Planning, implementing and operating for improved energy performance in commercial buildings

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This article explains the steps to plan, implement and operate for improved energy performance in commercial buildings.

Planning for improved performance

• Strategic planning -- benchmarking
  • Australian Building Greenhouse Rating (ABGR) scheme
• The role of users
• The role of the facility/energy manager
  • Energy management
  • Conducting energy audits
  • Undertaking an energy management program
    

Strategic planning - benchmarking

Source: Cheung, 2006

Energy benchmarks for buildings provide a set of representative values on building energy consumption, against which users can compare a building's actual performance.

These benchmarks are designed to:

• allow users to benchmark their building's energy consumption levels against those of other buildings in their respective sector
• help designers or building management professionals set targets for energy consumption.

Benchmarks are based on surveys of buildings and evaluations of systems considered good practice at the time. It is anticipated that the establishment of benchmarks will lead to improved energy performance by average commercial buildings, as well as significant energy savings. Benchmarks are recognised as valuable tools for both government and the private sector to manage energy usage with respect to climate and specific building typology. If the energy consumption of a building falls outside prescribed limits, the design or building management team can seek advice for improving energy performance.

There are two major types of building energy benchmarks:

• simple benchmarks, which define overall annual energy consumption per unit floor area, or annual greenhouse gas emission per unit floor area
• detailed benchmarks, which have sub-benchmarks for most essential services, including lighting, cooling, heating, ventilation, equipment and vertical transport.

Comparing simple benchmarks of annual energy use per square metre of floor area allows energy efficiency to be assessed, and enables remedial action to be taken. More detailed benchmarks can help pinpoint problem areas within a building.

A number of local and overseas energy benchmarks are summarised in Table 13. Some of these benchmarks include energy-efficient guidelines that address issues of good management, along with proposed energy targets achievable through good design practice.

Examination of the detailed benchmarks of individual building services shows that Victorian benchmarks are more relaxed on lighting systems when compared to benchmarks from outside Australia. While benchmarks for most services are comparable between the Victorian benchmarks and benchmarks set in the UK, both acceptable lighting power density (W/m^²) and lighting energy consumption (kWh/m^²/year) are significantly higher in the Victorian benchmarks. One obvious exception is the heating energy benchmark, which is higher in the UK, as the UK climate has a greater number of days requiring heating. Another significant observation is that while the Victorian benchmarks show half to three-quarters of the energy consumption of the UK benchmark, Victoria's benchmark for greenhouse gas emissions is one and a half to two times that of the UK benchmark. This raises concern about the selection of energy sources in Victorian office buildings, and further stresses the need to reduce energy consumption.

The Building Owners and Managers Association's (BOMA) 1994 design target (see table below) illustrates growth in energy consumption in cooling, ventilation and office equipment. Improved efficiency of building services and office equipment should lead to a reduction in energy consumption, and hence lower the benchmarks. These changes, contrary to the latest benchmarks, can gradually improve the energy performance of buildings over time by raising the energy efficiency target. However, the density of office space has become higher in recent years, resulting in higher ventilation and space-conditioning requirements. Likewise, newer and more powerful desktop computers generate more heat, which explains the increased energy consumption of office equipment, and the increased cooling load required to remove the extra heat.

Australian Building Greenhouse Rating (ABGR) scheme

Office buildings can be rated for their energy efficiency using the Australian Building Greenhouse Rating (ABGR) scheme. Energy efficient buildings have lower operating and life cycle costs, giving a very competitive advantage to owners and tenants.

The Australian Building Greenhouse Rating scheme assists office building owners and tenants to reduce energy use, reduce energy costs and reduce greenhouse emissions. ABGR was developed and is managed by Government, is endorsed by the Property Council of Australia and supported by other major Industry associations and property owners.

