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Western starAs Western Australia’s first 6 star Green Star – Office Design v2 rated building, 2 Victoria Avenue has reaffirmed its owner’s commitment to sustainable office design and development. Sean McGowan reports on a building that has set a new benchmark for office space in Perth’s CBD.

Onwhatwasonceaflatbitumencarpark now sits a distinctive example of sustainable office design for Perth.

Designed by Woodhead Architects for Stockland, 2 Victoria Avenue is a 7,185 sq m four-level A-grade office building that takes its environmental cue from the greenery of the Swan River parklands opposite.

With its striking glass and orange metal façade, the building adjoins Stockland’s 13-storey Durack Centre, and was designed from the outset to set a new sustainability benchmark in the city.

Along with targetting the 6 Star Green StarOfficeDesignv2rating,italsosetitssights on a 5 star NABERS Energy rating, the first building to achieve this under a NABERS Commitment Agreement.

“About halfway through the design phase we realised that the building design had evolved such that it was on track (for these ratings), and Stockland had the opportunity to create a new benchmark in Western Australia,” recalls Sven De Jonghe, group leader of building engineeringforAECOM’sWesternAustralian consultancy.

“There were a few other buildings going for 5 stars (Green Star) at the time so we wanted this building to aim a little higher.”

AECOMwascommissionedin2007todesign all engineering services, as well as ESD and acoustics, and quickly set about incorporating a number of energy-efficiency elements to the building’s design, most of which had not been seen in Perth at that time.

These include an active chilled beam air conditioning system; fully automated louvres to shade the façade; and rooftop wind turbines to offset some of the building’s electricity consumption.

Such design decisions were made easier because Stockland understood that such sustainable initiatives would save money in the day-to-day running of the building – offsetting the initial outlay costs.

“Developers who make decisions purely on initial capital cost are likely to shortchange themselves,” De Jonghe says.

“With energy costs continuing to rise sharply, buildings that are poorly designed now run the risk of becoming obsolete well within their own life-cycle. There will be buildings that simply can’t afford their own

2 Victoria Avenue was designed to set a new sustainability benchmark in Perth.

C O V E R F E A T U R E

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The building’s orientation started out as a serious disadvantage, but clever design and building automation technology turned this around.

running costs, and as outgoings become a higher portion of the rental, tenants will eventually be selecting buildings based on outgoings plus rental as a total.”

fRoM tHe outsIDe InAlong with being a key architectural element of the building, the inclusion of louvres on the entire west-facing, double-glazed façade was a significant contributor to the building’s rating achievements.

De Jonghe says the building’s orientation started out as a significant disadvantage, but was able to be turned on its head through clever design and the use of building automation technology.

Made up of lightweight aluminium blades fixed both vertically and horizontally, the louvre system is fully automated and controlled by the BMS.

As Perth enjoys the most sunshine of any Australian capital city, the system has been designed to track the trajectory of the sun and its impact on the western façade at any time of day, as well as any time of year.

As the sun hits the facade, the louvres close to protect the building from

significant heat gain, and conversely open as the sun moves away – revealing the street view to occupants while opening up the floor-to-ceiling glass façade to those in the street below.

With energy costs

continuing to rise sharply,

buildings that are poorly

designed now run the risk

of becoming obsolete well

within their own life-cycle’Where street trees and adjacent buildings throw shade on the façade, individual bays of louvres are designed to operate independently of those around them. Furthermore, on cloudy days or during unseasonal weather conditions, the system can be overridden to compensate.

The building’s entrance on Victoria Avenue is also located behind this louvre system, sheltering it from the weather.

Successful treatment of the tinted glass façade was considered vital both in removing occupant glare as well as reducing heat gain that could impact on the HVAC design.

“Active chilled beams can achieve much more capacity than passive chilled beams,” says De Jonghe of the selected system. “However, they still need a fairly good façade to be effective.

“But to be honest, the latest version of the NCC (BCA) Section J has made it impossible to get away with unshaded glass boxes anyway, which is a really good thing.

“Even though this wasn’t in play at the time we designed the building, we were just following the basics of good building design. The NCC has now had the opportunity to catch up.”

