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Energy Wise HotelsTOOLKIT DECEMBER 2007
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City of Melbourne, December 2007
PO Box 1603, Melbourne, Victoria 3001
Hotline 61 3 9658 9658
TTY 61 3 9658 9461
Email [email protected]
Web www.melbourne.vic.gov.au
This is a publication of the Melbourne City Council.
The Energy Wise Hotel Toolkit is printed on Monza Satin Recycled. Monza has a high 55%
recycled fibre content, including 30% pre-consumer and 25% post-consumer waste and FSC
certified pulp. Monza Recycled is sourced from sustainable plantation wood and is Elemental
Chlorine Free (ECF).
Disclaimer statement
The content that appears in this publication is provided for information purposes only. No claim
is made as to the accuracy or authenticity of the content. Sustainability Victoria does not accept
any liability to any person for the information or advice (or the use of such information or advice)
which is provided in this publication or incorporated into it by reference.
The information in the Sustainability Victoria publication is provided on the basis that all persons usingthe publication undertake responsibility for assessing the relevance and accuracy of its content.
Sustainability Victoria does not accept any liability for loss or damages incurred as a result
of reliance placed upon the content of this publication.
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Introduction
The hotel industry is one of the fastest growing industries in the world due to
increased tourism and market globalisation.
At the same time hotels are providing more facilities and services to customers,
leading to increased energy consumption.
As the cost of energy in Australia is increasing, and its use is shown to accelerate
climate change, the hotel industry is becoming more aware of the impact of their
business on the environment. Today most guests are aware of climate change due
to the generation and consumption of energy.
The Energy Wise Hotels Toolkit has been developed to assist accommodation service
providers to reduce their energy consumption. The toolkit also outlines energy
consumption patterns in hotels and the impact this has on our environment.
This toolkit provides comprehensive recommendations on energy reduction
opportunities with technical explanations. Hotel management can use the toolkitto develop the action plans necessary to improve the energy efficiency of the hotel,
without sacrificing the comfort of guests. This not only makes the hotel business
more profitable but presents a favourable image of hotels that can be marketed.
Who is this Toolkit for?
The Energy Wise Hotels Toolkit has been developed for:
hotel management;
engineers; and
staff members responsible for training and work practices.
The toolkit is divided into chapters to enable hotel operators to apply relevant
information to their own hotel. Each chapter may not be relevant for every hotel,depending on the structure and utilities at each hotel.
The toolkit is based on information obtained from a series of 10 energy audits
undertaken as part of the City of Melbournes Savings in the City Green Hotels
program. Case studies carried out by Energy Efficiency Opportunities Australia
(EEO) are also sourced throughout the toolkit, as well as information collected
from general surveys and consultancies in energy conservation.
The Energy Wise Hotels Toolkit
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Using this Toolkit
This toolkit comprises nine sections:
Section 1: Why be energy efficient?
Outlines benefits of conserving energy
Section 2: Energy use and performance indicators
Identifies which areas in hotels are generally the largest energy consumers
Section 3: Energy monitoring and tracking
Deals with the key parameters to be monitored and tracked in order to improve
energy efficiency
Section 4: Taking action
Explains how to start implementing energy saving ideas in your hotel
Section 5: Understanding energy
Basic explanation of energy
Section 6: Energy saving initiatives
Outlines possible energy saving opportunities for hotels
Section 7: Involving staff and guests
Outline of engagement and training techniques for staff and guests
Section 8: Renewable energy
Explains the role and value of sourcing energy from renewable sources such
as wind, power and solar power
Section 9: Technology discussion
Includes three fact sheets with more detailed information and tips to aid energy
conservation in your establishment. These include:
lighting;
heating, ventilation and air conditioning;
variable speed drives; and
environmental management systems.
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The Energy Wise Hotels Toolkit
05
Acknowledgements
We would like to thank the following organisations for their help and information:
Enman Pty Ltdwww.enman.com.au
EEO, Department of Industry, Tourism and Resources
www.energyefficiencyopportunities.gov.au
Crowne Plaza, Melbournewww.crowneplaza.com.au
Grand Hyatt, Melbournewww.grandhyatt.com.au
Hotel Ibis, Melbournewww.hotelibis.com.au
Jasper Hotelwww.jasperhotel.com.au
Saville City Suites, East Melbournewww.savillehotelgroup.com
Saville on Russell, Melbournewww.savillehotelgroup.com
Melbourne Marriottwww.marriott.com.au
Sofitel Grand Hotel, Melbournewww.sofitel.com.au
Sebel Melbournewww.mirvachotels.com.au
Hilton on the Park, Melbournewww.hiltonhotels.com.au
This Energy Wise Hotels Toolkit was researched and produced by Enman Pty Ltd.
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Why save energy?
Energy is fundamental for maintaining comfort standards in a hotel however
it is important this energy is used efficiently. Like water and waste efficiencies,
the benefits of being energy efficient are:
reducing your hotels environmental impact;
cost saving on energy bills; and
enhancing your hotels reputation for protecting the environment.
Energy is the largest generator of human-induced greenhouse gas emissions.
Greenhouse gases cause global warming which is detrimental to our natural
environment systems.
Some of the effects of global warming are:
a rise in sea level causing coastal damage;
an increase in the likelihood of extreme weather conditions such
as droughts, floods and cyclones;
health impacts because of the spread of tropical-borne diseases,the increase of flooding and other such climate changes;
damage to ecosystems and species diversity;
damage to agricultural output and food supply; and
an increase in the earths surface temperature causing heatstress and damage.
Reducing the energy consumption in hotels helps reduce greenhouse gas emissions.
Refer to Appendix B for details about the environmental impact due to energy
generation and use.
Why be energy efficient? 1
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Energy use and performance indicators 2
09
Before energy use can be reduced in a hotel, motel, servicedapartment or hostel, it is necessary to understand where energyis being consumed. It is also helpful to compare your hotels
energy consumption to other similar hotels.
2.1 Energy balance
An energy balance shows where and how much energy is being used in the hotel.
The two most common sources of energy consumed in hotels are:
electricity; and
thermal energy this is usually natural gas, however in remote places LPGand other forms of fuel are used.
Typical energy consumption in hotels is spread relatively evenly to a number of uses
including kitchens, heating, cooling and lighting. This is shown in Figure 2.1 below.
Figure 2.1: Example of total energy consumed in a hotel
Most of these uses are serviced by electricity (See Figure 2.2), with gas primarily
used for hot water and heating (see Figure 2.3).
Figure 2.2: Typical electricity consumption
Energy Wise Hotel TOOLKIT
10% AHU, FCU and ventilation fan
10% Laundry
10% Lighting
3% Refrigeration
13% Space heating
14% Domestic & pool water heating
15% Chiller
1% Miscellaneous
7% Pump
7% Kitchen
10% Electric heating
17.6% AHU, FCU and ventilation fan
17.2% Electric heating
26.6% Chiller
5.6% Refrigeration
12.0% Pump
18.7% Lighting
2.3% Miscellaneous
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Figure 2.3: Typical thermal (gas) consumption
2.2 How much energy can you save?
It is very important to know how energy efficient your hotel is and where potential
savings could be made through energy conservation.
Performance indicators and benchmarking
Benchmarking your initial energy use is a convenient way to compare the energy
efficiency of hotels. It is important for the benchmark to consider the star quality
rating of a hotel so that the comparison is meaningful. Benchmarks are also
known as an energy index or as performance indicators.
Energy performance benchmarking is an internal management tool designed
to provide ongoing, reliable and verifiable tracking of the hotels performance.
Realistic targets can then be set for improving efficiency by hotel management.
The most useful performance indicators of hotels are:
gigajoules (GJ) per square metre of floor area; and
GJ per guest.