The scheme benchmarks a building's greenhouse performance on a scale of one to five, one having the worst greenhouse performance and five the best. Three stars represents current market best practice. The rating system is derived from the actual amount of energy (electricity, gas, coal or oil) your building/tenancy consumes in a year. This means the rating reflects the way energy is managed as well as how efficiently the building is designed. The benchmark allows comparison with the greenhouse performance of other buildings within the state. The stars are arranged as follows:

• 1 Star - Poor energy management or outdated systems. Building is consuming a lot of unnecessary energy. There are cost effective changes that can be implemented to improve energy consumption, cut operating costs and reduce greenhouse emissions.
• 2 Star - Average building performance. Building has some elements of energy efficiency in place and reflects the current market average. There is still scope for cost-effective improvements, and minor changes may improve on this building's energy and operating costs.
• 3 Star - Current market best practice. Building offers very good systems and management practices and reflects an awareness of the financial and environmental benefits of optimising energy use.
• 4 Star - Strong performance. Building demonstrates excellent energy performance due to design and management practices or high efficiency systems and equipment, or low greenhouse intensive fuel supply.
• 5 Star - Best building performance. Building is exceptional due to integrated design, operation, management and fuel choice.
  
  

The role of users

Source: Department of Sustainability and Environment, 2006

Having energy-efficient equipment in an office has a significant impact on energy use. However, if the equipment is not used efficiently, then the efficiency gains can be lost. In fact, having staff behave in an energy-efficient manner can reduce typical energy use by up to 15%.

Encouraging staff to switch off office equipment is not always easy. Generally, some staff will do this as a matter of course, but others will need a bit more encouragement.

A campaign to encourage staff to be more energy-efficient could include the following steps:

1. Notify staff of the campaign (some prefer to do 'spot checks', but notifying staff first will give staff an opportunity to change their behaviour voluntarily).
2. Come in to the office outside of normal operating hours and put a chocolate (or a healthier treat) on people's desk where they have turned off their computer and monitor – you can also put a treat on printers/faxes/photocopiers that have been switched off.
3. Take a note of who has turned off their equipment and who hasn't, so you can monitor the impact of the campaign.
4. Send an email around to explain why some people have a treat and others don't, and encourage people to change their behaviour by telling them there will be more opportunities to receive a treat in future.
5. Repeat the activity – the more often you repeat the activity, the more likely you are to sustain the change in behaviour. A common approach is to repeat after a week, then two weeks, then three weeks, and then monthly.
6. Monitoring the response of staff will enable you to judge how often you need to repeat the activity.
   

The role of facility/energy manager

The facility manager has been a core position in many commercial buildings for decades. The responsibilities of facility managers have been wide-ranging, revolving around managing and maintaining the building facilities that provide services to the occupants. A growing part of the facility manager's role is managing the energy aspects of a building. Indeed, for some large buildings, this role has evolved into a dedicated position, with energy managers becoming more common. Energy costs generally represent 15% of the outgoing costs for a typical office building, and are one of the best sections to target for cost reductions through energy-efficiency programs and good energy management.

Energy management

Source: Department of Infrastructure, 1998
Energy management is a program of well-planned actions, aimed at reducing an organisation's energy bills while offering improvements in comfort for users and reducing detrimental environmental impacts.

There are two central energy management strategies:

• energy conservation – avoidance of wasteful energy use and reduction in demand for energy-related services (i.e. if you don't need it, turn it off)
• energy efficiency – reduction in the consumption of energy for current operations (i.e. if you need it, do it more efficiently).

Energy management involves:

• devolving responsibility for energy bills to those with the authority to change the way energy is used
• providing resources where required
• collecting and analysing existing energy use data
• undertaking an energy audit to determine where, and how efficiently, energy is used
• implementing energy-saving measures
• regularly reporting the savings that have been achieved.

Appropriately applied energy management strategies will lead to a reduction in the cost of delivering government services and improve the quality of services provided.

Energy needs to be managed because it makes good economic and organisational sense. One of the principal benefits of effective energy management is the improved quality of service it provides: a well-designed, well-maintained and well-operated facility will be energy-efficient and offer a high degree of amenity to its users. Managing the consumption of energy is an important element in the process of providing cost-effective services and minimising the indirect costs passed on to the community.

