1 low carbon strategies at the university of east anglia low energy buildings providing low carbon...
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Low Carbon Strategies at the University of East Anglia
• Low Energy Buildings• Providing Low Carbon Energy on Campus
Keith Tovey (杜伟贤 )
HSBC Director of Low Carbon Innovation
Acknowledgement: Charlotte TurnerCRed
Carbon Reduction
Buildings and our Changing ClimateThe Tate Britain, 16 November 2006
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
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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.
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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
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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
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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.
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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
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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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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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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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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
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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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 absorbs and
store heat
Heat is transferred to the air before entering
the room
Winter day
17
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 NightWhen the internal air temperature drops, heat stored in the
concrete is emitted back into the room
Winter night
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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%
20
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
Performance of PV cells on ZICER
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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
25
Actual Situation excluding Grant
Actual Situation with Grant
Discount rate 3% 5% 7% 3% 5% 7%
Unit energy cost per kWh (£) 0.89 0.90 0.91 0.56 0.57 0.57
Avoided cost exc. the Grant
Avoided Costs with Grant
Discount rate 3% 5% 7% 3% 5% 7%
Unit energy cost per kWh (£) 0.36 0.37 0.38 0.03 0.04 0.05
Grant was ~ £172 000 out of a total of ~ £480 000
Performance of PV cells on ZICER
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
27
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
28
Conversion efficiency improvements
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
29
Conversion efficiency improvements
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
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30
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
31
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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