1 Sustainability in Building and Occupation Energy Science Director HSBC Director of Low Carbon Innovation CRed Carbon Reduction Cotman Housing Dunstan.

1

Sustainability in Building and Occupation

Energy Science Director HSBC Director of Low Carbon InnovationCRed

Carbon Reduction

Cotman Housing Dunstan Hall, Norwich4th May 2007

CRed

Keith Tovey (杜伟贤 ) MA, PhD, CEng, MICE, CEnv

Acknowledgement: Karla Alcantar

2

• Background• Issues of Sustainable Building Construction

– Thermal Performance– Renewable Energy– Life Cycle analyses– Integration of Design– Future Proofing Buildings

• Management of Building Energy Use• Behaviour of the Occupants• Conclusions

Sustainability in Building and Occupation

• Background

3

Concentration of C02 in Atmosphere

300

310

320

330

340

350

360

370

380

1960 1965 1970 1975 1980 1985 1990 1995 2000

(ppm

)

Changes in Temperature

4

1.0

0.5

0.0

-0.51860 1880 1900 1920 1940 1960 1980 2000T

emp

erat

ure

Ris

e (o C

)

1.0

0.5

0.0

-0.51860 1880 1900 1920 1940 1960 1980 2000

Tem

per

atu

re R

ise

(o C)

1.0

0.5

0.0

-0.51860 1880 1900 1920 1940 1960 1980 2000

Tem

per

atu

re R

ise

(o C)

Source: Hadley Centre, The Met.Office

actual

actual

actual

predicted

predicted

predictedIs Global Warming man made?

Prediction: Anthropogenic only

Not a good match between 1920 and 1970

Prediction: Natural only

good match until 1960

Prediction: Natural and Anthropogenic

Generally a good match

Predictions include:

• Greenhouse Gas emissions

• Sulphates and ozone

• Solar and volcanic activity

5

• Background• Issues of 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

Sustainability in Building and Occupation

6

• 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 ESCO’s 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?

Thermal Performance Issues: Future Proofing

7

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

Changes in heating and cooling requirements for buildings over last 50 years

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

Impact of Changing Climate

Sustainability in Building and Occupation

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

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

9

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

10

• 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

11

• 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

0

20

40

60

80

100

120

140

160

180

-2 0 2 4 6 8 10 12 14 16 18 20

Mean External Temperature (oC)

Gas

Con

sum

ptio

n (k

Wh/

day)

0.840.850.860.870.880.890.9

0.910.920.93

0 2 4 6 8 10 12 14 16 18 20 22 24

Time Lag (hours)

Coe

ffic

ient

of

Cor

rela

tion

Thermal Properties of Buildings

Data collected 10th December 2006 – April 29th 2007

12

• Background• Issues of 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

Sustainability in Building and Occupation

13Annual Solar Gain 910 kWh

Solar Collectors installed 27th January 2004

Options for Renewable Energy: Solar Thermal

14

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

Solar Gain (kWh/day)

0

12

3

4

56

7

8

10 17 24 31 7 14 21 28 4 11 18 25 4 11 18 25 1 8 15 22 29

Day of Month

Sol

ar G

ain

(k

Wh

) DecemberJanuaryFebruaryMarchAprilMay

15

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)

0

12

3

4

56

7

8

10 17 24 31 7 14 21 28 4 11 18 25 4 11 18 25 1 8 15 22 29

Day of Month

Sol

ar G

ain

(k

Wh

) DecemberJanuaryFebruaryMarchAprilMay

16

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

17

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

18

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

19

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

20

– 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

21

• Background• Issues of 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

Sustainability in Building and Occupation

22

• 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

23

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%

24

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

25

• Background

• Issues of Sustainable Building Construction– Thermal Performance

– Renewable Energy

– Life Cycle analyses

– Integration of Design

– Future Proofing Buildings

• Management of Building Energy Use

• Behaviour of the Occupants

• Conclusions

Sustainability in Building and Occupation

26

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.

27

0

50

100

150

200

250

Elizabeth Fry Low Average

kWh/

m2/

yr

gas

electricity

User Satisfaction

lighting +25%

air quality +36%

A Low Energy Building is also a better place to work in

Careful Monitoring and Analysis can reduce energy consumption.

Conservation: management improvements –

thermal comfort +28%

noise +26%

28

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

29

Storeys = 2 & options

Mapping Consumption automatically in existing buildings

30

Mapping Consumption automatically in existing buildings

31

• Background

• Issues of Sustainable Building Construction– Thermal Performance

– Renewable Energy

– Life Cycle analyses

– Integration of Design

– Future Proofing Buildings

• Management of Building Energy Use

• Behaviour of the Occupants

• Conclusions

Sustainability in Building and Occupation

32

• 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

33

Personal Attitudes to Energy Use can be significant

34

Social Awareness of Occupational Impact on Climate Change

35

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

36

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

Lao Tzu (604-531 BC) Chinese Artist and Taoist philosopher

"If you do not change direction, you may end up where you are heading."