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Ecolibrium

71MAY 2018 • ECOLIBRIUM

F E A T U R E

One of Canberra’s landmark commercial buildings is defying its age thanks to an energy overhaul that has reduced emissions by 37 per cent.

London callingBy tackling energy efficiency from every angle, one of Canberra’s most iconic commercial buildings – 221 London Circuit – has achieved a reduction in emissions of more than one-third, lifting the NABERS performance of this nearly 50-year-old building from 3.5 to 4.5 stars.

The building has long been a part of Canberra’s CBD, first opening in 1969 as Electricity House, and served as headquarters for ActewAGL (the ACT’s local utility provider) until 2009.

It was purchased by Molonglo Group in 2008 and refurbished into a modern commercial office in 2010. The refurbishment breathed new life into the HVAC systems, including new chiller plant, cooling towers, VAVs, BMS control system and a solar domestic hot water system.

In 2015, Energy Action assessed the building at 3.5 stars NABERS energy. Molonglo Group, wanting to unlock the asset’s full potential, engaged Energy Action to identify and oversee further upgrades to achieve a 4.5 star rating without the use of GreenPower.

The project was not straightforward in any way, as the building had been refurbished multiple times over its life and there was very little “low-hanging fruit” left for easy efficiency gains; achieving energy savings required innovative and leading-edge strategies. To further add to the challenge, the upgrades were carried out with the building mostly occupied.

The subsequent works demonstrated the value of a holistic approach to upgrading pre-loved buildings, beyond conventional replacement of end of life plant.

By examining areas such as façade performance, ductwork configuration, latent defects and system interdependencies, most of the HVAC energy savings were realised in a cost-effective manner without major capital works.

Key facts▲ 8,588m2 commercial office

building with ground floor cafe and basement parking

▲ NABERS base-building energy rating increased from 3.5 starsto 4.5 stars from July 2015 to Dec 2017

▲ 38 per cent reduction in electricity use and 34 per centreduction in natural gas

▲ Emissions reduction of 281 tonnes CO2 equivalent per annum (Scope 1, 2 & 3)

▲ $67,000 p.a. saving in avoidedenergy costs.

ECOLIBRIUM • MAY 201872

F E A T U R E

CLOSING THE CIRCUITThe building’s top floor had significant thermal comfort issues during Canberra’s cold winters, struggling to reach temperature set point during morning warm-up. As a result, the central heating system had been scheduled to start up at midnight in an attempt to bring this area up to a comfortable temperature by 8am.

An air leakage test confirmed that poor air tightness was the culprit. The air change value was measured in excess of 40ACH50 (air changes per hour at 50Pa), well above recommended values.

As a result, most of the heat was being lost through the building envelope.

Building works were conducted to seal as many gaps as possible. The main source of leaks was the acoustic ceiling, which was made from perforated plasterboard. This posed a significant challenge because there was no simple way to fill these holes without ruining the ceiling’s aesthetic.

A solution was devised where coloured acoustic panels were affixed over the ceiling. This allowed the holes to be blocked without compromising the fitout’s acoustics or aesthetics.

These works improved air tightness from 40ACH50 down to 15ACH50, allowing the HVAC system to more efficiently service this zone.

After these works were completed, the winter warm-up time on the plant was reduced from eight hours to one hour, and comfort conditions were easily achieved.

The design of existing rigid ductwork is often overlooked on upgrades. In this case, the ductwork configuration was causing balancing issues that required excessive fan energy to compensate. Addressing this provided energy savings that would have typically been overlooked on a conventional upgrade.

The centre-zone AHU ductwork had a poorly designed junction where flow to the two risers branched apart. The duct was shaped such that most of the flow went down the north riser, and the southern zones were often starved for flow, even when the supply air fan was running at maximum speed.

Due to space limitations, this issue couldn’t be rectified by installing a proper splitter damper. Instead, a custom duct scoop was designed and installed into the branching point, such that enough airflow was diverted to the south riser to better balance the system and reduce fan energy.

Additional fan energy savings were achieved by fixing various latent defects throughout the floors, such as flexible ductwork that was bent or crushed, or in some cases not connected to diffusers.

Figure 1: Air leakage

testing though a

fire escape door.

Figure 2: Acoustic panels being installed over the perforated ceiling

to improve air tightness

ECOLIBRIUM • MAY 201874

F E A T U R E

>B< MaxiPro in pole position as ACR solution at Tailem Bend Motorsport Park

When people think of a racetrack, speed and safety are two key issues that will always be top of mind. For the newly-launched Tailem Bend Motorsport Park in South Australia that also applied to the installation of its heating and air-conditioning systems.

Air-conditioning and mechanical services expert Specialist Air Management chose Conex Bänninger’s flame-free, easy-to-fit ACR press fitting >B< MaxiPro for the more than 1,000 joints needed to complete this major project.

The newly-constructed Tailem Bend Motorsport Park is home to a racetrack, second only in size to Germany’s Nürburgring. It features a world-leading single lay race surface of over 7km and includes a 128-bed hotel, corporate and media centre and all-important race control.

