Energy

Parties Involved

Energy Management

The day-to-day management of energy use should be the first step in any organisation’s energy efficiency strategy – ahead of investment in renewables or other technologies. This requires accurate measurement and monitoring of a building’s energy use and communication of that information to the respective users of the building. Appropriate metering and sub-metering systems, installed so as to record the energy consumption of different elements throughout the building, are central to efficient building management. They have become increasingly valuable tools for owners and a necessary requirement for Tenants given their many benefits. These include the potential for energy, cost and CO2 savings, as well as the provision of data to support corporate reporting and compliance with increasing environmental legislation such as the National Greenhouse Emissions Reporting Scheme and the Energy Effiicency Opportunities Act. Furthermore, transparency in terms of utility tariff selection and the detailed breakdown of costs is becoming increasingly important for tenants. Energy inefficiency and wastage not only results in unnecessary costs to business, but is detrimental to corporate efforts to drive down CO2 emissions in line with national and international emissions reduction targets.

Information & Actions

Smart Metering & Sub-metering

What are they?
Smart utility meters allow a utility company to access energy consumption data remotely. Energy readings are typically recorded on a fifteen minute basis, providing much more accurate and up-to-date energy usage data than is available through monthly or quarterly bills. The fifteen minute data is transmitted over a communications network to a meter reading company that relays the data to the electricity retailer. The data can then be passed on to the building management team for analysis. Similarly, smart meters can be used as sub-meters (i.e. non-utility) to provide more accurate and up-to-date energy consumption data for a sub-meter which measures a specific location or energy load. Data for these non-utility meters is transmitted to an internal meter reading system (typically a dedicated metering system or the Building Management System) where performance can be analysed to ensure efficient operation and to identify energy reduction opportunities. In a high quality installation, sub-metering should enable the categorisation of energy use by sub-system, e.g. chiller plant, heating plant, fans, lifts, lighting, and plug loads.

Advantages / Disadvantages

Provides better understanding of energy consumption and where energy efficiency opportunities exist; also provides better information with which to promote behaviour change.
Enables more detailed benchmarking of performance, including setting subsystem \ targets.
Allows owners and tenants to cross check that they are being billed correctly.
Reduces facilities management costs in a building where regular manual readings take place by reducing the requirement for manual meter inspections.
Requires time and resource for the active monitoring and reporting of data and setting targets and actions for reducing energy consumption.

Energy efficiency
Smart meters and sub-meters do not by themselves save any energy. However, they are a valuable aid to any efforts to reduce energy consumption.

Running costs
There are additional maintenance, data collection and analysis costs associated with a smart metering and sub-metering strategy. However, the benefits of accurate billing and increased transparency and understanding of energy consumption generally warrants the investment.

Retrofit / improvement opportunities
Retrofit installation of submeters is straightforward, although often an electrical shut-down will be required to permit installation of meters on major risers. If this is done after hours there is little disruption to tenants.

Applicable buildings
Smart meters and sub-meters can be used in all building types.

Floor plate implications
None.

Occupant comfort
No issues.

Maintenance implications
The energy utility company will carry out all necessary maintenance on the main electricity or gas meter. Periodic checking and servicing of any sub-metering will need to be undertaken by the building owner.

How to identify them
Utility meters are typically located in or near the main switch board and in or near the switchboards the serve tenancies. Submeters will typically be found in plant areas and riser cupboards.

Questions to ask

Is there smart metering in place covering both the mains electricity?
Is there remote reading of gas meters, providing time-of-use information on gas consumption?
Is there remote reading of water meters, providing time-of-use information on water consumption?
Is there a sub-metering system in place that is automatically read, with the information collated and presented in a manner that facilitates its use in managing building operations?
How extensive is the sub-metering strategy e.g. location specific (such as each floor or tenant) or energy user specific (such as lighting, power, heating or cooling), as opposed to a general strategy that may mix multiple unassociated items onto a single meter?
Have meters been validated in accordance with the NABERS standard in order to ensure that the meters are correctly configured and the readings are being read correctly?
Who monitors and reports the data and is taking action to reduce energy consumption?
On what basis are energy bills split and recharged to tenants?

More information
SmartMeters Victoria Fact Sheet

Building Management Systems

What are they?
A building management system (BMS) is a computer based central control system which is installed within a building to manage the operation of its services – heating, cooling, ventilation, hot water and lighting, and in some cases the integration of these services with the building envelope through control of shading devices and windows. A BMS system comprises two key elements: controllers in the field, often in cabinets within plant rooms, and a computer ‘head end’. Each controller sends and receives signals to / from the various items of building services equipment. The computer ‘head end’ provides an interface with the controllers, showing real-time temperatures and plant operating conditions, allowing the user to change and program system settings.

Advantages / Disadvantages

Programmable to meet tenant and owner requirements.
If well managed, will reduce energy consumption and costs and improve occupant comfort.
Requires skilled personnel to operate with regular monitoring and review.
Can result in unnecessary energy wastage and occupant discomfort if badly managed or operated.

Energy efficiency
A correctly set up and well managed BMS should result in energy savings of up to 30% together with lower maintenance requirements. It provides building management the ability to implement more complex and demand-responsive strategies for managing building services in real-time.

Running costs
Low cost to run, but annual maintenance and regular monitoring is required to ensure control settings are appropriate for the building.

Retrofit / Improvement opportunities
An existing BMS can be easily upgraded or extended to provide greater control of a building’s services, although outdated systems may require a full replacement. It is feasible and worthwhile to retrofit a BMS into most medium to large buildings where none exists currently. Space is required in a plant area to accommodate the central control panel.

Applicable Buildings
BMS systems are applicable to all buildings, but generally better suited to larger buildings with complex services and systems. They are rarely installed in small or simple buildings such as strata offices, warehouses or shop units, which are more likely to benefit from a simple timeclock.

Floor plate implications
None.

Occupant comfort
A building with a well-managed BMS installed should provide occupants with a high level of comfort in relation to heating, cooling, ventilation and lighting requirements as well as providing improved visibility of space temperatures to enable monitoring of comfort issues when they occur.

Maintenance implications
A BMS requires regular monitoring and review by building management to ensure the system is operating efficiently and is well matched to the changing operational needs of the building. Regular maintenance is required. This is typically undertaken by the system supplier under a service agreement. Sites that do not have a service agreement generally show a poorer level of efficiency and comfort as a result.

Identification
The easiest identifier for a BMS is the “head end” computer – which is typically located in the building managers office or in a plant room and has graphical information on the operation of items of plant.

Questions to ask

Does the building have a BMS?
Does the site have a maintenance contract that provides for regular maintenance of the BMS?
How old is the BMS?

More information
AIRAH Guide DA28 Building Management and Control Systems

Australian Government Department of Climate Change and Energy Efficiency (DCCEE) BMS Fact Sheet

Air-Conditioning

Air conditioning systems, more accurately referred to as heating, ventilation and air conditioning (HVAC) systems, typically consume more energy than any other function in an air conditioned office building. They also have a significant impact on occupant satisfaction. A working knowledge of the key facts about different systems will enable an agent to provide either the owner or tenant with valuable information and advice on what they might expect from the air-conditioning system within a building. Different air conditioning systems are appropriate for different types of building in different locations. Systems vary in terms of how a space is ventilated and cooled / heated and the extent to which air, water, and/or refrigerant are circulated within a building. Some systems keep almost all equipment within the plantroom, whereas other systems require some or all of the equipment to be located in the tenancies. The tenants’ responsibilities for operations and maintenance can change as a result. While most Australian buildings have some form of active cooling, this is not true for warehouse and storage facilities. For such facilities, understanding how appropriate the system in place is to the needs and requirements of a client is crucial for avoiding unnecessary costs (if cooling is not required) or product damage (if cooling is required).

Information & Actions

Variable Air Volume Systems

What are they?
Variable air volume (VAV) systems supply air at a variable temperature from an air handling unit (AHU). The AHU draws in fresh air and return air from inside the building and either heats or cools it before reaching the occupied space. Within each space, the amount of air is adjusted to control the space temperature using VAV terminals, which may also have some local heating capacity. VAV systems either use central AHUs located on dedicated plant room floors that serve multiple levels of the building, or may use smaller units in plant rooms on each floor.

Advantages / Disadvantages

Highly flexible, but ideal for open plan spaces
Industry standard technology with plenty of industry experience in operation and maintenance
Potential for high efficiency operation when well controlled and maintained.
Air-handlers can be (and generally are) configured for the use of outside air for free cooling.
High component count and heavy dependence on control can make the system prone to energy-intensive failure modes that may also affect occupant comfort.
Large multi-storey air-handling systems may have difficulty adequately servicing floors with exceptionally high or low loads.
Large multi-story air-handling systems often less efficient at servicing after-hours loads.

Energy efficiency
When well controlled and maintained, VAV systems can achieve some of the highest levels of energy efficiency in the market. However, high efficiency is only achieved through superlative control, and relatively minor errors in control can have severe impacts on energy use.

