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Buildings in a Changing Climate
Energy Science Director HSBC Director of Low Carbon InnovationCRed
Carbon Reduction
UKERC Seminar9th May 2007
CRed
Keith Tovey (杜伟贤 ) MA, PhD, CEng, MICE, CEnv
Acknowledgement: Karla Alcantar
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• Issues of Sustainable Building Construction– Thermal Performance issues
• Future Proofing Buildings - Fabric Cooling?
– Renewable Energy and Integration of Design
– Life Cycle analyses
• Management of Building Energy Use
• Behaviour of the Occupants
• Conclusions
Sustainability in Building and Occupation
Thermal Performance issues• Future Proofing Buildings - Fabric Cooling?
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• 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
Thermal Performance Issues: Future Proofing
60
80
100
120
140
160
180
1960-1964
1965-1969
1970-1974
1975-1979
1980-1984
1985-1989
1990-1994
1995-1999
2000-2004
Heating
Cooling
Index 1960 = 100
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
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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
Cold air
Cold air
Draws out the heat accumulated during
the dayCools the slabs to act as a cool store the following day
Summer night
night ventilation/ free cooling
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Warm air
Warm air
Pre-cools the air before entering the
occupied space
The concrete absorbs and stores
the heat – like a radiator in reverse
Summer day
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
No air conditioning is needed even though the norm would have been to install air-conditioning
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
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• 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.
Heat Pumps: A solution for a Low Carbon Future
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• Issues of Sustainable Building Construction– Thermal Performance issues
• Future Proofing Buildings - Fabric Cooling?
– Renewable Energy and Integration of Design
– Life Cycle analyses
• Management of Building Energy Use
• Behaviour of the Occupants
• Conclusions
Sustainability in Building and Occupation
8Annual Solar Gain 910 kWh
Solar Collectors installed 27th January 2004
Options for Renewable Energy: Solar Thermal
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Solar Gain (kWh/day)
012345678
10 17 24 31 7 14 21 28 4 11 18 25 4 11 18 25 1 8 15 22 29 6
Day of Month
So
lar
Ga
in (
kW
h) December
JanuaryFrebruaryMarchAprilMay
Options for Renewable Energy: Solar Thermal
• Performance of an actual solar collector 9th December 2006 – 2nd May 2007
• Average gain (over 3 years) is 2.245 kWh per day
• Central Heating Boiler does not 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
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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.
Solar Gain (kWh/day)
012345678
10 17 24 31 7 14 21 28 4 11 18 25 4 11 18 25 1 8 15 22 29 6
Day of Month
Sol
ar G
ain
(k
Wh
) DecemberJanuaryFrebruaryMarchAprilMay
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Options for Renewable Energy: Solar Photovoltaic
Data based on Actual ZICER Building PV Costs
Actual Situation excluding Grant
Actual Situation with Grant
Discount rate 3% 5% 7% 3% 5% 7%
Unit energy cost per kWh (£) 1.29 1.58 1.88 0.84 1.02 1.22
Avoided cost exc. the Grant
Avoided Costs with Grant
Discount rate 3% 5% 7% 3% 5% 7%
Unit energy cost per kWh (£) 0.57 0.70 0.83 0.12 0.14 0.16
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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
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Arrangement of Cells on Facade
Individual cells are connected horizontally
As shadow covers one column all cells are inactive
If individual cells are connected vertically, only those cells actually in shadow are affected.
Options for Renewable Energy: Solar Photovoltaic
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Sometimes electricity is exportedInverters are only 91% efficient
Most use is for computers
DC power packs are inefficient typically less than 60% efficientNeed an integrated approach
Peak output is 34 kW
Options for Renewable Energy: Solar Photovoltaic
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– 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
Options for Low Carbon Technologies: Micro CHP
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• Issues of Sustainable Building Construction– Thermal Performance issues
• Future Proofing Buildings - Fabric Cooling?
