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The Importance of the Construction SectorLow Carbon Technologies

Norfolk Association of ArchitectsCPD Seminar

23rd October 2008Low Carbon Architecture

CRedCarbon Reduction

N.K. Tovey (杜伟贤 ) M.A, PhD, CEng, MICE, CEnv Н.К.Тови М.А., д-р технических наук

Energy Science Director CRed Project

HSBC Director of Low Carbon Innovation

Recipient of James Watt Gold Medal5th October 2007

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• Solar Thermal• Photo Voltaic• Ground source heat pumps• Bio fuels• Impacts of strategies on Code for Sustainable Homes• Wind/ Micro Hydro/ CHP generation

• Thermal Mass• Embodied Energy/Life Time Energy Issues


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Responding to the Challenge: Technical SolutionsSolar Thermal Energy

Basic System relying solely on solar energy

Optimum orientation is NOT due South!

The more hot water used the more solar energy is gained.3

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indirect solar cylinder Solar tank with combi boiler

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Normal hot water circuit

Solar Circuit


Dual circuit solar cylinder

Solar Pump

666Annual Solar Gain 910 kWh

Solar Collectors installed 27th January 2004


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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

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2007 2008

Output from a 2 panel Solar Thermal Collector

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Optimum size for a collector will be 2 – 3 panels depending on household size.

In winter, limited solar gain

Although few days without any benefit at all. Increased size of collector area increases gain in winter But 2 panels already give too much hot water in summer. An optimum size in financial terms needs to be considered.

Most cost effective solution and most carbon reduction in a Housing Association context: Have neighbouring houses hot water connected – say 3

houses with ~ 5 panels Winter: system supplies most (if not all) requirements for one

house. Other two use conventional means for hot water Summer: all houses have hot water solely from Solar

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How has the performance of a typical house changed over the years?

Bungalow in South West Norwich built in mid 1950s

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Annual Energy Consumption

0

5000

10000

15000

20000

25000

30000

Interwar

post-war

1960s 1976 1985 1990 1994 2002 2006

kWh

House constructed in mid 1950s

Part L first introduced

~>50% reduction

First attempt to address overall consumption. SAP introduced.

Changing Energy Requirements of House

In all years dimensions of house remain same – just insulation standards change

As houses have long replacement times, legacy of former regulations will affect ability to reduce carbon emissions in future

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Annual Energy Consumption

0

5000

10000

15000

20000

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Interwar

post-war

1960s 1976 1985 1990 1994 2002 2006 gas oil SAP2005

kWh


Changing Energy Requirements of House

Existing house – current standard: gas boiler

Improvements to existing properties are limited because of in built structural issues – e.g. No floor insulation in example shown.

House designed to conform the Target Emission Rate (TER) as specified in Building Regulations 2006 and SAP 2005.

As Existing but with oil boiler

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Annual CO2 Emissions

0

1000

2000

3000

4000

5000

6000

7000

8000

9000

Interwar

post-war

1960s 1976 1985 1990 1994 2002 2006 gas oil SAP2005

CO

2 em

issi

ons

(kg)


Changing Carbon Dioxide Emissions

Existing house – current standard: gas boiler

Notice significant difference between using gas and oil boiler.

House designed to conform the Target Emission Rate (TER) as specified in Building Regulations 2006 and SAP 2005.

As Existing but with oil boiler

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• Improved Fabric / standard appliance Performance• SAP 2005 standard reference

Responding to the Challenge:

Item SAP reference

Improved Value 1

Improved Value 2

Windows U-value = 2 U-value = 1.4

Walls U-value = 0.35 U-value = 0.25

U-value = 0.1

Floor U-value = 0.25

Roof U-value = 0.16

Boiler efficiency

78% 83% default 90% SEDBUK

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A B C D E F G H

CO

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(kg)

The Future: Code for Sustainable Homes

CO2 Emissions (kg) Reduction

A SAP Reference 2504 0B Boiler η = 83% (default) 2377 5%C Boiler η = 90% (SEDBUK) 2229 11%D η = 90%: Walls: U = 0.25 2150 14%E η = 90%: Walls: U = 0.10 2034 19%F η = 90%: Windows: U = 1.4 2112 16%G C + D + F 2033 19%H C + E + f 1919 23%

Improvements in Insulation and boiler performance

Code 1

Code 2

H nearly makes code 3

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0

500

1000

1500

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2500

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A B C D E F G

CO

2 em

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(kg)

CO2 (kg) Reduction

A SAP Reference 2504 0B Boiler η = 90% (SEDBUK) 2229 11%C η = 90%: Solar Thermal – 2 panels dual cylinder 2061 18%D η = 90%: Solar Thermal – 2 panels separate cylinder 2027 19%E η = 90%: Solar Thermal – 3 panels separate cylinder 1991 20%F η = 90%: Solar Thermal – 4 panels separate cylinder 1969 21%G η = 90%: Solar Thermal – 5 panels separate cylinder 1953 22%

Responding to the Challenge: Solar Thermal

Improvements using solar thermal energy

Code 1

Code 2

Note: little extra benefit after 3 panels, but does depend on size of house

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SResponding to the Challenge: Technical SolutionsSolar PhotoVoltaic

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.