Running costs
With good management, control, maintenance and commissioning, running costs can be low; without these costs can increase significantly. A building management system (BMS) is essential to achieve efficient operation.

Retrofit / improvement opportunities
Most VAV systems are capable of being refurbished to achieve a high level of efficiency even if the current level of efficient is poor, provided that basic plant is in reasonable condition. The major areas for improvement are:

Review and optimisation of control for VAV terminals and air-handlers. The most common failure modes for VAV systems result in fans operating at close to maximum speed all year around and VAV terminals causing extensive heating and cooling conflicts. These issues are largely rectifiable through improved control.
Optimisation of the use of outside air for free cooling when conditions are appropriate.
Upgrade of controls for boilers, chillers and associated pumps
Upgrade of pressure dependent VAVs to pressure independent VAVs, which provide much better feedback on control. This can require floors to be vacated.
Upgrade of chiller plant. Chillers have 15-20 year lifespan, although they generally have been superseded in terms of efficiency well before the end of their operational life. Replacement of chillers is best undertaken in winter.

Control improvements can be implemented with the tenants in-situ

Applicable buildings
VAV systems are typically found in large office buildings and some shopping centres from the 1970s onwards. They are less common in smaller buildings.

Floor plate implications
The size of riser ducts can be significant for multi-storey buildings served from a central AHU (located, for example, on the roof or in the basement). The risers may restrict flexibility on floor plates. In buildings with AHUs on each floor, the AHU plant room will take up a significant amount of space.

Temperature control / Occupant comfort
VAV systems can offer a high degree of temperature control when well controlled

Maintenance implications
The VAV terminals and controls require routine maintenance. Central plant requires standard levels of maintenance. Controls require careful configuration and management; arbitrary adjustment of temperature set-points within VAV systems is a leading cause of energy waste.

How to identify them
VAV systems are commonly found in larger office buildings, but are largely indistinguishable from other AHU based systems to the non-technical observer. Maintenance or operational staff will be able to advise whether a system is VAV.

Questions to ask

Does the system have an economy cycle to improve energy efficiency?
Are the VAVs pressure dependent or pressure independent?
Is there a building management system (BMS)?
Is the system regularly maintained (at least annually) and seasonally commissioned?

More information
AIRAH Guide DA08 HVAC&R An Introduction CIBSE Ventilation / Air conditioning / Technical Glossary

Hot Deck/Cold Deck Systems

What are they?
Hot deck/cold deck systems are an air handler based solution where the flow for the building is split into two, with one part being heated and one part being cooled. These two airflows are then mixed together to create the right amount of heating and cooling for each space. The main types of hot deck/cold deck system are: Multizone systems: For these systems, the hot air and cold air are mixed together in the plant room and the mixed air is ducted to each zone using dampers known as “face/bypass” dampers. Dual duct Systems: For these systems, the hot air and cold air are ducted to the zone and mixed together at the zone in a mixing box that is controlled from the zone temperature. Dual duct systems are most often configured to serve many floors from a single unit, while multizone systems are more commonly configured to serve a single floor. Advantages / Disadvantages

Highly flexible, and designed to service diverse loads from a single AHU
Industry standard technology with plenty of industry experience in operation and maintenance
Generally poorer efficiency
Face bypass dampers and mixing boxes prone to leakage, causing undesirable mixing of hot and cold airstreams
Large multi-story air-handling systems often less efficient at servicing after-hours loads.

Energy efficiency
These systems are generally poorer performers in terms of energy efficiency due to simultaneous heating and cooling, poorer fan control and reduced effectiveness of free cooling. It is possible to reconfigure a dual duct system to be as efficient as a VAV system but this is relatively uncommon. Multi-zone systems are difficult to operate efficiently especially when they service multiple diverse zones.

Running costs
Running costs for these systems are high due to poor energy efficiency. Dual duct systems also have a high component count due to the mixing boxes. A building management system (BMS) is essential to achieve efficient operation with either system type.

Retrofit / improvement opportunities
For hot deck/cold deck systems, the key opportunities are:

Reconfiguration of controls to minimise simultaneous heating and cooling
Improved fan control
Replacement/repair of face/bypass dampers to reduce leakage and possibly to provide independent hot/cold damper control (multizone systems). This can be achieved withut disturbance to tenants.
Replacement/repair of mixing boxes to reduce leakage and possible to provide independent hot/cold damper control (dual duct systems). This may need to be undertake after hours or in vacant spaces
Dual fan operation – one for the hot deck and one for the cold deck
Ducting of free cooling to the cold duct only to improve free cooling operation.

Control improvements can be implemented with the tenants in-situ.

Applicable buildings
Dual duct systems are often found in older large office buildings. Mutlizone systems are found in a wider variaety of building types and re typically on a smaller scale.

Floor plate implications
The size of riser ducts can be significant for multi-storey buildings served from a central AHU (located, for example, on the roof or in the basement). The risers may restrict flexibility on floor plates. In buildings with AHUs on each floor, the AHU plant room will take up a significant amount of space.

Temperature control / Occupant comfort
Hot deck/cold deck systems can offer a high degree of temperature control when well controlled

Maintenance implications
The mixing boxes and face/bypass dampers s require routine maintenance. Central plant requires standard levels of maintenance. Controls require careful configuration and management; arbitrary adjustment of temperature set-points within these system types is a leading cause of energy waste.

How to identify them
Hot/cold deck systems are found in older office buildings and in institutional buildings, but are largely indistinguishable from other AHU based systems to the non-technical observer. Maintenance or operational staff will be able to advise whether a system is a hot deck/cold deck type.

Questions to ask

Does the system have independent control of hot air and cold air for each zone?
Is there a building management system (BMS)?
Is the system regularly maintained (at least annually) and seasonally commissioned?

More information
AIRAH Guide DA08 HVAC&R An Introduction CIBSE Ventilation / Air conditioning / Technical Glossary

Fan Coil Unit Systems

What are they?
A fan coil unit (FCU) contains a fan which draws the air in a space into the unit then blows it over a cooling or heating coil. The air comes out of the FCU either cooler or hotter than before. They are used in some office buildings and shopping centres and typically specified where there are multiple small spaces requiring individual control. Typically an individual FCU serves only up to 150m², so there can be tens or even hundreds in a building. FCUs are, however, most commonly used as a supplement to a building for which other HVAC systems provide the majority of the air-conditioning. FCUs will generally have a chilled water coil for cooling and either a hot water coil for heating or an electric heating element. Chilled water is provided from a chiller located in the central plant, and hot water form a boiler. Each FCU is provided with a small supply of outside air to ensure adequate ventilation.

Advantages / Disadvantages

High level of flexibility in terms of subdivision and rearrangement of space.
Poorly suited to open plan spaces, as adjacent units can operate in conflict
Does not generally have the ability to use outside air for free cooling, making the system less efficient in cooling particularly in spring and autumn.
Chilled water valves and hot water valves in ceiling can be a maintenance problem

Energy efficiency
FCU systems are of average efficiency only but if well maintained and operated can produce a good level of efficiency. They are generally not as efficient as standard alternatives such as variable volume air conditioning, chilled beams and displacement systems.

Running costs
The age and condition of FCU systems will significantly affect running costs. Older systems tend to have higher rates of temperature controller failure, poorly operating valves and inefficient central plant, all of which can increase costs. As with all systems, efficiency will be improved by good management and commissioning, especially in relation to the calibration of temperature sensors and the maintenance of valves. A building management system (BMS) will provide a higher level of control and if well managed will help reduce running costs.

Retrofit / improvement opportunities
The major areas for improvement for FCU systems are:

Review and optimisation of zone temperature control for FCUs.
Recommissioning and maintenance of chilled water and hot water flow balancing and valve operation.
Upgrade of controls for boilers, chillers and associated pumps
Upgrade of chiller plant. Chillers have 15-20 year lifespan, although they generally have been superseded in terms of efficiency well before the end of their operational life. Replacement of chillers is best undertaken in winter.
Upgrade of FCUs. Ageing FCUs can be replaced by modern units which are quieter, more energy efficient and more reliable.

Control improvements can be implemented with the tenants in-situ

Applicable buildings
FCUs are found as a secondary HVAC system in most building types but are less common as a primary HVAC system type, except in shopping centres and smaller offices.

Floor plate implications
FCUs are typically ceiling mounted and thus do not take up floor space. Positioning of existing FCUs may adversely affect the subdivision of space. Units can, however, be moved and / or supplemented to accommodate different floor space configurations.

Temperature control / Occupant comfort
FCUs are generally considered a lower grade solution for office air-conditioning due to fan noise. They can deliver good control when well maintained but the small zone size and high component count often leads to occupant discomfort.

Maintenance implications
FCUs are simple to operate and are relatively straightforward to maintain, but the components that require most maintenance – the temperature controllers and the valves – are in the occupied space and therefore maintenance can be intrusive.

