Pacific heights. In a new build, optimum building energy performance does not just happen because you design it so

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1 Pacific heights Fact: it s not just old buildings that need attention relatively new buildings can also fail to perform as designed. Sean McGowan reports on the transformation of 100 Pacific Highway, North Sydney. It was work that earned its engineers a spot among last year s AIRAH Awards finalists. And get this: the building went from 2.5 star NABERS Energy performance to 5 stars without the addition of any new equipment. Featuring 22,500 sq m NLA of A-grade premium office space, the 22-storey building at 100 Pacific Highway, North Sydney was the first office tower to be built on the Harbour City s north shore this century. The first major office tower in North Sydney to target a 4.5 star NABERS Energy rating, it was specifically designed to accommodate the particular requirements of information technology (IT) corporate tenants. To this end, it was equipped with the required communications infrastructure and services capacity to deal with the associated power and internal heat-load requirements. This included a variable-air-volume (VAV) HVAC system featuring electric trim heaters. This system is broken down into low- and high-rise sections. Separate air-handling units service the various building zones for each rise. The central plant consists of two large centrifugal chillers and a smaller lowload chiller, as well as two multi-stage boilers and associated pumps. The integrated cooling tower condenser water system features four towers serving both the base building and tenancy cooling requirements. In a new build, optimum building energy performance does not just happen because you design it so Systems are controlled and monitored by a computerised building management system and direct-digital-control system. Following practical completion in late 2006, the building received its first tenants in January By mid 2008 the building had reached above 75 per cent occupancy, at which time NABERS performance monitoring commenced. This monitoring revealed the actual performance of the building was falling well short of its 4.5 star NABERS energy target, tracking at about 2.5 stars only. As one of Australia s prominent property fund managers, building owner ISPT immediately set about reviewing the building design, and the areas where performance was not as expected. ISPT s portfolio strategy is to ensure that all office assets perform to the highest sustainability level that they reasonably can, says Peter James, ISPT s commercial portfolio manager. Therefore, the underperformance of this asset did not meet with our investment expectations. We had entered into a commitment agreement to achieve a minimum 4.5 star NABERS rating by design. It was important to us to deliver on this commitment. AUGUST 2013 Ecolibrium 27

2 from other sites where the optimisation programs have been implemented and where the configurations are similar. Over a period of time and multiple optimisation projects, we have built up a database of experience that allows us to understand and accurately predict the effects of various tuning initiatives and regimes on various system designs and configurations, he says. Building energy optimisation Building owner ISPT overhauled the 22-storey 100 Pacific Highway after discovering it was performing well below its target 4.5 star NABERS rating. Following sustained efforts, with little success, from various stakeholders including the builder, mechanical consultants and contractors ISPT enlisted the help of specialists from A.G. Coombs to carry out an HVAC energy-optimisation project. A.G. Coombs had previously achieved successful outcomes with other buildings under the ISPT portfolio, which saw the buildings in question optimised to perform at or above their design ratings. The specialists were requested to review 100 Pacific Highway to determine if a similar approach could be applied. A.G. Coombs Building Energy Optimisation Program (BEOP) directly targets the tuning of energy-consuming systems. It uses the building management and control system (BMCS) as a diagnosis, tuning and reporting tool to optimise energy use against the buildings operational requirements. This represents a significant advance in control strategy philosophy, moving from simple temperature control to in-built seasonally adjusted energy conservation logic, says Andrew Smith, leader of building technologies for A.G. Coombs Advisory. Smith says the likely outcomes of the program can be predicted using an analysis of the performance data collected Providing a payback period under 12 months, the program was initially able to improve the building s NABERS Energy rating level from 2.5 stars to its design target of a NABERS Energy 4.5 star rating Smith says this information is then used to select the best approach for a particular building. It s also used to continue to drive efficiency over the longer term. According to James, the application of BEOP represented a no-risk approach for ISPT. This was particularly the case given it was predicted the program would lift the building s 2.5 star NABERS Energy performance to 5 stars without the addition of any new equipment. Rather, modifications were made to the front end of the installed building controls to provide the required control capability to optimise and tune the systems. The modifications also provided adequate levels of monitoring and diagnosis to support the process. The result was a BMCS that went from a black box requiring proprietary specialist operation to a user-friendly, intuitive monitoring interface. These improvements are enduring, and support ongoing efforts to retain and even further improve energy efficiency and support general system performance, Smith says. A two-phase program The BEOP program has two distinct phases. The first ensures the building s energy-consuming equipment is optimised to operate in a predictable, 28

