0.69

Buildings at UOW main campus that were similar to Building 4 in terms of construction characteristics (Building 18), decade where the building was built/ major refurbishment was undertaken (Building 3 and Building 22) as well as a recently constructed building (Building 32) were compared against Building 4 energy signature (Figure 7.6 and Table 7.5). Their energy consumption data was obtained following §5.2) and analysed from the 1st November to the 15th December 2012.

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Figure 7.6 Energy Signature for different buildings at UOW main campus from 1st

November 2012 to 15th December 2012. Each point represents the daily energy intensity (8.00am to 5.00pm) against the daily average air temperature.

Table 7.5 Slope and coefficient of the determination for the linear best fit of the

different energy signatures of the buildings in Figure 7.6.

Building Energy Signature Slope (kWh/m2 °C) R2

3 0.016 0.56

4 0.0056 0.52

18 0.0054 0.21

22 0.067 0.80

32 0.021 0.79

Building 4 presented comparable energy signature slope with Building 18 (Table 7.5). This is most probably attributed to the characteristics of the buildings. That is both buildings have similar percentage of conditioned spaces (40% versus 45%) and similar construction materials, i.e. external walls are double brick, with concrete slab floor, approximately 20% of fenestration and metal deck roof. The energy intensity in Building 18 was around six times higher than Building 4 due to the amount of laboratories and fume cupboards present.

Similar decade buildings (i.e. 3 and 22 from the late 90s early 00s, respectively) presented higher slopes than Building 4 despite both buildings showed equal or lower percentage of conditioned spaces. Therefore, possibly the higher cooling slope might be due to lower air-conditioning system COP. Additionally, the building fabric thermal performance could be poorer in Building 22 than Building 4; Building 22 was initially build in the mid 60s despite undergoing through major refurbishments in 1997.

173 The newest building of the studied in this section, 32, also presented a higher slope than Building 4. This is most probably because of a higher cooling demand, i.e. this building has 90% of the spaces, mostly offices, laboratories and lecture theatres, conditioned through the BMS during occupancy times.

Thermal Comfort Assessment

The indoor temperature measurements were conducted one year before installation of the new 23-kW air-conditioning (i.e. from 15th November 2010 to 24th January 2011) and after two years of the air-conditioning operation (15th November 2013 to 24th January 2014). The thermal comfort results for the two offices monitored with thermocouples (i.e 4.120 and 4.129, which location is shown in Figure 7.3) in terms of the percentage of occupied time exceeding certain temperatures are shown in Figure 7.7. According to UOW Work Health and Safety (WHS) guidelines, a thermally comfortable work space should be between 20°C to 26°C (UOW WHS Unit 2012). Two additional offices (4.126 and 4.132) were monitored only after the air-conditioning retrofit (15th November 2013 to 24th January 2014) with the iButtons A (iButtons are separated in A and B as defined in Figure 7.3, depending on the period and locations of the measurements) in terms of temperature and relative humidity. In this case, as humidity was considered, ASHRAE 55-2013 was applied to assess the thermal comfort results.

Figure 7.7 Percentage of occupied hours (8.00am to 5.00pm weekdays) when given temperatures were exceeded. The measurement period corresponds to before and after the air- conditioning was installed. That is from 15st November 2010 to 24st January 2011, and from 15st November 2013 to 24st January 2014, respectively. The Christmas period from 20th December to 3rd January was not included.

174 It is appreciated that installing air-conditioning reduced by 10 times the indoor air temperatures above 26°C in these two offices. The dry-bulb air temperature, humidity ratio, and comfort limits are shown in Figure 7.8. The percentage of time office 4.132 was outside the comfort zone, during normal occupancy hours, was approximately 30%, using the ASHRAE 55-2013 criteria. Indoor temperatures above 28°C occurred during more than 10% of the occupied period. In contrast, office 4.126 was outside the comfort limits only 13% of the occupied time, with temperatures above 28°C for less than 1% of the time. Therefore, the installation of air-conditioning appeared to address the overheating problem for offices 4.126, 4.129 and 4.130. However, the results in Figure 7.8 showed that office 4.132 was still uncomfortable for much of the time. To explore this issue further, indoor air temperatures were correlated with outdoor temperatures for conditioned office 4.126 and 4.132. Unconditioned office 4.G34 is also shown to demonstrate the correlation between indoor air temperature of unconditioned offices with the outdoors air temperature (Figure 7.9).

Figure 7.8 Air temperatures with acceptable comfort zone for summer and winter

clothing for office 4.126 and 4.132 (Air temperature is used instead of operative temperature, however as it is summer, the radiant temperature is expected to be higher than the air temperature and therefore operative temperature > air temperature).

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Figure 7.9 Indoor air temperature correlated with outdoor air temperatures for two

conditioned offices (4.126 and 4.132) and unconditioned ground floor office (4.G34).

The smallest coefficient of determination between indoor and outdoor temperature is presented for the conditioned office 4.126, whilst the higher correlation between indoor and outdoor temperature is the non-conditioned office (4.G34). Office 4.132 shows a coefficient of determination slightly higher (r2=0.27) than 4.126. This indicated that the relationship between the indoor and outdoor temperature is stronger in 4.132 than in 4.126, supporting the idea that the air-conditioning is probably not working as intended for that particular office. Therefore, the air-conditioning should be re-commissioned to determine whether there are any problems in the ducting system or the diffusers need to be balanced.