1 Concrete in Construction and the Impact of Climate Change Keith Tovey ( ) MA, PhD, CEng, MICE, CEnv Energy Science Director HSBC Director of Low Carbon

1

Concrete in Construction and the Impact of Climate Change

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

Energy Science Director HSBC Director of Low Carbon Innovation

CRedCarbon Reduction

Concrete Society MeetingNorwich

30th October 2007

CRed

Recipient of James Watt Medal5th October 2007

2

ZICER Building

Heating Energy consumption as new in 2003 was reduced by further 57% 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.

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

19792003

Climate ChangeArctic meltdown 1979 - 2003

• Summer ice coverage of Arctic Polar Region– Nasa satellite

imagery

Source: Nasa http://www.nasa.gov/centers/goddard/news/topstory/2003/1023esuice.html

•20% reduction in 24 years

http://www.nasa.gov/centers/goddard/news/topstory/2003/1023esuice.html

5

"Clean Coal"

Traditional Coal ~40%- coal could

supply 40 - 50% by 2020

Available now: Not viable without Carbon Capture & Sequestration

2.5 - 3.5p - but will EU - ETS carbon trading will affect

this

Options for Electricity Generation in 2020 - Non-Renewable Methods

nuclear fission (long term)

0 - 30% (France 80%) - (currently 20% and falling)

new inherently safe designs - some practical development needed

2.5 - 3.5p

nuclear fusion unavailablenot available until 2040 at earliest

potential contribution to Supply in 2020

costs in 2020

Wholesale Price of Electricity since NETA

0

10

20

30

40

50

60

70

2001 2002 2003 2004 2005 2006 2007

Bas

eloa

d P

rice

s (£

/MW

h)

first 5 years

last 12 months

0

2000

4000

6000

8000

10000

12000

14000

1955 1965 1975 1985 1995 2005 2015 2025 2035

Inst

all

ed C

ap

aci

ty (

MW

)

New Build ?

ProjectedActual

Nuclear New Build assumes one new station is completed each year after 2018.

Gas CCGT0 - 80% (currently

35% )

available now, but UK gas will run out within current decade

~ 2p + but recent trends put figure

much higher

6

On Shore Wind ~25% available now for commercialexploitation

~ 2p

Hydro 5% technically mature, but limitedpotential

2.5 - 3p

Resource Potential contribution to electricity supply in2020 and drivers/barriers

Cost in2020

Options for Electricity Generation in 2020 - Renewable

7

Photovoltaic 50% available, but much research neededto bring down costs significantly

10+ p


~ 2p


2.5 - 3p


Cost in2020


Area required to supply 5% of UK electricity needs ~ 300 sq km

But energy needed to make PV takes up to 8 years to pay back in UK.

8


10+ p

Energy Crops/ Biomass/Biogas

50% + available, but research needed in some areas

2.5 - 4


~ 2p


2.5 - 3p


Cost in2020


But Land Area required is very large - the area of Norfolk and Suffolk would be needed to generated just over 5% of UK electricity needs.

Transport Fuels:

• Biodiesel?

• Bioethanol?

• Compressed gas from methane from waste.

9


10+ p

Energy Crops 100% + available, but research needed insome areas

2.5 - 4

Wave/Tidal Stream

100% + ultimately

techology limited - major development unlikely before 2020 ~ 3–4%

4 - 8p


~ 2p


2.5 - 3p


Cost in2020


10


10+ p


2.5 - 4


~ 2p


2.5 - 3p


Cost in2020


Wave/Tidal Stream

100% + ultimately


4 - 8p

11

Wave/Tidal Stream

100% + ultimately


4 - 8p


10+ p


2.5 - 4

Tidal Barrages 10 - 20% technology available but unlikelywithout Government intervention

notcosted


~ 2p


2.5 - 3p


Cost in2020


Output (MWh)

0

100

200

300

400

500

600

700

01/0

1/20

02

15/0

1/20

02

29/0

1/20

02

12/0

2/20

02

26/0

2/20

02

12/0

3/20

02

26/0

3/20

02

09/0

4/20

02

23/0

4/20

02

07/0

5/20

02

21/0

5/20

02

04/0

6/20

02

18/0

6/20

02

02/0

7/20

02

16/0

7/20

02

30/0

7/20

02

13/0

8/20

02

27/0

8/20

02

10/0

9/20

02

24/0

9/20

02

08/1

0/20

02

22/1

0/20

02

05/1

1/2

002

19/1

1/2

002

03/1

2/20

02

17/1

2/20

02

31/1

2/20

02

Out

put

(MW

h pe

r da

y)

Output 78 000 GWh per annum

Sufficient for 13500 house in Orkney

Save 40000 tonnes of CO2

12


10+ p


2.5 - 4

Wave/TidalStream

100% + techology limited - extensivedevelopment unlikely before 2020

4 - 8p

Tidal Barrages 10 - 20% technology available but unlikelywithout Government intervention

notcosted

Geothermal unlikely for electricity generationbefore 2050 if then


~ 2p


2.5 - 3p


Cost in2020


13

Solar Energy - The BroadSol Project

Annual Solar Gain 910 kWh

Solar Collectors installed 27th January 2004

14

Performance of a Solar Thermal System

Solar Gain (kWh/day)

0

1

2

3

4

5

6

7

8

9

10 20 30 9 19 29 8 18 28 10 20 30 9 19 29 9 19 29 8 18 28 8 18 28 7 17 27 6 16 26 6 16 26

Day of Month

Sola

r G

ain

(kW

h)

December January February

March April May

June July August

September October

Data collect 9th December 2006 – 30th October 2007

15

House in Lerwick, Shetland Isles with Solar Panels

- less than 15,000 people live north of this in UK!