3 stable, reliable and repeatable manner, and that all components are configured to operate as a single cohesive system. The second phase is to implement proven energy-efficiency control strategies to further optimise the building s performance. Following a thorough audit and review of the building s operations and its HVAC systems, A.G. Coombs was able to determine how the building was operating, how it should operate, and what energy-conservation measures would best suit the space to ensure all HVAC systems and sub-systems would operate optimally together. There was substantial engineering and technical input to evaluate at controlcode level how parameters interact, how they can be aligned and how energy initiatives can be implemented in the most cost-effective manner, says Smith. This process identified that the HVAC systems and their various sub-systems were working in a constant state of flux. This was not only causing excess energy consumption but also resulted in an inability to provide the required internal conditions. This was leading to unacceptable fluctuations in conditions, as well as draught and stuffiness issues. To remedy these problems, a structured and iterative program of adjustment, review and readjustment was required. Smith says enhancements to the existing BMCS were also identified to enable this to be used as a tuning tool. The existing BMCS was enhanced to enable it to be used to its full capacity as a diagnosis, tuning and reporting tool, adds Smith. BEOP activities were carried out at programming-code level in the first instance to ensure a full understanding of the control logic. Alternative logic strategies were subsequently developed and implemented. Tuning parameters such as PID loops, reset schedules and set-points were utilised. Smith says the BMCS was remotely interrogated and monitored almost on a daily basis during the tuning period. The ability to remotely and seamlessly connect into the BMCS system to review building operation, analyse trends and view software programs is pivotal to the success of a cost-effective HVAC optimisation process, he says. Regular visits were also made to the building to ensure the accuracy of BMCS information, as well as to physically inspect the system and plant operation. Taking initiative Among a number of key findings to emerge from the audit process was that there was poor, and at times no interaction between individual HVAC components at 100 Pacific Highway. Therefore, the program of tuning initiatives included a range of activities to align the control logic, from the floor sensor through air distribution to central

4 plant. This was done to eliminate energy waste, with the objective of achieving the correct and optimal interaction between zone controls, air-handling operation and central plant operations. This resulted in the correct cascading set-point architecture being established. Also achieved was the automated seasonal adjustment of systems, including independent operating parameters, to differentiate and optimise control in both normal and after-hours modes. Tuning activities also included the review of existing strategies to debug existing code and understand the control logic. This is an important step in the process, says Smith. Typically system programmers do not seek to uniformly connect all set-points so individual adjustment does not cause overlap between heating and cooling, which is energy inefficient. Other actions included a review of the existing optimal start arrangements, so as to optimise warm-up time and ensure all HVAC elements act in unison. Heating and cooling calls were also modified to provide an indication of demand. This can assist in central plant initiation, staging and optimal stop. Central water balance against pumping capacities and control abilities was also reviewed. A number of pre-existing problems were identified during the optimisation program, including those around the building s air-handling units (AHUs). For instance, supply air temperature set-points were found to be continually hunting between 12 C and 15 C, and supply-air static-pressure set-points were constantly at their maximum. Supply air temperature control was also hunting load all day. The optimisation program was able to stabilise air temperature set-points, reduce supply-air static-pressure setpoints with load, and provide stable control of the supply-air temperature all day. Chiller plant staging control was also identified as problematic, with continuous cycling of chillers all day. The building energy optimisation project was able to achieve stable loading all day. Efficient outcomes Smith says a range of important and lasting outcomes have been achieved from this project, which was carried out over a 24-month (two seasonal cycles) period from late Providing a payback period under 12 months, the program was able to initially improve the building s NABERS Energy rating level from 2.5 stars to its design target of a NABERS Energy 4.5 star rating by late Incredibly, about 90 per cent of this improvement resulted from HVAC system energy optimisation. A regime of energy efficiencyfocused maintenance and continuing enhancement of the operation of the building s HVAC systems subsequently took the building to a NABERS Energy 5 star rating in November This 2.5 star NABERS Energy rating improvement is equivalent to a 2,000,000 kwh reduction in energy use, and has delivered energy cost savings of over $230,000 per annum. Along with these substantial energyperformance improvements, the building s tenants are enjoying improved internal building conditions and occupant comfort. Where once fluctuating conditions, draughts and stuffiness were experienced, tenants now report high levels of satisfaction with the building s air conditioning systems. Optimising the building s energyconsuming systems has also resulted in significantly reduced operational starts, reduced component operating time and improved duty cycles for most HVAC system components. In this building, individual chiller start calls have been reduced from over 30 a day, in some instances, to now usually no more than two or three a day, Smith says. [It is] a very substantial reduction, which will result in a significant drop in wear associated with starting and operation, and a commensurate increase in expected life-cycle and reduction in overall life-cycle maintenance costs. It is expected that these benefits will equate to tens of thousands of dollars over the life of the building s HVAC equipment. Water, too The seasonal tuning cycle. Although it was not a primary objective, the energy optimisation of the building s HVAC and other building services systems has also reduced the amount of water consumed in the building s coolingtower-based heat-rejection system. This has contributed to the building receiving a 3.5 star NABERS Water rating. Following on from the initial tuning works, a continuing strategy of energy efficiency-focused maintenance, as well as regular checking and continual operational enhancement, was put in place. This has coordinated BMCS, HVAC, essential safety measures, electrical and other maintenance activities. 30