– Renewable Energy and Integration of Design
– Life Cycle analyses
• Management of Building Energy Use
• Behaviour of the Occupants
• Conclusions
Sustainability in Building and Occupation
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• 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 ~ 0.06 kg/kWh
• To what extent does embodied carbon from construction and demolition affect total carbon emission?– Example: ZICER Building
Sustainability in Building and Occupation
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As Built 209441GJ
Air Conditioned 384967GJ
Naturally Ventilated 221508GJ
Life Cycle Energy Requirements of ZICER as built compared to other heating/cooling strategies
Materials Production
Materials Transport
On site construction energy
Workforce Transport
Intrinsic Heating / Cooling energy
Functional Energy
Refurbishment Energy
Demolition Energy
28%54%
34%51%
61%
29%
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0
50000
100000
150000
200000
250000
300000
0 5 10 15 20 25 30 35 40 45 50 55 60
Years
GJ
ZICER
Naturally Ventilated
Air Conditrioned
Comparison of Life Cycle Energy Requirements of ZICER
Compared to the Air-conditioned office, ZICER recovers extra energy required in construction in under 1 year. 0
20000
40000
60000
80000
0 1 2 3 4 5 6 7 8 9 10
Years
GJ
ZICER
Naturally Ventilated
Air Conditrioned
Comparisons assume identical size, shape and orientation
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• Issues of Sustainable Building Construction– Thermal Performance issues
• Future Proofing Buildings - Fabric Cooling?
– Renewable Energy and Integration of Design
– Life Cycle analyses
• Management of Building Energy Use
• Behaviour of the Occupants
• Conclusions
Sustainability in Building and Occupation
21Careful Monitoring and Analysis can reduce energy consumption.
Conservation: management improvements –
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.
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The Energy Signature from the Old and the New Heating Strategies
0
200
400
600
800
1000
-4 -2 0 2 4 6 8 10 12 14 16 18
Mean external temperature over a 24 hour period (degrees C)
Hea
tin
g an
d h
ot-w
ater
co
nsu
mp
tion
(k
Wh
/day
)
New Heating Strategy Original Heating Strategy
The space heating consumption has reduced by 57%
Good Management has reduced Energy Requirements
800
350
Acknowledgement: Charlotte Turner
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• Issues of Sustainable Building Construction– Thermal Performance issues
• Future Proofing Buildings - Fabric Cooling?
– Renewable Energy and Integration of Design
– Life Cycle analyses
• Management of Building Energy Use
• Behaviour of the Occupants
• Conclusions
Sustainability in Building and Occupation
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• 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
0
100
200
300
400
500
600
700
Gol
den
Triang
le
Mile
Cro
ss
Upper
Hell
esdon
Laken
ham
Eaton
Rise
Tucks
wood
Bowth
orpe
kW
h/m
onth
0
200
400
600
800
1000
1200
0 1 2 3 4 5 6 7
No. people
Ave
rage
kW
h/m
onth
Average Norwich
Electricity Consumption
Data from 114 houses in Norwich
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Personal Attitudes to Energy Use can be significant
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Social Awareness of Occupational Impact on Climate Change
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0
2000
4000
6000
8000
10000
12000
14000
16000
1
Lighting
Refrigeration
Entertainment
Miscellaneous
Air/Public Travel
Washing/Drying
Private Car
Heating
Social Awareness of Occupational Impact on Climate Change
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• Provide optional environmentally efficient systems within all new buildings – even if they are not mandatory.
• Revise way we address costs and benefits.
– Is traditional Cost Benefit Analysis the correct way to appraise low carbon systems?
– Lower capital costs vs lower environmental running costs.
– Are ESCO’s a way forward?
• Improved control – Smart (Sub) Metering
The Future
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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.
Conclusions (2)
Lao Tzu (604-531 BC) Chinese Artist and Taoist philosopher
"If you do not change direction, you may end up where you are heading."