Keith Tovey ( 杜伟贤)

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Energy Management as Part of a Long Term Strategy for Energy Efficiency at

the at the University of East Anglia

• Low Energy Buildings• Energy Management• Life Cycle Issues

• Providing Low Carbon Energy on Campus

Energy Management as Part of a Long Term Strategy for Energy Efficiency at

the at the University of East Anglia



Keith Tovey (杜伟贤 )

Energy Science Director HSBC Director of Low Carbon Innovation

Acknowledgement: Charlotte TurnerCRed

Carbon Reduction

University College London, 17th January 2006

CRed

2

Original buildings

Teaching wall

Library

Student residences

3

Nelson Court

Constable Terrace

4

Low Energy Educational Buildings

Elizabeth Fry Building

Medical School

ZICER

Nursing and Midwifery School

5

Constable Terrace - 1993

• Four Storey Student Residence

• Divided into “houses” of 10 units each with en-suite facilities• Heat Recovery of body and cooking

heat ~ 50%.

• Insulation standards exceed 2006 standards

• Small 250 W panel heaters in individual rooms.

Electricity Use

21%

18%

17%

18%

14%

12%

Appliances

Lighting

MHVR Fans

MHVR Heating

Panel Heaters

Hot Water

Carbon Dioxide Emissions - Constable Terrace

0

20

40

60

80

100

120

140

UEA Low Medium

Kg

/m2 /y

r

6

The Elizabeth Fry Building 1994

8

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.

Would have scored 13 out of 10 on the Carbon Index Scale.

7

Quadruple Glazing

Thick Insulation

Air circulates through whole fabric of building

Principle of Operation of TermoDeck Construction

Exhaust air passes through a two channel regenerative heat exchanger which recovers 85+% of ventilation heat requirements.

Mean Surface Temperature close to Air Temperature

8

Conservation: management improvements –

Careful Monitoring and Analysis can reduce energy consumption.

0

50

100

150

200

250

Elizabeth Fry Low Average

kWh/

m2/

yr

gas

electricity

thermal comfort +28%User Satisfaction

noise +26%

lighting +25%

air quality +36%

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

9

ZICER Building

Heating Energy consumption as new in 2003 was reduced by further 50% by careful record keeping, management techniques and an adaptive approach to control.

Incorporates 34 kW of Solar Panels on top floor

Low Energy Building of the Year Award 2005 awarded by the Carbon Trust.

10

The ZICER Building - Description

• Four storeys high and a basement• Total floor area of 2860 sq.m• Two construction types

Main part of the building

• High in thermal mass • Air tight• High insulation standards • Triple glazing with low emissivity

11

The ground floor open plan office

The first floor open plan office

The first floor cellular offices

12Air enters the internal

occupied space

Return stale air is extracted from each floor

Incoming air into

the AHU

Regenerative heat exchanger

FilterHeater

The air passes through hollow

cores in the ceiling slabs

The return air passes through the heat

exchanger

Out of the building

Operation of the Main Building• Mechanically ventilated that utilizes hollow core ceiling slabs as supply air ducts to the space

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Operation of Regenerative Heat Exchangers

Fresh Air

Stale Air

Fresh Air

Stale Air

A

B

B

A

Stale air passes through Exchanger A and heats it up before exhausting to atmosphere

Fresh Air is heated by exchanger B before going into building

Stale air passes through Exchanger B and heats it up before exhausting to atmosphere

Fresh Air is heated by exchanger A before going into building

After ~ 90 seconds the flaps switch over

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Importance of the Hollow Core Ceiling 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

Summer Night – night ventilation/free cooling

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Warm air

Warm air

Summer DayPre-cools the air before entering the

occupied spaceThe concrete absorbs and stores

the heat – like a radiator in reverse

Summer day

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Winter Day

The concrete slabs absorbs and

store heat

Heat is transferred to the air before entering

the room

Winter day

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Winter NightWhen the internal air temperature drops, heat stored in the

concrete is emitted back into the room

Winter night

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Energy Management as Part of a Long Term Strategy for Energy Efficiency at the at the University of East Anglia



