Life cycle building tuning strategies are necessary for assured long-term building performance and reduced carbon emissions, writes WARWICK STANNUS from the property management specialist AG Coombs.
At the recent Green Cities Conference 2010, Jerry Yudelson – one of the US’s leading green building experts – noted that underperforming buildings are not green and built environmental performance is ultimately what counts. His observation echoed increasing concerns within the property and facility management sectors. Governments have also recognised that improvements to the efficiency of existing building stock can make an important and cost-effective contribution to reducing the nation’s carbon emissions. Through a range of reporting schemes including the National Greenhouse and Energy Reporting Act and the proposed ‘Mandatory Energy Efficiency Disclosure Scheme’, the Federal Government is driving significant improvements in building performance.
These two strategies are seeing an increasing focus on the value of the building tuning process and how it should be used to optimise and then maintain a building’s long-term performance. Whether transitioning a project from construction to operation, or managing long-term building performance, it is likely that facility management professionals will need to increase their understanding and involvement in the building tuning process.
In the past, building tuning has generally been considered to be a discrete activity forming the final phase of a building commissioning process; however, building tuning is increasingly being seen as a full life-cycle management process if it is to be effective. Change drivers in this move to life-cycle building tuning are driven by a number of key factors:
- Green Star: Green Star awards credits for the implementation of a building tuning program, which typically covers a 12-month period following practical completion. This is supported by a number of credits related to the installation of energy monitoring systems, commissioning and handover, as well as the engagement of independent commissioning agents. These are all aimed at assuring the life-cycle management information and processes are in place to manage long-term performance. In many ways, project developers, designers and contractors are yet to fully recognise the underlying premises shaping Green Star or to fully embed Green Star into the design of effective ESD (ecological sustainable development) project delivery models. This becomes evident in the differences that arise from certified designs to ‘as built’ performance.
- NABERS: warranted outcomes in terms of NABERS performance is becoming an increasingly common project brief requirement. It is widely recognised that a minimum 12-month building tuning period will be required to optimise the control strategies across each season, as well as to address any installation and/or performance issues. This is often then followed by a 12-month official NABERS rating period. Use of warranted outcomes is a powerful tool in terms of assuring built performance; however, the contract structures, definition of roles and responsibilities and the transition from construction to long-term operation of a fully tenanted building require further development as experience in these forms of contract grows.
- Mandatory reporting: with the expected introduction of Mandatory Energy Efficiency Disclosure, managing and reporting on NABERS base building performance will become an important part of the building’s ongoing management processes, similar to those required for Essential Safety Measures. Closely linked to leasing and asset purchase/sale, the provision of annual NABERS ratings will become an important area of focus for facility managers.
It is worth noting that both Green Star and NABERS are well-pitched in terms of the necessary measures described to achieve a particular rating. The higher ratings have significant implications on the building.
Life cycle building tuning strategies can commence at any point in the building’s life; however, their effectiveness increases over time as increasing knowledge of the building’s characteristics and performance develops and improvements are initiated and bedded down. Below are some of the key components of a building tuning life-cycle model that need to be managed:
ENERGY MODELLING
Energy modelling forms a key tool in ESD projects, providing guidance in design, commissioning and building tuning processes. The energy model and its design assumptions should be fully integrated into the project brief design criteria, as well as the green leases, and updated through the project delivery process. Ultimately the energy model becomes an important building record.
The majority of existing buildings will not have energy models and a more cost-effective approach to providing a basis for reviewing building performance will be to undertake an energy audit providing a ‘normalised energy model’ as the basis for assessing performance. Energy profiles for various building types are generally well-established and these can form a useful starting point for starting a tuning process.
ENERGY MONITORING SYSTEM
Energy metering systems are driven by requirements set out in Green Star, NABERS protocols and (in some states) tenant sub-metering. Energy metering continues to present challenges in terms of complexity, system commissioning and reliability, while energy monitoring reporting formats also offer significant scope for improvement in many cases.
The best systems report at different levels, comprising:
- NABERS performance tracking – thereby requiring dynamic integration of the building leased NLA as well as after-hours air-conditioning data
- energy use – tracking energy use against key energy end use parameters such as HVAC fan power, chillers, lifts and proprietors light and power – energy reporting ideals tracking usage against the energy model and historical data
- tuning – allowing energy use to be tracked down to individual sub-systems and plant in some cases to enable accurate building tuning to be conducted, and
- energy alarming – combined with established energy profiles this system reviews energy use against standard profiles to determine when systems are using excessive energy.
Leading edge energy monitoring systems will also track building performance against monthly heating and cooling design hours. Greater clarity is required in the design and specification of energy metering systems in order to ensure that they are fit for purpose.
FUNCTIONAL DESCRIPTIONS & DESIGN SCHEMATICS
Control functional descriptions and design schematics form the key documents in the building tuning process. The majority of building tuning processes involve continuous development of the control strategies and tuning of control parameters. The design schematics should not only show the water and air arrangements, but also equipment capacities and control intent. Leading edge building tuning IP focuses on innovative control strategies targeting after-hours operation, optimum starts and shutdowns, as well as part load operation.
TUNEABLE CONTROL SYSTEMS
Open control systems have become established technical standards, yet few of today’s building control systems are fully open or are specified adequately to support effective long-term building tuning processes. Some of the key requirements for building tuning include provision of building tuning information and access to all variables needed to tune a building. Also important is the specified requirement for remote access to the system to allow offsite monitoring and analysis of a building tuning system.
GREEN LEASES
For buildings targeting four-, 4.5- and five-star NABERS ratings, the impact of tenant fitouts and their activities cannot be underestimated. Base Building Design Briefs and Green Leases and the integration of the tenancy fitouts into the building often fail to address the important engineering and commissioning requirements needed to ensure that the tenants do not compromise the base building performance. There are a number of cases where buildings designed to achieve over four-star NABERS base building ratings have been operating at under two stars, largely attributable to poorly integrated tenancies.
Building transition to operation: This phase of the building life-cycle is perhaps the most important transition in terms of building performance. The process involves many parties, including the building owners, designers, constructors, facility managers and tenants. Ideally, those responsible for the long-term operation of the building should be involved in the final stages of commissioning and handover, particularly from a training perspective. The old paradigms, which effectively saw a single handover to building management, are being replaced with an integrated approach extending over one to two years, underpinned by the requirements for building tuning and NABERS rating process.
In a three-year transition plan the key phases would be:
Year 1 practical completion – 12-month tuning/defects liability period:
- completion of integrated fitouts, and
- building tuning and reporting.
Year 2 NABERS rating:
- completion of integrated fitouts, and
- fine-tuning and NABERS tracking.
Year 3 transition to long-term operation:
- energy-efficient maintenance, and
- NABERS tracking.
It is likely that building tuning and mandatory reporting will become an important part of the long-term management plans for all buildings seeking to achieve and maintain NABERS four-, 4.5- and five-star NABERS ratings. While significant progress has been made towards a whole-of-life building tuning strategy, significant opportunities exist to further improve the design, construction and operation processes to assure built performance.
Warwick Stannus is group engineering manager at AG Coombs Advisory.
