district cooling design & case study

District Cooling Power & Cost savings

January 2011

Designing for Life

District Cooling

Power & Cost Saving


District Cooling Power

and Cost savings

Main

Heading

Table of

Contents

01. District Cooling

02. Case Studies

03. Animation

District Cooling Power & Cost Savings

District Cooling

01


Description

Involves the provision of cooling for multiple buildings

or facilities from one or more central plant via a pipe network.

District

Cooling

History

Large District Cooling applications started in the 1930s for

the Rockefeller Center and United States Capitol Complex.


District

CoolingPiping

Distribution

DC Plant

Pipes

Valve Chamber ETS


District

CoolingPipes in

Tunnel

Pipes in Trench Pipes in Tunnel

Pipes in Tunnel with Branch-out


District

CoolingValve

Chamber


District

Cooling

Energy

Transfer

Station

Heat Exchanger

Schematic - Energy Transfer Station with Heat Exchanger to Apartment Block


District

CoolingDistrict

Plant

Chiller Plant at Ground Level Pumps in BasementCooling Tower at Roof Level

Vertical Arrangement

DC Plant – Verticle Arrangement


District

CoolingDistrict

Plant

Cooling Towers – Horizontal Arrangement

Kuwait University


District

CoolingDistrict

Plant

DC Plant– Horizontal Arrangement (Kuwait University)


Ice Storage Tank

District

CoolingThermal

Storage

1. Chilled Water

2. Ice

3. Eutectic Salts

Pre-stressed Concrete Tank Thermal Energy Storage


District

CoolingDistrict

Plant

District Cooling Plant – Architecture


CaseStudy

02

• Residential Areas• Inner-City


Residential Area Case Study based

on Jaber Al-Ahmad City

(Areas B & A5)


Residential

Area-

Design

Basis

Case

Study

Cooling Loads – Estimation Basis


Case

StudyResidential

Areas

Number of Houses = 1836

Estimated built up area of housing = 1,560,600 m2(95% of total Built up area)

Total Built up area including Mosques, Schools,Clinic, Shopping centre, Bank, Office Buildings etc. = 1,645,438 m2

Chiller plant capacity = 36,790 TR

Thermal Storage = 4879.6 TR (11.7% of total)

TOTAL DISTRICT COOLING PLANT CAPACITY = 41,670 TR


Case

StudyResidential

Areas

Plant Arrangement

&

Chilled Water Distribution


Residential

Areas

Case

Study

Roof Plan

Overall Area = 136m x 40m

Foot Print = 7.66 M2/TR


Residential

Areas

Case

Study

Ground Floor Plan


Residential

Areas

Case

Study

Enlarged view

Basement Floor Plan


Residential

Areas

Case

Study

Enlarged View - Basement Plan


Residential

Areas

Case

Study

Site Plan - Chilled Water Distribution

Enlarged view


Residential

Areas

Case

Study

Site Plan Enlarged view - Chilled Water Distribution


Residential

Areas

Case

Study

Chilled Water Network Flow Simulation


Residential

Areas

Case

Study

Typical Cross Section of Local Road with Bldg. Connection


Chilled Water Pipe Network

• System Static Pressure - 6 bar

• Pressure difference between closest and furthest node is 24m.

Residential

Areas

Case

Study


Chilled Water Temperature Increase

• Calculations indicate that water temperature increase over the

longest route is 0.3 deg-C

• The calculations were based on Supply at 5.0 Deg-C, Return at

14.0 Deg-C

• Loss in thermal energy due to pipe-work distribution is

approximately 1 % overall

Residential

Areas

Case

Study


Case

StudyResidential

Area

Power & Energy


Case

Study

Residential

Area-

Cooling

Load


Case

Study

Discharging Mode

Charging Mode

Charging / Discharging Mode (TES Tank)

