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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
222
• 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
The Importance of the Construction SectorLow Carbon Technologies
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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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Responding to the Challenge: Technical SolutionsSolar Thermal Energy
indirect solar cylinder Solar tank with combi boiler
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Normal hot water circuit
Solar Circuit
Responding to the Challenge: Technical SolutionsSolar Thermal Energy
Dual circuit solar cylinder
Solar Pump
666Annual Solar Gain 910 kWh
Solar Collectors installed 27th January 2004
Responding to the Challenge: Technical SolutionsSolar Thermal Energy
777
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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Responding to the Challenge: Technical SolutionsSolar Thermal Energy
2007 2008
Output from a 2 panel Solar Thermal Collector
999
Responding to the Challenge: Technical SolutionsSolar Thermal Energy
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
25000
30000
Interwar
post-war
1960s 1976 1985 1990 1994 2002 2006 gas oil SAP2005
kWh
House constructed in mid 1950s
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)
House constructed in mid 1950s
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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Annual CO2 Emissions
0
500
1000
1500
2000
2500
3000
A B C D E F G H
CO
2 em
issi
ons
(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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Annual CO2 Emissions
0
500
1000
1500
2000
2500
3000
A B C D E F G
CO
2 em
issi
ons
(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
19191919
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%
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
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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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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Annual CO2 Emissions
0
500
1000
1500
2000
2500
3000
A B C D E F
CO
2 em
issi
ons
(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%
The Future: Code for Sustainable Homes
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
The Importance of the Construction SectorLow Carbon Technologies
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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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Annual CO2 Emissions
0
500
1000
1500
2000
2500
3000
A B C D E F G H
CO
2 em
issi
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%
The Future: Code for Sustainable Homes
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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Annual CO2 Emissions
0
500
1000
1500
2000
2500
3000
A B C D E F G
CO
2 em
issi
ons
(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
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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
The Importance of the Construction SectorLow Carbon Technologies
36
• 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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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 also radiate heat back into room
Winter Night
In late afternoon heating is turned off.
Cool air
Cool air
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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.
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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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.
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
200
400
600
800
1000
-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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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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• 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
0
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4000
0 1 2 3 4 5 6
kW
h in
per
iod
No of people in household
Electricity Consumption
1 person
2 people
3 people
4 people
5 people
6 people
-100%
-50%
0%
50%
100%
150%
200%
1
% D
iffe
renc
e fr
om A
vera
ge
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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