5 It ensures an integrated focus on systems, their elements and their control, as well as anything that puts energy efficiency at risk, Smith says. And it ensures that these get an appropriate level and type of attention to ensure that once improved energy ratings are achieved, they are retained. This energy-efficiency maintenance regime has since resulted in an additional improvement over the 12-month period following on from the initial tuning program. The building is now tracking at about a 5.5 star NABERS Energy rating level. A new paradigm The experience at 100 Pacific Highway, and those projects like it, not only highlight the opportunities that exist to improve the performance of Australia s existing building stock, but also how the traditional approach to new builds can lead to underperformance. Smith says it highlights the shortcomings of the traditional building-delivery process, which usually has the various stages separate and sequential. In more recent times, he says these have become even more specialised and dislocated as the industry has attempted to drive costs out of each part. Given that the energy efficiency of the final occupied built product is an outcome of many coordinated and complimentary inputs along the way, this fractured approach doesn t help, says Smith. In a new build, optimum building energy performance does not just happen because you design it so. It requires a structured approach that starts with design and runs into installation, commissioning and post completion optimisation and fine tuning. It is problematic, he says, that buildings are still usually commissioned before they are occupied and before the systems and the building s operation have a chance to settle. The seasonal tuning processes that are now required in some projects during the warranty period rarely if ever achieve the full potential efficiency gains, Smith says. Often, they are conducted by the commissioning team with a commissioning rather than tuning mindset, and sometimes they are just a tick-box process. Smith says it is rare for new-build processes to recognise the opportunity for post-commissioning optimisation The lessons learned Andrew Smith, leader Building Technologies for A.G. Coombs Advisory shares his take-away lesson from the project. 1. A dedicated energy-optimisation approach can achieve a significant building energy-performance improvement beyond traditional installation and commissioning processes. Even in buildings that achieve their design rating, there is more efficiency to be had. 2. Success in building energy optimisation is predicated on a well-planned and structured approach to building commissioning, optimisation and fine-tuning. 3. A commitment from all stakeholders and a collaborative approach is important. Energy optimisation is a team effort. 4. Conventional VAV systems are capable of greater things than they are generally given credit for, if optimised correctly. 5. Ideally, the implementation of building optimisation needs to start early in a new building delivery process to ensure the best outcome. 6. HVAC systems need to be designed and implemented with the required control system tools embedded to allow for both the initial optimisation and the ongoing performance management of the facility. 7. Opportunities for improvement are ongoing. Not only do you need to keep your eye on the ball to ensure you don t lose efficiencies over time, you should continue to look for improvements. It certainly isn t set and forget. to significantly improve performance in an occupied, fully operational building. In existing buildings, however, he says tuning exercises are becoming more common. Yet it is still rare for them to take a holistic systems approach. Typically they are focused from a particular area of expertise from a controls perspective or from a mechanical services installation direction, or from a design viewpoint, Smith says. All these aspects need to be considered in an optimisation project. Additionally, Smith says HVAC systems and their control systems need to be designed and commissioned to include the levers and tools required for the optimisation process and the ongoing energy-efficient operation of the facility. Generally, systems in new and existing buildings are not set up with adequate controls access or enabled capabilities to allow optimisation, he says. And they do not have enough diagnosis and monitoring capabilities to support the initial optimisation and the ongoing activities to retain efficiency and further improvements. From a building owner s perspective, James says the experience at 100 Pacific Highway highlights the need for building owners and managers to ensure proper rigour is maintained in the monitoring of energy performance. He says regular review of the performance of HVAC system components, back to the base-building energy model, is critical to ensure that each component is operating in accordance with its design parameters. Trend monitoring is a useful tool for early identification. Following its experiences with energy-optimisation programs across a number of buildings in its portfolio, ISPT has identified four key building blocks to achieving exceptional energy performance. These can be readily translated to any asset, regardless of age or grade. They include a committed owner with a unified and skilled delivery team, a good design refined for the site and building, a collective focus on the energy model and achieving the best possible NABERS outcome, and good delivery and good management throughout all phases of a project. 32