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Energy efficient technologies (HOW)
Dr. Sam C. M. HuiDepartment of Mechanical Engineering
The University of Hong Kong
E-mail: [email protected]://web.hku.hk/~cmhui Oct 2015
CCST9016 Energy: Its Evolution and Environmental Impacthttp://me.hku.hk/bse/CCST9016/
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Contents
Energy Efficiency Strategies
Passive Design
Lighting Technologies
Air Conditioning Systems
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Energy Efficiency Strategies
Possible benefits from energy efficiency: Improved building design and operation
Better working environments
Life-cycle cost savings
Added market value of buildings
Reduced CO2 emissions and consumption of finitefossil fuels
Reduced capital cost by better integration of
building fabric and systems
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Outdoor
Environment
Human
Environment
Shelter
Design of the built environment
Energy supplyto the buildingEnergy demand and energy use by
the building and its building systems
Do you know
how to design
energy efficientbuildings?
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Energy Efficiency Strategies
Aims:
Use of technologies and their innovativeintegration in buildings to assist energy useminimisation
Demand side energy issues and energy supplyoptions, especially renewable energy technologies
Hints for successful application: Understand the technical properties & limitations
Balance between economics and other factors
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Energy Efficiency Strategies
Design strategies:
Minimise thermal loads & energy requirements
e.g. by reducing heat gains from equipment
Optimise window design & fabric thermal storage Integrate architectural & engineering design
Promote efficiency in building services systems
Use of heat recovery & free cooling methods Energy efficient lighting design & control
High-efficiency mechanical & electrical systems
Adopt total energy approach (e.g. district cooling,combined heat & power)
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Passive design ()
Design the building and the spaces within it to
benefit from natural light, ventilation and even
temperatures Ensure the fabric of the building and the spaces
within it respondeffectively to local climate and
site conditions in order to maximise comfort for
the occupants
Passive Design
(Source: www.level.org.nz/passive-design/)
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Key factors of passive design:
Climate and site analysis
Solar design and shading control
Correct orientation and use of windows
Use of thermal mass and insulation
Provision for ventilation (natural) Further reading:
Passive Cooling in Tropical Climates http://www.btsquarepeg.com/sustainable/energy/passiv
e-coolin -in-tro ical-climates/
Passive Design
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Dry-bulb temperature patterns in Hong Kong
What date/time is the hottest?
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Relative humidity patterns in Hong Kong
What date/time is most humid?
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(Source: Energy Efficiency in Buildings: CIBSE Guide F)
Building designersshould consider all
these to achieve
better energyefficiency.
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Qgs(glass solar)
Qwc
(wallconduction)
Qgc
(glass
conduction)
Heat transmission through building envelope
(reduce heat flow/gain => reduce cooling energy)
(reduce heat loss in winter => reduce heating energy)
Sh di d i ( t l d i t l) f t l
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Shading devices (external and internal) for sun control
Overhang
Louvers Awnings Shutters
Drapes and
curtains
Venetian
blinds
Roller
shades
(reduce direct sun light => reduce cooling energy & glare)
Advanced window and insulation technology
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Advanced window and insulation technology
Gas filled panel (high
performance insulation)Low-e (emissivity)
glazing
(reduce solar heat gain => reduce cooling energy)
Examples of passive cooling designs
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Thermal chimney Natural ventilation
Examples of passive cooling designs
(promote passive & natural cooling => reduce mechanical energy)
(See also: http://en.wikipedia.org/wiki/Passive_cooling and http://passivesolar.sustainablesources.com/)
Examples of passive cooling designs
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Promote wind
effect by wing walls
Venting a thermal mass wall
Examples of passive cooling designs
Prevailing wind
Typical techniques for passive house
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Typical techniques for passive house
(See also: http://en.wikipedia.org/wiki/Passive_house)
Examples of passive cooling designs (cooling by evaporation)
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Examples of passive cooling designs (cooling by evaporation)
Passive cooling using a roof spraying system (Japan)
Examples of passive cooling designs
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Examples of passive cooling designs
Earth tube cooling (Japan)
(outdoor fresh air cooled by the earth before entering the building)
Examples of green building design features/issues in Hong Kong
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(Source: www.susdev.org.hk)
Examples of green building design features/issues in Hong Kong
Building
separation
Building
setback Urbangreenery
Solar energysystemsSun shades
Rooftop
greening
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Energy efficient lighting design strategies:
1. Promotion of natural daylighting
2. Use of energy efficient lamps and luminaires
3. Switching and control of artificial light
4. Combination of general and task lighting
5. Electric lighting integrated with daylight 6. Proper room surfaces and space design
Lighting Technologies
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Daylighting design and control
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Energy efficient
fittings (e.g. compactfluorescent lamps)
Lighting controls andinteractions with windows
Energy efficient lighting design strategies
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Daylight contribution and lamps control
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Daylighting Example:
CSAA Office Building,
Antioch, California
- photo controls automatically
turn lights on off and adjust
light louvers to maintain
designed lighting level- also incorporates occupancy
sensors to provide light when
needed to occupied areas.