Table 2.1 shows energy benchmarks that are used by hotels in Australia.
Table 2.1: Benchmarks for energy consumption per square metre (GJ/m2.year) for a hotel
Note: Benchmark figures are based on surveys conducted on hotels in various regions,
and buildings of similar nature by Benchmark Hotel, EEO (Energy Efficiency Office)
and IHG Hotels operating results.
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16% kitchen
32% domestic & pool water heating
30% Space heating
22% Laundry
Rating Energy use
(GJ/m2.year)
Very Good < 0.95
Good 0.95 - 1.09
Satisfactory 1.09 - 1.24
Poor 1.24 - 1.38
Very Poor > 1.38
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To achieve energy savings it is important to monitor and track energy consumption,and generate reports on a regular basis. Such a system forms the basis of any ongoingand sustainable energy management program.
There are standard software packages available to monitor and track energy and greenhouse gas emissions.
However, hotels and hotel groups can easily create their own simple database. Some of the key features
required for tracking energy efficiency are:
comparison of energy consumption and key performance indicators;
bar graphs of energy use and performance index for 12 months over the pastfew years as shown in Figure 3.1 and Figure 3.2; and
comparison of actual energy use against target consumption (Figure 3.3).The target can be generated according to seasonally adjusted monthly energy use.
Figure 3.1: Bar graph of electricity consumption over three years
Energy monitoring and tracking 3
11Energy Wise Hotel TOOLKIT
0
20
40
60
80
100
120
Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
2004 2005 2006
ElectricityConsumptions(MWh/year)
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Figure 3.2: Bar graph of natural gas consumption over three years
Figure 3.3: Actual electricity consumption versus target consumption
0
20
40
60
80
100
120
Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
2004 2005 2006
GasConsumptions(G
J/year)
0
20
40
60
80
100
120
Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
Actual Target
ElectricityC
onsumptions(MWh/year)
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Taking Action 4
13Energy Wise Hotel TOOLKIT
In order to implement successful energy saving you must have a well structured and realisticplan with management support.
4.1 Following an energy management frameworkAdopting a sustainable energy management framework is the first step of any energy and greenhouse gas emission
reduction program. When developing an energy management plan it is recommended you consider the steps shown
in the following flow chart:
Figure 4.1: Energy management plan represented in a flow chart
The following sections outline each stage of the framework in more detail.
4.1.1 Corporate energy policy
A corporate energy policy sets the directive and basis on which the energy management plan is developed.
This policy must be approved by senior management and endorsed by the CEO. The policy is then circulated
to all staff to ensure a common understanding by staff at all levels.
The corporate energy policy should link to other environmental policies, primarily waste and water management.
An example of a corporate energy policy is shown at Appendix A.
Adopt a Corporate energy policy
Develop an
energy management plan
Adopt a Energy
management coordinator
Identify and train energy champions
Non-capital intensive
Energy Management Initiative
Capital intensive
Energy Management Initiative
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4.1.2 Developing an energy management plan
The energy management plan is the plan of action to improve the energy efficiency of a hotel by setting out clear
objectives and targets. To achieve these objectives, management needs to assign responsibilities and allocate resources.
4.1.3 Energy management coordinators
An energy management coordinator is required for all accommodation establishments; one per hotel or one per
group of hotels of the same chain. Their responsibility is to manage and coordinate all energy management functions
in the hotel.The coordinator needs to monitor and report energy consumption and performance as well as drive all of the planned
energy management initiatives (EMIs) of the hotel. The coordinator must be fully trained and motivated to carry out
the required tasks efficiently and effectively.
4.1.4 Energy champions
Energy champions are staff members who can assist with the day-to-day energy management action plan.
Hotel service engineers and other supervising staff are the ideal people to be designated as energy champions.
Energy champions should be properly trained along with the energy coordinator to achieve satisfactory outcomes
for the hotel. This is a great professional development opportunity for motivated staff.
4.1.5 Introduce energy awareness program
Introducing an energy awareness program consists of several components which are discussed in detail
later in this toolkit. These are:
education program;
display of corporate commitment in staff member common areas; and
promotion of energy management through various means including stickers.
Figure 4.2: An example of energy sticker
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Understanding energy 5
15Energy Wise Hotel TOOLKIT
It is important to understand the basics of energy to monitor and control it.
A guide to understanding energy units
What does the term power mean?
The term power refers to the rate of change of energy. It is a way of describing the capacity needed
to make appliances or equipment operate effectively.
For example:
A lamp of 100 wattage: Power is 100 wattage
A heater rated 1 kilowatt (KW): Power is 1 kW (1000 wattage)
What does the term energy mean?
The term energy links power to length of time.
ENERGY = POWER x TIME OF OPERATION
ENERGY = WORK DONE BY A SOURCEUnit of energy = Joule (J) 1 kilowatt hour (kWh) = 1 kilowatt operates for 1 hour 1 kW = 3.6MJ/hr
= 10 lamps operate for 1 hour 1 kWh = 3.6 MJ
= The heater operates for 1 hour
How do energy and power link together?
Most common units:
POWER = kW , joules/sec
ENERGY = kWh , GJ
1 kWh = 3.6 MJ
What are the main types of electric power transmission?
1. Three-phase electricity
Many electric motors employ a three-phase load design which runs three alternating currents of the
same frequency at different times to give constant power in an efficient, compact and longer-lasting way.
Used in pumps, fans, blowers, compressors and some air-conditioning units.
Power (kW) = Volts (line) x Amps (line) x 3 x Pf
Note: The power factor (Pf) of electric motors is designed at around 0.8 to 0.9. The Pf decreases as motor load decreases.
2. Single-phase electricity
Employs a single circuit of electricity current.
kW = Volts x Amps x Pf
Example 1:1 kW motor (full load) operates for 16 hrs/day, 300 days/year
Power = 1 kW
Energy = 1 x 16 hrs/day x 300 days /year
= 4,800 kWh/year
1 Btu = 1.05506 kJ or 2519 kcal
1 calorie = 4.187 joules
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5.1 Greenhouse gas emission factors
Once the amount of power and energy used for operations is understood, it can then be converted into
greenhouse gas emissions.
Factors used to calculate the greenhouse gas emissions associated with consumption of different fuels
and activities are provided below:
Electricity greenhouse gas emission factor: 1.325 kg CO2-e/kWh
Natural gas greenhouse gas emission factor (Small user
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Energy saving initiative 6
17Energy Wise Hotel TOOLKIT
Energy savings equal financial savings. Hotels can deliver a rangeof energy saving initiatives grouped as either:
Initiatives that require little or no capital.
These are the energy management initiatives to consider first in your energy
management plan as they require little or no finance and are simple to do.
Initiatives that require capital investment.
These should be considered based on individual merit.
These opportunities are outlined in more detail in the following sections.
6.1 Energy management initiatives the first steps
Simple energy management initiatives that require little or no financing include:
changing operations and practices around the hotel;
purchasing energy efficient equipment;
energy efficient maintenance; and
introducing an energy awareness program for staff and guests.
6.1.1 Change of operational practice
By simply altering the operations of your accommodation facility you can save
a large amount of energy with little cost.
Some of the simplest ways to conserve energy are:
Lights
Turn off lights when not required. Lights in common areas are under staffcontrol; therefore staff should turn off lights in common areas when not in use.This can be achieved by conducting a staff awareness program.
Dim reception and foyer lights from late night to early morning when thereis minimal activity. This can be achieved whilst still maintaining guest safetyand comfort.
Lights in guest rooms are under guest control. Encourage guests to turn off lightsthrough energy and climate change promotional stickers. Invite guests to join theefforts of the hotel to reduce greenhouse gas emissions and inform them of someof the hotels initiatives. This will encourage guests to reduce their own energy use.
