arch6026 - building systems ii (2000/2001) energy and environmental systems for green buildings...
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Arch6026 - Building Systems II (2000/2001)Energy and Environmental Systems for Green Buildings
Lecture 04 -Efficient Use of Energy in Buildings
Contents
Energy Use in Buildings
Design Factors
Design Strategies
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 energyelectricity, town gas/LPG, oil/coal products
Energy end-useHVAC, lighting, equipment, hot water, and processes
Energy end-use in Hong Kong by sectors, 1984-97
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
Energy consumption patterns in commercial buildings(Data source: Energy Efficiency Office, HK)
Energy consumption patterns in commercial buildings (cont’d)(Data source: Energy Efficiency Office, HK)
Energy consumption patterns in residential buildings(Data source: Energy Efficiency Office, HK)
Energy Use in Buildings
Energy and environment (global) energy/electricity generation
greenhouse gas emissioncause global warming and climate change
CO2 emissions factorselectricity = 0.832 kg/kWh (natural) gas = 0.198 kg/kWhcoal = 0.331 kg/kWh
Key factors influencing energy consumption
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)
Major Factors
Climate and site climate
temperatures, humidity, solar radiation, wind dataaffect thermal performance, daylighting, solar energy
utilisation, and ventilation
sitetopography, vegetation, built forms, waterin harmony with the environment and make effective
use of local conditions
Major climatic elements of Hong Kong
Wind
Water
Light
Matter
Major site factors
Major Factors
Building envelope walls, roofs, windows, skylights, etc.
thermal properties, e.g. U-value
considerationsclimate 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?
Look at me.Is my face (building
envelope) energyefficient?
* Face House, Kyoto, Japan
Main criteria:• wall area• window area• thermal properties• orientations• thermal mass• shading device
Properties of window glasses
Major Factors
Building services systems HVAC systems lighting systems electrical services systems lifts and escalators water supply systems town gas supply system
Thermal energy balance in a building space
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
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
Design Strategies
Thermal ventilation strategies cooling strategies heating strategies
Light lighting strategies daylighting strategies
Services strategies
Good design practices
Good house-keeping
Efficientsystems
Efficientoperation
User education& awareness
Interdisciplinaryteam approach
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