Identification
An FCU will typically be installed in the cavity above a ceiling. The visible parts will be either a pair of supply and extract grilles, or a ceiling cassette. FCUs may also be found mounted on the wall, on the ground, or occasionally in a floor void. Maintenance or operational staff will be able to advise whether a building uses FCUs.

Questions to ask

Is the heating electric or via hot water?
Is there a building management system (BMS)?
Is the system regularly maintained (at least annually) and seasonally commissioned?
How often are the filters cleaned?

More information
AIRAH Guide DA08 HVAC&R An Introduction CIBSE Ventilation / Air conditioning / Technical Glossary

Package Air-Conditioning Systems and Split Systems

What are they?
Split systems have an indoor unit which provides heating and cooling and an outdoor unit which houses the heat rejection coil and compressors. Refrigerant is circulated between the indoor and outdoor units. These systems are most common in small buildings. Package units have heating, compressor, heat rejection and compressors all in one unit, and are typically mounted on the roof and connected to the occupied spaces via a duct through which the heated or cooled air is provided. Water cooled package units have heating, cooling and compressor mounted in a single unit mounted in the ceiling space of the occupied area, and reject heat to a condenser water loop which is cooled by a cooling tower and may also be heated by a boiler All three of the above types may be “reverse cycle”, whereby the refrigerant system can provide heating or cooling. Alternatively, the refrigerant system may provide cooling only while heating is provided by electric duct heaters or hot water coils.

Advantages / Disadvantages

Low install cost. These system types are typically the cheapest to install
Moderate energy efficiency. These units tend to be designed for price rather than efficiency, although some quite efficient units exist. Water-cooled package units have quite limited options for efficiency.
Simple maintenance requirements. These are stand-alone systems designed for operation in a low-maintenance environment
Poor heating efficiency if water-cooled or direct electric heating units are used.
Limited lifespan. Split systems and packaged units typically have a life span of 10-15 years only, and less than this if poorly maintained.
Refrigerant costs. Some of the common refrigerants used in these systems , most notably R22, are being phased out through legislation, because of their negative impact on the environment. This will mean that the costs of this refrigerant will rise markedly and ultimately many R22 split and packaged systems may need to be replaced before the end of their operational life.
Refrigerant leakage is common and badly affects both the capacity of heating and cooling provided and the efficiency of the unit. However, it is often not detected in standard maintenance.
Very sensitive to blocked air filters. Blocked filters lead to a reduction in airflow which will lead to excessively low and excessively high supply air temperatures which drastically reduce effectiveness and comfort.

Energy efficiency
Split and package systems are available in a large range of efficiencies. Smaller systems are rated using the appliance rating system and should always be selected for the highest star rating available in the right size. For most air-cooled systems it is possible to source a unit with an inverter-controlled compressor which reduces energy use by upwards of 20%, and should always be selected where available.

Running costs
The age and condition of split and package units will significantly affect running costs. Older systems tend to have higher rates of temperature controller failure, refrigerant loss, coil damage as well as less efficient underlying hardware, all of which can increase costs. As with all systems, efficiency will be improved by good management, especially in relation to the calibration of temperature sensors and the maintenance of filters, coils and refrigerant charge.

Retrofit / improvement opportunities
The major areas for improvement for split and package units systems re:

Ensure filters and coils are not blocked
Ensure control set-points are consistent and appropriate.
Ensure that refrigerant charge is correct
Ensure that there is good airflow around the outdoor units so htat heat can be rejected and does not “pool” around the outdoor unit.
Replace older units with new more efficient units preferably with inverter driven compressors.
For water cooled package unit systems, install valves to prevent condenser water flow through the unit when the compressor is not operating, and improve condenser water pump control.
Install free cooling so that outside air can be used for free cooling when conditions are appropriate.

Applicable buildings
Air-cooled split systems and packaged units are common in smaller buildings, for which they are a reasonable solution. Water cooled packaged units are used in a wider range of building types, including retail and office developments of significant size, owing to the convenience of condenser water distribution as a means of moving heat.

Floor plate implications
Split and package units systems are ceiling and/or roof mounted and so do not take up floor space.

Temperature control / Occupant comfort
Split systems and ceiling mounted package units systems are generally considered a lower grade solution for office air-conditioning due to fan noise. Roof mounted package unit systems avoid this problem. All of these system types have limited control of supply air temperature which can produce occupant comfort issues.

Maintenance implications
These system types are reasonably low maintenance but nonetheless require regular maintenance to maintain efficient and effective operation. Filters, coils and refrigerant charge must be well maintained.

Identification
Split systems have an outdoor compressor unit which is typically mounted at ground level or on a roof. Indoors, these systems may use wall mounted terminals or have a ducted indoor unit within the ceiling space. Air-cooled package units are generally roof mounted, and are recognisable by the presence of ductwork leading to and from the unit and the operation of compressors within the unit. Water-cooled package units are ceiling mounted and have a cooling tower on the building roof (typically). Maintenance or operational staff will be able to advise whether a building uses split systems and package units.

Questions to ask

Are the split systems/package units reverse cycle? If not, where does the heating come from?
Do water cooled package units have automatic isolation valves that shut down condenser water flow when the compressor is not operating?
How old are the split systems/package units?
Do the units have inverter compressors?
Do the units have free cooling?

Is the system regularly maintained (at least annually) and seasonally commissioned?
How often are the filters cleaned?

More information
AIRAH Guide DA08 HVAC&R An Introduction Appliance Rating Scheme – www.energyrating.gov.au

VRF/VRV Systems

What are they?
Variable Refrigerant Flow or VRF systems (Also known as Variable Refrigerant Volume systems) are like a split system except that rather than having one outdoor unit for each indoor unit, they have up to 20 indoor units for each outdoor unit. This allows a higher level of technology and sophistication to be used in the outdoor unit, leading to efficiency improvements. Advantages / Disadvantages

Moderate-to-high install cost. VRF systems are a premium solution for small to mid scale buildings
Flexibility. VRF systems provide a high level of flexibility and ability to control small spaces independently. However, owing to limitations on indoor unit capacity, they are poorly suited to serving large spaces such as halls
Proprietary Systems. VRF systems are a highly integrated system in which all the components are part of an integrated single-vendor system. This creates excellent opportunity for efficiency but does lead to a high degree of dependence upon the vendor to deliver.
Very sensitive to blocked air filters. Blocked filters lead to a reduction in airflow which will lead to excessively low and excessively high supply air temperatures which drastically reduce effectiveness and comfort.
Refrigerant costs. VRF systems have large amounts of refrigerant. Refrigerants of all types are becoming more expensive, and as a result refrigerant replacement during maintenance can become a major cost
Moderate (15 year) lifespan. VRF systems do not have as along a lifespan as chilled water or AHU systems.

Energy efficiency
VRF systems can be highly efficient particularly in three pipe format and with free cooling included.

Running costs
The age and condition of VRF Systems will significantly affect running costs. Older systems tend to have higher rates of temperature controller failure, refrigerant loss, coil damage as well as less efficient underlying hardware, all of which can increase costs. As with all systems, efficiency will be improved by good management, especially in relation to the calibration of temperature sensors and the maintenance of filters, coils and refrigerant charge.

Retrofit / improvement opportunities
The major areas for improvement for VRF systems re:

Ensure filters and coils are not blocked
Ensure control set-points are consistent and appropriate.
Ensure that refrigerant charge is correct
Ensure that there is good airflow around the outdoor units so that heat can be rejected and does not “pool” around the outdoor unit.
Install free cooling so that outside air can be used for free cooling when conditions are appropriate.

Applicable buildings
VRF systems are best applied in small to medium buildings, and are commonly used in office park and industrial office park developments.

Floor plate implications
VRF system indoor units are ceiling mounted and so do not take up floor space.

Temperature control / Occupant comfort
VRF indoor units are generally quiet. As with all refrigerant based systems, VRF systems have limited control of supply air temperature which can produce occupant comfort issues.

Maintenance implications
VRF systems are reasonably low maintenance but nonetheless require regular maintenance to maintain efficient and effective operation. Filters, coils, controls and refrigerant charge must be well maintained.

Identification
VRF systems have large outdoor compressor units which are typically mounted on a roof. Indoors, these systems generally use ceiling mounted units. Maintenance or operational staff will be able to advise whether a building uses VRF systems.

Questions to ask

Are the VRF systems capable of providing heating and cooling simultaneously within the same system?
How old is the VRF system?
Do the units have free cooling?

Is the system regularly maintained (at least annually) and seasonally commissioned?
How often are the filters cleaned?