Air conditioning
Similar to lighting, the air conditioning can be turned off when its useis not necessary.
Increasing the room temperature during cooling provides energy savingsof around five to 10 per cent of the cooling load.
It is recommended the cooling temperature is set to 24C.
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Heating
Decreasing the room temperature during the cooler months can lower theheating load by five to 10 per cent. It is recommended the heating temperatureis set at 18C.
Kitchen
Turn off the exhaust fans in the kitchen when not required.
Reduce the speed of fans during times of low kitchen activity by using a variable
speed drive. Installing a variable speed drive is a wise financial investment,as the reductions in energy bills quickly repay the initial investment.
Hot water
Set hot water temperature to as low as possible. The recommended hot watertemperature is around 60C.
Office equipment
Turn off office equipment such as computers, computer screens and printers whennot in use, especially after hours. Explain the benefits to staff so they participate inreducing the energy needs from office equipment.
Always enable energy star features on office equipment to give it the ability topower down or sleep when they are not being used and wake up when they areneeded. For more information refer to the Australian Department of EnvironmentGreen Office Guide 2001.
6.1.2 Buying energy efficient equipment
Incorporate the purchase of energy efficient equipment into the energy
management program.
Typically energy efficient equipment is more expensive than the standard option;
however the energy savings achieved usually provide adequate paybacks.
In addition, equipment needs to be replaced periodically anyway so this is
often a perfect opportunity to invest in energy efficient equipment.
Some examples of energy efficient equipment are:
Office equipment typically any equipment with a star rating showing is a highlyenergy efficient product.
A flat screen monitor uses less energy than a traditional CRT monitor; and laptops
consume less energy than desktops.
The hard drive of an average computer uses 49 watts when fully turned on, 29 watts
when asleep and two watts when switched off.
The average monitor uses 60 watts when in use, 6.5 watts when in sleep mode and
one watt when switched off.
Make sure energy saving modes are installed on computers and are operational.
Use recycled paper which requires 90 per cent less water and 50 per cent
less energy to produce and whenever possible print on both sides of the page.Buy other recycled or reused products wherever possible such as furniture.Lease photocopiers where possible.
Laundry services buy washing machines and dryers with higher energy starratings that show energy efficiency performance. Be sure to consider waterefficiency when making these purchases.
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Motors and chillers purchase higher energy efficiency equipment. It is worthpaying more for an energy efficient motor (likely to be an increased cost of around10 to 20 per cent) with an efficiency of between two and four per cent. Over thelikely 20-year life of the equipment, the capital outlay is small compared to thecost of running it as shown in Figure 6.1 below.
Figure 6.1: Life Cycle Costs of a 55 kW Motor
Assumption: 20-year service life with an electricity price of 10/kWh.
Lighting buy compact fluorescent lamps instead of incandescent, this canachieve energy saving of around 75 per cent.
Refrigeration the energy efficiency of refrigerators varies by 50 per cent evenif they meet new stringent minimum energy performance standards (MEPS)introduced in 2005. When purchasing a new refrigerator consider high energystar ratings over cheaper, low star refrigerators as these models will offergreater cost savings.
6.1.3 Energy efficient maintenance
The present trend in the accommodation industry is to cut down maintenance costs
allowing just enough to keep everything running smoothly. However, extending the
maintenance from preventative or breakdown maintenance to energy efficient
maintenance proves to be cheaper in the long-term.
Energy efficient maintenance reduces energy costs and extends the life of equipment.
Some of these maintenance procedures are:
Air handling units
Air handling units condition the air and recirculate it to areas for cooling, heating and
ventilation. Maintenance procedures include:
Replacement of filters in air handling units and fan coil units. The filters can becleaned or replaced about twice a year. This improves energy efficiency as wellas room air quality.
Regular calibration check of thermostat control for the air conditioning system.
Cleaning the motor casings.
Belt drive A V-belt is one of the most common types of power transmission
to fans in air handling units. If the tension of the belt is too high or low or the beltis worn out, the transmission efficiency of the motor is reduced. Transmissionefficiency is dependent on pulley size, torque, under or over belting and V-beltconstruction. Belt tension is also a very important parameter. Under and overbelting can cause an efficiency drop of as high as five per cent.
Energy saving initiative 6
1.4% Motor cost
98.6% Energy cost
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Regular checking of the damper control many of the air handling units foundin hotels have an economy cycle. This allows the fresh air and relief air dampersto open or close depending on ambient weather conditions. The economy cyclecan reduce the cooling load by up to 30 per cent. It has been observed previouslyin other hotels that dampers are often faulty or frozen which causes the systemto operate inefficiently.
Cooling towers
New types of cooling towers with condensers are emerging. These are mixed wet
and dry types which are more water and energy efficient. These condensing cooling
towers operate as air-cooled systems in winter and water-cooled systems in summer.
Regular checking of cooling tower performance it is sometimes found that coolingtower capacity reduces due to: unequal water distribution; water not wetting thecooling tower pack; or the spay nozzles not spraying efficiently. As a result, thecooling capacity is reduced along with the energy efficiency of supplied chillers.
Motors
Rewinding motors motors are used for pumps, fans, chillers and a large amountof other equipment. As they fail they are normally rewound. Rewinding a motor ischeaper than purchasing a new motor; however each time a motor is rewound itsenergy efficiency is reduced.
The efficiency of rewound motors drops due to the intense heat applied in thestripping of old windings and from using cheaper, thinner gauge wire. Rewinds are
normally priced at between 60 and 80 per cent of the price of a standard new motor.
On average, the efficiency of a motor decreases by about one per cent each time
the motor is rewound.
Supply voltage when the three-phase voltages are not equal, the motor lossesincrease substantially. This is normally due to unequal distribution of the single-phaseloads, such as lighting. A modest phase imbalance of two per cent can increasemotor losses by 25 per cent or overall motor efficiency by around 1.6 per cent.
When operating at less than 95 per cent of design voltage, motors typically lose
efficiency by two to four per cent. Supply voltage over and under the rated voltage
can also significantly reduce energy efficiency.
6.2 Energy management initiatives capital intensive
Capital intensive initiatives are energy saving projects that require small to large
financing. These projects should be considered based on their individual merits
which include:
payback time how quickly the works pay for themselves in the formof reduced energy bills and maintenance costs;
quantity of saving of financial dollars and greenhouse emissions; and
other associated benefits such as water, waste, health, noise andamenity improvements.
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Energy saving initiative 6
6.2.1 Energy saving in HVAC systems
Heating, ventilation and air conditioning systems (HVAC) are typically a major energy
user in hotels. HVAC can consume as much as 70 per cent of a hotels total energy
consumption. However, this is also an area where significant improvements can be
made. Energy efficiency improvement of up to 50 per cent is achievable depending
on HVAC configuration control and operation.
The energy saving opportunities in HVAC systems are:
Economy cycle this is one of the most commonly recommended energy saving
functions for HVAC systems. The economics of retrofitting an economy cycle depend
on the following factors:
Capacity of the AHU fan sizes less than 5 kW are less economically viable.
Fresh air supply duct size if the fresh air duct which brings the fresh air to theAHU does not require any modification to bring 100 per cent fresh air it is easyand more economically viable to retrofit an economy cycle.
Control system if there is a building management system (BMS) the facility shoulduse direct digital control (DDC) and enthalpy-based control to provide more energysavings. The anticipated energy saving is around 25 per cent in Melbourne.If there is an economy cycle fitted, then check the operation as follows:
- Is the controller still functional?- Is the controller calibrated correctly?
Economiser an economiser is a heat recovery system. Installing an economiser
is a good way to improve the energy efficiency of a HVAC system. An economiser
is more economically viable when implemented during the installation of the HVAC
system. You should consider an economiser when the AHU system is on 100 per cent
fresh air. Economisers are generally more viable in extreme weather conditions such
as very cold or very hot. Melbournes weather is suitable for the use of economisers.
