Energy Efficiency in Buildings
Energy Efficiency in Buildings
Energy Efficiency in Buildings
[BA2-BT2, 2012-2013]
• Units of energy:
• Kilowatt-hour (kWh), often for electricity use
• 1 kWh = 3.6 x 106 Joule = 860 kcal = 3412 Btu
• Calorie (卡路里), 1 calorie = 4.2 x 103 J
• British thermal unit (Btu), 1 Btu = 1.055 x 103 J
• Tonne of oil equivalent (toe), 1 toe = 4.2 x 1010 J
• From oil industry http://en.wikipedia.org/wiki/Tonne_of_oil_equivalent
• Power unit:
• 1 W = 1 J/s = 0.86 kcal/h = 3.41 Btu/h
Different forms of
energy
(* Source: IEA, 2011. Key World Energy Statistics 2011, International Energy Agency,
Paris. Available at www.iea.org)
***Other includes industrial waste and non-renewable municipal waste
(* Source: IEA, 2011. Key World Energy Statistics 2011, International Energy Agency,
Paris. Available at www.iea.org)
Energy Basics
Energy
Economics Environment
Hong Kong Situation
Industrial
9% Commercial
40%
Energy end-use in Hong Kong
(Data source: EMSD)
120
Commercial 商業
100
End-use Energy (1000 TJ)
能源最終用途 (千兆焦耳)
Transport 交通
80
60
Residential 住宅
40
Industrial 工業
20
0
84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 00 01 02 03 04 05 06 07 08 09
Year 年份
Others
5%
Hot water &
refrig
Office
14%
equipment
Others 4%
63%
Lighting
4%
Other
Restaurants Commercials
(2009) (2009)
Space cond
14%
Space cond
26% Cooking Lighting
51% 8%
Office
equipment
13% Space cond
Space cond 37%
54%
Others
37%
Others
19%
Offices Retails
(2009) (2009)
Lighting
14%
Lighting
26%
Public
Housing Private
(2009) Housing
Refrig (2009)
Lighting 12%
6%
Hot water
19%
(Source: www.hompower.com)
Building Energy Efficiency
• Climate
• It has a major effect on building thermal and
energy performance
• Response of a building to climate:
• Thermal response of building structure
• Response of HVAC and lighting systems
• Building design must “fit” its climate
• Human comfort and bioclimatic design
Major climatic elements of Hong Kong
Building designer is like a “Feng Shui” master.
Wind Light
Water Matter
Main criteria:
• wall area
• window area
• thermal properties
• orientations
• thermal mass
• shading device
* Face House, Kyoto, Japan
Building Energy Efficiency
Qrh Qk Qrc
Qch X Qcc
Q A U T
Solar heat
gain through
window glass
0.5 1.0
1.0
Clear
0.9
Tints
0.8
Selective Tints
0.7 1.5
Shading coefficient (SC)
0.6
0.5 2.0
Reflective
0.4
0.2
0.1
0.0
0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0
Visible transmittance (Tvis)
Qgc
(glass
conduction)
Centralised
refrigeration
plant
• Lighting systems
• Have good potential for conserving electricity
• Also contribute to HVAC load reduction
• General principles of energy efficient lighting
• Illumination is not excessive
• Switching arrangements are designed
• Provide illumination in an efficient manner
Energy efficient
fittings (e.g. compact Lighting controls and
fluorescent lamps) interactions with windows
Daylighting design and control
Building Energy Efficiency
http://www.hku.hk/bse/save.exe
Building Energy Efficiency
• Human factors
• Comfort requirements
• Thermal comfort
• Visual comfort
• Noise control
• Occupant behaviours
• Patterns of use
• Periods of occupation
• Management issues
• Building use, operation & maintenance
Good design practices
Efficient
Good house- operation
keeping User education
& awareness
Further Reading