More information
AIRAH Guide DA08 HVAC&R An Introduction

Passive Chilled Beams

What are they?
Passive chilled beams are essentially a cooling coil (supplied with high temperature chilled water, typically 14°C) attached to or suspended from the ceiling. Chilled water is circulated through the coil, thereby cooling the air in the room. The cooling happens by natural convective movement of air (hence “passive”) through the coil and to the occupied space. Outside air, and commonly heating, is provided by central air handling units (AHUs) and chillers. Chilled beams also require humidity control within the occupied space to prevent condensation forming on the coils.

Advantages / Disadvantages

High energy efficiency and low running costs.
Quiet operation.
Low maintenance costs.
Reduced ductwork and AHU size.
Reduces flexibility of internal space.
Need for a high temperature chilled water circuit circulating around the occupied areas of the building.
High installation cost
Less common system type can lead to design, operation and maintenance issues
Dehumidification operation can be energy intensive
Generally small overall plant means that systems maintain a low level of energy use even when operating poorly, but at the expense of occupant comfort.
Need for humidity control means that they must only be used in well sealed buildings
Limited ceiling space requirements

Energy efficiency
Passive chilled beams typically have low energy consumption and running costs, although they are matched by some of the better VAV systems. Passive chilled beams work best when there is an exposed ceiling soffit, but can also be used in conjunction with a suspended ceiling. Dehumidification control can be a significant weak-spot for the efficiency of these systems, leading to excessive chiller and boiler operation. Superior performance will be achieved in drier climates.

Running costs
Chilled beams / ceilings can be expected to have low running costs. There will be less demand placed on chillers which will, therefore, consume less energy. A building management system (BMS) is critical to the successful operation of the system

Retrofit / improvement opportunities
The major areas for improvement for passive chilled beam systems are:

Recommissioning and maintenance of high temperature chilled water flow balancing and chilled beam valve control.
Testing and flushing to remove air build up from chilled beams
Optimisation of dehumidification controls
Upgrade of controls for boilers, chillers and associated pumps
Upgrade of chiller plant. Chillers have 15-20 year lifespan, although they generally have been superseded in terms of efficiency well before the end of their operational life. Replacement of chillers is best undertaken in winter, but care is required as passive chilled beams still need chilled water through winter.

Control improvements can be implemented with the tenants in-situ Chilled beams can be retrofitted into existing buildings as long as there is adequate ceiling space and the building is well sealed. Retrofitting would, however, need to be undertaken when a building is vacant.

Applicable buildings
Mainly used in office buildings.

Floor plate implications
Chilled beams require more work to relocate than air-based systems. Open ceilings and perforated metal ceilings may not be aesthetically pleasing to some occupants.

Temperature control / Occupant comfort
Passive chilled beam systems can be slow to respond if the demand for cooling increases rapidly and can be less effective at dealing with peak temperatures than more conventional systems. Passive chilled beams are unusually quiet, to the extent that white noise generators are often added to reduce the distance across which occupant conversations carry.

Maintenance implications
Passive chilled beams and ceilings have very low maintenance requirements and a 30+ year life span. Passive chilled beams can be badly affected by poor waterside balancing and by the accumulation of air in poorly installed beams.

Identification
Passive chilled beams are generally directly visible in the occupied space or are hidden above a perforated metal grid ceiling. The beams look like the wire and tube radiators that used to be on the back of old fridges.

Questions to ask

Are they passive or active chilled beams?
When was the water balance last checked for the chilled beams?
Is there a building management system (BMS)?

Is the system regularly maintained (at least annually) and seasonally commissioned?
Is the system providing good comfort control?

More information
AIRAH Guide DA08 HVAC&R An Introduction

Active Chilled Beams and Induction Units

What are they?
Active chilled beams consist of a ceiling-mounted cooling coil (supplied by high temperature chilled water, typically 14°C) with air circulated from an air handler forcing airflow through it. Induction units are an older version of the same thing, and come in ceiling and floor mounted types. Active chilled beams and induction units are frequently used to service the perimeter of buildings due to the relatively high capacity of the units; in such cases, a VAV system is often used to service the internal zones of the building. Less commonly, active chilled beams or induction units are used for internal zones as well. Outside air, and commonly heating, is provided by central air handling units (AHUs). Most active chilled beams and some induction units also require humidity control within the occupied space to prevent condensation forming on the coils.

Advantages / Disadvantages

Medium energy efficiency.
Reduced ductwork and AHU size.
Reduces flexibility of internal space.
Operating requirements of active chilled beams and induction units can make the central AHUs inefficient.
Need for a high temperature chilled water circuit circulating around the occupied areas of the building.
Dehumidification operation can be energy intensive
AHU supply air pressure requirements, particularly for older induction units, can lead to excessive fan energy and high levels of AHU air leakage.
Need for humidity control means that they must only be used in well sealed buildings

Energy efficiency
Active chilled beams and induction units can achieve good efficiency but are not as efficient as passive chilled beams and are matched or surpassed by better VAV systems. Dehumidification control can be a significant weak-spot for the efficiency of these systems, leading to excessive chiller and boiler operation.

Running costs
Running costs for these systems are average to good depending on the quality of installation and operation. A building management system (BMS) is critical to the successful operation of the system

Retrofit / improvement opportunities
The major areas for improvement for active chilled beam systems are:

Recommissioning and maintenance of high temperature chilled water flow balancing and chilled beam valve control.
Recommissioning of primary airflows to the active chilled beams and induction units
Optimisation of dehumidification controls
Upgrade of controls for boilers, chillers and associated pumps
Upgrade of chiller plant. Chillers have 15-20 year lifespan, although they generally have been superseded in terms of efficiency well before the end of their operational life. Replacement of chillers is best undertaken in winter, but care is required as passive chilled beams still need chilled water through winter.

Control improvements can be implemented with the tenants in-situ Active chilled beams are often retrofitted to replace older induction units and in doing so typically improve heating/cooling performance and efficiency. Retrofitting would, however, need to be undertaken when a building is vacant.

Applicable buildings
Mainly used in office buildings.

Floor plate implications
These are generally similar to other air-based systems in terms of floor plate. As they are typically supplied by central AHUs, there can be some loss of floor space due to the riser ducts. The primary supply ducts for these system are generally smaller than for other AHU systems.

Temperature control / Occupant comfort
Active chilled beams and induction units can provide temperature control when well controlled and commissioned. However, neither technology has particularly good air-diffusion characteristics, which may lead to occupant complaints about draughtiness.

Maintenance implications
Active chilled beams and induction units have a 25 year lifespan, during which the major challenge is to ensure that both waterside and airside balance are well managed, as either can cause the unit to become ineffective.

Identification
Ceiling mounted active chilled beams and induction units are difficult to tell from other air-based systems unless one looks in the ceiling space to find the chilled water pipes. Floor mounted induction units are generally mounted around the perimeter of an office floor and are easy to spot. Questions to ask

Are they passive or active chilled beams?
When were the water and air balance last checked?
Is there a building management system (BMS)?
Is the system regularly maintained (at least annually) and seasonally commissioned?

More information
AIRAH Guide DA08 HVAC&R An Introduction

Displacement Ventilation Systems

What are they?
Displacement ventilation systems use the principles of natural convection to maintain a comfortable internal air temperature within the occupied space while allowing hot air to rise to the ceiling. Air is diffused into the occupied space at floor level (normally through floor grille diffusers or columns) and is extracted at high level (normally at ceiling height). As the air rises through the space, it collects heat from people and equipment. The occupied space is therefore a “pool” of cooler air that it not mixed with the heat gains, smells and occupant CO2. As with other types of cooling system, displacement ventilation systems are served by central air handling units (AHUs) and chillers.

Advantages / Disadvantages

Good energy efficiency potential
Air quality is generally better compared to fan coil units (FCUs) or variable air volume (VAV) systems due to the lack of mixing of air within the space
Larger floor to ceiling height required.
For open plan offices, raised floors required.
Significant duct riser space requirements.
May not provide sufficient cooling in a building with a high cooling load, in which case a supplementary cooling system will be required.

Energy efficiency
This system can provide good efficiency provided that the fans are well controlled and maximum use is made of free cooling. Enhanced results can generally be achieved where the system operates n a variable volume basis rather than constant volume.

Running costs
Running costs should be lower than conventional FCU or refrigerant based systems. Displacement ventilation is often supplemented by localised cooling systems for areas with higher than normal cooling requirements, such as IT server rooms. Typically, these areas will form a small proportion of the total floor space. Therefore the overall benefits will not be negated. A building management system (BMS) is essential to provide adequate control for successful operation of the system

Retrofit / improvement opportunities
The major areas for improvement for displacement ventilation systems are:

Control and commissioning of airflows within occupied spaces to ensure that these are as low as permissible
Optimisation of dehumidification controls
Upgrade of controls for boilers, chillers and associated pumps
Upgrade of chiller plant. Chillers have 15-20 year lifespan, although they generally have been superseded in terms of efficiency well before the end of their operational life.

Control improvements can be implemented with the tenants in-situ The potential for retrofitting displacement ventilation into an existing building is constrained by the need for duct riser spaces and adequate floor to ceiling heights.

