Energy Efficient Cities

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Energy Efficient Cities

• Ann Dowling
• University of Cambridge

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The importance of addressing Energy Efficiency in
Cities

• 80 of the population of the UK lives in towns
  and cities
• Of the demand for energy in the UK
• buildings account for approx 40
• (excluding embodied energy of construction
  materials)
• ground transportation 27
• Addressing energy demand reduction in the urban
  environment involves assessing a series of
  trade-offs
• For example,
• Low density buildings
• provide more scope for distributed power
• reduce heat island effect
• more opportunity to use natural convection,
  shading by vegetation etc to control internal
  temperatures
• but increase transportation demands
• New build
• provides more opportunities to incorporate
  energy efficiency but embedded energy in
  construction is substantial. It can take 40
  years to energy savings to match energy used in
  producing construction materials

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Energy in different products life cycles
Which phase dominates?
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Energy Efficient Cities

• Is a new interdisciplinery collaboration
  involving the Departments of Engineering,
  Architecture and Chemical Engineering, the
  Computer Laboratory, Judge Business School and
  the BP Institute at the University of Cambridge
• Currently 13 external partners including BP, Ove
  Arup, Short Associates
• Hoare Lea Consulting Engineers, BT,
  Howes-Macnaghten Technology
• Quiet Revolution, Department of Health,
  Rolls-Royce plc, Rolls-Royce Fuel
• Cells Ltd, Jaguar, Denso, Johnson Matthey
• Kick-started with 2.9M funding from the
  Engineering and Physical Sciences Research
  Council
• Many current staff of the University involved
• In addition, we are appointing three new
  Lecturers associated with the Initative, one in
  Civil Engineering, one in Mechanical Engineering
  and one in Architecture

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Energy Efficient Cities

• Addresses energy demand reduction in urban
  environment by integrating design and the
  development of novel technologies for energy
  efficient cities, with links to economic, policy
  and regulatory considerations
• Aim to develop a systems view of energy
  utilisation (buildings and transport) and
  distributed power generation and so that trade
  offs can be assessed within a unified framework
• Areas range from urban planning, building design,
  transport and micro-generation

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Urban planning

• Areas include
• city layout, use of green spaces, transport
  system
• Examples from colleagues current activities

• Peter Guthrie is working with property developer
  Land Securities plc is investigating issues
  around Building Sustainable Communities using
  their Ebbsfleet Valley development in North Kent
  Thameside as a case study
• Partner BT is looking at the scope for IT to
  support an energy efficient community also at
  Ebbsfleet

• Koen Steemers is co-ordinating an International
  Network with China on sustainable building and
  urban design

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Urban planning

• Urban planning and policies for transport
• Marcial Echenique (Arch)
• Testing alternative designs
• assessment of economic, social and
• environmental impacts

London region commuter - simulation

• Smart networks for traffic control
• Andy Hopper, Jean Bacon (Computer Lab)
• research, application development and deployment
  of urban transport monitoring systems
• Applications
• bus arrival time displays
• notification of traffic delays
• empty taxi location etc

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Urban planning

• Role of city/road layout and use of green spaces
  for buildings

• In heat transfer issues (surface albedos for
  reduction of the urban heat island effect,
  turbulence around and heat loss from groups
  buildings, turbulence and ventilation patterns to
  facilitate

• removal of heat from urban areas, effect of
  roofs with vegetation)
• Optimal selection of vegetation (for benefits
  of evapotranspiration and CO2 uptake, for
  avoidance of overshadowing)

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Design and technologies for low carbon buildings

• Overhead
• renewables solar thermal, photovoltaics, wind
  energy
• role of the canopy in heat transfer and
  ventilation, reduction of heat island effect
• capture and use of rainwater

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Design and technologies for low carbon buildings

• Overhead
• renewables solar thermal, photovoltaics, wind
  energy
• role of the canopy in heat transfer and
  ventilation, reduction of heat island effect
• capture and use of rainwater

• The ground
• ground source heat pumps
• energy storage in below ground in man-made
  structures

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Design and technologies for low carbon buildings

• Overhead
• renewables solar thermal, photovoltaics, wind
  energy
• role of the canopy in heat transfer and
  ventilation, reduction of heat island effect
• capture and use of rainwater

• The buildings
• lower energy consumption in production of
  traditional materials (eg concrete, aluminium)
• addressing heat transfer through and ventilation
  flows in buildings
• phase-change materials
• surface treatments, eg green walls (effects on
  thermal insulation, potential for increased
  biodiversity)
• sensors and smart computer-based systems to
  optimise energy use
• interaction of daylighting with next generation
  LED lighting
• combined heat and power

• The ground
• ground source heat pumps
• energy storage in below ground in man-made
  structures

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Design and technologies for low carbon buildings

• Overhead
• renewables solar thermal, photovoltaics, wind
  energy
• role of the canopy in heat transfer and
  ventilation, reduction of heat island effect
• capture and use of rainwater

• The buildings
• lower energy consumption in production of
  traditional materials (eg concrete, aluminium)
• addressing heat transfer through and ventilation
  flows in buildings
• phase-change materials
• surface treatments, eg green walls (effects on
  thermal insulation, potential for increased
  biodiversity)
• sensors and smart computer-based systems to
  optimise energy use
• interaction of daylighting with next generation
  LED lighting
• combined heat and power