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A. B.
C. D.
Which of the following window patterns will givebetter daylighting in a room? (the total area ofwindow glazing is the same in each case)
Window
Wall
Window
Wall
Window
Wall
WindowWall
Light tube system
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This can help to direct daylight into building interior
Light pipe system
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Vertical
light
pipe
Horizontal
light pipe
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Lighting Technologies
Typical lighting controls
Switches
Occupancy sensing
Scheduling (timeclocks)
Daylight dimming
Tuning Preset dimming
Building management
Remember: switch off unnecessary lights!
Which ones are more energy efficient?
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Various light sources for general lighting(Source: Advanced Lighting Guidelines 2001)
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Historical and predicted efficacy of light sources(Source: US Department of Energy)
Higher efficacy => better energy efficient
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Lighting Technologies
Video: Energy 101: Light Bulbs (4:47)
http://youtu.be/Pk60-D61h34
Our animated correspondent, Little Lee Patrick
Sullivan, kicks off our Energy 101 series withan inside look -- literally -- at light bulb
technology. He goes inside an incandescent, a
compact fluorescent and an LED bulb to see whatmakes them work, and their potential drawbacks.
Evolution of light bulbs
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Edison
lamp
Incandescent
lamp
Compact
fluorescentlamp
LED lamp
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Lighting Technologies
Fluorescent lamp:
Advantages
High efficiency
Super efficacy at high frequency operation
Wide range of colour choices
Disadvantages Require ballast
Temperature sensitivity
T12
T8T5T3
Do you know what is T5 lamp?
(See also: http://www.lrc.rpi.edu/programs/nlpip/lightinganswers/lat5/pc1.asp)
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Lighting Technologies Compact fluorescent lamp (CFL)
Advantages Compact size
High efficacy
High CRI
Long life Dimmable (some)
High frequency operation
Excellent lumen maintenance
Disadvantages Position sensitive
Thermal sensitivity
Require ballast
Higher initial cost (over incandescent)
CFL = energy
saving lamp
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Lighting Technologies
Light emitting diode (LED)
Produces light by electroluminescence at low
voltage p-n junction (e.g. indicator lights)
Development of white light & high output LEDsenables wider use in lighting systems
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Examples of LED lamp application
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Lighting Technologies Light emitting diode (LED)
Advantages Low power consumption
Long lasting (long useful life)
Durable (withstand impact & vibration)
Cool (little heat produced)
Modular design & compact size
Controllability (colour balance & intensity)
Instant on, frequent switching No annoying flicker
Low cost of manufacture
No ultraviolet & infrared radiation
Mercury freeLED candles
Disadvantages Focused, directional light Need different optics design May need heat sink (thermal
management)
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Lighting Technologies
Solid state lighting (SSL)
Emits light from semi-conductor (solid)
Light emitting diode (LED)
Organic light-emitting diodes (OLED) Polymer light-emitting diodes (PLED)
Advantages:
Low power consumption
Reduced heat generation
Greater resistance to shock, vibration, and wear
Good
potentialfor future
lighting
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Lighting Technologies
Video: OLED Light from small molecules
(9:29) (International Year of Light 2015)
http://www.fraunhofer.de/en/fields-of-
research/2015-international-year-of-the-light.html The Fraunhofer Institute for Organic Electronics,
Electron Beam and Plasma Technology FEP in Dresden
develops innovative lighting and displays based onorganic light emitting diodes (OLED). Fluorescent
wallpaper, designer lamps, rollup screens are just a few
examples that are feasible with OLED technology.