It is all very well for South East, but what about the North?

House on Westray, Orkney exploiting passive solar energy from end of February

16

Actual Nuclear

Projected Nuclear

Actual Coal with FGD

Opted Out Coal

Renewables

New Nuclear?

New Coal ???

0

10000

20000

30000

40000

50000

60000

2000 2005 2010 2015 2020 2025 2030

MW

• Opted Out Coal: Stations can only run for 20 000 hours more and must close by 2015• New Nuclear assumes completing 1 new nuclear station each year beyond 2018• New Coal assumes completing 1 new coal station each year beyond 2018

Our Choices: They are difficult: Energy SecurityThere is a

looming capacity shortfall

Even with a full deployment of

renewables.

A 10% reduction in demand per

house will see a rise of 7% in total demand

- Increased population decreased

household size

17

Our Choices: They are difficult

If our answer is NO

Do we want to return to using coal? • then carbon dioxide emissions will rise significantly

• unless we can develop carbon sequestration and apply it to ALL our COAL fired power stations within 10 years - unlikely.

If our answer to coal is NO

Do we want to leave things are they are and see continued exploitation of gas for both heating and electricity generation? >>>>>>

Do we want to exploit available renewables i.e onshore/offshore wind and biomass. Photovoltaics, tidal, wave are not options for next 20 years.

If our answer is NO

Do we want to see a renewal of nuclear power

• Are we happy with this and the other attendant risks?

18

Our Choices: They are difficult

If our answer is YES

By 2020

• we will be dependent on around 70% of our heating and electricity from GAS

• imported from countries like Russia, Iran, Iraq, Libya, AlgeriaAre we happy with this prospect? >>>>>>

If not:

We need even more substantial cuts in energy use.

Or are we prepared to sacrifice our future to effects of Global Warming by using coal? - the North Norfolk Coal Field? –

Aylsham Colliery, North Walsham Pit?

Do we wish to reconsider our stance on renewables?

Inaction or delays in decision making will lead us down the GAS option route

and all the attendant Security issues that raises.

19

The Climate Dimension

Heating requirements are ~10+% less than in 1960

Cooling requirements are 75% higher than in 1960.

Changing norm for clothing from a business suite to shirt and tie will reduce “clo” value from 1.0 to ~ 0.6.

To a safari suite ~ 0.5.Equivalent thermal comfort can be achieved with around 0.15 to 0.2 change in “clo” for each 1 oC change in internal environment.

Care in design is needed to avoid overheating in summer and to minimise active cooling requirements

Thermal Comfort is important: Even in ideal environment 2.5% of people will be too cold and 2.5% will be too hot.

Estimate heating and cooling requirements from Degree Days

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

Heavy Weight Buildings can help to reduce energy requirements in a warming climate.

20

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.

21

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%

22

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

23

The ground floor open plan office

The first floor open plan office

The first floor cellular offices

24Air enters the internal

occupied space

Return stale air is extracted from each floor

Incoming air into

the AHU

Regenerative heat exchanger

FilterHeater

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 using hollow core ceiling slabs as supply air ducts to the space Recovers 87% of

Ventilation Heat Requirement.

25

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

Winter Day

The concrete slabs absorb and

store heat

Heat is transferred to the air before entering

the room

Winter day

26



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

concrete is emitted back into the room

Winter night

27



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

28



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

29

• 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

30

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

But this has only been possible because of realtively heavy weight construction

31

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%

32

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

33

• 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

34

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.

35

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

36

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

37

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

38


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

39


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

40

A 1 MW Adsorption chiller

• 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

41

Target Day

Results of the “Big Switch-Off”

With a concerted effort savings of 25% or more are possibleHow can these be translated into long term savings?

42

The Behavioural Dimension

Electricity Consumption

0

200

400

600

800

1000

1200

0 1 2 3 4 5 6 7No. people

Ave

rage

kW

h/m

onth

• 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

43

Conclusions• Hard Choices face us in the next 20 years

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

• Heavy weight buildings can be used to effectively control energy consumption

• Photovoltaic cells need to take account of intended use of electricity use in building to get the optimum value.

• 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.

• Promoting Awareness can result in up to 25% savings

• The Future for UEA: 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."

Documents

1 Concrete in Construction and the Impact of Climate Change Keith Tovey ( ) MA, PhD, CEng, MICE, CEnv Energy Science Director HSBC Director of Low Carbon