Overall Building Performance

After examining the values of all the aforementioned KPIs, the normalised value for each building 𝛷j was obtained. In this example, for simplicity the subjective weighting was assumed the same across all KPIs, whereas typically it was expected to vary in each case depending on stakeholder needs and priorities. Table 5.6 shows the priority list of overall performance value, averaging all KPIs for the worst 15 buildings. The KPIs considered here were energy performance (electricity consumption and peak-to-average demand ratio), water consumption, complaints performance (comfort complaints, envelope complaints, plumbing and HVAC maintenance complains), Work, Health and Safety (WHS) hazards related with temperature and space utilisation. They included ranking, building name and performance value calculated following §4.4.2 Eq. 4.6.

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Table 5.6 Prioritisation list for all KPI

Table 5.7 provides information available for UOW Main Campus buildings with respect to when they were due for capital investment and/or replacement, i.e. significant work with an expenditure above $30,000 within two years of the time of writing, and the anticipated nature of the works, as recommended in the Building Condition Appraisal Reports. The buildings that showed the worst overall performance (Table 5.6) were typically scheduled for capital works in the following year (Table 5.7), e.g. Building 18, 41, 20, 31 and 36.

Rank Building Aggregated Weighting, 

1 18 -208.2 2 41 -181.3 3 5 -107.7 4 20 -106.7 5 42 -97.8 6 36 -94.9 7 28 -77.8 8 39 -76.3 9 37 -70.6 10 2 -67.6 11 35 -62.3 12 10 -61.4 13 30 -61.4 14 4 -55.1 15 1 -47.9

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Table 5.7 Building year due for capital investment and type of replacement for the next

three years

Building number

Year due for capital investment

Type of capital investment/replacement

20

2014

Office Level 1 refurbish/Lecture theatre refurbish

11 Office spaces (west) and HVAC refurbish

36 HVAC and electrical upgrades

39 Security system and fire system upgrades

22 Upper level refurbish/Lower level refurbish

4

staff offices, circulation spaces and electrical distribution upgrades/ refurbish research student offices and teaching spaces

2 HVAC upgrades

41 offices and corridors upgrades

17

2015

HVAC upgrades & student central and ground floor upgrades

16 Lighting upgrades/ Roof upgrades

14 Lecture theatre sittings and finishes and lighting control

upgrades

67 Office refurbishment/ HVAC upgrades

19 Upgrade security

3 HVAC upgrades

40 HVAC upgrades/ lighting upgrades

10

2016

bathroom and HVAC upgrades

18 HVAC upgrade, i.e. replace fume cupboards and lab

finishes

25 spaces upgrades (teaching rooms, lecture theatres,

performance theatre and music rooms)/offices upgrades

28 Offices and teaching spaces upgrades

36 Fabric (walls, ceiling and tiles) upgrades

23 Ground level upgrades

This procedure facilitated the comparison of the buildings performance across different KPIs. It was possible to examine the performance of a particular building further. This was demonstrated via the results obtained from the in-depth audits, modelling, and retrofit identification outlined in the next chapters.

5.6 Summary

This chapter has outlined how the proposed building portfolio characterisation process and decision support framework was applied to the University of Wollongong building stock portfolio as a case study.

139 Relationships between space typologies and KPIs were investigated. Laboratories were found to be the space type with the highest energy consumption, whilst buildings with naturally ventilated offices demonstrated lower energy consumption compared to other spaces. The building performance for each KPI and the probable reasons for any high and low performance were investigated and then, the correlations between the different KPIs were examined. Results indicated that recently constructed buildings tended to have less complaints recorded than older buildings, but those buildings due for capital investment/work were more likely to have higher occupant’s complaints. Therefore, a larger budget should be allocated to maintenance of older buildings.

The framework proposed provided a normalised baseline performance for each KPI and building, and allowed each building to be ranked on the value of the KPI. This combination through the objective weighting of KPIs for each building resulted in a ranked list of UOW buildings for upgrading.

Once a building has been selected for upgrading, the next step was to conduct a comprehensive audit to understand how the building performs across a broad range of attributes, which, in turn, will reveal the detailed building characteristics and help to identify an optimal retrofit strategy. The methodology for determining the best retrofit strategy is explained in the next chapter.

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6. Building Retrofit Optimisation Methodology

6.1 Introduction

This chapter describes the methodology used to identify optimal retrofit strategies to be implemented on individual university buildings. It is divided into two major parts as shown in Figure 6.1.

Figure 6.1 Process schematic to find an optimal retrofit strategy.

The method involves:

 Building Performance Assessment. Experimental techniques are used to evaluate building performance, revealing how data is collected through a comprehensive audit and survey of occupant perceptions via a Post Occupancy Evaluation (POE).

 Retrofit Optimisation. Entails simulating a building to create a calibrated model and then performing a sensitivity analysis to reveal the most significant parameters affecting energy consumption and thermal comfort. Those

141 parameters and their associated costs in retrofitting are then used to define an ‘objective function’, which is then minimised to provide optimal values of the parameters of interest.

The following sections outline the methodology used for assessing building performance and developing the building simulations.