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Low Energy Cooling BRE, 17th April 2007

• Low Energy Buildings - heating/cooling of Termodeck Buildings at UEA.

• Life Cycle Issues

• Providing Low Carbon Energy and cooling on the UEA Campus

Case Study: Termodeck Buildings at the University of East Anglia and Low Carbon Strategies at UEA

• Low Energy Buildings - heating/cooling of Termodeck Buildings at UEA.

• Life Cycle Issues

• Providing Low Carbon Energy and cooling on the UEA Campus

Keith Tovey (杜伟贤 ) Energy Science Director HSBC Director of Low Carbon Innovation

Acknowledgement: Charlotte TurnerCRed

Carbon Reduction

CRed

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Original buildings

Teaching wall

Library

Student residences

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Nelson Court

Constable Terrace

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Low Energy Educational Buildings

Elizabeth Fry Building

ZICER

Nursing and Midwifery

School

Medical School

Medical School Phase 2

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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.

Careful Monitoring, Analysis and Adaptive control can reduce energy consumption.

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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.

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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

~ U – value ~ 1.0 W m2 K-1

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The ground floor open plan office

The first floor open plan office

The first floor cellular offices

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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

10Air enters the internal

occupied space

Return stale air is extracted from each floor

Incoming air into

the AHU

Regenerative heat exchanger

Filter Heater

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

Space for future chilling

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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

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

Pre-cools the air before entering the

occupied space

The concrete absorbs and stores

the heat – like a radiator in reverse

Summer day

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Effect of New Control Strategies on Thermal Comfort

0

10

20

30

40

50

-3 -2 -1 0 1 2 3

Actual Vote

Per

cen

tage

Year 2

Year 1

0

10

20

30

40

50

-3 -2 -1 0 1 2 3

Actual Vote

Per

cent

age

Year 1

Year 2

Number Mean Vote Number Mean Vote

2004 224 0.10 352 0.12

2005 256 0.12 273 0.44

Winter Summer

Only data for relevant Metabolic Rates included in above table

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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%

15

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

Life Cycle Energy Requirements of ZICER compared to other buildings

Compared to 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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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

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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

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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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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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The Future

• New Medical School – 5th Termodeck Building on Campus– Will have full backup central computing server in

basement.– Cooling for this area will reject heat into heater banks

for heating building during winter. – May not need any other heating for building.– Initially chilling provided locally – ultimately connected

to UEA chilling network

• Top Floor of ZICER – Seminar Room– Investigate provision of Heating / Cooling of room

linked to room booking – i.e. only provide heating cooling to a high thermal acceptance level if room is booked in advance.

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Conclusions• The Termodeck construction is an effective method to

provide heating and cooling.

• Pre-cooling building overnight is an effective method to avoid /reduce the need for air-conditioning

• Close integration between client and designers regarding functional use of building is required to ensure effective provision of cooling.

• 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.

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

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