Applicable buildings
Best suited to building / space type with high ceilings, such as atria and auditoria and low density office space with 3m+ floor to ceiling heights.

Floor plate implications
These systems require a high ceiling (ideally 3m+) and preferably a floor void / plenum (with a depth of 0.3–0.45m) to operate. Alternatively, wall or column diffusers can be used but these take up floor space.

Temperature control / Occupant comfort
These systems can provide a comfortable working environment as they typically provide a higher level of outside air, and with less mixing with return air, than conventional overhead supply systems. In some instances, however, they can be perceived as creating uncomfortable temperature gradients or draughts. Floor grilles are sometimes covered over by occupants (deliberately or accidentally); this adversely impacts on the system’s performance.

Maintenance implications
Comparable maintenance levels to other AHU systems. May have fewer terminal units, which will reduce maintenance but may negatively affect efficiency

Identification
Supply grilles are typically be located at floor level (requiring a raised floor) and are fairly distinctive. Wall mounted diffusers and column diffusers are identifiable as large structures typically with perforated metal faces, from which air is supplied at very low velocity. Extract grilles are located at high level.

Questions to ask

Is the air supply variable volume or fixed volume?
Is there a supplementary cooling system in any space or capacity for one to be fitted?
Is there a building management system (BMS)?
Is the system regularly maintained (at least annually) and seasonally commissioned?
Is the system variable volume or constant volume?

More information
Displacement ventilation (* references to go in here)

Natural Ventilation and Mixed Mode Systems

What are they?
Natural ventilation systems use external air to cool the building without using mechanical cooling. Air supply and extract is provided through opened windows and / or air intake louvres, either manually controlled or automatically linked to a building management system (BMS). More complex systems make use of the ‘stack effect’, by which the natural buoyancy of warm air moves air up to high level exhausts (e.g. atria). Pressure differences caused by external wind can also be used to enhance air movement and cooling. For example, ‘windcatchers’ can be placed on roofs to provide downward ventilation into a space. Natural ventilation is typically supplemented with a heating system incorporating a boiler and radiators. High summer temperatures will generally lead to poor comfort conditions but this may be acceptable in some environments such as warehouses. Office buildings can be designed to be ‘mixed mode’, a system which uses natural ventilation when external temperatures are moderate and air conditioning when higher temperatures are experienced. A system can be included which informs tenants when windows should be opened to optimise internal comfort and when they should be closed and the mechanical system relied upon. This approach is particularly applicable to cell offices, where an individual can make decisions about their own window without affecting others; in open plan configurations, the natural ventilation component of mixed mode operation needs to be automatically controlled and requires relatively subtle operation to be successful.

Advantages / Disadvantages

No energy is required to provide ventilation or cooling where the building operates a natural ventilation strategy only.
For the Sydney climate, mixed mode is more practical than natural ventilation except in spaces that have limited comfort requirements.
Opening windows have higher infiltration than sealed windows, which can increase heating and cooling loads in extreme conditions.
Management of opening windows in open plan areas is difficult due to wind effects and different perceptions of comfort for different occupants.
Open windows and louvres can permit external noise and pollutants into the space, especially in an urban setting.
Natural ventilation is difficult to provide to deep plan buildings

Energy efficiency
A very low energy solution when no active cooling is provided. A mixed mode strategy will also be a low energy solution compared to conventional systems, although actual savings will depend on how frequently the mechanical cooling system is used instead of natural ventilation.

Running costs
The cooling effect from opening a window is ‘free’. If windows are open and the mechanical cooling or heating system is also running then this will waste energy. Effective building management will help reduce running costs in this situation e.g. if the system is automatically controlled by a building management system (BMS).

Retrofit / improvement opportunities
The major areas for improvement for natural ventilation and mixed mode systems are:

Measures to eliminate windows being open when the building is actively heating or cooling
Optimisation of the control changeover between natural ventilation and active conditioning
Review and improvement of airflows during natural ventilation mode
Upgrade of controls for boilers, chillers and associated pumps

Control improvements can be implemented with the tenants in-situ Replacing non-openable windows with openable windows to provide natural ventilation is not a cost effective solution to saving energy. If, however, a building has been provided with openable windows in addition to an air conditioning system, that system may be turned off at some points during the year to save energy / cost and become a mixed mode building.

Applicable buildings
Natural ventilation is possible for light industrial spaces, but most other spaces will use mixed mode as active cooling is required on hot summer days. Natural ventilation and mixed mode operation is typically not suited to buildings with surrounding pollution issues e.g. city centres.

Floor plate implications
Opened windows on a single elevation will only ventilate to a depth of circa 7m, which increases to 15m (including allowance for 1m wide central walkway across floor plate) if windows are on opposing elevations. Spaces deeper than 15m need a more complex ventilation strategy which typically requires an open central atrium to achieve the required stack effect.

Temperature control / Occupant comfort
Natural ventilation is generally unsuitable for buildings with a high cooling demand or in city centres where noise and pollution make opening windows undesirable. Windows provide limited control of how much air enters a space, which will differ depending on external conditions. For example, air flow will fluctuate depending on whether it is a still or windy day. Natural ventilation is difficult to implement in open plan floor plates owing to the conflicting perceptions and preferences of occupants, and may cause occupant dissatisfaction as a result.

Maintenance implications
Manual windows will require occasional adjustment to ensure they are in a fully operable condition. Automatic window / louvre opening devices will require more maintenance.

Identification
There will be no or very few air grilles and no mechanical plant where the building operates a natural ventilation strategy. The majority of windows will be openable. There may be a horizontal transfer grille for the air to leave a room or floor area and enter an atrium. A building operating a mixed mode strategy will feature an air conditioning system as well as openings such as windows and louvres.

Questions to ask

Is the building wholly or partly naturally ventilated?
Do the windows open automatically?
If windows open automatically, how are they controlled?
Are the windows regularly maintained?

More information
More refs to be provided.

Internal Blinds

What are they?
Internal window blinds reduce the amount of ‘solar gain’ (or heat) entering a space, cutting glare and reducing the requirement for cooling. This is particularly useful on north and west facing façades.

Advantages / Disadvantages

Reduces the need for air conditioning
Reduces natural light, therefore increases the need for artificial lighting.

Energy efficiency
Internal blinds reduce the cooling demand in a building, thereby saving energy. The level of energy saving will depend on the level of solar gain avoided and how the blinds are used by tenants.

Running costs
Internal blinds have minimal maintenance requirements, although older installations may require some restoration.

Retrofit / improvement opportunities

Internal blinds are easy to retrofit with minimal disruption to tenants.

Applicable buildings
All building types.

Floor plate implications
None.

Temperature control / Occupant comfort
Will improve temperature control and comfort if used effectively.

Maintenance implications
Low maintenance costs. Blinds need to be kept in full working order and require regular cleaning.

Identification
Venetian, vertical or roller blinds fitted on the internal face of windows. Some buildings have venetian blinds located between the inner and outer panes of the window.

Questions to ask

Are there areas of the building where solar glare is a problem?
Have blinds been fitted and if so when were they fitted?
How old are the blinds and what is their general condition?

More information
Ref required

External Shading Devices

What are they?
External shading can either take the form of:

External solid or perforated shade devices such as panels mounted on the outside of the building. Shades may be static or movable (typically under automatic control).
Reflective film that can be applied to glazing; or
‘Fritting’, which is architectural glazing with an applied opaque pattern.

They all act by deflecting the sun’s rays from the building glazing, thereby reducing solar gain within the occupied space.

Advantages / Disadvantages

Reduces the need for air conditioning
Considerably more effective at reducing solar gain than internal blinds.
Higher cost to retrofit than internal blinds.
Reduces natural light and therefore increases the need for artificial lighting.
Can impact on occupant views.

Energy efficiency
External shading devices reduce the cooling requirement in a building, therefore saving energy. The effectiveness of the shading depends on building form, the shading design and the amount and orientation of glazing.

Running costs
External shading will add to the cost of cleaning the external façade. Maintenance costs will be higher if the shading is automated because there are moving parts that require periodic overhaul and adjustment. Some shading systems may also make it difficult to clean the building’s windows, and may also attract birdlife and the associated droppings. Solar film has a short lifespan (5 years) if applied to the exterior of the glass, but is more effective in that location. When installed on the interior face of the glass, it will be less effective but has a much longer lifespan (15 years)

Retrofit / improvement opportunities
External shading devices are technically challenging to retrofit depending on the type of building façade. For example, glazed curtain walling does not readily allow sufficient fixing points to allow installation. It can also be difficult to retrofit from a planning perspective because the external appearance of the building will be affected. Adding external shading to an existing building is typically undertaken as part of any façade modernisation works. Solar film does not typically require planning approval unless it alters the external appearance of the building or the building is listed or in a conservation area.

Applicable buildings
All building types.