Although traditional VAV systems are commonly implemented in Perth buildings,AECOM’sdesignteamlookedfor greater efficiency gains in order to achieve the NABERS Energy rating it sought.

In doing so it also created a first, with 2 Victoria Avenue the first building of its type in Perth to have active chilled beams installed.

“Active chilled beams are more efficient than VAV systems, and water is a 4,000 times better heat-carrying medium than air,” De Jonghe says. “They are also designed to fit within a regular 1,200

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by 600mm ceiling grid, and for the uninitiated tenant they wouldn’t be able to tell them apart from a regular HVAC system.”

leARnIng on tHe JoBEngaged by builder Diploma Construction as the mechanical services contractor, West Australian Mechanical Services had no previous experience with active chilled beam systems before working on the 2 Victoria Avenue project.

According to Daniel Hunt, M.AIRAH, it was approached in much the same way as any other project, with the thermal zoning of chilled beams similar to any other HVAC system.

“The chilled beams are arranged into perimeter and internal zones, controlled to maintain the temperature set point within the zone served,” says Hunt, engineering development manager for Western Australia Mechanical Services.

The active chilled beams used were supplied with constant volume primary air from an air handling unit (AHU) featuring a chilled and hot-water coil. In this case, the AHU was matched to serve a particular zone of chilled beams, with eight AHUs per floor.

The primary air delivers the required conditioned fresh air for the zone and is also used as the source of heating for the zone.

Chilled water is delivered to the AHUs at the primary temperature of 7°C, which aids with dehumidification of the introduced outside air, and at 13°C on the secondary side serving the chilled beam network.

the latest version of the

nCC (BCA) section J has

made it impossible to get

away with unshaded glass

boxes anyway, which is a

really good thing.’The chilled water temperature to the beams is kept at or above the space dewpoint temperature to remove the risk of condensation forming at the chilled beam, with the space dewpoint monitored at several strategic points across the floor.

Hunt says there are significant energy efficiencies in such a system compared to traditional VAV systems.

“A VAV system relies on the transfer of heat via the air passing through the space, whereas the chilled beam system uses a consistently much lower volume of air and transfers heat via the chilled water within the chilled beam,” he says.

“Water is much more efficient at transferring heat, and also there is less fan power required due to lower volumes of air passing through the space (in a chilled beam system).”

The use of floor-by-floor air handling plant was also important in achieving energy efficiency, particularly during after-hours operation, as this allowed for the system to operate only where the building was occupied.

Efficiencies were also achieved through the use of a central, water-cooled chiller at roof level along with two centrifugal chillers incorporating variable-speed compressors.

Although the requirement for ductwork is typically reduced compared to a VAV system, other issues in relation to space were encountered during the active chilled beam installation.

This put available ceiling space at a premium.

The entire construction and design team had a good relationship, and worked together to achieve the best result.

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Hunt says the physical profile and density of the chilled beams meant there were instances where duct needed to pass over chilled beams, and in some cases crossed over ducts serving other zones.

Indoor environment quality

was also important in the

building achieving its 6 star

green star office Design

v2 rating, with a 50 per cent

increase in fresh air rates

compared to the industry

standard achieved’“Because of this, the need for adequate ceiling space was just as important for this installation as it would have been for a VAV installation,” he says.

Though the active chilled beam system is the primary source of base-building air conditioning, a tenant condenser water loop was provided for each floor level to allow for the installation of water-cooled supplementary air conditioning units should tenants require them.

This system also served a number of large meeting rooms where occupant density exceeded base design limitations, and communications and server rooms with a concentrated heat load. The chilled

beams were typically removed in these instances.

According to Hunt, the firm’s lack of experience with a chilled beam installation was little more than a small hurdle, only requiring more thought than would otherwise be the case to coordinate “constructability” issues.

He says that like all projects, a number of “small tweaks” to the control methodology needed to be carried out during the post-commissioning phase, but in general it all went according to AECOM’sdesign.

“We were fortunate that the entire construction and design team all had a good relationship and worked together to achieve the best result for the client,” Hunt says.