Energy audits indicate that more than 20% of energy consumed can be saved by implementing relatively simple measures, which will pay back the investment in less than three years. Management, operating and maintenance measures, which require little or no capital investment, can achieve a 10% saving in energy usage. These energy savings translate to commensurate cost savings and reductions in greenhouse gas emissions.

Conducting energy audits

An energy audit establishes both where and how energy is being used, and the potential for energy savings. It includes a walk-through survey, a review of energy-using systems, analysis of energy use and the preparation of an energy budget. The audit provides a baseline from which energy consumption can be compared over time. An audit can be conducted by an employee of the organisation who has appropriate expertise, or by a specialist energy auditing firm.

An energy audit report also includes recommendations for actions that will result in energy and cost savings. It should indicate the costs and savings for each recommended action, and a priority order for implementation.

Links:
AIRAH energy auditor register

Undertaking an energy management program

Energy management should be seen as a continuous process. Two key strategies for establishing an energy management program are

• Identify a strategic corporate approach: The starting point in energy management is to identify a strategic corporate approach to energy management. Clear accountability for energy management needs to be established, appropriate financial and staffing resources must be allocated, and reporting procedures should be initiated. An energy management program requires commitment from the whole organisation in order to be successful.
• Set up an energy monitoring and reporting system: Successful energy management requires the establishment of a system to collect, analyse and report on the organisation's energy costs and consumption. This will enable an overview of energy use and its related costs, and will facilitate the identification of savings that might otherwise not be detected. The system needs to record both historical and ongoing energy use, as well as cost information from billing data, and be capable of producing summary reports on a regular basis. This information will provide the means by which trends can be analysed and tariffs reviewed.

Once established, a comprehensive energy management program will include the following key activities:

• Formalisation of an energy management policy statement: A written energy management policy will guide efforts to improve energy efficiency and represents a commitment to saving energy. It will also help to ensure that the success of the program is not dependent on particular individuals in the organisation. An energy management policy statement includes a declaration of commitment from senior management, as well as general aims and specific targets relating to:
  • energy consumption reduction (electricity, gas, petrol, oil etc.)
  • energy cost reduction (by lowering consumption and negotiating lower unit rates)
  • timetables
  • budgetary limits
  • energy cost centres
  • organisation of management resources.
• Preparation and undertaking of a detailed project implementation plan: A project implementation plan should be developed as part of the energy audit and be endorsed by management. The plan should include an implementation time line and state any funding and budgetary requirements. Projects may include establishing or changing operational procedures to ensure that plant and equipment use minimum energy, renegotiating electricity supply arrangements, or adopting asset acquisition programs that will reduce energy consumption. An overall strategy could be to introduce energy management projects that will achieve maximum financial benefits at least cost to the organisation.
• Implementation of a staff awareness and training program: A key ingredient to the success of an energy management program is maintaining a high level of awareness among staff. This can be achieved in a number of ways, including formal training, newsletters, posters and publications, and by incorporating energy management into existing training programs. It is important to communicate program plans and case studies that demonstrate savings, and to report results at least at 12-month intervals. Staff may need training from specialists to demonstrate energy-saving practices and use of equipment.
• Undertaking of an annual review: An energy management program will be more effective if its results are reviewed annually. The energy management policy and strategies should be reviewed in the light of the results achieved so far; this will form the basis for developing an implementation plan for the next 12 months.
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Implementing and operating for improved performance

• Commissioning
  • Commissioning costs
  • Commissioning process
• Controls and sensors
  • Lighting
  • HVAC
• Monitoring
  • International performance measurement and verification protocol
  • Electrical energy
  • Electrical demand
• operations and maintenance
  

Commissioning

Source: US Department of Energy, 2004

Building commissioning is a systematic process of ensuring that a building performs in accordance with the design intent, contract documents, and the owner's operational needs. Commissioning is necessary because of the sophistication of building designs and the complexity of modern building systems. However, it is not automatically included as part of the typical design and construction process. Commissioning is critical for ensuring that the design developed through the whole-building design process is successfully constructed and operated. It is a critical part of ensuring that all energy efficiency measures that have been incorporated into the building are performing as required.