CRedCarbon Reduction


19

Performance of ZICER Building

• Initially performance was poor• Performance improved with new Management Strategy

20052004

EFry

ZICER

New Management

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Temperature of air and fabric in building varies little even on a day in summer (June 21st – 22nd 2005)

Performance of ZICER Building

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Management of Energy: Heating/ Hot Water/ Cooking

0

2

4

6

8

10

12

-5 0 5 10 15 20 25 30Mean Temperature

kW

Gradient of Heating Line is Heat Loss Rate

Cooking/ Hot Water

No Heating

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y = -0.2533x + 5.9478

R2 = 0.9098

0

1

2

3

4

5

6

7

8

-2 0 2 4 6 8 10 12 14 16

Mean External Temperature

kW normal occupancy

increased occupancy

overnight heating

no cooking/hot water

Analysis of Energy Consumption in a house

9th December 2006 – 14th January 2007

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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 a

nd

ho

t-w

ate

r

con

sum

pti

on

(k

Wh

/24

ho

ur

per

iod

)

New Heating Strategy Original Heating Strategy

350

The space heating consumption has reduced by 57%

Good Management has reduced Energy Requirements

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Operation of Building

Construction of Building

Life Cycle Energy / Carbon Emissions

Transport of Materials

Materials Production

On site Energy Use

On site Electricity Use

Furnishings including transport to site

Transport of Workforce

Specific Site energy – landscaping etc

Operational heating

Operational control (electricity)

Functional Electricity Use

Intrinsic Refurbishment Energy

Functional Refurbishment Energy

Demolition

Intrinsic Energy Site Specific Energy

Functional Energy Regional Energy Overheads

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Life Cycle Energy Requirements of ZICER compared to other buildings

All values in Primary energy Termodeck Comparison Comparison

Based on a GFA of 2573 m2 ZICER as built (GJ)

Naturally Ventilated ZICER (GJ)

Air conditioned ZICER (GJ)

Materials Production 22613 19348 19524

Transport of materials 1544 1566 1544

On site construction energy 2793 2793 2793

Workforce transport 2851 2851 2851

Operational Heating/Hot Water 24088 68175 94436

Plant Room Electricity 34474 6302 142117

Functional Electricity e.g. from lights, computers etc (60 years)

113452 113452 113452

Replacement energy - materials 6939 6349 7576

Demolition 687 674 674

TOTAL embodied energy over 60 years (GJ)

209441 221508 384967

Total excluding the functional electricity (GJ)

95990 108057 271516

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As Built 209441GJ

Air Conditioned 384967GJ

Naturally Ventilated 221508GJ


Materials Production

Materials Transport

On site construction energy

Workforce Transport

Intrinsic Heating energy etc.

Functional Energy

Refurbishment Energy

Demolition Energy

28%54% 34%51%

61%

29%

28

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


Compared the Air-conditioned office, ZICER as built 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

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• 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

ZICER Building

Photo shows only part of top

Floor

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Load factors

0%

2%

4%

6%

8%

10%

12%

14%

16%

Jan Mar May Jul Sep Nov Jan Mar May Jul Sep Nov

2004 2005

Lo

ad

Fa

cto

r

façade roof average

0

2

4

6

8

10

12

14

16

18

Jan Mar May Jul Sep Nov Jan Mar May Jul Sep Nov

2004 2005

kWh

/ m

2

Façade Roof

Façade (kWh)

Roof (kWh)

Total (kWh)

2004 2650 19401 22051

2005 2840 19809 22649

Output per unit area

Little difference between orientations in winter months

Performance of PV cells on ZICER

Winter Summer

Façade 2% ~8%

Roof 2% 15%

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02040

6080

100120140

160180200

9 10 11 12 13 14 15Time of Day

Wh

01020

3040506070

8090100

%

Top Row

Middle Row

Bottom Row

radiation

0

10

20

30

40

50

60

70

80

90

100

9 10 11 12 13 14 15Time of day

Wh

0

10

20

30

40

50

60

70

80

90

100

%

Block1

Block 2

Block 3

Block 4

Block 5

Block 6

Block 7

Block 8

Block 9

Block 10

radiation

All arrays of cells on roof have similar performance respond to actual solar radiation