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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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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

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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%

On roof ~100 kWh/ m2 per annum In Norwich, domestic consumption is ~ 3700 kWh per annum >>> Need ~ 37 sq m

202020

02040

6080

100120140

160180200

9 10 11 12 13 14 15Time of Day

Wh

01020

3040506070

8090100

%

Top Row

Middle Row

Bottom Row

radiation

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9 10 11 12 13 14 15Time of day

Wh

0

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%

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

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8.00 9.00 10.00 11.00 12.00 13.00 14.00 15.00 16.00

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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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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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A B C D E F

CO

2 em

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(kg)

CO2 (kg) Reduction

A SAP Reference 2504 0B Boiler η = 90% (SEDBUK) 2229 11%C η = 90%: Solar PV 5 sqm 2052 18%D η = 90%: Solar PV 10 sqm 1874 25%E η = 90%: Solar PV 5 sqm + 2 panel solar thermal 1883 25%F η = 90%: Solar PV 7.4 sqm + 2 panel solar thermal 1798 28%


Improvements using solar Photovoltaic

Code 1

Code 2

Code 3

Note: 2 panels of solar thermal have same benefit as 5 sqm of PV

Responding to the Challenge: Solar PhotoVoltaic

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• Solar Thermal• Photo Voltaic• Ground source heat pumps• Bio fuels• Impacts of strategies on Code for Sustainable Homes

• Wind generation• Thermal Mass• Embodied Energy/Life Time Energy Issues


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Responding to the Challenge: Technical SolutionsThe Heat Pump

Images from RenEnergy Website

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Responding to the Challenge: Technical SolutionsThe Heat Pump

Any low grade source of heat may be used• Coils buried in garden 1 – 1.5 m deep• Bore holes• Lakes/Rivers are ideal• Air can be used but is not as good

• Best performance is achieved if the temperature source between outside source and inside sink is as small as possible.

Under floor heating should always be considered when installing heat pumps in for new build houses – operating temperature is much lower than radiators.

Attention must be paid to provision of hot water - performance degrades when heating hot water to 55 – 60oC

Consider boost using off peak electricity, or occasional “Hot Days”

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0

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A B C D E F G H

CO

2 em

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ons

(kg)

CO2 (kg) Reduction

A SAP Reference 2504 0B Boiler η = 90% (SEDBUK) 2229 11%C Ground to Water Heat Pump (Radiators) 1661 34%D Air to Water Heat Pump (Radiators) 1962 22%E Ground to Air Heat Pump 1606 36%F Air to Air Heat Pump 1907 24%G Ground to Water Heat Pump (Under floor) 1553 38%H Air to Water Heat Pump (Under floor) 1830 27%


Improvements using Heat Pumps

Code 1

Code 2

Code 3

Code 4

Code 3

Responding to the Challenge: The Heat Pump

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A B C D E F G

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(kg)

CO2 (kg) Reduction

A SAP Reference 2504 0%B Boiler η = 90% (SEDBUK) 2229 11%C Biomass Boiler 673 73%D Biomass Boiler with Solar Thermal 670 73%E Biomass Boiler with 5m Photovoltaic 496 80%F Biomass Boiler with 10m Photovoltaic 318 87%

GBiomass Boiler + 10m PV + improved insulation + 100% Low Energy lighting

147 94%

The Future: Code for Sustainable Buildings

Improvements using Biomass options

Note: Biomass with solar thermal are incompatible options

Code 1

Code 2

Code 3

Code 4

Code 4

Responding to the Challenge: Biomass Boilers

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Micro CHP

Ways to Respond to the Challenge: Technical Solutions

• Micro CHP plant for homes are being trialled.• Replace the normal boiler• But there is a problem in summer as there is limited demand for

heat – electrical generation will be limited.• Backup generation is still needed unless integrated with solar

photovoltaic?• In community schemes explore opportunity for multiple unit

provision of hot water in summer, but only single unit in winter.