Building commissioning involves:

• systematically evaluating all pieces of equipment to ensure that they are working according to specifications. This includes measuring temperatures and flow rates from all HVAC devices and calibrating all sensors to a known standard
• reviewing the sequence of operations to verify that the controls are providing the correct interaction between equipment.

Specific building commissioning activities include:

• engaging a commissioning authority and team
• documentation
• verification procedures, functional performance tests and validation
• training.

Building commissioning does not include:

• construction observation (punch list)
• start-up
• testing, adjusting and balancing (TAB)
• final punch-out.

While these activities are individual steps in the systematic process of commissioning, by themselves they cannot meet the goals of building commissioning.

Commissioning HVAC systems is even more important in energy-efficient buildings because equipment is less likely to be over-sized and must therefore run as intended to maintain comfort. Also, HVAC equipment in better performing buildings may require advanced control strategies. Commissioning goes beyond the traditional HVAC elements. More and more buildings rely on parts of the envelope to ensure comfort.

Commissioning includes evaluating static building elements to ensure that shade management devices are in place, glazing was installed as specified and air-leakage standards have been met. Commissioning can also evaluate other claims about the construction materials, such as VOC emission content and durability. It is important that the products that were specified for the building meet the manufacturer's claims and are appropriate for the project.

Continuous commissioning ensures that the building operates as efficiently as possible, while meeting the occupants' comfort and functional needs throughout the life of the building. Continuous commissioning differs from building operation and maintenance.

Benefits of building commissioning include:

• energy savings and persistence of savings
• improved thermal comfort with proper environmental control
• improved indoor air quality
• improved operation and maintenance with documentation
• improved system function that eases building turn-over from contractor to owner.

Project documentation relevant to commissioning includes:

• quality assurance project plans
• construction management plans
• test and inspection plans
• acceptance test procedures
• O&M manuals.

However, building commissioning goes beyond these plans and manuals, using a more systematic and integrated process.

Commissioning costs

Building owners are finding that the energy, water, productivity and operational savings resulting from commissioning offset the cost of implementing a building commissioning process. Recent studies indicate that, on average, the operating costs of a commissioned building range from 8%-20% below that of a non-commissioned building. The one-time investment in commissioning at the beginning of a project may result in reduced operating costs that will last the life of the building. In general, the cost of commissioning is less than the cost of not commissioning.

The cost of commissioning is dependent upon many factors, including a building's size and complexity, and whether the project consists of new construction or building renovation. In general, the cost of commissioning a new building ranges from 0.5% to 1.5% of the total construction cost, as shown in the table below. For an existing building that has never been commissioned previously, the cost of retro-commissioning can range from 3% to 5% of the total operating cost.

Commissioning scope and costs

Commissioning scope	Cost
Entire building (HVAC, controls, electrical, mechanical)	0.5%-1.5% of total construction cost
HVAC and automated control system	1.5%-2.5% of mechanical system cost
Electrical systems	1.0%-1.5% of electrical system cost
Energy efficiency measures	Approx. $3.00/m2

Commissioning process

Commissioning is a strategy that:

• begins early in the design process
• requires special bidding requirements during contractor selection
• controls the static and dynamic testing that acceptance is based on
• finishes with staff training and warranty monitoring.

Building energy systems that should be commissioned include:

• HVAC/mechanical systems
• electrical systems
• lighting systems.

Commissioning ideally occurs through all phases of a building project. A commissioning agent should be designated as early as possible in the project time line, ideally during the pre-design phase. While it is beneficial to have a third-party commissioning authority for more comprehensive design and construction review, it is acceptable for a project to use a qualified member of the design team as the commissioning agent (CA). The commissioning provider serves as an objective advocate of the owner, directs the commissioning process, and presents final recommendations to the owner regarding the performance of commissioned building systems. The commissioning provider introduces standards and strategies early in the design process, and then ensures implementation of selected measures by clearly stating target requirements in construction documents. The CA then verifies that the minimum targets have been met after construction completion. In addition, the CA should provide guidance on how to operate the building at peak efficiency.

