Building Energy Auditing - Department of Energy

1

DEPARTMENT OF MINERALS AND ENERGYDME-Danida Capacity Building in Energy Efficiency & Renewable Energy

Building Energy Auditing

Energy Assessment andSavings OpportunityIdentification


Module 1: A Context forBuilding Energy Audits

Energy Efficiency in SouthAfrican Buildings


Module 2: Basic Principles ofEnergy

Understanding how energyworks in buildings

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DME Building Energy Audit Course 4

DEPARTMENT ofMINERALS and ENERGY

Learning objectives

Define energy in its various forms and energy relatedproperties;Use the correct units for energy and power, and convertfrom one unit to another as needed;Determine the properties of steam and moist air;Describe the mechanisms by which heat is transferred;Explain the effect of insulation on heat transfer, and themeans by which radiative heat transfer is controlled.



Energy in its variousforms

Chemical – in fuelsThermal – sensibleand latentMechanicalElectrical

Energy Equivalents

1000 joules (J) 1 kilojoule (kJ)

1 kilowatt-hour (kWh) 3,600,000 J or 3.6 MJ



Basic electricity

VoltageThis is what pushes electricity through a circuit - the

“driving force”

Units are Volts (V)

CurrentThis is what is pushed through by the voltage - the

“flow”

Units are Amperes (A) (“Amps”, for short)

3



Electrical power

When voltage and current work together todo something useful - such as turn a motoror light a lamp

Units are Watts1000 Watts = 1 kilowatt (kW)1 horsepower (HP) = 746 Watts



AC/DC

220 volts DC vs. time

220

0 1/50 sec

310

220

0

-310

220 volts RMS



Calculating power

Watts = Volts x Amps x Power FactorVA = Volts x Amps

Power factor (PF) indicates how well thecurrent and voltage are working together

Incandescent Lamps 100%Large Motors 80-90%Small Motors 60-75%

4



Power Factor - laggingcurrent

310

220

0

-310

310

220

0

-310



Why should I care aboutpower factor?

Utilities may bill for Volts x Amps (kVA) or apply asurcharge for PF below a set value

Note that kVA is always greater than or equal tokW

Increased line currentsLow PF may suggest lightly loaded motorsFacilitates interpretation of electrical profiles



Power factor correction

Add capacitanceAt service entranceIn distribution systemAt point of use – e.g. on motors

5



Power and energy

Power = How Fast(Demand)

Energy = How Much(Consumption)

Energy = Power x TimeUnits are kilowatt-hours (kWh)



What is efficiency?

Electric HeatIncandescent Lamp

MotorsPumps/Fan

Air Compressor

100% Elec - Heat10-20% Elec - Light

50-95% Elec - Power20-60% Elec - Flow

5-15% Elec - Air

Output Input

Efficiency = x 100%

Device Efficiency Input - Output



Thermal energy units

Unit of thermal energy is a Joule (J)Typically use MJ or GJ.

1 Joule per second = 1 Watt1 kWh = 3.6 MJ (0.0036 GJ)1 boiler HP = 9,810 Watts

6



Other useful units

1 kWh = 3413 BTU1 Ton of refrigeration

= 12,000 BTU/Hr= 3.6 kW



Sensible and latentheat

0EC for Water

100EC for Water at Sea Level Steam Only

Water & Steam

Ice & W aterIce

Heat Removed Heat Added

0% Steam Quality100% Steam Quality

Latent HeatLatent Heat SensibleHea t

SensibleHea t

SensibleHea t



Humid air -psychrometry

7



“Quality” of heat - aquestion of usefulness

Required Temperature: 60ECRequired Energy: 16,800 kJ

250 litres @ 100EC84,000 kJ

1000 litres @ 40EC84,000 kJ

100 litres@ 20EC

Which will do thejob?

The 100 litres willbe heated byimmersing its

container in one ofthe larger

containers.



Large Body @ 20EC

Small Body@ 60EC

Conduction

Radiation

ForcedConvection Convection

Air &Surrounding

@ 20EC

Heat transfermechanisms



Thermal resistance ofinsulation

R = thickness/thermal conductivity

8



Controlling heat loss -insulation

Types:FibrousCellularGranular

Forms:Rigid boardFlexible sheetFlexible blanketsCement



Protective coverings

Weather barrierVapour retarderMechanical protectionFire and corrosion resistanceAppearance coverings and finishesHygienic coverings



Radiation heat loss

Radiation from a hotbody to a cold bodyDepends onε, the emissivity ofthe surfaceThe temperaturedifferenceThe radiating area

Controlled byselecting low-emissivity materials

q = ε σ (Th4 - Tc

4) A

9



Heat flow calculations

Conduction:Q = U x A x (T2 - T1)

Air flow:Q = V x (T2 - T1) x 1.232

Humid air:Q = V x (H2 - H1) x 3.012

In liquids:Q = M x (T2 - T1) x C x1000

Pipe heat loss:Q = F x L

Refrigeration:Q = COP x Power toCompressor (kW)

Steam leaks:Q = M x h / 3600


Module 3: Overview ofBuilding Energy Audits

A Systematic Approach toEnergy Auditing



Learning objectives

Describe the theoretical framework for abuilding audit;Identify the information that should be collectedand analysed before the site visit;Develop a building audit plan and schedule;Identify the steps involved in conducting abuilding audit.