Variable speed drive (VSD) installing variable speed drives on supply and return
air fans is a new trend in energy management. Implementation as a retrofit is very
simple and economically viable. Conventionally VSD were viable only if the system
was designed as a VAV (variable air volume) system. However, an advanced controlalgorithm allows you to implement a VSD for any type of air conditioning system.
The anticipated energy saving is around 45 per cent of the fan energy depending
on the algorithm used for control and the humidity requirement in the space. As hotel
air conditioning generally functions to provide comfort conditions, humidity is not a
critical parameter.
Infiltration of air reducing the infiltration of ambient air into air conditioned spaces
reduces the air conditioning load. The guest entrance door in the foyer of the hotel
is an area where automatic double doors or revolving doors can be considered.
Room temperature setting room temperature setting is one of most
important criteria for energy conservation through change of operational practice.
It is recommended room temperatures in winter are set as low as possible;
even as low as 18C and during summer as high as 25C.
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Chiller system chillers are another large energy consumer in the hotel industry.
Chiller efficiency can be improved by measures outlined below.
Use energy efficient chillers: if chillers are old, replace them with a water-cooledturbo compressor fitted with a VSD. This can improve energy efficiency by upto 400 per cent.
Use a different size or capacity of chiller: a smaller capacity chiller shouldbe used in low load conditions and a larger chiller for high load conditions.Operating a chiller at part-load conditions reduces the efficiency of a
conventional fixed speed chiller.
Electronic expansion valve (for reciprocating compressors): if the expansion valveis electromechanical, replace it with modern electronic valve. This can improveefficiency by around 15 per cent.
Use a chiller with remote set point control facility.
It is common practice to design the cooling tower with minimum capacity.Increasing the cooling tower capacity can increase chiller efficiency.Therefore, provide adequate cooling capacity for cooling tower.
Use a common cooling tower for all chillers with common header and discharge -this not only provides the opportunity to save energy but also provides greaterreliability of the chiller system.
Use variable speed drives for the following areas:
- secondary chilled water pump;
- primary chilled water pump;
- condenser water pump; and
- cooling tower fans VSD for a cooling tower fan not only reduces fanenergy but also can improve energy efficiency of the chiller compressor.
Tune control system to avoid simultaneous heating and cooling.
Insulate ducts and chilled water pipes to prevent heat gain.
Energy efficient comfort condition of HVAC system the comfort level
of air conditioned spaces depends on the following variables:
- gender;
- activity;
- relative humidity and dry bulb temperature; and
- air movement.
Refer to section 9.2.2 for more information on air conditioning comfort
Why cool high?
Adjust your cooling comfort zone to as high as possible. An increase of 1C
in temperature will reduce your energy consumption by five to 10 per cent.
Why heat low?
Adjust your heating comfort zone to as low as possible. A decrease of 1C
in room temperature will reduce your energy consumption by five to 10 per cent.
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Glazing and shading glass windows are one of the major contributors to air
conditioning load. Appropriate measures must be taken to ensure hotel windows
are efficient. Some energy saving measures that can be implemented are:
window glazing a double-glazed window will not only reduce the coolingand heating load of the building but also reduces noise levels in the building;
use of energy efficient glass that allows less heat to transfer through the glass;
use of tinted glass to reduce solar absorption this not only reduces energy
consumption but also improves comfort conditions in the hotel. It is especiallyeffective for windows facing north and west.
Building insulation building insulation also helps reduce the heating and cooling
load of a hotel. The following forms of insulation will be of assistance:
roof and wall insulation;
roof paint use light or white colour, or specialised solar coating to deflectsolar radiation;
building shading planting of trees around the sunny side of the buildingto provide shade for lower levels of the building.
6.2.2 Key card room control
Hotel key card control is one of the largest potential energy savings of all initiativesidentified during this program. Guest rooms are the largest energy consumers
in hotels due to air conditioning and lighting use by guests. Rooms are usually
unoccupied for a substantial amount of time but the air conditioning and lights are
normally left on by guests. Depending upon the policy of the hotel, the cleaners
sometimes turn off the air conditioning, lights and television.
Key card room control is a convenient way to turn off air conditioning and lighting
when the rooms are not occupied. Some 41/2 to 5-star rated hotels are opposed to
the concept of key card control as the room temperature is outside the comfort zone
when guests return to the room (warm in summer and cold in winter). Introducing key
card room control is recommended with either of the following two options:
option 1 turn off air conditioning and lighting when room is unoccupied.
option 2 turn off lighting only when room is unoccupied, and reset the roomtemperature to an acceptable temperature such as 26C in warmer monthsand 18C in cooler months.
6.2.3 Lighting systems
Lighting is one of the major energy consumers in hotels. However, lamp technology
is continually evolving, resulting in increased energy efficiency. There are also many
simple lighting control techniques that can be implemented to improve energy
efficiency or reduce energy wastage.
Major energy saving opportunities are:
Use of energy efficient lamps:
Incandescent lamps: change incandescent lamps to compact fluorescent lamps (CFL).
This can provide energy savings of up to 80 per cent. The cost of CFL is continually
dropping due to increased demand. The life of CFL is also much longer at around
6000 to 15,000 hours, compared to 1000 to 2000 hours for incandescent lamps.
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Dichroic lamps: replace dichroic lamps either with compact fluorescent or LED
lamps. A 50W dichroic lamp can be replaced by a 7W compact fluorescent or 2W
LED. The same fittings can be used for the new lamps, decreasing the installation
costs. A 2W LED lamp has a little less light output than a 50W dichroic lamp.
Fluorescent lamps: replace 36 W standard fluorescent lamps with 36W energy
efficient triphosphor tubes. The triphosphor tube provides around 30 per cent
greater light output than the 36W tube. The most efficient fluorescent lamps are
T5 lamps. These lamps require new electronic ballasts with a dimming option.
They are economically viable when a complete lighting refurbishment is undertaken.
High bay lamps: replace mercury vapour lamps by pulse-type metal halide or sodium
lamps. Low pressure sodium lamps have an orange colour light output and may not
be suitable for some applications.
Lighting level: over lighting wastes energy. It is important to measure the lux levelof areas and minimise these levels where necessary in order to meet AustralianStandards for the activities undertaken. If an area is over lit, de-lamping or dimmingmay be considered to reduce lighting levels. Australian Standards for lighting levelsfor different areas are shown in Table 9.3.
Lighting control
- Use energy saving voltage control for fluorescent lamps.
- Use timer control for areas which have set occupancy times.
- Use of motion detectors when lighting is not required continuously in areassuch as conference rooms.
- Use lux controllers in areas that receive ambient daylight through windows.These controllers can turn lamps off and on, or dim them depending on theambient daylight. This type of control is also called daylight compensation control.
Refer to section 9.1 for more information about how much you can save with energy
efficient lighting.
6.2.4 Hot water boiler
Hot water boilers are generally used in domestic hot water generation and
space heating. There are many energy saving opportunities in hot water systems.Some of these are:
Fuel switching replace electric heating systems with natural gas systems.This not only has cost benefits but also provides a reduction in associatedgreenhouse gas emissions.
Separate boilers keep the space heating hot water boiler separate fromthe domestic hot water boiler.
Switch off space heating boiler during warm weather.
Water temperature reduce the domestic hot water temperature settingto around 50-60C.
Use an energy efficient hot water boiler some of the new generation boilers
are designed with heat recovery from flue gases. This can improve energy efficiencyby around 15 per cent but can only be used in space heating. The cost of sucha system makes the conversion economically unattractive.
Use a VSD in hot water recirculation pumps this can reduce energy consumptionby around 40 per cent and is economically attractive.