Residential

Areas


Case

Study

Residential

Area-

Cooling

Load

District Cooling Efficiency

With TES = 0.86 KW/TR

Without TES = 1.00 KW/TR

Based on R-134a Refrigerant

Conventional Air Cooled Systems (excluding Indoor Units)

Efficiency = 1.6 - 1.8 KW/TR (peak load/peak cooling)

Assume Air Distribution Equipment Efficiency = 0.2 KW/TR

Based on R22 Refrigerant and

equivalent diverse electrical load

PEAK POWER SAVING = 50% (on average)


Case

Study

Residential

Area-

Cooling

Load

Annual DCS

Energy Demand = 101.9 GWh

Annual Air Cooled System

Energy Demand = 182.2 GWh

Yearly Energy Saving = 40% on average

when compared with conventional

Air-cooled systems (1.6-1.8 kW/TR)

District Cooling vs. Air cooled Energy Demand


Peak Daily Demand

Total Demand = 7048 m3

Yearly Demand

Fresh Water Demand = 1,156,000 m3

If TSE is utilized = 1,502,800m3

Sea Water can be utilized for installations near the sea

Case

Study

Residential

Area-

Water

Demand


CODE OF PRACTICE MEW/R-6 (Revised)

• Clause 8.8 District Cooling states

"District cooling shall be applied for new townships, university

campuses and similar neighborhood, in view of its proven

advantage for energy saving and peak load shaving. HVAC design

report shall include detailed feasibility study highlighting energy

savings potential and cost effectiveness over a 30 year life for plant

and equipment”

Residential

Areas

Case

Study


Residential

Areas

Case

Study

Electicity Cost VS Fuel Cost

0

10

20

30

40

50

60

70

80

90

0 20 40 60 80 100

120

Barrel of Oil Cost ($)

Ele

ctr

icit

y U

nit

Co

st

(Fil

ls/K

W-H

r)

Fuel Cost

Transmission Cost

Opportunity Costs


Residential

Areas

Case

Study

Power Plant Savings

Saved Power (50% saving) 39,586 KW

Capital Costs

Power Generation 400 KD/KW 15,834,400

Distribution Saving 50 KD/KW 1,979,300

Total KD 17,813,700

Annual Energy Saving (40% on average) 73 GW-HR

Power Generation & Distribution 60 Fils/Unit 4,138,000

Total KD 4,138,000


Residential

Areas

Case

Study

Water Generation Costs Cost (KD)

Plant Capital Cost

Peak Day Water Requirement 7048 M3

Desalination Cost - RO Plant @ 820 KD/m3 5,779,360

Production & Distribution

Annual Water Requirement 1,156,000 M3

Fresh Water Cost @ 768

(3,494)

Fils/M3

(1000 Gal)

887,808


Capital and Running Cost Savings

Potential Savings in Capital Cost = KD12,034,340

Potential Savings (Opportunity) = KD 3,250,192/year@ 90$ US/barrel

Case Study

Case

Study

Residential

Areas


Case

Study

Residential

Areas

Extract from MEW R-6

“HVAC design report shall include detailed feasibility study highlighting energy savings potential and cost

effectiveness over a 30 year life for plant and equipment”

Suggested incentives to achieve cost effectiveness

Passover some of the savings by Government to the DC Provider

Pass over some of the capital savings by:

Covering cost of chilled water pipe installation (same as other piped

utilities)

Provide land (as for sub-stations)

Set chilled water generation charges based on ‘unsubsidized rates’ with

incentives linked to production efficiencies


Residential

Areas

Case

Study

The Main Environmental Benefits

• Smaller Carbon Emission Foot Print

• Energy Conservation

• Less Noise From Air- Cooled Units

• Less Thermal Impact on Local Environment

• Better usage of built space (roof garden etc.)