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What is energyauditing?

“An energy audit is developing an understanding of the specific energy using patterns of a particular facility.”

Carl E. Salas, P.E.

“An energy audit is developing an understanding of the specific energy using patterns of a particular facility.”

Carl E. Salas, P.E.



How is energymanagement done?

Purchase energysupplies at thelowest possibleprice.Manage energy useat peak efficiency.Utilize the mostappropriatetechnology.



Managing Technology

No cost -housekeepingmeasuresLow cost - sometechnology, lots ofpeople inputHigh cost - capitalinvestment

11



Energy consumingsystems in buildings

Organization /Site

Building B

Department BDepartment A Department C

System BSystem A System C

Equipment A

Building A

Department ...

System _System _

Equip...Equip...Equip...Equip...Equip...Equipment CEquipment B



A basis for the energy audit. . . what comes in, goes out

Oil or Natural Gas

Energy Inflow

Boiler Stack Loss

Exhaust

Warm Fluid to DrainDoor Heat Loss

Wall Heat Loss

WindowHeat Loss

Ventilation

Process Exhaust

Electricity

Energy Inflow

SolarEnergy Inflow

Energy System Boundary



Two levels of audit

Preliminary AuditHigh level assessmentAssesses merits ofdoing detailed auditIdentifies areas offocus for detailedauditIncludes walk-throughand preliminary dataanalysis

Detailed AuditGreater detail inassessment of specificareasIdentifies specificEMOs

12



DME’s Audit Process



Pre-site inspection datarequirements

Historical energy and water consumption and billingsdata for at least 12 months, preferably multi-year;Basic building configuration information, including atleast conditioned floor area;Building schedule and occupancy data;Breakdown of building uses by area (i.e. general office,computer facilities, library, cafeteria, etc.);Any other energy assessment data that may beavailable, including demand profiles, equipmentinventories, etc.Degree-day information applicable to the buildinglocation.



Preliminary dataanalysis

Organise historical dataWhat are the patternsand trends?Calculate theEnergy/DemandIntensityCorrelate consumptionwith weather/occupancy

13



Preliminary Audit

Purposethe need for or meritsof a detailed audit,based on performanceindices:

consumption index

demand index

Stepshistorical analysiscollect building datademand profilewalk-throughtariff analysis

MJ/m2/year

VAaverage/m2/month



Preliminary auditfindings

Building performanceindicesDemand profileanalysisPotential savingsopportunitiesConfirmation of tariff



Detailed audit

Purposeidentify specificmeasures to reduceconsumption, demand,cost

Stepsexamine site drawingsprepare load inventoryassess demand profileassess all energy loadareasprovide baselinecriterionassess tariff changeopportunity

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Auditing – the “bigpicture”

How and where energy enters the facility,department, system or piece ofequipment;Where it goes and how it is used;Any variances between inputs and uses;How it can be used more effectively orefficiently.



Ten StepsPreliminary Client Meeting and

Historical Data Analysis1. Conduct a Walk-through

Inspection2. Analyze Energy Consumption

and Costs3. Compare Energy Performance4. Establish the Audit Mandate5. Establish the Audit Scope6. Profile Energy Use Patterns7. Inventory Energy Use8. Identify Energy Management

Opportunities9. Assess the Benefits10.Report for Action

Initial ClientMeeting

(1) PreliminaryWalk-through

Historical DataAnalysis

(2) AnalyseEnergy

Consumption &Costs

(3) ComparativeAnalysis

Preliminary Audit

(4) DetermineAudit Mandate

(5) Define AuditScope

Audit Plan

(1) Detailed Walk-throughs

(6) AnalyseEnergy Use

Patterns

(7) InventoryEnergy Use

(8) Identify EMOs

EMOA ssessment

Required

(9) Assess theBenefits

(10) Audit Reportf or Action

Engineering Study

Engineering Report

Detailed Audit

EMOs

EMOs

EMOsEMOs

EMOs

EMOs

DetailedAssessment



Planning for the audit

Audit mandate and scopeDates and places where the audit is to be conductedDetails of the organizational and functional units to beaudited and contactsIdentification of the energy audit elements that are ofhigh priorityExpected time and duration for major audit activitiesIdentification of audit team membersAudit report content and format, expected date of issueand distribution.

