Buildings account for 23% of Australia’s greenhouse gas emissions and energy efficiency is key to a more sustainable future, writes Sascha Thyer, who halved consumption at an energy-hungry Queensland aquarium.
As an organisation which advocates for sustainability, Reef HQ Aquarium in Townsville wanted to make a real difference in reducing energy consumption, so halving grid energy use seemed appropriately ambitious – and a nice round number.
In retrospect, for a business using 2.4GWh of energy each year it was a tad naive, since at that time in 2007 there was no money or strategy to achieve this goal. This vision did become reality in 2014 when the aquarium, a major tourist attraction in Far North Queensland, reached that ambitious target through a range of operational changes and targeted infrastructure investments, including a 206kW roof top solar power system.
The milestone was achieved whilst remaining fully operational and continuing to grow the business.
As the national education centre for the Great Barrier Reef, an arm of the Great Barrier Reef Marine Park Authority, showcasing energy efficiency and renewable energy technologies is a key objective. However, Reef HQ Aquarium faces similar pressures to other businesses. We care about the environment but also have operational resourcing constraints. Our building is unusual, with specialised equipment, but it shares a lot in common with most commercial buildings with most energy consumed in lighting, heating, ventilation, air-conditioning and refrigeration (HVAC-R), machinery and catering equipment.
Our case study demonstrates that energy efficiency can be achieved whether you have no extra money to spend or significant funds for capital investment. Over eight years, $1.7 million was spent at Reef HQ Aquarium on energy efficiency measures. This year, complete financial payback for all measures combined was achieved. This is impressive considering the most costly initiatives were implemented in 2012.
At the start of the journey in 2007 no funds were available for energy efficiency measures, but Reef HQ Aquarium staff who were concerned about climate change impacts on the Great Barrier Reef and were determined to find energy efficiencies. We were confident we could eliminate some energy wastage through a better understanding about how energy was being used and by implementing low- or no-cost strategic operational and technical changes. The ease and impact of these simple changes was surprising and inspired staff to look at our infrastructure in a different light.
Too cold inside?
It is 35°C outside but you walk around the office and see some people at their desks wearing cold-weather clothes. Most people have an expectation that even with temperatures soaring to 35°C outside, if you come in to a building (especially if you have paid to be there) you will feel cool. Now that we understand how precious energy is, is this a realistic expectation?
Historically, the Reef HQ Aquarium indoor temperature was 23.5°C, but since some people complained of feeling cold we decided to raise the temperature to 24.5°C, in 0.2°C increments over a few weeks. Initially some people complained about the change but anecdotal evidence suggested that over time people adjusted their thermal comfort or at least their expectations.
A 2016 experiment tested the effect of raising indoor temperature by 1.5⁰C. The results showed there was no significant difference in overall thermal comfort and no effect on self-assessed worker productivity. This measure, as well as improved HVAC&R maintenance and elimination of air leaks through the building envelope, reduced the energy consumption by a whopping 13%.
This is consistent with other studies that have shown for every degree you raise the indoor temperature, 6% energy consumption can be saved. So that’s one myth busted: you don’t have to have lots of funds available for capital investment to significantly reduce your energy consumption.
By 2008 we still had little capital funding to spend on energy efficiency, so we focused on gradually phasing out energy inefficient equipment such as lighting which had fast payback times. This measure allowed education staff to engage visitors in conversations about energy efficiency using a product we all use and see in all buildings.
It also had many unforeseen benefits such as less fixtures required (in the case of LED panel ceiling lights), significantly reduced maintenance costs, increased safety (since staff spend much less time on ladders or scissor lifts changing light globes) and reduced toxic waste (the old lights contained heavy metals). In the later years we moved to engineered skylights to replace artificial lighting over some aquarium tanks.
Energy efficient lighting is the norm these days, but inefficient flood lights are still common and many homes still use inefficient lighting. At Reef HQ Aquarium, energy use for lighting was reduced by 40% and the payback on average was 2.5 years.
Old habits die hard
Major renovations occur rarely over the life of a commercial building and are usually triggered by the end of life of equipment. This is an important opportunity for a shift towards greater energy efficiency, but the opportunity could be easily missed if the facility manager or decision makers are not aware of what possibilities exist to reduce operational and life cycle costs.
These costs may be indirect, such as the real lifecycle cost of using non-renewable energy compared to renewable energy. One of the biggest opportunities for the aquarium came from the end of life of the main chilling system, where capital was already budgeted for the lifecycle of the asset.
It would have been easy to choose the slightly cheaper like-for-like system, but great results were achieved by settling on an innovative design and working through the issues associated with retrofitting a system into a property built in 1986.
The installation of the new chilling system and other measures related to the chilling requirement reduced the energy consumption of the HVAC&R by 66%.
Many people may not be aware that using more energy efficient equipment located in the air-conditioned space (such as lighting and machinery) also reduces cooling requirement for the building’s air-conditioning system. These combined benefits can be hard to quantify at the outset but they can be significant.
If every piece of energy using equipment or infrastructure is seen through the lens of energy efficiency, opportunities to minimise energy use are everywhere. When we examined the use of machinery such as pumps and associated piping, the inefficiencies in some cases were very high. In one case an oversized pump motor was changed to an appropriately sized one as at cost of $1,500, and the electrical cost savings were $10,000 per year.
It is easy to cringe about this now but when the pump was purchased (12 years prior), energy efficiency was not the highest priority and since it was doing the job required it wasn’t scrutinised. System design and links between machinery systems were also important considerations to achieve efficiencies. Now all systems and purchases are scrutinised through the energy efficiency lens.
Increased resilience, an unexpected benefit
Like the corals on the Great Barrier Reef, the corals in Reef HQ Aquarium, home to the world’s largest living coral reef exhibit, will bleach and die if the water temperature goes beyond 29⁰C for a sustained period. Prior to the replacement of the chilling system, temperatures within the large aquarium tanks could not be reliably maintained below critical thresholds, putting the corals at risk. With the new chilling system installed, the optimum temperatures can easily be achieved with a much lower overall energy demand.
Halving the overall energy demand also meant that the emergency standby diesel generators could accommodate the energy demand of the entire site whereas previously they had inadequate capacity to accommodate the high demand of the chilling system. In a location where tropical cyclones are a real and increasing threat, this added resilience is a huge bonus.
Using photosynthetic algae in their tissues, corals harness sunlight to make the energy they need, and positioned in a sunny spot they can take advantage of this abundant resource. Reef HQ Aquarium is also located where solar radiation is abundant, so the move towards rooftop solar PV seemed like a logical step.
In 2010 we installed what was then the second-largest solar PV system in Far North Queensland. If we hadn’t taken this important step operational costs would be well beyond current funding arrangements today. As the energy minimisation measures exceed expectations, during peak solar periods solar generation produces a surplus. To avoid any wastage the building management system has been adapted to store surplus PV generation as thermal energy in a chilled water storage tank as well as the in the large aquarium tanks.
Since chilling represents about 25% of the Aquarium’s energy use, this type of energy storage is a cost-effective solution for re-distributing the energy generation.
Reef HQ Aquarium is in the process of expanding its solar PV system by 50kW and storage will be required to make use of any surplus generation. We are also trialling the use of small wind generators and exploring energy recovery systems. There are many opportunities for greater efficiencies for plant and equipment and we are utilising indoor ventilation to offset slightly higher indoor temperatures. A mix of solutions will most likely provide the best outcomes for the facility including energy storage solutions using phase change materials for thermal storage and electrical battery storage.