• The ground
• ground source heat pumps
• energy storage in below ground in man-made
  structures

Distributed power use of biomass, wind, solar,
fuel cells integration of electrical vehicles and
building supply
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Materials

• 20 global GHG emissions from energy arise in
  the production of five key materials cement,
  steel, plastic, paper, aluminium
• Should consider energy use in production of
  materials when choosing which materials to use

Ashby map
stiffness versus energy
Research into energy efficient ways of producing
cement, steel and aluminum
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Exploiting natural ventilation and thermal mass

• Andy Woods BPI, Koen Steemers and Alan Short
  Department of Architecture
• Heat transfer and ventilation flows in buildings
  from modelling, lab experiments, design and use
  in real buildings, monitoring
• Being commercialised through spin-out company
  E-stack Ltd which develops ventilation stack
  systems for schools and offices
• Research has identified strategies for control
  of these non-linear convective flows which often
  involve multiple steady-state regimes, and
  complex transition between states

An experiment showing overturn in a naturally
ventilated model theatre
Alan Shorts design for the School of Slavonic
East European Studies UCL making use of passive
downdraft cooling, because of its central London
location, natural convection was not sufficient
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Other relevant research

• Using less energy intensive materials in building
  construction, Michael Ramage, Architecture
• Energy audit of materials and processes, Julian
  Allwood, Engineering
• Green concrete Abir Al Tabba, Engineering
• Surface treatments, active glass, Mauro Overend,
  Engineering
• Low power lighting, next generation of LEDS,
  Colin Humphreys, Material Science
• New sensors and smart computer-based systems to
  optimise energy use (Andy Rice, Computer Lab)
• Reducing computers power consumption (Andy Rice,
  Computer Lab)

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Distributed Power

• When electricity is generated for the grid
• Centralised power stations are only about
• 45-55 efficient - gas combined cycle
• 35 efficient coal
• Grid losses account for a further 7.7
• So for every 1 KWH of electricity consumed in the
  home between 2 and 3 KWH of fuel has been burned
• Demand on centralised power generation can be
  minimised by combining urban design with district
  heat and power generation from medium-scale power
  generators, small scale on site generation, and
  even integrating the energy use in buildings with
  the power to/from hybrid electric cars

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Distributed Power Generation

• Combustion/Gasification of Biomass
• Dennis (Chem Eng), Scott (Engineering)
• fluidised bed gasifiers to convert locally
  available fuels (sewage sludge, wood coppice) to
  syngas for use in power generation cycles
• Fuel cells
• Young (Engineering)

• Solid oxide fuel cells (SOFC) coupled to a gas
  turbine (SOFC-GT) can generate electrical power
  from natural gas with
• an efficiency of 75
• with near-zero levels of NOX, SOX and
  particulates
• future developments could include fuel
  pre-processing to reform the primary fuel to H2
  and remove the CO2 at source for sequestation

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Research on the future generations of
photovoltaics

• ,

• Within the University we have research on the
  next generations of photovoltaics
• This includes low cost methods for producing
  solar-grade silicon (Mats. Sci, Fray)
• low-cost, nano-oxide arrays for use in hybrid
  solar cells (Mats. Sci, Driscoll)
• Polymer Photovoltaics Prof. Sir Richard Friend
  and others in Physics
• Conjugated polymer semiconductors
• Low-temperature deposition from solution
• Potential for roll-to-roll printing of cheap
• solar cells, lt1/Wp

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Grid Connected Solar Power

• Gehan Amaratunga in Department of Engineering
• Research to remove the bottleneck to make solar
  a true consumer product

• Cost of electronics for conditioning variable dc
  solar power for connection to stable ac grid
• Solution small inverter on each panel
• Research challenge

• to overcome feeding small powers (10W)
  efficiently with good power quality, reliability,
  low cost, safe easy installation
• currently being commercialised by spinout company
  Enecsys

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Vertical Axis Wind Turbines

• Holger Babinsky (Engineering) in partnership with
  quietrevolution

• Horizontal axis wind turbines do not work well in
  gusty conditions
• Vertical axis wind turbines do and so are ideal
  for urban environment
• Co-locates energy use and generation, minimising
  transmission loss
• Aesthetics are important
• Have been
• Optimising design and operation for urban wind
• Developing controller strategies to optimise
  power output
• Investigating installation effects

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Summary

• No one specific technology, but rather the
  integration of many different technologies into
  an energy efficient city
• Requires more integration than a traditional
  design
• At urban level integration of layout of
  buildings, transport systems, green spaces,
  opportunities for distributed power, IT
  infrastructure, etc
• At building level great integration of building
  and building services
• All with a consideration of how people will
  interact with and use the buildings
• Emphasis on any new technologies being developed
  with a consideration of use and the overall life
  cycle energy consumption

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Current Industrial Partners

• BP International Limited
• Ove Arup Partners Ltd
• Short and Associates
• Hoare Lea Consulting Engineers
• BT
• Howes-Macnaghten Technology Ltd
• Quiet Revolution
• Department of Health
• Rolls-Royce plc
• Rolls-Royce Fuel Cells Ltd
• Jaguar Cars Limited
• Denso Sales UK Ltd
• Johnson Matthey