“It also helps to have a client who is willing to be supportive and be an active and understanding participant during all stages of the project, including design, construction and post-occupancy commissioning.”

sHootIng stARsIn addition to the energy-efficient HVAC solution, the building’s 5 star NABERS Energy rating was achieved through the use of an efficient, programmable lighting system featuring motion sensors, dimmable ballasts and T5 fluorescent lamps.

Light fixtures were arranged in individually switched groups, each serving areas not larger than 100 sq m, while lighting power density is less than 2W/sq m/100 lux.

The lighting energy was designed to be partially offset by the operation of three 5kW wind turbines installed on the rooftop.

Developed and manufactured in Holland, the turbines feature helical-style blades that rotate through a vertical axis as opposed to the more traditional type such as those used on wind farms.

According to De Jonghe, helical-style blades have a much lower tip speed and therefore lower noise emissions than axial alternatives. However, in what he says has been a disappointing series of events, the turbines were rejected by the local council due to concerns from residents.

This decision was successfully appealed on technical grounds only to be overturned again.

Now after approximately two years of hearings, a single helical wind turbine has been approved for installation. At the time of publication, its installation was imminent.

Although the turbine will only account for around 10 per cent of the building’s lighting energy, other initiatives have contributed to the building’s sustainability credentials, including

After a year of occupancy it was found the building performed almost exactly as predicted.

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a greywater recycling system, water-efficient fittings and cooling towers designed to achieve six or better cycles of concentration.

Furthermore, all water used for testing hydrant systems, and drain downwater from sprinkler systems is returned to the fire reserve tank or used for irrigation.

Indoor environment quality was also important in the building achieving its 6starGreenStarOfficeDesignv2rating,with a 50 per cent increase in fresh air rates compared to the industry standard achieved.CO2 monitoring as well as refrigerant leak detection and recovery also feature.

Due to the design of the floor plate, which placed the building’s cores along the perimeter, all floor space is within

12.5m of a window, allowing for extensive daylight penetration. This results in 60 per cent of the net lettable area being within direct line of sight of external views.

Importantly, the building also features extensive energy and water sub-metering.

PeRfoRMAnCeIn designing the building’s services, AECOMdevelopeda3Dmodeltosimulate their operation in order to determine energy consumption over a year. It was on these results that the pre-commitment agreement for a 5 star NABERS Energy Rating was entered.

Following commissioning managed by an independent commissioning agent (ICA), who Hunt says made the process easier for all parties, the building was handed over for occupancy at the end of 2009.

During the first year of occupancy, AECOMmonitoredthebuilding’senergyconsumption to ascertain performance against that predicted by modelling.

It found that the building performed almost exactly as predicted, with the actual consumption of the building within 3 per cent of the modelled figure. Furthermore, the predicted performance of individual components closely matched their real-world operation.

“The closeness between the predicted and actual results is an outstanding achievement, demonstrating how accurate modelling capabilities are in simulating the energy performance of both new and existing developments,” De Jonghe says.

During this time, as the building “tuned in”, both building staff and facilities management also received training on optimising energy efficiency, the operational features of the building, its control systems and its energy and environmental features.

It is hoped that further energy-efficiency improvements will be made as a result.

Following assessment earlier this year, 2 Victoria Avenue has been found to outperform the 5 star NABERS Energy rating by 20 per cent. Moreover, it is expected to deliver operating cost savings of approximately $85,000 per annum compared to an average building.

Stockland is now in the process of seeking a Green Star As-Built rating that will round out the building’s sustainability credentials. ❚

PRoJeCt At A glAnCethe professionals

Architect: Woodhead Architects

Builder: Diploma Construction

Controls: MizCo

Developer: Stockland Mechanical/Electrical/Fire

ESD/Acoustics Engineers: AECOM

Independent Commissioning Agent: Andrew Crabtree, M.AIRAH, from IBMS

Mechanical services contractor: West Australian Mechanical Services

Structural engineers: Arup

the equipment

Active chilled beams: Dadanco

AHus: Trane

BMS: Johnson Controls

Chillers: Powerpax

Humidity/Temperature sensors: Johnson Controls

Supplementary AC units: Temperzone

Metering/ Sub-metering: Johnson Controls