Temperature control / Occupant comfort
External shading devised will improve temperature control and comfort if positioned effectively, but will reduce the amount of natural light entering a space.

Identification
External shading devices most typically comprise fins or a louvre system on the external face of the building – either a fixed system or automatically adjustable depending on sunlight levels. Window films are difficult to see when but close inspection often reveals small lines around the edge of the window pane where the film has not covered. Fritting is visible as opaque elements within the glass itself.

Questions to ask

Is the shading system fixed or automatically controlled?
Is the window film applied to the interior or exterior of the glass?

More information
Carbon Trust How to implement solar shading (CTL065) CIBSE TM37 Design for Improved Solar

Lighting

Inefficient lighting systems in commercial buildings can be responsible for consuming as much energy as the air conditioning or IT systems. The provision of energy efficient lighting and careful management of the lighting system substantially reduces energy consumption and therefore the occupancy costs of a building. There are a number of straightforward energy efficient lighting options that can and should be considered.

Information & Actions

Are the lights too bright?

If the lighting is too bright in a building then it goes without saying that energy is being wasted. Light intensity in a space is known as the ‘lux level’. Lower lux levels will save energy; Australian Standard AS1680 defines the minimum lux level for offices as 320 lux and provides design guidelines for other aspects of lighting design and lighting quality.

Progressive improvements in lamp technology mean that older lighting installations are too bright with modern lamps. For most sites this is most cost-effectively resolve through refurbishment or replacement of the lighting system. Reducing the electrical power to the lights provides a direct energy saving but also reduces the load on the cooling plant, providing air-conditioning savings as well.

Fluorescent Lamps

What are they?
Fluorescent lamps (FLs) are commonly used across a range of commercial buildings. The standard T8 (26mm diameter) FLs are commonly found in older buildings but in modern buildings and in retrofits the thinner T5 (16mm diameter) FL is often more energy efficient and is increasingly being fitted as standard.

Advantages / Disadvantages

Standard technology with excellent industry support
Efficiency of lamp depends somewhat on the control gear used, which is not immediately obvious to the untrained eye.
The lifespan of fluorescent lamps is negatively affected by switching, so a minimum switch-on period of 10 minutes should be used.
Be wary of retrofits that change the lamp without addressing the overall optics of the light fitting. Lighting system quality can be badly affected by poorly specified retrofits.

Energy efficiency
FLs are the dominant technology for open area office lighting, and are an efficient solution for this. LED systems are not quite ready to overtake FLs in this application, although this is only a matter of time given the rate of improvement of LED technology. Shorter lamps of all diameters are less efficient than their longer counterparts. T8 lamps with electronic ballast and T5 lamps (which always have electronic ballasts) are of approximately equivalent efficiency. T8 lamps with magnetic ballasts are less efficient than either. The final efficiency however must always be judged based on the total installation (lamps + fitting + diffuser + fitting arrangement) rather than the lamps, as a poorly designed T5 installation can have a poorer efficiency than a well designed T8 installation, even if the latter uses magnetic ballasts.

Running costs
Lamps, starters and ballasts require replacement from time to time. Maintenance costs are equivalent for all lamp types.

Retrofit / improvement opportunities
T5 FLs retrofit adapters are available to enable T5 lamps to be directly retrofit into T8 fittings. However, care is required to ensure that lamp position is not changed in the fitting, as this will affect light distribution in the space and glare. The adapters also have a relatively short warranty period which can make them a maintenance problem. T5 lamps also have a lower light output than T8 lamps so care is required to ensure that the final installation maintains adequate light levels. For older installations, it is preferable to completely redesign the installation either through extensive refurbishment of light fittings or through complete replacement. This has a longer payback but produces an engineered outcome with a 20 year life. Lighting refurbishments can be conducted out-of-hours in an occupied office with minimal disruption to tenants.

Applicable buildings
All building types.

Occupant comfort
Badly designed lighting installations can cause significant discomfort due to glare or non-uniformity. Any refurbishment or new lighting design should be judged on overall lighting quality rather than just illuminance and lighting power density. Electronic ballasts have a higher lighting quality than magnetic ballasts. FLs can take a few seconds to ‘warm up’, but this rarely produces problems for occupants.

Maintenance implications
Replacement of FLs on failure leads to a very high maintenance cost on a per lamp basis. A bulk replacement program at 80% of design life will produce a considerably lower maintenance costs and improved quality of light in the space.

Identification
A T5 lamp has a diameter of approximately 16mm compared to 26mm for a T8 lamp. A magnetic ballast can often be distinguished from an electronic ballast by the presence of a starter, which is a small cylindrical component.

Questions to ask

What lamps are installed – T5 or T8?
Have T5 adapters been used?
Do the T8 lamps have electronic or magnetic ballasts?
What is the Nominal Lighting Power Density as determined via the Buildign Energy Efficiency certificate?

More information
Commercial Building Disclosure program www.cbd.gov.au

LED Lamps

What are they?
Light emitting diode lamps (LEDs) are electronic light sources that have high energy efficiency. LED technology is advancing very rapidly and in the past five years has advanced from a curiosity to a viable replacement for most point-source lights (especially halogen downlights and compact fluorescent downlights). Although equivalent to marginally more efficient than linear fluorescents they are expensive, but should be expected to surpass this technology by 2015.

Advantages / Disadvantages
Significant energy savings can be achieved when LEDs are used for the replacement of downlights, especially halogen and compact fluorescent types. LEDs have far better switching performance than fluorescent lamps and achieve 100% light output instantly. There are many brands of LED available, and industry quality standards are not uniform, so some care in selection of lamps is advised. Long life expectancy compared to FLs. Initial cost is high compared to FLs.

Energy efficiency
LEDS are the most efficient lights source available for most applications. Indeed the rate of improvement is so great that current LED lamps may significantly outperform those bought only a few years ago. A further efficiency benefit of LED lamps is that they can be switched on and off with no damage or reduction in lamp life. This makes them particularly competitive for situations where control can be used to reduce operating hours.

Running costs
Maintenance costs are lower for LEDs because lamps have longer replacement intervals compared with FLs. Energy savings are greater compared with FLs. LEDs, as with all types of fitting, will require regular cleaning to maintain light output levels.

Retrofit / improvement opportunities
Luminaires may need to be replaced if retrofitting LEDs, which can significantly add to the replacement cost. Replacement of light fittings can generally be undertaken after-hours with minimal disruption to tenants.

Applicable buildings
All building types.

Occupant comfort
No issues. While earl LEDs had dubious colour rendering, modern LEDs have excellent colour rendering and indeed some are now designed to vary the visual warmth of the light to suit the time of day.

Maintenance implications
Lamp replacement intervals are significantly longer for LEDs than FLs. Older LEDs may require replacement of the entire light fitting upon failure. Newer LED are available with interchangeable light sources which avoids this problem.

Identification
LEDs are available in a variety of design formats and colours. They are often distinguishable by the small dots of light emitted, which are often clustered into a fixture that resembles a halogen spotlight. However in some applications they are provided in flat panels in which no dots are visible.

Questions to ask

Have LEDs been installed in the building and if so, where?

More information
Reference required

Natural Light

What are they?
Natural light most commonly enters a building through windows but may also enter by other means such as skylights, atria, solar tubes (which take light from roof level into single storey buildings) and south lights. Natural light can be used to supplement artificial lighting, or wholly replace it for much of the day. Any obstructions outside the window, such as buildings or trees, will reduce how much natural light enters a building.

Advantages / Disadvantages
Reduces the amount of electricity consumed to provide general and task lighting. Natural light has a health and wellbeing benefit for staff. Direct sunlight can cause glare and ‘solar gain’, which increases the cooling demand in a space. Setting up effective daylight controls in a complex space such as an office can be remarkably difficult, so energy savings are often not achieved.

Energy efficiency
Natural light enables artificial lighting to be switched off to save energy.

Running costs
Natural light provides a cost saving from the reduced use of artificial lighting. Lighting controls can be provided which automatically adjust artificial lighting to reflect the amount of natural light entering the space. Large north and west facing windows may result in additional energy consumed for cooling during summer months due to solar gain. West facing window are prone to glare from low-angle late afternoon sun. Similar issues can occur with east facing windows, but these tend to occur prior to normal occupancy hours. Note that running costs will only be reduced if artificial lighting is reduced in response to natural light levels; no savings will be made if artificial lights continue to operate unchanged. It is generally easier to configure daylight control to work in less sensitive areas such as lobbies and halls than in offices.

Retrofit / improvement opportunities
Increasing window size and introducing atria are costly and impractical. Retrofitting sun-pipes or north lights into the roof of a single storey building or the top floor of a multi-storey can be practical solutions.

Applicable buildings
All building types.

Floor plate implications
Natural light entering through a window diminishes across a deep floor plate. Sky lights, atria or sun-pipes can be used to provide natural light to internal spaces although these have implications on building form and configuration.