Controls and sensors

Lighting

Source: US Department of Energy, 2005

Lighting controls not only help conserve energy, they also make a lighting system more flexible. The most common light control is the on/off switch. Other types of lighting control technologies include:

• manual dimming
• photosensors
• occupancy sensors
• clock switches and timers
• centralised controls.

Manual dimming
Manual dimming controls allow occupants of a space to adjust the light output or illuminance. This can result in energy savings through reductions in input power and peak power demand, as well as enhanced lighting flexibility.

Slider switches allow the occupant to change the lighting over the complete output range, and are the simplest of the manual controls. Pre-set scene controls change the dimming settings for various lights all at once with the press of a button and allow different settings for the morning, afternoon and evening. Remote-control dimming is also available – this type of technology is well-suited for retrofit projects, where it is useful to minimise rewiring.

Fluorescent lighting fixtures require special dimming ballasts and compatible control devices. Some dimming systems for high-intensity discharge lamps also require special dimming ballasts.

Photosensors
Photosensors automatically adjust the light output of a lighting system, based on detected illuminance. The technology behind photosensors is the photocell. A photocell is a light-responding silicon chip that converts incident radiant energy into electrical current.

While some photosensors just turn lights off and on, others can also dim lights. Automatic dimming can help with lumen maintenance. Lumen maintenance involves dimming luminaires when they are new, which minimises the wasteful effects of over-design. The power supplied to them is gradually increased to compensate for light loss over the life of the lamp.

Nearly all photosensors are used to decrease the electric power demand for lighting. In addition to lowering the electric power demand, dimming the lights also reduces the thermal load on a building's cooling system. Any solar heat gain that occurs in a building during the day must be taken into account for a whole-building energy usage analysis.

Occupancy sensors
Occupancy sensors turn lights on and off, based on their detection of motion within a space. Some sensors can be also be used in conjunction with dimming controls to keep the lights from turning off completely when a space is unoccupied. This control scheme may be appropriate when occupancy sensors control separate zones in a large space, such as in a laboratory or an open office area. In these situations, the lights can be dimmed to a predetermined level when the space is unoccupied. Sensors can also be used to enhance the efficiency of centralised controls by switching off lights in unoccupied areas during normal working hours, as well as after hours.

There are three basic types of occupancy sensors:

• passive infrared
• ultrasonic
• dual-technology (hybrid).

Passive infrared (PIR) sensors react to the movement of a heat-emitting body through their field of view. Wall box-type PIR occupancy sensors are best suited for small, enclosed spaces, such as private offices, where the sensor replaces the light switch on the wall and no extra wiring is required. They should not be used where walls, partitions or other objects might block the sensors' ability to detect motion.

Ultrasonic sensors emit an inaudible sound pattern and re-read the reflection. They react to changes in the reflected sound pattern. These sensors detect minor motion better than most infrared sensors. Therefore, they are good to use in spaces such as restrooms with stalls, which can block the field of view, since the hard surfaces will reflect the sound pattern.

Dual-technology occupancy sensors use both passive infrared and ultrasonic technologies to minimise the risk of false triggering (lights coming on when the space is unoccupied). They also tend to be more expensive.

Clock switches and timers
Clock switches or timers control lighting for a pre-set period of time. They come equipped with an internal mechanical or digital clock, which automatically adjusts for the time of year. The user determines when the lights should be turned on and when they should be turned off. Clock switches can be used in conjunction with photosensors.

Centralised controls
Centralised building controls, or building automation systems, can be used to automatically turn on, turn off, or dim electric lights around a building. In the morning, the centralised control system can be used to turn on the lights before employees arrive. During the day, a central control system can be used to dim the lights during periods of high power demand. At the end of the day, the lights can be turned off automatically. A centralised lighting control system can significantly reduce energy use in buildings where lights are left on when not needed.

HVAC

Source: Australian Greenhouse Office, 2005

Controls for air-conditioning are the key item that will make or break the performance of a system. Poor controls can make a building very unpleasant, whereas the best controls will be so good that they're not really noticed.