The three arrays on the façade respond differently

Performance of PV cells on ZICER - January

Radiation is shown as percentage of mid-day maximum to highlight passage of clouds

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0

5

10

15

20

25

8.00 9.00 10.00 11.00 12.00 13.00 14.00 15.00 16.00

Time (hours)

Elev

atio

n in

the s

ky (d

egre

es)

January February November DecemberP1 - bottom PV row P2 - middle PV row P3 - top PV row

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0

1000

2000

3000

4000

5000

6000

7000

(Jan ) 1 (Mar) 11 (May) 21 (Aug) 31 (Oct) 41 (Dec) 51

Time (week number)

Ele

ctri

city

use

d/ge

nera

ted

(kW

h)

0

10

20

30

40

50

60

70

PV

per

cent

age

of th

e to

tal e

lect

rici

ty u

sage

Electricity from conventional sources PV electricity PV % of total


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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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Use of PV generated energy

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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Performance of PV cells: Unit Cost of Electricity Generated

is

ncn ruEI )1(.

Discounted Income from generation in the nth year of operation is:

Cumulative Income over all n years of lifetime must equals capital cost C and is:

n

x

xc ruECI

1

)1(.

nr

rm

E

Cu

)1(1

Rearranging and adding an annual maintenance cost m (expressed as a percentage of capital cost gives:

Annual Electricity generation Unit cost

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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

Grant was ~ £172 000 out of a total of ~ £480 000


Cost of Generated Electricity

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EngineGenerator

36% Electricity

50% Heat

GAS

Engine heat Exchanger

Exhaust Heat

Exchanger

11% Flue Losses3% Radiation Losses

86%

efficient

Localised generation makes use of waste heat.

Reduces conversion losses significantly

Conversion efficiency improvements – Building Scale CHP

61% Flue Losses

36%

efficient

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Conversion efficiency improvements

1997/98 electricity gas oil Total

MWh 19895 35148 33

Emission factor kg/kWh 0.46 0.186 0.277

Carbon dioxide Tonnes 9152 6538 9 15699

Electricity Heat

1999/2000

Total site

CHP generation

export import boilers CHP oil total

MWh 20437 15630 977 5783 14510 28263 923Emission

factorkg/kWh -0.46 0.46 0.186 0.186 0.277

CO2 Tonnes -449 2660 2699 5257 256 10422

Before installation

After installation

This represents a 33% saving in carbon dioxide

41


Load Factor of CHP Plant at UEA

Demand for Heat is low in summer: plant cannot be used effectivelyMore electricity could be generated in summer

42


Condenser

Evaporator

Throttle Valve

Heat rejected

Heat extracted for cooling

High TemperatureHigh Pressure

Low TemperatureLow Pressure

Heat from external source

Absorber

Desorber

Heat Exchanger

W ~ 0

Normal Chilling

Compressor

Adsorption Chilling

19

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A 1 MW Adsorption chiller

1 MW 吸附冷却器

• Adsorption Heat pump uses Waste Heat from CHP

• Will provide most of chilling requirements in summer

• Will reduce electricity demand in summer

• Will increase electricity generated locally

• Save 500 – 700 tonnes Carbon Dioxide annually

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Conclusions• Buildings built to low energy standards have cost ~ 5% more, but

savings have recouped extra costs in around 5 years.

• Ventilation heat requirements can be large and efficient heat recovery is important.

• Effective adaptive energy management can reduce heating energy requirements in a low energy building by 50% or more.

• Photovoltaic cells need to take account of intended use of cells to get the optimum use of electricity generated.

• Building scale CHP can reduce carbon emissions significantly

• Adsorption chilling should be included to ensure optimum utilisation of CHP plant, to reduce electricity demand, and allow increased generation of electricity locally.

• The Future: Biomass CHP? Wind Turbines?

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

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

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Keith Tovey (杜伟贤 )

http://www.cred-uk.org/

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Keith Tovey ( 杜伟贤)