Occupant comfort
Occupant health, wellbeing and productivity benefits are often cited for buildings with high levels of natural light compared to those with limited natural light or entirely lit using artificial lighting. However window glare and direct sunlight must be well managed to achieve these outcomes. Lighting control in office spaces must be very well managed to avoid becoming an irritant to staff. Typically this means that dimming is required, rather than switching on and off, and

Maintenance implications
Windows need to be cleaned regularly as dirt will reduce the light entering the building. Daylight-linked control systems require careful design, commissioning and maintenance to operate successfully.

Identification
Sufficient natural light in a building is the point at which tasks can still be performed if the lights are off.

Questions to ask

are controls in place to dim or switch off Is artificial lighting regularly switched off during the day because natural light is sufficient to perform tasks?
Are there areas of the building where solar glare is a problem during the year?

More information
Carbon Trust Lighting Technology Overview (CTV021)

Lighting Controls

Lighting makes up a significant portion of energy demand in a building and measures should be taken to avoid lighting areas that are not in use. Natural light can be used to light areas close to windows and atria instead of artificial lighting. This can be assisted by lighting controls which automatically adjust artificial lighting to reflect the amount of natural light entering the space, and by ensuring lighting circuits are designed so that whole floors do not remain lit whilst a small area is in use or where there are sufficient levels of natural light.

Information & Actions

Occupancy Sensors

What are they?
Occupancy sensors detect people moving in the building and can be used to automatically switch lights on and off. Typically, the light will turn off following a set period of inactivity in a space and on again once activity is detected, usually when someone enters the space. There are several different types of occupancy sensor, including passive infrared sensors (PIR) which are the most cost effective but least sensitive, ultrasonic, microphonic and microwave, as well as some sensors that use more than one of these technologies. The best type of sensor depends on the application.

Advantages / Disadvantages
Energy is saved by the automatic switching off of lighting in unoccupied areas. A low cost feature, this typically achieves payback in less than 5 years. Poorly designed or commissioned systems can cause annoyance to occupants due to lights turning off while occupants are still present.

Energy efficiency
Energy is saved by the occupancy sensor switching off the lights after a period of inactivity in a particular area.

Running costs
Occupancy sensors require periodic checking to ensure they are functioning correctly. Overall running costs will reduce due to the energy savings achieved.

Retrofit / improvement opportunities
Occupancy sensors can be readily fitted to many existing lighting installations. Successful retrofit involves careful selection of the appropriate sensor for the job and careful commissioning to ensure that it works properly.

Applicable buildings
Occupancy sensors are suitable for any part of a building that does not have continuous and constant occupancy.

Floor plate implications
Occupancy sensor locations need to selected to match the coverage pattern of the sensor and the configuration of the space being covered. Sensors will generally need to be repositioned if tall partitions or walls are moved.

Occupant comfort
Frequent switching of lights caused by poor positioning and configuration of occupancy sensors can be frustrating for occupants. Low use spaces, such as toilets, fire stairs, and storage areas are less likely to cause problems, as long as occupants are not left in the dark

Maintenance implications
Occupancy sensors have low maintenance requirements but need to be kept clean. The operation of the sensors should be routinely checked.

Identification
Sensors mounted high on the wall, in a suspended ceiling or as part of a light fitting.

Questions to ask

Are occupancy sensors used in the building, and if so, where?
When were the PIR sensors last checked / maintained?

More information
References needed

Photoelectric Sensors

What are they?
Photocelectric (PE) sensors that detect light level and can be used to turn off or dim lights in response.

Advantages / Disadvantages
Energy is saved through automatic dimming. A low cost feature, this typically achieves payback in less than 5 years. Best applied to large open spaces as spaces with complex fitout – or individually operated internal blinds – will rquire large numbers of sensors to cover each unique space. Can be frustrating for tenants if lighting levels keep changing (on sunny / cloudy days). If used to turn lights on and off, this should only be done in low sensitivity spaces such as warehouses and lobbies Certain lamp types such as hibay lights used in warehouses may not be well suited to daylight control due to the characteristics of the lamp.

Energy efficiency
Photoelectric l sensors can reduce the energy consumed by artificial lighting close to windows. Artificial lighting in areas more than a few metres from windows (distance depends on window height) will not benefit from photocell sensors as natural light will have negligible impact in these areas. Savings achieved with photoelectric sensors in offices are far less than those achieved by occupancy sensors, so the latter should always be considered as the first priority.

Running costs
Photocell sensors require periodic checking and recalibration to ensure they are functioning correctly. Overall running costs will reduce due to the energy savings achieved.

Retrofit / improvement opportunities
Photocell sensors typically need replacement every 15–20 years. Photocell sensors can be easily retrofitted to modern lighting systems and can be fitted out of hours to minimise disruption to the tenants. Photocells are only applicable for lights adjacent to windows or skylights.

Applicable buildings
Photocell sensors are applicable to a wide range of building types and are commonly used in open plan offices adjacent to windows. Buildings with good levels of natural light will particularly benefit.

Floor plate implications
Spaces with complex fit-out are poorly suited to the use of photoelectric sensors.

Occupant comfort
Photoelectric sensors will prevent the areas adjacent to windows becoming too bright by reducing artificial lighting levels accordingly. Natural light is considered to improve wellbeing. An override switch should be provided so lights can be kept on when required, for example, for viewings when letting a space.

Maintenance implications
Photocell sensors have low maintenance requirements but need to be kept clean. The operation of the sensors should be routinely checked.

Identification
Sensors situated close to the perimeter of the floor plate and either mounted high on the wall, in a suspended ceiling or as part of a light fitting.

What to ask for

Does the perimeter lighting have photoelectric sensors in place?
How do the lights responds to the photoelectric sensors – by switching or dimming?
When were the photocell sensors last checked / maintained?

More information
References required

On-site Renewable Energy Generation

On-site generation of renewable energy refers to energy that is generated from sources that are naturally and easily replenished, as opposed to non-renewable energy supplies such as fossil fuels. Renewable technologies include photovoltaic panels that generate electricity from sunlight, wind turbines, solar thermal panels that generate heat from sunlight, ground source heat pumps and boilers that run on biomass.

Information & Actions

Photovoltaics

What are they?
Photovoltaic (PV) panels generate electricity from sunlight and are typically referred to as ‘solar panels’. PV panels are different to solar thermal panels which utilise sunlight to heat water. PV panels need direct line of sight to the sun, so are usually mounted on a north facing pitched roof or on a flat roof using an A-frame (facing north) to support them. Electricity generated can be consumed by the building to which they are attached or exported and sold to the electricity grid.

Advantages / Disadvantages
Provide a strong and visible environmental / sustainability message. Low maintenance as panels need periodic cleaning only. Limited capacity relative to building demand for many building types. High installation costs, although these have reduced remarkably over the past 5 years to the point where they are competitive with some efficiency measures, The technology is only appropriate to use on buildings with good solar access for much of the day

Energy efficiency
A PV panel uses sunlight to generate DC electricity that can be converted into AC electricity and used in the building. This reduces the energy required from the national grid. Excess electricity produced by the PV panels can be exported back to the electricity grid.

Running costs
The electricity generated will reduce the amount of energy purchased from the grid, thereby reducing running costs. Formerly generous feed-in tariffs have been abolished, but exported electricity is generally being bought back at wholesale prices (around 7.5c/kWh). Optimum return on investment is achieved where the amount of export is minimised.

Retrofit / improvement opportunities
PV panels should work effectively for at least 25 years after installation before needing replacement. The DC / AC invertors will typically need replacing once over this period. PV panels can be easily retrofitted to a roof with adequate accessible space and where an unshaded north facing orientation can be achieved. Consideration also needs to be given to roof loadings, electrical safety requirements, the safety of roof access and the avoidance of any compromise of the watertightness of the roof.

Applicable buildings
All buildings with available roof space and where an unshaded north facing orientation can be achieved will benefit from the application of PV panels.

Floor plate implications
None.

Occupant comfort
No issues.

Maintenance implications
PV panels are very low maintenance as only periodic cleaning is required. The DC / AC invertors located inside the building typically require replacing every 15 years.

Identification
PV panels will normally be on the roof and orientated to receive maximum sunlight. The panels have a shiny / reflective appearance and there will be electrical connections to them. There will not be any insulated water pipework connected to the panels.

Questions to ask

Who owns the PV panels?
Who in the building receives the power that the PV panels generate?
What costs / savings do the panels create for the tenant?
Was the system registered for the Feed-in Tariff and if so, who gets the income generated?

More information
References required

Solar Thermal

What are they?
Solar thermal (ST) panels utilise sunlight to heat water and are typically referred to as ‘solar hot water heaters’. ST panels are different to photovoltaic panels which produce electricity from sunlight. ST panels transfer the sun’s energy to a liquid which is heated and then circulates between the panel and the building, and are most often used to provide domestic hot water. To maximise their efficiency, ST panels are usually mounted on a north facing pitched roof or on a flat roof using an A-frame (facing north) to support them. ST panels still produce significant heat on a cloudy day.

