The house has two storeys with a total floor area of 213 m2 and has well insulated reverse brick veneer external walls. The windows of the house are double glazed 4 mm clear with 12 mm argon filled and low E film. It has solid construction external doors.

Figures 2 — 4 show monthly profiles of cooling, space heating and domestic water heating loads for the house exposed to Adelaide, Brisbane and Sydney typical year weather data.

Fig. 3. Monthly cooling, DHW and SH load profiles — BRISBANE

Fig. 4. Monthly cooling, DHW and SH load profiles — SYDNEY

Monthly cooling and space heating loads for the house were calculated using AccuRate package [9]. The house exposure to different weather data results in 6.9, 7.7, and 7.6 star ratings of the house in Adelaide, Brisbane and Sydney. The star rating is a measure of energy performance of the house based on the fabric and form, not including the effect of the cooling / heating system used in the house. This rating system is mandatory for new Australian houses.

Adelaide is a semi arid region with low humidity, mild winter and hot summer. Brisbane is warmer with relatively high humidity, mild summer and short heating period. Sydney is cooler and less humid and has a slightly longer heating season than Brisbane. These are clearly illustrated in Figs. 2 — 4 above and Fig. 5 which shows the montly latent load as a percentage of the total load.

J FVIAMJ J ASOND Fig. 5. Latent load as a percentage of total cooling loads

The monthly figures for DHW loads were derived from Australian Standard 4234 [10] for a medium size system which provides seasonal (monthly) load profile, hourly load profile and monthly cold water temperatures. Monthly space heating (SH) and cooling loads were estimated using an Australian building energy rating software, AccuRate.

Monthly profile total loads are shown in Fig. 6. As seen, Adelaide monthly total loads are much higher than Brisbane and Sydney loads which are very similar. As expected, monthly loads peak in peak summer and winter months and level during spring and autumn.

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2. Results and Discussions

For the analysis, the main metrics used to illustrate the system performance are the solar fraction (SF) and total useful heat. Solar fraction is defined as the fraction of solar energy used to satisfy the load. The load not met by solar energy is handled by an auxiliary system.

Figure 7 shows the solar fractions as functions of collector area for systems serving houses in the three cities. Two hot water tank sizes (315 L and 450 L) were studied; the collector were tilted at 25° and 45 °C.

As shown, for Brisbane and Sydney, a collector area of 6 m2 can provide more than 80% of the heat required for cooling, heating and hot water. On the other hand, for Adelaide, much lower solar fractions are delivered by the same system size without much improvement in the solar fraction when a larger collector area is used. Two other interesting findings revealed by Fig. 7 are: (1) a tank size of 315 L performs as well as 450 L tank, and (2) collector slope between 25 — 45 is insensitive to system performance.

Fig. 7 shows clearly that for Brisbane and Sydney, application of an integrated thermal system is appropriate. On the other hand, due to drier climate (Fig. 5), the application of such a system in Adelaide is not leading to large energy savings.

Futher analysis shows that thermal performance of an integrated thermal system is as good as the combisystem performance (heating and hot water only) in terms of solar contribution to handle the total load (Figs. 8 — 9).

2 3 4 6 8 10

Collector Area, m2

Fig. 8. Solar Fraction for Combisystem (heating and hot
water only) and Integrated System — Brisbane

4 6 8

Collector Area, m2

Fig. 9. Solar Fraction for Combisystem (heating and hot
water only) and Integrated System — Sydney

The system performance can also be measured in terms of monthly useful energy delivered by the system to satisfy the loads. This is illustrated in Figs. 10 — 11 which compare the useful heat delivered by an integrated thermal system and a combisystem with a 6 m2 collector area installed in Brisbane and Sydeny. As shown, the integrated system delivers much higher useful energy than the combisystem, particularly during the summer months. For a collector area of 6 m2 and a 315 L storage tank, the annual useful heat delivered by the intgerated system for Brisbane and Sydney are 17.0 GJ and 11.6 GJ, respecticely, compared to 15.7 GJ and 11.9 GJ delivered by the combisystems.

3. Conclusion

An analysis of the thermal performance of an integrated heating system for the provision of hot water, space heating, cooling and dehumidification has been presented. It was observed from numerical investigation that for a location like Adelaide with semi arid climate, such a system will work with a minimum role for the solar liquid desiccant cooling sub-system. In such a case, a combisystem or the use of an absorption cooling system is more suitable. On the other hand, for locations such as Sydney and Brisbane, such systems are appropriate. An integrated thermal system with a 315 L tank, and a 6 m2 evacuated tube collector area can serve typical house in either Brisbane or Sydney.

References

[1] Australian Greenhouse Office, Australian Residential Building Sector — Greenhouse Gas Emissions 1990 — 2010 — Executive Summary Report, 1999.

[2] Lee, T., Ferrari, D., Donnelly, E. (2003): Active Solar Space Heating for a Cool Temperate Climate: A Case Study, 41st ANZES Solar Energy Society Conference, Melbourne.

[3] Saman W. Y. and Mudge, L. 2002, Development, implementation and promotion of a scoresheet for household greenhouse gas reduction in South Australia, Australian Greenhouse Office.

[4] Henning, H.-M. (2004): Solar Air-Conditioning of Buildings, EuroSun2004, Freiburg, Germany, 24.­26.6.04.

[5] Krause, M., Saman, W. Y. Vajen, K. (2005), Regenerator Design for Open Cycle Liquid Desiccant Systems — Theoretical and Experimental Investigations, International Conference on Solar Air Conditioning, Staffelstein, Germany, 6.-7.10.2005.

[6] Krause M., Saman W. and Vajen K. (2006): Optimisation of a regenerator for open cycle liquid desiccant air conditioning systems, Proc. 2006 Eurosun Conference, Glasgow, Scotland.

[7] TRNSYS 16 Reference Manual, 2004.

[8] Halawa, E., Bruno, F., Saman, W. (2007): Potential Application of Combisystem for An Australian Climatic Region, ISES Solar World Congress 2007, Beijing, September.

[9] Hearne Website — http://www. hearne. co. nz/ — Residential Building Thermal Performance Assessment (2006) — viewed 20 June 2007.

[10] Australian Standard AS 4234-1994: Solar Water Heaters — Domestic and Heat Pump — Calculations of Energy Consumption.