15



Coordination with O&M personneland building occupants

Review the purposes, scope and plan of the audit –change as neededDescribe audit methodologiesDefine communication linksConfirm availability of resources and facilitiesConfirm schedule of meetings with management groupInform about site health, safety and emergencyproceduresAnswer questions - create comfort level with the auditpurposes and outcomes.



Step 1: the walk-through

Where energy isbeing wasted;Where repair ormaintenance work isneeded;Where capitalinvestment may beneeded to improveenergy efficiency.


Historical DataAnalysis

(2) AnalyseEnergy

Consumption &Costs



Step 2: Analyse energyconsumption and costs

Understand the tariffsAssess the trendsCorrelate to independentvariables (e.g. weather,occupancy, schedule)Unit energy costIncremental energy cost– what does the next unitconsumed, or the firstunit saved cost


(2) AnalyseEnergy

Consumption &Costs


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Step 3: Comparativeanalysis

Two kinds ofcomparison:

Internal - period toperiod, site to site;External - tostandards ofperformanceestablished in thebuildings sector.


(2) AnalyseEnergy

Consumption &Costs




Data analysis

Energy density:MJ/m2/year

Demand density:VAaverage/m2/month

Correlation withweather - HDD andCDD



Performance indices

Consumption

Demand

MJ/m2/year

VAaverage/m2/month

17



Energy use drivers

ClimateFacility size & AgeSchedulesEquipment typeBuilding designProcessesOrganisational cultureBehaviour



Types of comparisons

External benchmarksInternal benchmarks

multiple facilitiesHistorical consumptionTrends and patterns



Benchmarking is…

A methodology to improve energyperformanceComparison of energy performance to a“standard”Investigation of the differences betweenexisting and “standard” practicesDriving action to improve practices

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Selected benchmarks

Demand intensityVA/m2

relates to size/number of electricity consumers

Electric energy intensitykWhE/m2

relates to size/number/duration of electricity use

Cooling or heating energy intensitykWhC/m2 or kWhH/m2

Total energy intensitykWhT/m2 = kWh(C or H)/m2 + kWhE/m2



Best practices

Proven solutions for improvingperformanceExternal sources:

Industry / sector case studiesSurvey / study groups

Internal sources:Individuals/groupsBest historical performance



“This facility is different from those benchmarks!”

Investigate thedifferencesThe opportunitieslie in thedifferences

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Step 4: Define the auditmandate

Clarification of thegoals and objectivesof the audit, and thekey constraints thatwill apply to actionson itsrecommendations



Audit Plan



Step 5: Define the auditscope

Specification ofThe physical extent ofthe auditThe energy inputs andoutputsThe sub-systems to beassessed



Audit Plan



Step 6: Profile energyconsumption

Electrical demand profile:Time pattern ofconsumptionSystem sizingDemand reductionopportunitiesPower factor correction?Loads on when they don’tneed to be?

(1) Detailed Walk-throughs


Patterns


EMOs

EMOs

EMOs

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Step 7: Inventoryenergy loads

Electrical load inventory:How much and how fast?Where?

Thermal load inventory:An energy flow diagram


Patterns


(8) Identify EMOs

EMOs

EMOs



Step 8: Identify EMOs

STEP 1 - Match usageto requirementSTEP 2 - Maximisesystem efficienciesSTEP 3 - Optimise theenergy supply

Begin the search for opportunitieswhere the energy is the most

expensive – at the point of end use!


(8) Identify EMOs

EMOAssessment

Required

EMOs



Step 9: Assess the costsand benefits

What benefits shouldbe taken into accountWhat costs should beincluded in theanalysisWhat economicindicators should beused

EMOAssessment

Required


(10) Audit Reportfor Action

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Costs and benefits

Benefitsdirect energy savingsindirect energysavingscomfort/productivityincreasesoperating andmaintenance costreductionsenvironmental impactreduction

Costsdirect implementationcostsdirect energy costsindirect energy costsO&M cost increase



Step 10: Report forimplementation

Provide a clearaccount of the factsupon which yourrecommendations aremadeInterest those whoread the report inacting upon thoserecommendations

EMOAssessment

Required


(10) Audit Reportfor Action


Module 4: HistoricalEnergy Assessment

Understanding the patternsof energy use

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Learning objectives

Identify data sources for the assessment of thebuilding’s energy performanceDescribe the instrumentation used for energyauditsAnalyse the energy tariffs that apply to thebuildingCorrelate energy consumption to buildingoperational parameters and weather



Analyzing performancerequires energy data

0 200 400 600 800 10000

40

80

120

160

200

240

280

320

Weather ( HDD )

