Arch6026 Building Systems II 20002001 Energy and Environmental Systems for Green Buildings

1
Arch6026 - Building Systems II (2000/2001)Energy
and Environmental Systems for Green Buildings
Lecture 04 - Efficient Use of Energy in Buildings
2
Contents

• Energy Use in Buildings
• Design Factors
• Design Strategies

3
Energy Use in Buildings

• Energy (or heat) unit
• 1 kWh 3.6 MJ 860 kcal 3412 Btu
• Power unit
• 1 W 1 J/s 0.86 kcal/h 3.41 Btu/h
• Forms of energy
• electricity, town gas/LPG, oil/coal products
• Energy end-use
• HVAC, lighting, equipment, hot water, and
  processes

4
Energy end-use in Hong Kong by sectors, 1984-97
5
Energy Use in Buildings

• Buildings (comm. resid.) is an important energy
  consumer (30-50 of total)
• energy consumption patterns
• affected by building functions, occupant
  behaviour, climate, and building design
• energy saving potential is often large
• goal of energy efficiency
• optimise energy performance w/o compromising the
  human comfort and well-being

6
Energy consumption patterns in commercial
buildings (Data source Energy Efficiency Office,
HK)
7
Energy consumption patterns in commercial
buildings (contd) (Data source Energy
Efficiency Office, HK)
8
Energy consumption patterns in residential
buildings (Data source Energy Efficiency Office,
HK)
9
Energy Use in Buildings

• Energy and environment (global)
• energy/electricity generation
• greenhouse gas emission
• cause global warming and climate change
• CO2 emissions factors
• electricity 0.832 kg/kWh
• (natural) gas 0.198 kg/kWh
• coal 0.331 kg/kWh

10
Key factors influencing energy consumption
11
Major Factors

• Major design factors
• climate and site
• building envelope and form
• building services systems
• human factors
• Energy design guidance (see notes)
• design guidelines
• checklist for energy efficiency in buildings
• sketch design (from CIBSE Guide)

12
Major Factors

• Climate and site
• climate
• temperatures, humidity, solar radiation, wind
  data
• affect thermal performance, daylighting, solar
  energy utilisation, and ventilation
• site
• topography, vegetation, built forms, water
• in harmony with the environment and make
  effective use of local conditions

13
Major climatic elements of Hong Kong
14
Wind
Light
Water
Matter
Major site factors
15
Major Factors

• Building envelope
• walls, roofs, windows, skylights, etc.
• thermal properties, e.g. U-value
• considerations
• climate excluding or climate responsive?
• use building fabric for thermal storage?
• thermally heavyweight or lightweight?
• deep or shallow plan?
• highly glazed or little glazing?
• need for solar control?

16
Look at me. Is my face (building envelope)
energy efficient?

• Main criteria
• wall area
• window area
• thermal properties
• orientations
• thermal mass
• shading device

Face House, Kyoto, Japan
17
Properties of window glasses
18
Major Factors

• Building services systems
• HVAC systems
• lighting systems
• electrical services systems
• lifts and escalators
• water supply systems
• town gas supply system

19
Thermal energy balance in a building space
20
Design Strategies

• Process of energy efficient design
• identify user requirements
• meet the requirements with minimal energy use
• establish energy efficient brief design team
• set up energy targets
• design efficient, maintainable flexible systems
• check the final design meets the targets

21
Design Strategies

• Minimise energy requirements
• optimise internal heat gains
• optimise natural ventilation
• design for use daylighting
• better use of fabric thermal storage
• heat recovery
• free cooling
• minimise distribution losses

22
Design Strategies

• Thermal
• ventilation strategies
• cooling strategies
• heating strategies
• Light
• lighting strategies
• daylighting strategies
• Services strategies

23
Good design practices
Efficient systems
Interdisciplinary team approach
Efficient operation
Good house- keeping
User education awareness
24
Design Strategies

• Important things to do
• develop a better understanding of energy
  efficient technologies and methods
• acquire the techniques and skills for building
  energy analysis
• evaluate the energy performance of different
  design options in your projects
• examine the energy design and green building
  issues in context