Advantages / Disadvantages
Provide a strong and visible environmental / sustainability message. Low maintenance as panels need periodic cleaning and checking only. The technology is usually only appropriate to use on buildings north facing orientation can be achieved and which aren’t overshadowed. Costly, to the point that it is often more effective to spend money earmarked for ST panels on PV panels instead.

Energy efficiency
ST panels generate hot water to contribute to the domestic hot water system, which means less gas or electricity is consumed for this function in the building. Impacts of solar thermal applications are generally small.

Running costs
The hot water generated will reduce electricity or gas costs depending on the fuel being displaced.

Retrofit / improvement opportunities
ST panels should work effectively for 20 to 25 years after installation before needing replacement. Other parts of the system (such as storage cylinders and pumps) may need replacement in this period. ST panels can be easily retrofitted to a roof providing the building has a demand for hot water and a hot water distribution system (i.e. not point-of-use electric water heaters). Adequate, accessible roof space with exposure to the sun is important. Consideration also needs to be given to roof loadings, the safety of roof access and the avoidance of any compromise of the watertightness of the roof.

Applicable buildings
All buildings with available roof space and where an unshaded north facing orientation can be achieved will benefit from the application of ST panels. Careful design is required to ensure that the building can use or adequately store the hot water produced otherwise the panels can be damaged.

Floor plate implications
None.

Occupant comfort
No issues.

Maintenance implications
ST panels have relatively low maintenance requirements. Periodic cleaning is required and a leak inspection and check of pumps should take place every year.

Identification
ST panels are likely to be north facing or as close to south-facing as possible to maximise their output. Panels either have a shiny reflective appearance or are a series of tubes mounted together into a panel formation. There will be insulated water pipework connected to them.

Questions to ask

Who owns the ST panels?
Who in the building receives the hot water that the ST panels generate?
What costs / savings do the panels create for the tenant?
More information

References required

Cogeneration and trigeneration

What are they?
Cogeneration is typically based on an on-site electricity generator that is fuelled by gas. The heat produced by the generator is captured for the building’s hot water system. This means both heat and electricity are being generated. In systems that also provide cooling, the hot water is fed to an absorption chiller which produces chilled water from the hot water resource. ‘Tri-generation’ refers to the production of electricity, heat and chilled water. Chilled water is produced through the incorporation of an absorption chiller into a co-generation system. Absorption chillers use the waste heat from the cogeneration plant to create chilled water for cooling a building. Typically the cogeneration system will not provide all of the site heating needs and a trigeneration system will not provide all of the site’s chilled water needs. As a result the building will still have boiler and chiller plant.

Advantages / Disadvantages
Cogeneration and trigeneration make better use of the input fuel than the power stations on the grid, which throw away the waste heat. Also, gas is a lower impact fuel than the coal that comprises the input fuel to the majority of grid electricity. Optimum applications require continuous electrical and thermal loads which are present in some retail and industrial applications (especially where the industrial process has process heating or cooling requirements) but are uncommon in offices. Specialist maintenance is required to operate cogeneration and trigeneration systems with adequate reliability It is not always possible to operate cogeneration or trigeneration within a local electricity distribution network. Permission must be sought from the owner of the electricity distribution network.

Energy efficiency
Less electricity is imported from the national grid as it is being generated on-site. CO2 emissions are reduced because the gas used provides both electricity and heat rather than just heat from a boiler, and grid electricity uses coal which has higher emissions. Cogeneration and trigeneration are best suited to sites with a simultaneous year-round demand for heating / cooling and power, such as data centres, industrial buildings with high process loads, shopping centres and office buildings with large IT suites and server rooms (for example, trading floors).

Running costs
Running costs vary dependent on the nature of site energy demands. Some installations cause a net increase in cost, while others can reduce costs.

Retrofit / improvement opportunities
Cogeneration and trigeneration systems require more plant room space than conventional gas boiler and chiller plant. If there is adequate plant room space then a retrofit is feasible. The plant room is likely to require an acoustic upgrade, as the generators can be noisy.

Applicable buildings
The building should have a high demand for heat and / or cooling if the cogeneration or trigeneration is to be cost-effective. For example, modern offices have a low demand for heat and a highly variable electrical demand, with the result that CHP may not be economically viable.

Floor plate implications
None.

Occupant comfort
Noise levels can be a problem, so it is important to ensure that there is sufficient acoustic treatment to the plant room housing the cogeneration or trigeneration equipment.

Maintenance implications
Maintenance requirements are more frequent and complicated than for conventional plant. This extra cost can be an important factor when considering affordability.

Identification
The most common generator type is a large and very noisy gas engine. Turbine generators are also available which are much quieter and look like boxes, and are typically installed in banks of two or more.

Questions to ask

Who maintains the cogeneration/trigeneration unit and at what are the costs of operation?
How much, if any, of the energy generated is exported to the grid?

More information
More references required

Ground Source Heat Pumps

What are they?
A ground source heat pump (GSHP) system uses the ambient temperature of the ground to heat or cool the water used in a heating or air conditioning system. Pipes (known as ‘ground loops’) are installed underground and circulating water is either cooled or heated in them before it is passed through a heat pump. The GSHP can be used in a building for space heating in winter and space cooling in summer. GSHPs run on electricity, and are more efficient than air-cooled refrigenat systems (which they otherwise resemble) due to the more constant temperature of the water from the ground loop. The ground loops will either be laid horizontally under a very large external area, or vertically under the building, car park or other open space adjacent to the building.

Advantages / Disadvantages
Energy efficient means of heating and cooling a building. Low maintenance costs. Visually unobtrusive Expensive to install and disruptive to retrofit because of the requirement to install vertical boreholes or lay pipes horizontally across large areas. Pumping energy needs to be well managed or this can cancel out benefits

Energy efficiency
The energy saved using a GSHP system is greatest when the outdoor conditions are extreme. Savings in mild weather are minimal if any. These systems are best suited to inland and high altitude climates in Australia. The efficiency of the system will be maximised where the system is used for both winter heating and summer cooling.

Running costs
The heating and cooling provided by a heat pump will reduce gas and electricity consumption and provide a net saving in electricity which will reduce energy bills.

Retrofit / improvement opportunities
GSHP systems are rarely retrofitted because they are expensive to install and because of the disruption caused to the building and the occupants.

Applicable buildings
All buildings, providing there is sufficient space to install the pipework, either horizontally or vertically. Generally easier to install in open sites than in CBD locations.

Floor plate implications
None.

Occupant comfort
No issues.

Maintenance implications
The GSHP will require periodic servicing and maintenance, comparable with conventional heating and cooling plant.

Identification
A GSHP is about the same size as a gas boiler and will be connected to a series of lagged water pipes.

Questions to ask

Who maintains the heat pump unit and at what cost to the tenants?
Where is the heat loop?
Is there a back-up heating / cooling supply during periods of GSHP maintenance?

More information
References to be provided

Wind Turbines

What are they?
Wind turbines generate energy from wind. They come in a variety of designs and sizes. They will only generate energy when the wind blows sufficiently to turn the turbine blades. The speed of the wind is critical to the power output. The energy they generate can be exported back to the grid or used within a building.

Advantages / Disadvantages
Very efficient at generating electricity in locations where wind speeds are consistently high. A clear statement of the environmental / sustainability credentials of a building. Micro turbines in urban locations - where wind speeds are typically low or erratic - will produce little energy. Noise and appearance can make wind turbines unpopular.

Energy efficiency
The turbine generates electricity which displaces electricity demand from the electricity grid.

Running costs
Specialist maintenance is required to keep moving parts operating.

Retrofit / improvement opportunities
Retrofitting turbines to the roof of a building will depend on the structure’s ability to withstand the additional loadings in a location that is exposed to the prevailing winds. Wind turbines have an expected lifetime of 20 years or more.

Applicable buildings
Wind speed is critical to generating power and therefore wind turbines are only appropriate for buildings on exposed windy sites with sufficient external space to accommodate them. Wind turbines can be noisy, so proximity to other buildings is also an important consideration. Wind turbines that are attached to buildings may be affected by turbulence close to the edge / roof of the building and as a result their power output may be lower than surrounding wind speeds would indicate. Wind turbines mounted on buildings can also cause vibration issues within the building.

Floor plate implications
None.

Occupant comfort
None, however it is important to ensure that there is no risk of ‘flicker’ caused by the blades due to poor positioning of the turbine between the sun and windows, and no noise or vibration transmission into the building..

Maintenance implications
Require regular servicing to ensure they remain fully operational.

Identification
Either roof mounted or ground mounted near to the building.

Questions to ask

Does the building receive the power that the wind turbine generates?
What cost / saving does the wind turbine create for the tenant?
Who is responsible for the cost of maintenance of the turbine?

More information
References required

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