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Energy saving initiative 6Energy saving initiative 6
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6.2.5 Swimming pool
Hotel swimming pools use a substantial amount of energy through keeping the water
temperature warm and circulating water through the filter. There are two forms of heat
loss from a swimming pool and pool house:sensible and latent heat losses.
Sensible heat loss is due to temperature difference, such as the temperature
difference across the building envelope or the difference between make-up ventilation
air and exhaust air. Latent heat loss is caused by exhausting moisture evaporating
from the pool surface and/or by expending energy to dehumidify the air. Almost allthe heat loss from the pool itself is due to surface evaporation.
Hotels can reduce sensible heat loss by adjusting the indoor air temperature,
insulating the building and using heat exchangers. To reduce latent heat loss for indoor
pools, adjust temperatures and humidity, use a pool cover during unoccupied hours
and install a heat pump dehumidifier. Installing an efficient water heater and adjusting
the circulation pump's operating hours can also be effective measures.
A few energy saving ideas for your swimming pool:
As a no-cost step, investigate adjusting the pool temperature, indoor airtemperature and indoor relative humidity. It is possible to reduce the evaporationfrom a pool surface to a low level or even nil via this strategy.
Cover the pool consistently during unoccupied hours. A pool cover can resultin energy savings of 50 to 70 per cent and also saves water. Liquid insulationis available on the market however its success is questionable.
Install a solar pool heater; this will significantly reduce swimming pool heating costs.
Install a heat pump water heater and dehumidifier with heat recovery. A heat pumpwater heater may also include heat pump dehumidification and heat recovery.The dehumidification process recovers latent heat from condensing moisture inthe air and uses it to heat pool water. These heat pump dehumidifiers with heatrecovery are commercially available from many companies.
Reduce the circulation pump's operating hours when the pool is closedfor the season, and filtration can be reduced by as much as 50 per cent.
Use a properly-sized, energy-efficient circulation pump. The pump should not
be over-sized.
6.2.6 Lifts and escalators
Lifts and escalators typically use around four to eight per cent of total energy in hotels.
Although energy saving in lifts is not going to be as large as other areas of the hotel,
there is still scope for improving energy efficiency. Some of these energy saving
measures are:
reduction of standby power use by developing sleep mode;
no lifts on, or doors under power, when the lift is not in use;
use of efficient drives;
optimisation of counter weight; and
use of a variable speed drive with sensors in escalators. This can reduce energyconsumption by 20 per cent. However they are more economically viable whenpurchasing a new escalator.
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6.2.7 Energy conservation through control
Automation, control and optimisation is one of the major energy saving opportunities
in the hotel industry. Building management systems (BMS) are becoming more popular
in medium to larger hotels.
Building management system (BMS)
BMS are conventionally used for:
Time schedule allows for switching equipment such as lights, fans and chillerson and off at set times.
Direct digital control (DDC) of cooling and heating. DDC is the regulatory digitalcontrol algorithm which provides more accurate control than analogue systemsand hence opportunities to increase energy efficiency. A DDC control systemhas the potential to improve energy efficiency by up to 20 per cent from aconventional analogue system.
Energy management system (EMS)
The conventional BMS can be upgraded to EMS providing advance
and optimal control for:
chillers;
HVAC (heating, ventilation and air conditioning systems);
pumps;
cooling towers;
boilers; and
electricity demand.
Typically EMS can save energy between 20 to 50 per cent for chillers
and HVAC systems.
Refer to section 9.4 for more information.
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Involving staff and guests 7
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Energy awareness program
This is a program to motivate staff and guests to conserve energy. The focus of the
energy awareness program should be to reduce the impact of climate change rather
than achieve cost savings.
There are two major types of educational programs:
1. Energy awareness training
This is for key technical and operational personnel who are energy coordinators and
energy champions. The duration of such a program is around four to six hours and
deals with:
basic understanding of energy;
energy and our environment;
how to improve the energy efficiency of hotels in general;
basic understanding of energy efficient operation for HVAC,boiler and lighting systems; and
energy efficient technology.
2. Energy awareness seminars
These are seminars designed to educate and motivate all staff. The seminars should
be short, imparting a basic understanding of energy consumption and the associated
environmental impacts with guidelines on how to improve energy efficiency through
behavioural and operational practices. The recommended course outline is:
a discussion about global Issues: energy and the environment;
benefits to the company and staff;
presentation about energy misuse based on historical analysis of users;
brief discussion of recommended energy saving opportunities, mainly throughoperational change;
personnel participation to develop methods of reducing energy consumption;
achievements in energy conservation and reduction in greenhouse gasemissions; and
clear messages that everyone can help reduce energy and greenhousegas emissions.
3. Guest motivation
Hotel guests can also be motivated to reduce energy use through displays and
stickers on energy and climate change and the commitment of the hotel to be green.
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Renewable energy 8
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Renewable energy does not produce any greenhouse gas emissions.Renewable energy is energy produced from sources that areconsidered infinite (will not run out) and are essentially non-polluting.
The common renewable energy sources are: solar power using technologies that convert sunlight into electricity or
mechanical power such as photovoltaic cells or solar hot water systems;
wind power converting wind energy into more useful forms, such as electricity,using wind turbines;
hydro power using the force or energy of moving water in such systemsas hydroelectric schemes, tidal power, and wave power;
geothermal power generating energy from the heat stored beneath theEarth's surface; and
combined heat and power using an engine to simultaneously generate bothelectricity and useful heat.
The Renewable Energy Act 2001 requires a minimum amount of renewable energy
to be sold by each electricity retailer within Australia. There is a government rebate
available on photovoltaic solar power generation.
8.1 Go carbon neutral
Many businesses are finding their corporate image benefits from pledging to be
carbon neutral by a set date such as 2020.
Being a carbon neutral business means any greenhouse gases emitted to meet
energy needs are offset by absorbing greenhouse gas elsewhere. This is described
in more detail below.
The benefit of your hotel becoming carbon neutral is both in terms of improved
corporate image as well as being able to service a growing number of business clients
that have also pledged to become carbon neutral.
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8.2 How does a hotel become carbon neutral?
Step 1: reducing energy and travel needs
The best way a hotel can reduce its impact on climate change is to save energy.
This will make your hotel very efficient in delivering its services and reduce operating
costs. Travel in cars and aeroplanes needs to be calculated and reduced where possible.
Step 2: sourcing renewable energy instead of traditionalcoal-fired energy
Businesses are able to source renewable energy for some or all of their energy
needs from an accredited electricity supplier.
GreenPowerTM is more expensive than traditional energy and hotels need to
manage this expense. This may be managed by using the financials savings from
energy efficiencies or by phasing in GreenPowerTM gradually over an agreed
number of years.
GreenPowerTM is energy produced from renewable sources which is bought
by energy suppliers and provided to their customers. The purchase of GreenPower
means the production of greenhouse gases due to electricity manufacture is
non-existent, resulting in a decreased rate of global warming.
Many energy suppliers now provide GreenPower. Most suppliers offer a renewableenergy option, however it is important these are GreenPower approved products.
These approved products ensure the supplier meets stringent government
environmental and reporting standards, which ensures that you, the customer,
can be confident your money is going directly to helping the environment.
GreenPower is regulated by the GreenPower Auditor. Submission of regular
reports ensures confidence in the GreenPower program and provides transparency
for customers.
Step 3: Purchasing off-sets to absorb any remaininggreenhouse gases
If there are remaining greenhouse gas emissions after undertaking the above first
two steps these can be off-set by accredited programs that absorb carbon-dioxidesuch as tree-planting.
For example, there are online systems enabling travel kilometres to be
off-set by paying a small fee for trees to be planted locally to off-set the amount
of emissions your travel generated.