There are several different controls systems that can be applied to buildings:

• Manual controls: While manual controls can be used to good effect in naturally ventilated buildings, people are generally very poor controllers. This is partly because people often don't agree on what's comfortable, and partly because most people don't fully understand the systems they are trying to control.
• Pneumatic controls: In the days before cheap electronics, compressed air control systems were commonly installed in buildings. These have very high maintenance characteristics and are generally a liability where they are still present.
• Electronic controls: These have become the standard control system in modern buildings and are best thought of as a system of mini-computers.

The emergence of electronic controls has led to the widspread development and implementation of building management systems (BMS). These are computer-based systems that allow users to monitor and control just about anything happening in a building. A well-designed building management system can be the backbone of an efficient building.

BMS' have the potential to provide substantial efficiencies in the operation of buildings through integrated control methods that look at how the whole building is operating. Modern BMS' have a high level of intelligence programmed in at all levels, so that there is a central 'brain' in charge, but each part of the system can operate independently for some time without connection to the central brain.

These systems can also be used to monitor and control other items, such as building security and access. However, adding too many systems to a BMS many cause it to slow down and become less effective.

Of particular interest to the energy manager is the incorporation of energy management functions into BMS'. However, until recently, this has been an afterthought. As a result, some of the functions desirable for energy management are not always available on any one given system.

What to control?
A key temptation to avoid is the over-burdening of the BMS with useless information. As a BMS is designed to monitor and control, it is sometimes assumed that almost every system event should be monitored by the BMS. This philosophy results in a huge amount of data being collected. However it is important to ask whether all of the data collected will actually be useful to the building manager. Data by itself is useless unless it can be associated with other data to provide some useful information. Indeed, unlimited data can cause enormous problems – a building in Sydney, with 7,000 BMS points, had 15,000 alarm signals a day for the first six months of operation, and to this day still has hundreds. The operators just ignore these.

Decisions on what data to collect should be made from the perspective of the building or energy manager, and only data that is important to managing the building should be selected. This gives a top-down approach to selecting correct data that can be combined with present information. Data collected may include:

• room temperatures
• outside air temperature
• chiller common faults
• cooling tower common faults
• boiler system common faults
• electricity consumption for each tenancy
• gas consumption
• fire alarm activation
• security alarm
• plant operation (on/off).

Data may be presented to an operator in several different forms, such as trend graphs for later analysis, graphic system diagrams with flashing alarm areas, alarm printouts or callout paging.

A building management system that only provides screens of numbers is more useful as a paperweight than as an information system!

A final point to consider with real control systems is access. If only one person understands how to use the control system, then problems will arise when that person is not available. Therefore, it is important to have a body of people who understand and can use the system. It is also essential to ensure that access to the controls is limited to those who actually understand the system, so that changes are made in an informed manner. In addition, there should be coordination and documentation of changes, as the integrity of the control system may otherwise collapse under the strain of multiple uncoordinated and ad-hoc changes.

Efficiency opportunities
From an energy management perspective, the most important function of control systems is their ability to reduce HVAC energy use. Any control option can be programmed into a control system, as long as the hardware and software are suitable. For modern systems, the capability of the system is more likely to be constrained by the ability of the person programming the system, rather than the hardware or software.

Monitoring
One of the key advantages of modern control systems is that they gather and store vast amounts of data. This can be a goldmine if users have the time and energy to look through it. However, most users identify a handful of key data items and get regular updates from the control system on those variables.

Key items may include:

• energy use on a continuous basis
• sub-meters for different parts of the building
• building entry and exit patterns
• space temperatures in key areas
• VAV terminal unit performance
• terminal reheat operation
• boiler and chiller operation.

The controls operator should generate a regular report with the information required and provide the information to the building or energy manager on a weekly basis. This will tell the building manager an enormous amount about how the building works.