• More Efficient Temperature Control


Residential

Areas

Case

Study

Carbon Emission Savings

• Every MW-Hr Demand Produces 0.788 Tons of CO2

• 41,700TR DC Plant Reduces CO2 Emission by 65,800 Tons per Year


Inner-City

Inner-City Area Design

Case Study based on

Abdullah Al-Ahmed Street


Inner-City

Case

Study

Perspective – Abdullah Al-Ahmed Street


Inner-City

Case

Study


Building Type Built Up Area (m2)

Residential 124,630

Offices 436,800

Commercial 133,463

Total 694,463

Inner-City

Case

Study

District Cooling Power & Cost savingsDC Plant integrated in Car Park Building to optimize on Parcel Usage

Inner-City

Case

Study


Inner-City

Case

Study

Ground Floor Plan – Chiller Plant Layout


Inner-City

Case

Study

Basement Plan – Pump Room Layout

Detail view


Inner-City

Case

Study

Ice Storage Tank Lay-out Schematic – Detail view

Images


Inner-City

Case

Study

Charging / Discharging Mode (Internal Melt Ice Storage)

Charging Mode

Discharging Mode

District Cooling Power & Cost savingsSite-Wide Chilled Water Pipe Distribution Network

Inner-City

Case

Study


Case

Study Inner-City

Power & Energy


Inner-City

Case

Study


Plant Item Plant Cooling Capacity

KWh Ton-hr KW TR

Water Cooled Chillers 1,270,880 361,363 54,162 15,400

Glycol Chiller Capacity 419,920 119,387 30,950 8,800

Thermal Ice Storage 144,860 41,189 23,145 6,581

Total DC Plant Capacity 1,835,660 521,939 108,257 30781

Plant Efficiency – KW/TR 0.805

Inner-City

Case

Study


Energy Demand Profile (DCS Ice Storage vs.

Conventional Water-Cooled System)

Inner-City

Case

Study


Inner-City

Case

Study

Energy Demand Profile (DCS Ice Storage vs. A mix of 70% Capacity

Conventional Water-Cooled System & 30 % Air Cooled


Inner-City

Case

Study


Case

Study

Economical Consideration

&

Sustainable Design

Inner-City


Inner-City

Case

Study

EXCERPTS FROM LATEST MEW/R-6 REGULATION (2010)

• Clause 8.5 Use of Partial Cool Storage (Chilled Water Storage)

“Building with part-day occupancy pattern and chilled water systems servingbuilding peak load of 100 RT or above, partial cool storage is mandatory.Some examples of building with part-day occupancy are: commercial offices,community centers, schools, public offices, banks, games and sportscenters, gymnasiums, clubs etc.”


Inner-City

Case

Study

why District Cooling?

• Larger chiller plant better efficiency (less power)

• Better energy management through better qualified staff

• Reduces building construction cost by removing central plant and improving building net-to-gross efficiency

• Can help improve building aesthetics

• Allows End User to better focus on core business.

• Less noise generation


Incentive Factors

• Pass over savings in central plant and building costs by the developer to the DC Provider (capacity and connection charges)

• Pass over running costs savings (operation, maintenance, consumables)

• Introduce Government incentives to offset capital costs –

allow integration of DC plants within multistory car parks or provide land

allow incentive schemes based on DC plant efficiencies (KW/TR)

Case

Study Inner-City


Inner-City

Case

Study

• Match capacity of the central chiller plant with the buildings

• Select pipe sizes & material based on economical factors

• Match Primary & Secondary flow arrangements (variable flow)

• Install controls with good response times

• Provide thermal storage to help operate plant at optimum condition

• Maintain highest Chilled water ΔT possible

• Maintain highest chilled water flow temperature possible

• Use high efficiency motors

• Consider Variable speed cooling tower fans

• Use Water conservation and backwash recovery

Sustainable Design Considerations


Animation

03


Animation

District

Cooling


Thank you

district cooling design & case study

Engineering

provision of cooling

central plant

residential areas innercity

case studies

area total

m2 chiller plant capacity

tunnel pipes

area of housing