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Caltex Airport StarMart (Canberra): Geothermal air conditioning and other energy efficiency measures

One of Canberra‘s newest service stations showcases a collection of energy saving ideas which prove that you can save many thousands of dollars in running costs every year, while still providing a comfortable environment for customers and employees during long hot summers and frosty winter mornings. The eco-efficiency achievements of its design were recognised when the site won the Master Builders‘ Association of the ACTACT Environmental Best Practice Award – Commercial Division in 2002. The key to its success lies in applying some commonsense, taking advantage of available technologies, and not simply accepting the way that such facilities are usually built.


In September 2001 Peter and Dianne Taylor opened a brand new Caltex Airport StarMart on Commonwealth land adjacent to the Canberra Airport terminal and an office complex. The site comprises a service station, large retail area, mechanical workshop and car wash. The design of this development drew on the owners‘ previous experience with other service stations and commercial premises in the Canberra region and demonstrates their commitment to both sound business principles and the environment.

The Excisting Process and Problem Being Addressed

Typical solutions in service station design include large air conditioning units in the roof for heating and cooling, fluorescent tubes for lighting and little or no heating in workshops. Running costs are generally high, with significant amounts of electricity being consumed by artificial lighting and for coping with the wide variation in ambient temperatures between night and day at all times of the year. Workshops are a particular problem in winter as their large door areas are generally left open during working hours, making efficient heating a big challenge.

This Caltex site operates 24 hours and is subject to company standards related to maintaining lighting at certain levels at all times. The commercial operators of the airport set energy efficiency targets and placed strict limitations on protruding elements, such as fan coil units and cooling towers, which could be seen from either the road or air. Due to the proximity to the airport runway and safety concerns, reflective surfaces such as photovoltaic cells on the roof were not an option.

An architect was selected who had experience in designing energy efficient commercial buildings. He was asked to design a series of buildings that worked together to provide a large, light and airy retail space, and a warm and sunny mechanical workshop (especially during the Canberra winter).

Eco-efficiency Initiative

The architect‘s response to the brief was to incorporate as many passive solar design features as possible into the layout and design of the buildings. Both the retail area and workshop face due north and use dark tiles and black oxide concrete flooring respectively for thermal mass. The wide expanse of glass of the retail area is shaded by the service station canopy, while the workshop is protected by both the retail building and additional canopy space.

West-facing windows in the retail area are double-glazed, but the cost of double-glazing proved to be prohibitive for the large north-facing glazed areas. Insulation was included in the roof, ceiling and slab of the retail area. The automated doors respond to the difference in temperature between inside and outside via a simple thermostat so that they open less when there is a greater difference.

In winter, sun projects right to the back wall of the workshop through the open north facing wall. Natural lighting is enhanced by south facing windows high up in the back wall of the workshop. These were used in preference to skylights that would have compromised the integrity of the roof insulation. White aluminium sarking was also used in the workshop roof to increase light reflectance.

Caltex Airport Sun diagram

Figure 1.

Energy efficient lighting has been used in all areas, with metal halide tubes in the canopy area and workshop and triphosphor tubes in the retail area. All are fitted with reflectors and no diffusers. Lighting in the workshop is adjusted automatically via a sensor on the roof that measures the level of ambient light.

A geothermal vertical loop system has been installed with pipes drilled 100 metres into the ground. The system provides efficient, safe and reliable heating and cooling to the retail and office areas. It also has the important advantage of being a completely self contained indoor unit that meets the landlord‘s requirements to avoid unsightly external fixtures. The air conditioning system is zoned so that office and other areas can be switched off when they are not in use.

Waste heat from the refrigeration, cool room and freezer units is recovered and used to pre-heat water used in the car wash to 25C. This has meant that the natural gas water heater that was included at the design phase has proven to be unnecessary.

Many water saving ideas were also included in the design, including the recycling of car wash water through an innovative series of underground storage tanks.


Building construction costs were less than many conventional service stations and running costs are significantly lower than comparable sites. Energy and associated cost savings have been delivered through lower power consumption and more even energy profiles that largely avoid higher business hours tariffs.

Based on the geothermal air conditioning suppliers‘ calculations for this site, a payback period of four years was expected, but this has become much shorter due to escalating electricity prices over the last two years. The suppliers estimate that geothermal technology can save over 30% on monthly energy bills. Further savings have been made by using waste heat to pre-heat car wash water, thereby avoiding the upfront installation and ongoing operating costs of a gas water heater.

Table 1: Costs and savings
Total outlay  
Upfront additional cost of installing geothermal airconditioning (4 zoned units) instead of conventional airconditioning (2 drop in units) $23,200
Upfront additional cost of installing a heat exchanger and insulated plumbing instead of a conventional fan coil assembly $500
Additional cost of energy efficient fluorescent tubes compared with conventional tubes Nil
Upfront saving by not installing gas water heater  
Savings per annum  
Savings in energy costs compared with conventional site $11,000
Savings in running costs of gas water heater $4,800
Payback period One year

Temperatures throughout the retail area are more even than with many alternative air conditioning units, and heaters are rarely used in the workshop. The additive used to colour the workshop floor has also made the surface less porous and therefore better able to prevent ground contamination as a result of oil and other spills. This is especially important where the floor's protective coating has been damaged.

Despite the best of intentions, there are times when the sun shines in the console operator's eyes for short periods of time. The ideal design solution would be moveable visors that track the angle of the sun, but the less expensive option of fitting a reflective sunblind has been chosen to rectify the problem. There can also be a time delay in reaching the air conditioning set point, as the geothermal system provides a gradual stream of air conditioning, rather than short energy intensive bursts of hot or cold air used by more conventional systems.


The environmentally aware owner/operators and their airport operator lessors provided the motivation to investigate energy efficient design within a traditional service station design. The intention was to produce a building that minimises running costs and maximises staff and customer comfort.

In hindsight, the building design proved to be of critical importance as the facility was opened on the day of the September 11 tragedy and in the wake of the collapse of Ansett Airlines. Because of its relatively low operating costs, the business was better able to hold on through lean times while other businesses located at the airport folded.


Although landlords, oil companies and government agencies all placed constraints on how the building could be designed and what technology could be used, cost was the major barrier in implementing many of the owners‘ ideas.

In the early days of construction, persistence and determination were also required to convince the builders to deviate from conventional service station specifications.

Additionally, there is currently a need to educate employees about the air conditioning system so that they alter their clothing or level of activity in response to the temperature, instead of overriding thermostat settings.

Further Developments

Further energy and water saving features are expected to be introduced as funding becomes available, including the purchase of waste engine oil heaters for the workshop.

Contact Information

Mr Peter Taylor
Caltex Airport Starmart
10 Tyson Drive
Ph: 61 2 6230 4755


This case study was prepared by the Motor Trades Association of the Australian Capital Territory, as part of an Eco-efficiency Agreement between the Australian Government Department of the Environment and Heritage and the State/Territory affiliates of the Motor Trades Association of Australia, with funding assistance from the National Heritage Trust and Product Stewardship for Oil Program.