Control system problems
The most common problems with controls systems can often be traced to one of the following:

• Outdated hardware: Pneumatic control systems are, almost without exception, a liability in terms of both energy efficiency and the quality of control. Often the best thing that can be done with such systems is to get them completely replaced. Other older electronic control systems may also be outdated ¿ control technology is advancing almost as fast as personal computers. From an energy perspective, however, control systems are good as long as they keep performing the required functions efficiently. Control equipment and sensors should always be properly calibrated.
• Poor maintenance: One of the greatest causes of control failure is poor maintenance. Most often this shows up in the mechanical components, such as valves and dampers. This has the effect of the controls thinking they have performed an action, but nothing actually happens. This in turn can cause other problems downstream. It is essential that all components of the control system are kept in good order. This can be achieved through a comprehensive, preventative maintenance contract.

More information on the maintenance of control systems is provided in AIRAH DA 19 HVAC&R, a sample of which is shown in the figure below. This is being recognised as an industry standard in Australia.

• Bad programming: The age-old principle of 'garbage in, garbage out' applies. If a control controls the temperature of the sixth floor of a building, it will not work well if the sensor is wrongly programmed to be the one on the ninth floor. This may sound ridiculous, but it does happen! At a more subtle level, building controls contractors have standardised methods of setting up control systems that may not suit a specific building and may not be particularly efficient. It is essential therefore that the control system allows other parties to gain access, in order to provide an independent overview of system operation.

Control strategies
Critical control strategies that can save energy include:

• selecting realistic operating hours – for any building that shuts down overnight, every extra hour per day of operation represents approximately 7% additional air-conditioning energy. Don't run the building for a handful of early birds or night owls; generally conditions in the building will be near enough to normal comfort levels without extended hours
• selecting realistic space conditions – controls should be set up to provide a 'dead-band' between 20 °C and 23°C where neither heating nor cooling will occur. This band reduces starting demands on plant and saves energy by recognising that people dress differently during heating and cooling seasons
• logical zoning of HVAC areas – zoning so that HVAC areas of similar load characteristics are controlled together can reduce energy use considerably, by avoiding the amount of reheat needed to maintain conditions. In general, this is only possible at the time of construction or major refurbishment. However, changing building use may mean that sensors can be relocated to better reflect building conditions. In some cases, relocation of partitions can isolate sensors from the systems they control, under which circumstances it is essential to relocate the sensor back into the relevant conditioned space
• early morning warm-up or cool-down – sealing the building from the introduction of outside air and applying maximum heating/cooling can achieve design conditions in the minimum time. It is necessary to establish that the building will not be occupied during this period and that the building has enough thermal storage to warrant using the system
• night-time purge (Australian term) – 'low-heat' night air can be used to cool the structure of the building when the internal temperature is above the lowest comfort temperature. An additional advantage of this is that internal air quality will be improved. When evaluating the economics of this system, the power requirements of the fans required should be assessed. It may be no cheaper than using the chiller plant for a short period before occupancy; however this technique does not improve air quality. Night-time purge works well where there is a large diurnal temperature range, but is not suitable for all climates
• fresh air control – when it is cooler outside than inside, it is often possible to use outside air to provide free cooling
• scheduling – sophisticated control systems with 365-day clocks can be scheduled to ensure that plant does not run on days when offices are not in use. Starting and stopping times can also be changed when daylight saving commences and ceases. Continued management is required to update the program for changes, such as public holidays and so forth
• optimum start/stop routines – these routines monitor the time taken for a building to reach design conditions in the morning and to depart from design conditions when the HVAC is shut off at night. The start and stop times are progressively modified over a number of days until a good match with the building requirements is achieved. The optimisation routine continues to modify the start and stop times as the seasons change.
  
  

Monitoring

When an organisation makes a commitment to reducing energy costs and protecting the environment, it is important to measure the results of these efforts. Senior managers need this information to justify budgets for capital improvements designed to produce long-term benefits, and to determine the benefits received from these investments. These measurements can provide feedback on whether investments are producing the anticipated benefits. If they are not, monitoring may identify reasons for the shortfalls and help facility managers improve performance with other projects.

Some of these measurements are relatively easy to quantify. For example, energy quantities and associated costs are provided monthly to the facility manager, and the cost-benefit of some energy reduction measures can be readily determined from these bills. Levels of specific indoor air pollutants can be measured, but the cost-benefit determination is less straightforward.