The months before opening were extremely busy with the installation of the park’s heating and air-conditioning systems taking place over the second half of 2017.

The contract was carried out by a four-man team from Adelaide-based Specialist Air Management (SAM), which has delivered air-conditioning and mechanical services to commercial and government clients for over 20 years.

For the hotel’s heating and hot water needs, the project utilised Mitsubishi VRF (variable refrigerant flow) and heat pump technology, coupled with indoor cassette and split units for cooling the bedrooms. For the race control and media centre a Temperzone air-conditioning system was used.

With around 3,000 metres of hard drawn copper pipework to piece together, SAM’s installation team needed a high performance jointing solution to complete the job. They chose >B< MaxiPro, which has become the company’s fitting of choice - having used it on the majority of projects since its launch in Australia in 2016.

For Tailem Bend, SAM also used Conex Bänninger’s copper >B< Press water system for the condensation drains to match the high-quality finish of the building.

>B< MaxiPro was developed specifically for air-conditioning and refrigeration applications, with a maximum operating pressure of 48 bar and a temperature range of -40 to 121.

As a flame-free mechanical joint, it means there is no requirement for a hot works permit or nitrogen purge. Following preparation, it takes just five seconds to complete a joint using a Rothenberger press tool.

Michael Gilroy, Managing Director of SAM said: “Each of the four SAM crews are equipped with >B< MaxiPro equipment. It is very much their tried and tested, preferred technology.

“As well as negating the need for a hot works permit, it increases productivity significantly. That’s not just down to no hot works permit but the crews could work in singles rather than pairs.

“With over 1,000 >B< MaxiPro fittings we estimate it gave us a faster installed project by around 25%.”

Conex Bänninger recommends using Rothenberger press tools and jaws which are designed specifically for use with >B< MaxiPro. The tooling system is lighter and much simpler to use when compared to traditional brazing, which requires the engineer to manhandle heavy gas bottles around.

>B< MaxiPro has the benefit of a 3-point press; two presses on each side of the bead and one press compressing the O-ring. This provides a permanent and secure joint.

Michael Gilroy added: “We encountered some extremely tight and sensitive areas, which we were able to overcome because you can use the press tool in confined spaces, but also by prefabricating sections of the pipework before making the final connections.

“Having completed the work we carried out a final test programme to confirm the installation as proven. We did an initial nitrogen pressure test for 24 hours then a vacuum test to 250 microns which showed a minimal drift over 12 hours.

Since the early days we had all our crews trained as certified >B< MaxiPro installers. “We are fully convinced of the system but it’s certainly nice to have the benefit of the extended warranty that comes into effect when you have completed the training. It also means something to the client as they know they are dealing with professional companies.

>B< MaxiPro can be used with hard, half hard or annealed copper tube conforming to AS/NZS 1571:1995. The innovative press system can be used with many refrigerants, including R1234yf, R1234ze, R32, R134a, R404A, R407C, R407F, R410A and R507.

For more information on Conex Bänninger’s complete range of valves and fittings solutions, visit www.conexbanninger.com.

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IN HOT WATERAlthough the site’s existing domestic hot water system already had several high-efficiency components such as solar collectors and insulated storage tanks, the efficiency suffered greatly from poor design and control issues.

The solar collectors were boosted by the central heating hot water plant, which resulted in inefficient operation (particularly in summer) because a 500kW boiler was often required to duty-cycle year-round to service a relatively small domestic hot water (DHW) load. Furthermore, the circulation pump operated 24/7, causing most of the residual heat in the system to be lost overnight through distribution losses.

The DHW system was de-coupled from the heating hot water plant by installing separate boosters. Although electric heat pumps were the preferred option, they were ultimately abandoned in favour of instantaneous gas-fired units due to space restrictions.

This presented its own challenge, as the DHW plant was located close to the building’s fresh-air intakes, making it difficult to flue the units in accordance with code. In addition, the circulation pump was placed on a timer and turned off for a few hours every night, helping to retain some heat in the insulated tanks for the next day while still managing Legionella risks.

The tenant condenser water system was one of the largest uses of electricity, operating at full flow 24/7. This was largely because downstream PAC units were poorly documented and most equipment wasn’t fitted with motorised control valves.

A full audit of the condenser water system was carried out to identify all supplementary PAC units and their operating hours. It was discovered that only one PAC unit actually required condenser water 24/7 (to service a small

server room). All other units served meeting rooms and only required water during scheduled occupancy (or for after-hours AC requests).

Retrofitting control valves to every tenant PAC unit would have been prohibitively disruptive and costly, so a more resourceful and cost-effective solution

was implemented. Large motorised isolation valves were installed in the plant room for two of the three condenser water risers, allowing most of the system to be isolated whenever the building was unoccupied. The third riser was kept open to provide condenser water to the large server room.

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Before Upgrade After Upgrade

Figure 3: Further fan energy savings were achieved by identifying and fixing latent defects, such as this kinked flexible ductwork.

Figure 6: Tenant condenser water consumption profile comparison – 3 days before and 3 days after upgrade

Figure 5: Newly installed motorised isolation valve on one of the three condenser water risers.