(See also: GE OLEDs: The Future of Lighting (3:30) http://youtu.be/_Qyodldq_0I)
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(Source: http://en.wikipedia.org/wiki/Air_conditioner)
Have you
examined
the air-conditioner
at your
home? It isusing most
of the
electricity.
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Example of HVAC (heating,
ventilating and air
conditioning) system --
aiming to remove heat and
maintain human comfort
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(Source: EnergyWitts newsletter, EMSD)
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Energy efficient air-conditioning systems
Key factors:
Thermal comfort criteria
Load calculation methods and design conditions System characteristics
Equipment and plant operation (part-load)
Other factors Heat recovery equipment
Energy management system
Thermal energy storage
Air Conditioning Systems
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Energy efficient air-conditioning systems
Thermal comfort &
design conditions
System design & controls
Plant efficiency
& operation
Air Conditioning Systems
Too coldToo hot
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Japanese Energy Strategy: Hawaiian Shirts
"Super Cool Biz" campaign (dress casual can reduce cooling needs)
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(Source: The Wall Street Journal, http://online.wsj.com)
Free cooling methods in HVAC system*
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(a) Air-side free cooling/economiser cycle
- intake more outdoor air when
its enthalpy (energy content)is lower than indoor air
- save energy in cooling systems by
using natural cool outdoor air
(b) Water-side free cooling or
free refrigeration
- chiller bypass whenthe system water can be
cooled by ambient
- save energy in refrigeration
or chiller plant
Enthalpy
line
(*See also: http://en.wikipedia.org/wiki/Free_cooling)
Waste heat recovery e.g. double bundle heat recovery chiller
Strategy: use of heat recovery
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Strategy: use of heat recovery
Make use of waste heat
from condenser to
produce warm/hot water
or for heating the space.
- Waste heat = dumped heat that can
still be reused
- Waste heat recovery saves fuel
(*See also: http://www.energyefficiencyasia.org/energyequipment/ee_ts_wasteheatrecovery.html)
District cooling system (DCS) Strategy: total energy approach
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Centralised
refrigeration
plant
>> Do you know what are the advantages of DCS?
Individual buildings
(Video: District Cooling System (5:58) http://www.youtube.com/watch?v=DDY32Chx6Gg)
(*See also: http://www.energyland.emsd.gov.hk/en/building/district_cooling_sys/)
Combined heat and power (CHP), also known as cogeneration,reduces energy use by 30%
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(Source: www.revival-eu.net)
Further information: http://en.wikipedia.org/wiki/Cogeneration
A typical trigeneration system (cool + heat + electricity)
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(Source: http://en.wikipedia.org/wiki/Cogeneration)
Ai C diti i S t
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Air Conditioning Systems
Zero energy building (ZEB)
A building that produces as much energy on-site
as it consumes on an annual basis
Net zero energy building Advantages of ZEB:
Reduce energy consumption and costs
Reduce carbon emissions
Reduce dependence on fossil fuels
(*See also: Zero Carbon Building in HK, http://zcb.hkcic.org)
Ai C diti i S t
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Air Conditioning Systems
Video: Achieving Net-Zero-Energy Buildings
- ASHRAE (2:05) http://youtu.be/pQFJr5E7_R0
By American Society of Heating, Refrigeratingand Air-conditioning Engineers (ASHRAE)
1. Building envelope measures
2. HVAC, service water heating and lightingmeasures
3. Renewable energy measures
Further Reading
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Further Reading
Passive Design
www.level.org.nz/passive-design/
Passive Cooling in Tropical Climates
http://www.btsquarepeg.com/sustainable/energy/passive-cooling-in-tropical-climates/
Energy Efficient Lighting (Eartheasy.com) http://eartheasy.com/live_energyeff_lighting.htm
HVAC Wikipedia
http://en.wikipedia.org/wiki/HVAC