New Challenges in Energy Efficiency in Buildings

1
Broadland Housing Forum 12th September May 2007
Keith Tovey (???) MA, PhD, CEng, MICE, CEnv
New Challenges in Energy Efficiency in Buildings

Energy Science Director HSBC Director of Low
Carbon Innovation
CRed
Acknowledgements Karla Alcantar, Charlotte
Turner
2
New Challenges in Energy Efficiency in Buildings

• Background

• Background
• Energy Efficiency and Sustainable Building
  Construction
• Thermal Performance
• Future Proofing Buildings - Fabric Cooling?
• Renewable Energy
• Life Cycle analyses
• Integration of Design
• Functional Energy Use
• Management of Building Energy Use
• Behaviour of the Occupants
• Conclusions

3
Changes in Temperature
4
New Challenges in Energy Efficiency in Buildings

• Background
• Energy Efficiency and Sustainable Building
  Construction
• Thermal Performance issues
• Future Proofing Buildings - Fabric Cooling?
• Renewable Energy and Integration of Design
• Life Cycle issues
• Management of Building Energy Use
• Behaviour of the Occupants
• Conclusions

5
Thermal Performance Issues Future Proofing

• Thermal performance has improved with better
  insulation.
• With better fabric insulation, ventilation can
  represent up to 80 of heating energy
  requirements.
• Careful design of ventilation is needed
• lower capital costs vs lower environmental
  running costs.
• Are ESCOs a way forward?
• Provide optional environmentally efficient
  systems within all new buildings.
• Improved control Smart (Sub) Metering
• Is traditional Cost Benefit Analysis the correct
  way to appraise low carbon systems?
• Issues of overheating need to be addressed

6
Sustainability in Building and Occupation
Impact of Changing Climate
Changes in heating and cooling requirements for
buildings over last 50 years
Heating requirements are 10 less than in
1960 Cooling requirements are 75 higher than in
1960. Care must now be taken to ensure buildings
are now designed to avoid overheating in summer
and to minimise active cooling requirements
7
Fabric Cooling using Hollow Core Slabs
The concrete hollow core ceiling slabs are used
to store heat and coolness at different times of
the year to provide comfortable and stable
temperatures
Draws out the heat accumulated during the day
Summer night
night ventilation/ free cooling
8
Fabric Cooling using Hollow Core Slabs
The concrete hollow core ceiling slabs are used
to store heat and coolness at different times of
the year to provide comfortable and stable
temperatures
Pre-cools the air before entering the occupied
space
No air conditioning is needed even though the
norm would have been to install air-conditioning
Summer day
The concrete absorbs and stores the heat like a
radiator in reverse
In future, with Global Warming, when
air-conditioners may be installed, they will be
run over night to pre-cool building and improve
efficiency of chillers
9
Heat Pumps A solution for a Low Carbon Future

• Ground Source Heat Pumps are an effective route
  to low carbon heating can save 50 60 of
  carbon emissions.
• Work most efficiently with under floor heating.
• Can be used with fabric pre-cooling in summer
  with very modest air-conditioning
• Can be to provide some inter-seasonal heat store
• i.e. reject heat in summer to acquifer/ground
  recover during winter. There is 3 months
  thermal lag in peak temperature in ground
  corresponding with early heating season use, and
  much improved coefficients of performance.

10
Thermal Properties of Buildings

• Heating energy requirement is strongly dependant
  on External Temperature.
• Thermal Lag in Heavy Weight Buildings means
  consumption requirements lags external
  temperature.
• Correlation with temperature suggests a thermal
  lag of 8 hours.
• Potential for predictive controls based on
  weather forecasts

Data collected 10th December 2006 April 29th
2007
11
New Challenges in Energy Efficiency in Buildings

• Background
• Energy Efficiency and Sustainable Building
  Construction
• Thermal Performance issues
• Future Proofing Buildings - Fabric Cooling?
• Renewable Energy and Integration of Design
• Life Cycle issues
• Management of Building Energy Use
• Behaviour of the Occupants
• Conclusions

12
Options for Renewable Energy Solar Thermal
Solar Collectors installed 27th January 2004
Annual Solar Gain 910 kWh
13
Options for Renewable Energy Solar Thermal

• Performance of a solar collector 9th December
  2006 3rd September 2007
• Average gain (over 3 years) is 2.245 kWh per
  day
• Boiler rarely used to provide Hot Water from
  Easter to 1st October
• More Hot Water used the greater amount of
  solar energy is gained
• Optimum orientation for solar hot water
  collectors for most houses is NOT due
• South

14
Options for Renewable Energy Solar Thermal

• Significant surplus of energy in summer
• Explore increasing temperature limit
• provided there is an
  anti-scald device fitted.
• Training needed to educate users to get
  optimum from solar collector in mid-
• season (setting of Central Heating Hot Water
  timers)
• Energy/Carbon benefits to be gained by
  providing solar hot water on a multi-
• house basis.

