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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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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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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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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


(promote passive & natural cooling => reduce mechanical energy)

(See also: http://en.wikipedia.org/wiki/Passive_cooling and http://passivesolar.sustainablesources.com/)


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Promote wind

effect by wing walls

Venting a thermal mass wall


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)


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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


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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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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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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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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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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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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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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


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Energy efficient air-conditioning systems

Thermal comfort &

design conditions

System design & controls

Plant efficiency

& operation


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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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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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

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