Instrumentation and measurement plays a role throughout the process, from measuring baseline energy use to commissioning new systems, optimising long-term performance and serving as the basis of performance metrics and contractor payments.

International performance measurement and verification protocol

The International Performance Measurement and Verification Protocol (IPMVP) provides a wide range of measurement and verification (M&V) alternatives, including stipulation based on engineering calculations, metering, and using the results of a short-term test to calibrate computer models. In general, more detailed and labour-intensive efforts yield more information, but the value of the information must be weighed against the cost of the M&V program. Simple, low-cost measurements are often adequate and cost-effective. Energy management system tracking features are an effective way to collect consumption and demand information.

Two documents have been published by IPMVP: Volume I – Concepts and options for determining energy savings and Volume II – Concepts and practices for improved indoor environmental quality. They are available to download from the National Renewable Energy Laboratory website.

Factors affecting the costs of measurement and verification include:

• the number of energy measures implemented
• the size and complexity of energy conservation measures
• interactions between energy conservation measures
• how risk is allocated between the owner and the contractor in a performance contract.

The appropriate M&V strategy can be determined by assessing the project's complexity and the way risk is allocated between an energy service company and its customer. Risk allocation refers to whether the contractor is responsible only for equipment performance (efficiency), or also bears some risk related to operational factors, such as uncertainty in the load.

Electrical energy

Determining electrical energy consumption is relatively straightforward, and an ordinary electrical meter is adequate for simple daily, weekly, or other longer electrical energy determinations. If consumption versus time is required, either the manual method of taking frequent meter readings or automated data collection can be used. For the collection of time-based information, split-core current transducers and power transducers can be installed without disconnecting power. Data loggers can be used to collect data, which can then be downloaded as needed.

Electrical demand

Time-based information is required if electrical demand is to be determined. For this purpose, it is essential to have the appropriate software to determine the 'peak' value. The peak can be a time-averaged value over a sliding 15- or 30-minute time frame, in which single or multiple spikes are not indicative of the peak as measured by the local utility. Other software simply measure the highest demand in a month and base demand charges on that value.

Operations and maintenance

The best efforts to reduce energy consumption are doomed to failure unless well-crafted operations and maintenance (O&M) procedures are implemented. Furthermore, even the best O&M procedures are of no use unless they are understood and followed by building O&M personnel.

Facility managers play a key role in ensuring that this happens. An integrated team approach can be a big help. In this process, O&M personnel are active participants in the design of a facility and the development of O&M procedures. The integrated team approach promotes useful procedures that are efficient and, most importantly, faithfully executed.

Building operation and maintenance programs specifically designed to enhance operating efficiency of HVAC and lighting systems can reduce energy bills by 5%-20% without significant capital investment.

Addressing O&M considerations at the start of a project can contribute greatly to improved working environments, higher productivity, and reduced energy and resource costs. There are tremendous opportunities in most existing buildings and facilities to improve O&M procedures and make them more environmentally responsible. With new buildings, there are opportunities during design and construction to facilitate easy, low-environmental impact O&M. With all buildings, there are opportunities to derive multiple benefits. If implemented effectively, the multiple benefits of O&M practices should include reduced operating costs.

An effective O&M program includes the following procedures:

• Ensure that up-to-date operational procedures and manuals are available – recommend that schedules are based on industry standards, such as those in AIRAH DA19 HVAC&R maintenance.
• Obtain up-to-date documentation on all building systems, including system drawings.
• Implement preventive maintenance programs, complete with maintenance schedules and records of all maintenance performed for all building equipment and systems.
• Create a well-trained maintenance staff, and offer professional development and training opportunities for each staff member. NFEE education and training committee have just awarded two post-graduate qualification packages; one for engineers and one for facility managers. These will become the benchmark for recognised professionals.
• Implement a monitoring program that tracks and documents building systems performance to identify and diagnose potential problems and track the effectiveness of the O&M program. Include cost and performance tracking in this analysis.

For more information on operations and maintenance, refer to AIRAH DA19 HVAC&R maintenance and Section I of the BCA.

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