ECOLIBRIUM • MAY 201876

F E A T U R E

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COMPLEX CONTROLSDue to the many refurbishments over the decades, the building had a complex mix of HVAC systems, including VAVs, on-floor FCUs and PAC units.

The HVAC controls were overhauled, with a holistic approach taken. The central VAV system was used as the priority method for conditioning the zones.

Wider temperature dead-band controls were implemented on the on-floor FCUs and PAC units such that these units would only activate if the VAV system was struggling to satisfy heating/cooling demand. Care was also taken to turn off FCU and PAC unit fans wherever possible.

Due to restricted air flow through the cooling towers – the towers discharge horizontally due to height limits in

the plant room – the condenser water temperature control strategy needed to be carefully tuned to optimise the trade-off between cooling tower fan energy and compressor efficiency.

In addition, a full rebalance of the central and perimeter VAV systems was conducted after hours, all temperature sensors were recalibrated, and sensors in impractical locations were relocated.

Figure 7: PV System.

Figure 8: New condensing boilers.

77MAY 2018 • ECOLIBRIUM

F E A T U R E

These controls upgrades were followed up with a 12-month program of building tuning and performance monitoring to validate operation and identify further opportunities for improvement.

CAPITAL WORKSThe height, structure and layout of this building presented considerable challenges to providing an on-site generation solution that would deliver the desired NABERS uplift. To address these issues, the design included maximising the available roof space while maintaining service access and coping with roof sub-structure constraints, wind loadings and multiple obstructions.

Due to the nature of the PV layout, it wasn’t possible to ensure all panels in a string could receive the same insolation at the same time, presenting a problem that would severely reduce the system output.

To address this, the design included voltage optimisers on each panel. The optimisers allowed each panel to operate independently without impacting the rest of the panels in its string when shaded.

On this building, these optimisers provided an improvement in output of approximately 20 per cent.

Voltage optimisers

on each PV panel

. . . provided an

improvement

in output of

approximately

20 per cent.

LESSONS LEARNED• Investigate and rectify latent

defects as early as possible,otherwise they can undermineyour predicted energy savingsfrom controls upgrades

• Look to the building envelopefor ways to reduce heating andcooling loads; the opportunitiescan be larger than you expected

• Post-project monitoring andverification (M&V) is an invaluabletool to ensure your upgradeshave had the intended outcome.It can be used to identify tuningopportunities and take correctiveactions in a timely manner.

ECOLIBRIUM • MAY 201878

F E A T U R E

Furthermore, with the system being remotely monitored, the operation of every panel can be viewed and action taken to correct faults occurring down to panel level rather than the traditional inverter level.

Meanwhile, the site’s two 500kW atmospheric boilers were upgraded to high-efficiency condensing boilers under their end of life replacement.

With these new boilers, a variable supply temperature control strategy was implemented, resetting the supply set point between 80°C and 60°C dependent on outside temperature. This allowed gas savings to be achieved through reduced thermal losses and operation under condensing conditions.

Having achieved 4.5 stars, further works are currently underway to improve the resilience of the rating and potentially target 5 stars:

• An automated fault diagnostics platform is being installed over the BMS to identify new maintenance and controls opportunities to improve energy efficiency performance.

• The common area lighting is being upgraded from compact fluorescent downlights to LED equivalents, which is expected to halve lighting energy in these areas.

As of January 2018, the site had reduced its annual electricity consumption by 38 per cent and natural gas consumption by 34 per cent. A 4.5 star NABERS energy rating has also been achieved. In terms of energy costs, $67,000 per year has been avoided.

Notable sub-system savings include the tenant condenser water system (reduced by 25 per cent), domestic hot water system (down 45 per cent) and the heating hot water pumps (down 40 per cent).

Tenant comfort complaints have also been significantly reduced, largely due to the draught-proofing works.

The success of the project is further proof that, with intelligent improvements, pre-loved buildings can enjoy a bright future. ❚

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The personnel

■ Building owner: Molonglo Group

■ Project management: Energy Action

■ Building management: Knight Frank

■ Mechanical services: CCS Group

■ BMS controls: Control & Electric

■ Air leakage tests and draught-proofing: Air Leakage Measurement Australia

■ Solar installation: Clean Energy Corporation Australia

■ Electrical services: Star Group

■ Plumbing services: Zammit Hydronic and Mechanical

■ Ductwork: J. Sainsbury & Co

■ Balancing and commissioning: Superior Balancing Services

The equipment

■ Boilers: Automatic Heating

■ Valves: Belimo

■ BMS: Siemens

■ Acoustic panels: Autex

■ Domestic hot water units: Rinnai

■ Solar panels: LG Energy

■ Inverters: SMA

■ Voltage optimisers: Tigo Energy

PROJECT AT A GLANCE

AIRAH would like to thank James Spears, M.AIRAH,

for providing this case study, and Dr Paul Bannister, F.AIRAH,

for reviewing it.

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Figure 9: Monthly NABERS monitoring results to date.

Figure 10: Level 12 office.