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Other Renewable Technologies

Micro Wind

Vertical Axis Mini Wind

http://www.quietrevolution.co.uk/video/qr5_320/320_video.htm

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6 kW Proven Turbine powering a Heat Pump providing heating for Parish Kirk, Westray

Horizontal Axis Mini Wind

In 2007/8, mini wind turbines had a load factor of ~ 10.5% on average>>> annual output of approximately 5500 kWh/annum

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Micro Hydro Scheme operating on Syphon Principle installed at Itteringham Mill, Norfolk.

Rated capacity 5.5 kw

Other Renewable Technologies

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Medium to Large Scale Turbines – sensible option in new developments, provided they are connected by Private Wire

Sub-station

Connection to Distribution Network

Load Factor for large on-shore in 2007 - 8 ~ 26.5%

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• Solar Thermal• Photo Voltaic• Ground source heat pumps• Bio fuels• Impacts of strategies on Code for Sustainable Homes• Wind/ Micro Hydro/ CHP generation

• Thermal Mass• Embodied Energy/Life Time Energy Issues


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• As fabric insulation levels improve, ventilation starts to become the dominant issue in heat loss/heat gain

• Can be in in excess of 60+% of heating/cooling requirements

• Adequate ventilation is needed for health and well being

• BUT, outside air has to be heated/cooled and can be a significant energy requirement in uncontrolled natural ventilation.

• Consider heat recovery using regenerative heat exchangers

• Buildings with thermal mass allow pre-cooling of building overnight reducing cooling demand.

Ventilation Issues? Thermal Mass

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The Climate Dimension: Cooling Issues

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.

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

Estimated 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

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Incoming air into

the AHU

Regenerative heat exchanger

Operation of Main BuildingMechanically ventilated using hollow core slabs as air supply ducts.

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Air enters the internal occupied space

Filter Heater

Air passes through hollow

cores in the ceiling slabs

Operation of Main Building

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Return stale air is extracted

Return air passes through the heat exchanger

Out of the building

Operation of Main Building

Recovers 87% of Ventilation Heat Requirement.

Space for future chilling

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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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Fabric Cooling: Importance of Hollow Core Ceiling Slabs

Hollow core ceiling slabs store heat and cool at different times of the year providing comfortable and stable temperatures.

Heat is transferred to the air before entering

the room

Slabs store heat from appliances and body

heat

Winter Day

Air Temperature is same as building fabric leading to a more pleasant working environment

Warm air

Warm air

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Heat is transferred to the air before entering

the room

Slabs also radiate heat back into room

Winter Night

In late afternoon heating is turned off.

Cool air

Cool air

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Draws out the heat accumulated during the

day

Cools the slabs to act as a cool store the following day

Summer night

night ventilation/ free cooling

Cold air

Cold air

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Slabs pre-cool the air before entering the

occupied spaceconcrete absorbs and stores heat less/no need for air-

conditioning

Summer day

Warm air

Warm air

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0

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

Mean |External Temperature (oC)

En

ergy

Con

sum

pti

on (

kW

h/d

ay)

Original Heating Strategy New Heating Strategy

Good Management has reduced Energy Requirements

800

350

Space Heating Consumption reduced by 57%

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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

494949

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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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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• How can low carbon homes be provided at an affordable cost?• Energy Service Companies (ESCos)• Home costs same initial cost as traditional home• Any additional costs for providing renewable energy, better insulation/controls are financed by ESCo• Client pays ESCo for energy used at rate they would have done had the house been built to basic 2005 standards• ESCo pays utility company at actual energy cost (because energy consumption is less)• Difference in payments services ESCo investment• When extra capital cost is paid off

• Client sees reduced energy bills• ESCO has made its money• Developer has not had to charge any more for property• The Environment wins•

Responding to the Challenge:

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The Behavioural Dimension

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kW

h in

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iod

No of people in household

Electricity Consumption

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2 people

3 people

4 people

5 people

6 people

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% D

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Variation in Electricity Cosumption1 person 2 people 3 people4 people 5 people 6 people

Social Attitudes towards energy consumption have a profound effect on actual consumption

Data collected from 114 houses in Norwich between mid November 2006 and mid March 2007

For a given size of household electricity consumption for appliances [NOT HEATING or HOT WATER] can vary by as much as 9 times.

When income levels are accounted for, variation is still 6 times

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Significant Improvements can be achieved• Better Insulation Standards• Heat Pumps• Biomass Boilers• Solar Thermal• Solar PV

Responding to the Challenge: Conclusions

But avoid incompatible options• Too large a Solar thermal Array• Biomass with solar thermal• CHP with Solar Thermal

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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