15
Options for Renewable Energy Solar Photovoltaic
16
ZICER Building
Photo shows only part of top Floor

• Top floor is an exhibition area also to promote
  PV
• Windows are semi transparent
• Mono-crystalline PV on roof 27 kW in 10
  arrays
• Poly- crystalline on façade 6/7 kW in 3 arrays

17
Arrangement of Cells on Facade
Options for Renewable Energy Solar Photovoltaic
Individual cells are connected horizontally
If individual cells are connected vertically,
only those cells actually in shadow are affected.
As shadow covers one column all cells are inactive
18
Options for Renewable Energy Solar Photovoltaic
Peak output is 34 kW
Sometimes electricity is exported
Inverters are only 91 efficient
Most use is for computers
DC power packs are inefficient typically less
than 60 efficient
Need an integrated approach
19
Options for Low Carbon Technologies Micro CHP

• Potential to substantially reduce CO2 emissions
• Significant reduction is losses from transmission
• but
• problem of heat disposal in summer
• Does not make sense to provide CHP with solar hot
  water heaters
• Consider using absorption chilling to provide
  cooling where required

20
New Challenges in Energy Efficiency in Buildings

• Background
• Energy Efficiency and Sustainable Building
  Construction
• Thermal Performance issues
• Future Proofing Buildings - Fabric Cooling?
• Renewable Energy and Integration of Design
• Life Cycle issues
• Management of Building Energy Use
• Behaviour of the Occupants
• Conclusions

21
Sustainability in Building and Occupation

• Life Cycle Issues an issue in Sustainability
• Does local sourcing of materials necessarily lead
  to a low carbon construction?
• In case of PV it emits LESS CO2 if cells are
  manufactured in Spain and transported to UK!
• despite the transport!!!!
• Need to be aware of how fuel mix used for
  generation of electricity affects CO2.
• UK 0.52 kg/kWh, Spain 0.46 kg/kWh
• France 0.077 kg/kWh
• To what extent does embodied carbon from
  construction and demolition affect total carbon
  emission?
• Example ZICER Building

22
Life Cycle Energy Requirements of ZICER as built
compared to other heating/cooling strategies
28
54
34
51
29
61
23
Comparison of Life Cycle Energy Requirements of
ZICER
Comparisons assume identical size, shape and
orientation
Compared to the Air-conditioned office, ZICER
recovers extra energy required in construction in
under 1 year.
24
New Challenges in Energy Efficiency in Buildings

• Background
• Energy Efficiency and Sustainable Building
  Construction
• Thermal Performance issues
• Future Proofing Buildings - Fabric Cooling?
• Renewable Energy and Integration of Design
• Life Cycle issues
• Management of Building Energy Use
• Behaviour of the Occupants
• Conclusions

25
The Elizabeth Fry Building 1994
Cost 6 more but has heating requirement 25 of
average building at time. Building Regulations
have been updated 1994, 2002, 2006, but
building outperforms all of these.
Runs on a single domestic sized central heating
boiler.
26
Conservation management improvements
User Satisfaction
thermal comfort 28
air quality 36
lighting 25
noise 26
Careful Monitoring and Analysis can reduce energy
consumption.
A Low Energy Building is also a better place to
work in
27
Good Management has reduced Energy Requirements
The space heating consumption has reduced by 57
Acknowledgement Charlotte Turner
28
New Challenges in Energy Efficiency in Buildings

• Background
• Energy Efficiency and Sustainable Building
  Construction
• Thermal Performance issues
• Future Proofing Buildings - Fabric Cooling?
• Renewable Energy and Integration of Design
• Life Cycle issues
• Management of Building Energy Use
• Behaviour of the Occupants
• Conclusions

29
Electricity Consumption

• Household size has little impact on electricity
  consumption.
• Consumption varies by up to a factor of 9 for any
  given household size.
• Allowing for Income still shows a range of 6 or
  more.
• Education/Awareness is important

Data from 114 houses in Norwich
30
Personal Attitudes to Energy Use can be
significant
31
Social Awareness of Occupational Impact on
Climate Change
32
Social Awareness of Occupational Impact on
Climate Change
33
Conclusions

• Sustainable Buildings require
• Initial sound design addressing high insulation
  standards, effective control of ventilation
  Attention to Future Proofing.
• Integration of use of building with provision of
  services.
• Avoidance of combining novel technologies which
  are incompatible.
• Use of most sustainable materials Local
  provision of materials is NOT ALWAYS best
  careful Life Cycle Assessments are needed.
• Provision of optional extras for all buildings
  including renewable technologies etc perhaps with
  alternative financing methods.
• Provision of SMART sub metering to inform the
  user.
• Improvements in training of users where newer
  technologies are used.
• a need for awareness raising.

"If you do not change direction, you may end up
where you are heading."
Lao Tzu (604-531 BC) Chinese Artist and Taoist
philosopher