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In the first stages of research, building modelling using EnergyPlus was carried out to develop the theoretical base for the decay method. During this time the test cells at Highett had temperature sensors and heat flux meters collecting data. blower door tests and heat-flux tests were conducted to inform creation of the EnergyPlus model for the rest of the simulations. Co-heating tests and decay tests were also carried out on the test cell.

Differences between the heat flux and the co-heating tests were then analysed via building simulations. Analysis of the experimental decay methods was then compared with the HTC from the co-heating tests conducted on each configuration. Finally building models that generated different decay test profiles were analysed with the goal of showing how the decay coefficient related to the HTC. First, this increased the number of data points for the experimental methods, and second, was the basis of the RMSE analysis. The success of the experimental methods is based on the ability to identify both a clear difference in the decay analysis of each case study, and the relationship between the decay coefficient and the HTC.

The RMSE tests already provide the link between the decay experiments and the co-heating experiment by simulating them on the same computer model. However, the success of

110 these variants is determined by how reliably they predict the HTC from the co-heating test conducted in the field.

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- Evaluation of Benchmarking Results and Analysis

5.1 Overview

This chapter details results and analysis of the heat flux, blower door and co-heating tests carried out both in-field and with the EnergyPlus simulation program, primarily from the second period of experimentation within the research period. These evaluation methods are generally understood and provide benchmarks against which the decay method can be compared. It also discusses the outcomes of the initial field experimentation that influenced refinements of the experimental set up, having identified some basic limitations and potential sources of error and uncertainty.

Experiment Timetable

There are two ways of determining the building’s HTC – either summing the conductivity of the thermal shell area and the air leakage determined via heat flux testing and blower door testing, or performing the co-heating test. These two methods will be compared against the decay method to determine a level of aptitude and accuracy for the decay method.

To determine the sensitivity of the decay method, experiments on Test Cell 2 have been conducted with three different levels of insulation, laid out in Table 5.1. This allows for discussion of the sensitivities of the current methods, as well as providing the baseline for the decay method to be evaluated against. The results are grouped by experiment and any possible influences discussed before the experiments are compared to each other.

112 1, Test A Estimated R2.0 glass wool insulation in all

four walls. No insulation in subfloor or

1, Test B Estimated R2.0 glass wool insulation in all four walls. No insulation in subfloor or south-east, north-east and north-west walls, and western half of the south-west wall. No insulation in subfloor or ceiling.

2 July to 16 July

17 July to 31 July

3 Estimated R2.0 glass wool insulation in south-east, north-east and north-west walls. No insulation in subfloor, ceiling or experiments are, however, more reliable in steady state internal conditions, which the co-heating test provides. The heat flux data collected during the co-co-heating tests has been analysed and is treated as four separate tests for comparison. The heat flux data collected during decay testing has not been analysed as part of this research.

113 Weather Data

Figure 5.1 Location of weather station within the CSIRO site at Highett

Three sets of external measurements were collected during the co-heating tests: one by a thermocouple at the test cell attached to the Campbell datalogger, a second set by the CSIRO weather station at the northern end of the site, approximately 500 m away, as shown in Figure 5.1, and the third set from the Bureau of Meteorology (BoM) weather station at Moorabbin Airport, 5.5 km south-west of the CSIRO site. The thermocouple, attached to the Campbell datalogger, takes readings only of the air temperature every 60 seconds. The CSIRO weather station takes dry-bulb air temperature, relative humidity, wind, rain and

CSIRO operated weather station

Test Cells

114 solar radiation readings, but only every 15 minutes. Data from the Bureau of Meteorology weather station at Moorabbin Airport was collected at 60 second intervals, and includes air temperature, humidity, wind, and rain observations. 60-second solar data for the Melbourne area collected by the Bureau of Meteorology is only available from the Melbourne Airport weather station, situated 35 km to the north-west.

5.1.2.1 Temperature

Figure 5.2 Comparison of external temperature data sources

The external air temperatures for the experimentation period are compared in Figure 5.2.

The BoM data generally shows lower temperatures than those recorded by the CSIRO weather station, though overall trends are similar. This suggests the test cells may not be under as much stress as the BoM data indicates, and the analyses could be slightly overestimating the thermal shell’s efficiency. The test cell data (Campbell Scientific with thermocouple) has much larger fluctuation in temperature which is likely to be partially due to lack of calibration during the equipment set up. As specific details of the CSIRO weather station are unavailable, the BoM dataset is considered more reliable. The similarities between CSIRO data and BoM data indicate that the BoM data is still applicable to the Highett site despite being collected from 5.5 km away.

115 5.1.2.2 Solar Radiation

Figure 5.3 Solar radiation data comparison

The BoM solar radiation data shown in Figure 5.3 is generally higher than the CSIRO data;

however, it follows a similar trend. The BoM data is provided with quality flags against each reading, and includes the azimuth for each reading. Using BoM data instead of CSIRO data will increase the values of the HTC from the co-heating test as the solar gains term in the heat balance equation will be larger. This increase will only be marginal as the average power input from the heater is much larger than the daily average solar radiation. Average power from the heater across each day approaches 1800-2000 W where the average solar radiation is approximately 50-100 W.

CSIRO’s reputation indicates its data should be of good quality; however, there is no information available regarding the pyronanometer. Aside from the distance between the locations causing different readings due to cloud patterns, the CSIRO readings may simply be lower based on differences in equipment age and maintenance procedures in each organisation. As this information is available from the BoM regarding their data sets, and there is no significant difference in the pattern of solar radiation readings, the BoM data is

116 used for all analysis in this research. In addition to data quality, BoM data is recorded at 1-minute intervals which matches the rest of the data sets. This also makes it possible to build 1-minute weather files for EnergyPlus without interpolating between the 15-minute intervals of the CSIRO data.