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There are four primary energy technologies that hotels need tounderstand and manage efficiently. These are discussed in more
detail in this section:
1. lighting;
2. heating, ventilation and air-conditioning systems;
3. variable speed drives; and
4. energy management systems (EMS).
9.1 Lighting systems
Lights are a major energy consumer in hotels and accommodation services.
The energy efficiency of lamps has significantly improved over the last few years and
it is worth replacing older, inefficient lights with these better performing alternatives.
Not only will this save on energy bills but it will also save on maintenance time in
replacing bulbs.
The main types of lamps being used in hotels are:
dichroic lights;
incandescent lamps;
LED lamps;
compact fluorescent lamps; and
fluorescent tubes, mostly 36W.
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9.1.1 Dichroic lamps
Dichroic lamps are extensively used as downlights in receptions, foyers and corridors.
These are known as cool beam lights. They are high brightness lamps suitable for
display and special effect lighting.
Advantages:
excellent colour rendering;
instant start; lamp life 2000 to 5000 hours;
higher lumens than incandescent type;
excellent lumens maintenance; and
can be dimmed.
Disadvantages:
power loss in transformers create heat loss (50W lamps require transformerof 12W loss). The 12W power used by transformers only transforms electricityto heat in the space;
ultraviolet content of light can fade some surfaces;
voltage fluctuation can reduce lamp life. A slight increase in main voltagesupply can reduce lamp life by 50 per cent;
lamp cost is greater than incandescent; and
touching of the quartz lamp may lead to premature lamp failure.
9.1.2 Incandescent lamps
These are the original filament type lamp. They consist of a glass enclosure with inert
gas. Here most of the power consumed dissipates as heat and does not transform
to light.
Advantages:
they are cheapest of all lamps; and
dimmable.
Disadvantages:
they are the most inefficient lamps; and
the life of the lamps is very short between 1000 to 2000 hours.
The efficiency of these lamps varies from eight to 17 lm/W compared to 85 lm/W
for fluorescent lamps with a lifespan of 10,000 hours.
Due to its inefficiency these lamps are in the process of being phased out of the
market by government regulation. It is worthwhile reorganising your lighting to
provide for this inevitable regulatory requirement.
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9.1.3 LED lamps
LED (light emitting diode) lamps are a new technology which fit all twist and lock
fittings and can replace the 50W halogen twist and lock lamp.
Advantages:
the anticipated life is 30,000 to 50,000 hours; and
a 2W LED lamp can be considered to replace 50W dichroic lamps withoutchange of light fittings.
Disadvantages:
energy efficient LEDs are expensive; and
require constant voltage transformer.
This technology is expected to increase in popularity and usage in the near future.
9.1.4: Compact fluorescent lamps
A compact fluorescent lamp (CFL), also known as a compact fluorescent light bulb
or an energy saving light bulb, is a type of lamp designed to fit into roughly the same
space as an incandescent lamp, but with the advantages of a fluorescent lamp.
Many CFLs can directly replace an existing incandescent lamp.
Compared to incandescent lamps of the same luminous flux, CFLs have alonger-rated life and use less energy. The initial purchase price of a CFL is higher
than an incandescent lamp of the same output, although this cost may be quickly
recouped in energy savings assuming average bulb use.
Although CFLs do radiate a different spectrum of light than incandescent
lamps, recent technological advances have reduced that difference dramatically.
The light emitted by the best soft white CFLs available today is similar in quality
to standard bulbs.
The life of CFL is around 6000 to 15,000 hours compared to the 1000 to 2000
hours of an incandescent lamp.
An 11W CFL provides almost the same lumens (light) as a 60W incandescent lamp.
Normally they are 75 to 80 per cent more energy efficient than incandescent lamps.However they are around six to 10 times more expensive than incandescent lamps.
Recently CFL technology has improved and the lamps are now available as dimmable.
Dimmable CFL are much more expensive than non-dimmable.
CFL are also available as a down-light to replace dichroic lamps which are being used
extensively in hotel foyers and corridors. A 9W CFL can replace a 50W dichroic lamp
using the same fittings.
9.1.5 Standard fluorescent lamps
This is a glass tube lamp that is conventionally used in offices. The length of tube
varies with power. More information about standard fluorescent lamps is set out
in Appendix D.
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9.1.6 Maintaining lamps
Maintaining lamps is very important for energy efficiency. The light output decreases
with the operation hours of the lamp and dirt builds up in the shield
Light depreciation with lamp life.As the lamp gets older it reduces output.Therefore it is important to replace lamps as they get older.
Loss of light resulting from build up of dirt. Lamps should be maintainedand cleaned regularly. Figure 9.1 shows light reduction against clean lamp.
Figure 9.1 - Loss of light from dirt built up
9.1.7 Lighting level standard
In all spaces including hotels, actual lighting requirements depend on the activity
of an area. The Australian Standard AS 1680-2006 is as follows for various activities.
Table 9.1 - Recommended lighting level
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Area Light level (Lux)
Office work 320
Store rooms and stock rooms 320
Kitchen 240
Entrance areas and waiting rooms 160
Corridors 40
Toilets 80
50
60
70
80
90
100
55
65
75
85
95
11109876543210
Expected loss of light resulting from dirt build-up
Time between cleaning (years)
%M
aintainedLight
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9.2 Heating, ventilation and air conditioning systems
As the heating, ventilation and air conditioning (HVAC) system is the major energy
user in a hotel, it is important to understand. The HVAC system delivers:
heating;
cooling; and
air circulation.
9.2.1 HeatingHeating can be provided by three different means:
Hot water (or steam) system the lowest energy cost system if natural gasis available and the most common heating system in older hotels.
Electric heating elements the most energy inefficient and high energy costsystem. Many hotels use electric heating systems which were historically installedas a convenient low capital cost system.
Heat pumps relatively new technology that is energy efficient. The energy costis similar to or slightly higher than gas-heated hot water systems. Consideringmaintenance and auxiliary equipment, heat pumps are one of the most overallcost-effective systems.
9.2.2 Cooling
There are different types of air conditioning systems. Each type of system has its
own advantages and disadvantages. Therefore they are selected based on their
application, capital cost and energy performance. However, in the past very little
consideration was given to energy efficiency. Capital cost is normally the dominant
factor in selecting and designing air conditioning systems. The most common
types of air conditioning systems are:
single zone systems;
reheat systems;
multi-zone systems;
dual duct systems;
induction systems;
variable air volume systems;
water source heat pump systems; and
air cooled heat pumps.
The cooling can be provided by:
Refrigeration system: this is the cooling media and requires a compressor formechanical compression or an absorber for an absorption-type cooling system.Electrical energy is being used for a compression-type system and thermalenergy as heat is required for an absorption system.
Evaporative cooling: this is a low energy intensive cooling system ideallysuitable in dry weather condition. It cools air by humidifying air and does not
need any refrigerant. Although it is around 80 per cent more energy efficientthan a refrigerated cooling system, it does not provide comfort levels as easilyas a refrigeration system and can be noisy and inconvenient.
Some HVAC systems do not have cooling towers. The condenser cooling is done
by blowing air over the condenser tubes. These are called air-cooled systems.
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Basics of an air conditioning system
Figure 9.2 - The schematic of a basic air conditioning system
Figure 9.2 is a typical guest room air conditioning system. This is a four pipe system,
with two pipes for chilled water and two pipes for hot water (the hot water piping is
not shown).
Chilled water is circulated by chilled water pumps and hot water is circulated by hot
water pumps.
In some hotels the guests rooms are heated by electric heating elements replacing
the hot water coils in the fan cool unit.
Economy cycle
Economy cycle reduces energy costs. The energy saving can be in the order of 25 to
30 per cent in Melbournes climate. Since an economy cycle brings in more fresh air,
the system may require slightly more cleaning of air filters.
