1 Buildings in a Changing Climate Energy Science Director HSBC Director of Low Carbon Innovation...

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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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• Conclusions


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


• 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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• 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.


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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


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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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• Conclusions


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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


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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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• Conclusions


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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• Conclusions


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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."

1 Buildings in a Changing Climate Energy Science Director HSBC Director of Low Carbon Innovation...

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