The cost of an economy cycle can be as low as $3000 plus additional costs for duct
modification, if required.
For more information about an economy cycle refer to Appendix E.
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COOLING
TOWER
CONDENSER
CHIL LER
CONDI TONED SPACE
COOLING
WATER
PIPING
COMPR ESSOR
CHIL LED
WATER
PIPING
AIR F ILTERS
INSUL ATED
RETURN AIR
DUC TING
COULD B E AIR
COOLED
COOLING
WATER PUMP
CHIL LED
WATER PUMP
AIR
HANDLING
UNI T
INSUL ATED
SUPP LY AIR
DUCT ING
AIR OUTLETS
SUPP LY
AIR FANCHILLED WATER
COOLING CO IL
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Technology discussion 9
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Economiser
It is possible to cool the fresh air by exhaust air with an air-to-air heat exchanger.
Types of heat exchangers are:
rotary heat exchange wheel;
plate heat exchanger; and
heat pipe system.
Expected energy savings from this system are between three and 15 per cent.
The higher the amount of fresh air used in the HVAC system, and the more extreme
the weather conditions, the higher the energy savings will be.
Figure 9.3 - Typical economiser
9.2.3 Heat pump technology
Heat flows naturally from higher to lower temperature. However heat pumps use
external energy to force heat flow in the opposite direction. All heat pumps require
a vapour compression cycle which is a mechanical refrigeration system.
There are two types of heat pumps, described below.
COP is the coefficient of performance which is the ratio of energy
output/energy input.
1. Conventional air-cooled heat pump
A conventional heat pump is commonly known as a reverse air conditioner which
can cool and heat. The COP of conventional air-cooled heat pumps for space
heating is shown in the table below.
Table 9.2 - COP of conventional air condenser heat pumps
COP is the ratio of power output to input and is the efficiency of the refrigeration
cycle. Higher the COP more energy efficient it is.
Return Air 22 C
Spill Air 27 C
Fresh Air 25 C
Fresh Air 30 C
Size (kWr) COP heating COP cooling
7 3.28 2.78
26 3.63 2.94
32 3.67 2.95
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2. Water source heat pump
This is a very energy efficient way to heat and cool hotel rooms. There is no central
compressor and instead there are central water heaters and a heat rejection (cooling
tower) system. Each room has a fan coil unit refrigerant compressor. During the
heating cycle the hot gas is used to heat the room (utilising condensing heat).
The hot water from the boiler is used to cool water from the evaporator.
Heat recovery: it is possible to recover some heat during cooling time to produce
hot water that can be used as domestic hot water.
Energy efficient comfort condition of HVAC system
The comfort level of an air conditioned space varies with the following variables:
gender of occupants as females generally feel colder than males;
activity within the building;
relative humidity and dry bulb temperature; and
air movement.
The comfort condition is not a single temperature level but a zone, which is shown
in the shaded area of Figure 9.4 below. It is recommended that HVAC systems
should be operated at a higher temperature in this zone when cooling and a lowertemperature in this zone when heating.
During the cooling cycle, every 1oC temperature rise will reduce energy consumption
by five to 10 per cent.
Similarly during the heating cycle, every 1oC temperature decrease will reduce energy
consumption by five to 10 per cent.
Figure 9.4 - Psychrometric chart of comfort zone
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0.002
0.006
0.004
0.010
0.008
0.012
0.014
0.016
0.018
10 13 16 18 21 24 27 29 32 35 38
Operative Temperature,C
HumidityRatio
-5
-10
5
0
10
15
20
Dew
PointTemperature,
C
90
80
70
60
50
40
30
20
10% RH
Data based on ISO 7730 and ASHRAE STD 55
Upper Recommended Humidity Limit, 0.012 humidity ratio
0.5 PMV Limits
1.0 Clo 0.5 Clo
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0
1
2
3
4
5
6
7
20253035404550
Speed (Hz)
Power Factor
Power
Power(kw)
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
8 0.8
15
PowerFactor
9.3 Variable speed drive
Air conditioning motors run at a fixed speed although the demand for air flow or water
reduces in lesser cooling load conditions. As the air or water flow demand reduces
the damper or valve throttles to restrict flow. Throttling is an irreversible process
(that is, wastes energy which can never be recovered).
It is possible to vary the speed of the motors through change of frequency of
electricity supply. To deal with the problem of throttling, a variable speed drive (VSD)
can be installed. This allows the controller to change the speed of the drive insteadof throttling and avoids the loss of energy.
Figure 9.5 - Power requirement for throttling with fixed speed and VSD drive with no throttling
Variable speed drives are one of the biggest and most economically viable energy
saving opportunities in HVAC systems for supply and return air fans, chilled and
condenser water pumps and chiller compressors.
Figure 9.6 - Power VS fan speed of a typical AHU fan
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0
20
40
60
80
100
120
120100806040200
Volume flow rate %
Damper control
Speed control
Comparative power requirements. Speed and Damper control of fan duty
Fan
Power%
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Figure 9.7 - Power VS fan speed of a typical cooling tower fan
Figure 9.8 - Power VS pump speed of a typical water circulation pump
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0
02
04
06
08
10
12
14
20253035404550
Speed (Hz)
Power(kw)
0
10
20
30
40
50
60
70
20253035404550
Speed (Hz)
Power(kw)
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9.4 Energy management system (EMS)
An energy management system (EMS) is a computer-based energy monitoring
and optimal control system for building services. Normally the system is based on
conventional BMS (building management systems). The functionality of a building
EMS is as follows:
Economy cycle control.An economy cycle is illustrated in Section 9. Althoughthere are stand alone economy cycle controllers available, they do not operate tooptimal efficiency. An energy management control system provides superior controlsuch as enthalpy-based control, which provides additional energy and cost savings.Refer to Appendix E for more information.
Optimal start of HVAC. Space heating and cooling always requires time topreheat or cool the space before it reaches comfort conditions. Normally suchpre-cooling or heating time is preset however this can be changed to be a functionof ambient temperature. On a hot day, the hotel requires more pre-cooling timethan on a more temperate day. Optimum start time resets pre-cooling time toavoid keeping the space cooled longer than required and hence reducing wasteof energy.
Night purge.This involves pre-cooling a building at night especially during hottermonths when the outside air temperature is low, thus reducing the energy requiredfor building pre-cooling.
Feed forward variable speed drive control is intelligent speed control of supplyand return air fans. The conventional speed control of a fan is based on a presetsupply pressure. When the HVAC system is not designed as a variable air volume(VAV) system, the conventional feedback control is not viable. The speed set pointis determined by a function of area cooling load.
Chiller and cooling tower optimal control.The chiller is used to provide buildingcooling and is one of the major energy consumers in a hotel. Larger to medium sizehotels typically have a centralised chiller system to provide chilled water for cooling.The chiller plant may consist of multiple chillers, which depend on the intelligence ofthe supervisory control for energy efficiency. The energy efficient functions of thesecontrollers are as follows:
- chiller optimal selection selects the combination of chillers to run at any giventime to meet the cooling load with minimum energy consumption. At low loadcondition it also cycles the operation of chillers;
- chiller loading and control ensures the optimum loading of each chiller to reduceenergy consumption;
- chilled water temperature reset. Conventionally the chilled water temperatureis set to a low temperature of 6C to 7C. When the cooling load is low, the setpoint of the chilled water system can be increased. Every 1C increase in chilledwater temperature reduces energy consumption by around 2.5 per cent.
- cooling/condenser water temperature reset. Similar to chilled water temperaturereset, the condenser water temperature increases the energy efficiency of boththe chiller and cooling tower. The decrease of condenser water temperaturereduces energy consumption by around 2.5 per cent per degree watertemperature reduction.
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Optimal pump control. Optimal pump control is useful when multiple pumps areused for chilled water, hot water or domestic water supply to the hotel. It involvesinstalling a VSD on one of the pumps and selecting the number of pumps tooperate, therefore controlling the supply pressure. Energy savings of 20 to40 per cent are achievable through this technique.
Hot water boiler
- optimal start/stop of boiler.
Demand management system- demand and energy monitoring;
- demand control; and
- energy sub-metering.
How much can you save with an EMS?
Chiller system:
reduce energy consumption by 20 to 40 per cent; and
reduce run hours by up to 30 per cent.
HVAC:
reduce fan energy cost by 40 to 50 per cent.
DDC control:
reduce cooling and heating load by up to 20 per cent.
House-keeping:
This is to monitor and track energy use and key performance indicators as well
as various energy efficiency parameters. As a rule of thumb, the saving is expected
to be around one to five per cent of the overall energy consumption.
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A corporate policy should be set to meet corporate goals andstandards. An example of a corporate policy is set out below.
Energy is one of our organisations major ongoing costs. Its impact on climatechange is a great concern to us. As a good corporate citizen we as a company
set the following policies:
1. Reduce energy consumption of each hotel by 10 per cent per year for the
next three years.
2. Energy efficiency should be considered in purchasing and maintaining
all equipment.
It is the responsibility of each individual employee to use energy wisely and efficiently.
Appendix A: Example of corporate policy A
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1. Energy and our environment
Greenhouse gas emissions cause global warming which is detrimental
to our environment.
The earth is covered by a blanket of gases in the atmosphere which allows light
energy from the sun to reach the earths surface. This light energy is converted
to heat energy. These gases are called greenhouse gases.
Most of the heat is re-radiated towards space but some is trapped by greenhouse
gases in the atmosphere. This is a natural effect, which keeps the earths temperature
at levels necessary to support life.
The problem we face is that human actions particularly burning fossil fuels and land
clearing are generating more greenhouse gases. These additional gases trap more
heat and raise the earths surface temperature.
This is known as the enhanced greenhouse effect it causes global warming and
is changing our environment.Reducing the use of energy reduces the power generation where the majority
of greenhouse gases are generated.
Figure B.1: Heat balance
Appendix B: Energy and our environment B
Atmosphere emits long
wave radiation (60%)
Transfer of heat between
Earths surface and
Atmosphere (zet zero)
Earths surface emits long
wave radiation (9%)
The increase in greenhouse gases within the atmosphere
traps more heat, and raises the Earths surface temperature.
Incoming solar
radiation (100%)
Increased used of fossil fuels
Earths surface reflects
solar radiation (6%)
Convection to atmosphere (31%)
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2. Global warming
Some of the effects of global warming are:
a rise in sea level causing coastal damage;
an increase in the likelihood of extreme weather conditions such as droughts,floods and cyclones;
health impacts because of the spread of tropical-borne diseases, the increaseof flooding and other such climate changes;
damage to ecosystems and species diversity; and
damage to agricultural output and food supply, and an increase in the earthssurface temperature causing heat stress and other damage.
3. Saving our environment
It is essential that all efforts are made to reduce greenhouse gas emissions.
Hotels can help by:
reducing energy use; and
using environmentally friendly refrigerants. The two most commonenvironmentally friendly refrigerants are:
- CFC 123: Environmentally friendly but not accepted by energy and
atmospheric credit #4, which is regarded as the current standard forenvironmentally friendly refrigerant. This gas has low global warmingpotential and high energy efficiency.
- HFC 134A: Environmentally friendly.
4. Measurement of greenhouse gas
Greenhouse gas is measured in carbon dioxide equivalent (CO2 e) which takes
into account the global warming potential of each of the greenhouse gases.
Energy related:
- Stationary: this is the source of greenhouse gas emission from energy usedby stationary equipment such as a boiler, generator or power station.
- Transport: greenhouse gas emission from cars, trucks and other vehicles,which Is used for the transport industry.
Non-energy related:
- Waste: this is the source of greenhouse gas emission from all types of wastes,such as paper, textile, wood and other sources.
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Figure B.2: Greehouse gas emissions for stationary energy
Figure B.3: Greenhouse gas emissions for transport energy
Figure B.4: Municipal solid waste
Appendix B: Energy and our environment B
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0
100
200
300
400
Coke Briquettes
(brown)
Coal
(brown)
Coal
(black)
Fuel Oil Diesel LPG Natural
Gas
Electricity
kg
CO2-e/GJ
0
20
40
60
80
100
Petrol Diesel Fuel Oil LPG
kgCO2-e/GJ
0
0.5
1.0
1.5
2.0
2.5
3.0
Paper Textiles Wood GardenFood
kgCO2-e/GJ
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For more information about the measurement of greenhouse gases refer to the
AGO Factors and Methods Workbook.
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Global warming potential (GWP)
1. Carbon dioxide CO2 GWP = 1
2. Methane CH4 GWP = 21
3. Nitrous oxide N2O GWP = 310
4. Hydro fluorocarbons (HFCs) GWP = 140 - 11,700
5. Per fluorocarbons (PFCs) GWP = 65,000 9,200
6. Sulphur hexafluoride GWP = 23,900
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What is power factor?
The power factor is the ratio of true or active power (kW) over the apparent power (kVA).
Figure C.1- Diagrammatic representation of power factor
The causes of reactive power are inductive devices such as AC motors, induction
furnaces, arc welders, fluorescent and mercury vapour lighting. These cause a time
lag between current and voltage cycles which causes large reactive currents.
How to correct power factor
Use of synchronous motor; or
Use of capacitor bank.
The required sizing of a power factor controller is calculated as follows:
Cos1 = Current power factor
Cos2 = Desired power factorkVAR required = kW x (tan-11 - tan-12)
Appendix C: Power factor correction equipment C
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kVAR 1
kVAR 2
kVA 1
kW
kVA 2
1
2
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A typical luminaries or fixture for fluorescent lamps is shown in thefigure below. This consists of:
housing;
reflector;
lamps;
ballast; and
shielding.
Figure D.1 - Typical luminare of a fluorescent lamp
The type of reflector, lamps and shielding can all contribute to light efficiency.
In a fluorescent lamp there is no filament as in incandescent lamps. Instead,
cathodes at each end send currents through mercury vapour sealed in the tube.
Ultraviolet radiation is produced as electrons from the cathodes knock mercury
electrons. The tubes are lined with phosphor to turn the radiation to visible light.
This requires ballasts which are in every fixture and regulate the voltage during start up.
The light output of these lamps varies from 69 to 104 Lumens/W. TL5 is the latest
fluorescent lamp technology and with electronic ballasts produces 3300 lumens
with 33W.
There are two types of ballasts:
electromechanical the standard ballast loss is around 10W; and
electronic which can be fixed or dimmable ballasts. The electronic ballastslosses are generally less than 2W.
Appendix D: Detail of a fluorescent lamp D
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When the ambient air enthalpy is less than that for return air it iseconomical to introduce as much fresh air as possible to cool thebuilding. However, this is restricted by the return air duct filter.
Therefore a motorised damper is required to regulate the fresh air make-up.
An increased supply of fresh air is more hygienic and comfortable. The economy
cycle of an air conditioner reduces energy costs. The energy saving can be in the
order of 25 to 30 per cent in the Melbourne climate. Since the economy cycle
brings in more fresh air, the system may require slightly more cleaning of air filters.
The cost of an economy cycle can be as low as $3000 plus additional costs for duct
modification, if required.
Figure E.1: Economy cycle
There are two types of economy cycle which are:
temperature-based; and
enthalpy-based.
Appendix E: Air conditioning economy cycle E