Energy (GJ)Gas Energy vs. Weather

ABC Facility for 1999

GJ = 0.395 x HDD + 12 [ R-sq = 0.91 ]

$0

$10,000

$20,000

$30,000

$40,000

JanFeb

MarApr

MayJun

JulAug

SepOct

NovDec

On-Peak Energy Off-Peak Energy Demand

Energy Cost Demand Cost

Electricity Cost Breakdown for 1999ABC Facility



Data requirements

Historical energyconsumption dataMetered energyconsumptionBuilding configurationWeather dataEnergy system nameplatedatamechanical, electrical,architectural plans andspecifications

building automationsystem (BAS)documentationmaintenance logskey plans (floor plans)contact information forbuilding operationalpersonnel or servicecontractors

23



Instrumentation forauditing

Electric Power MeterCombustion AnalyzerDigital ThermometerInfrared ThermometerPsychrometer (HumidityMeasurement)Air Flow MeasurementDevicesTachometerUltrasonic Leak Detector

Other useful items:A cameraBinoculars and a smallflashlightDuct tape & Tie WrapsMulti- screw driver, adjustablewrench and pliersTape measureBucket and stopwatchSafety Glasses, Gloves & EarPlugsCaution tape



Hand-held wattmeter



Single-phaseconnections

24



3-phase digital powermeter



Combustion analysis

Fuel - carbon - hydrogen - sulpher

Combustion Air (TC) - oxygen - nitrogen

Heat (75- 85%)

Combustion

Flue Gas (TS) - CO2 - nitrogen, NOx - water - excess air - SOx - VOC - CO



Light levelmeasurement

Table 5.14RECOMMENDED ILLUMINANCE LEVELS,

POWER DENSITIES AND SURFACE REFLECTANCESPower Den-

sityReflectances % Area and Task Illuminance

W/m2 Ceiling Walls Floor

Offices - accounting - drafting

-general

750 - 950750 - 950540 - 700

252518

70 - 80 40 - 60 20 - 40

Corridors 210 5.5 Lobbies 320 9

Cafeterias and Kit-chens

320 - 50014

70 - 80 40 - 80 20 - 40

Lecture Rooms 540 - 700 18 70 - 80 40 - 60 20 - 40 Toilet Areas 320 9 Laboratories 750 - 950 25 70 - 80 40 - 80 20 - 40

Production - general 750 - 950 25 Warehouses 320 9 Roadways 50 2

Parking 50 2

25



Temperaturemeasurement



Humidity measurement



Static pressure

26



Leak detection - ventilationand compressed air



Check your speed -digital tachometer



An electricity tariff

AdministrativechargeDemand chargeper kVA

May be time of use– on-peak/off-peak

Energy charge perkWh

27



Analysing theelectricity billings

Electricity Consumption Data Location:

[ C:\Project Files\Audit Manual\Spreadsheets\[Electricity Cost.xls]Electicity Consumption Data ]

Billing Metered Metered Power Billed Energy Daily Load Demand Energy Adjust Sub TotalDate kVA kW Factor kW kWh Days kWh Factor Cost Cost (+/-) Total Cost

01/01/99 1,800.0 1,800.0 1,006,703 30 33,557 78% $21,250 $50,365 ($11,147) $71,615 $64,70102/01/99 1,900.0 1,900.0 1,206,383 31 38,916 85% $22,750 $56,441 ($13,204) $79,191 $70,60703/01/99 1,400.0 1,400.0 842,286 28 30,082 90% $15,250 $42,144 ($9,263) $57,394 $51,50104/01/99 1,850.0 1,850.0 1,102,176 31 35,554 80% $22,000 $53,315 ($12,132) $75,315 $67,60605/01/99 1,870.0 1,870.0 1,213,021 30 40,434 90% $22,300 $56,641 ($13,252) $78,941 $70,28706/01/99 2,200.0 2,200.0 1,339,599 31 43,213 82% $27,250 $60,438 ($14,716) $87,688 $78,08007/01/99 1,560.0 1,560.0 850,195 30 28,340 76% $17,650 $42,540 ($9,438) $60,190 $54,30408/01/99 1,570.0 1,570.0 948,747 31 30,605 81% $17,800 $47,467 ($10,429) $65,267 $58,67709/01/99 1,950.0 1,950.0 1,213,798 31 39,155 84% $23,500 $56,664 ($13,308) $80,164 $71,53610/01/99 2,300.0 2,300.0 1,373,054 30 45,768 83% $28,750 $61,442 ($15,111) $90,192 $80,33711/01/99 2,100.0 2,100.0 1,347,059 31 43,454 86% $25,750 $60,662 ($14,731) $86,412 $76,69912/01/99 2,400.0 2,400.0 1,024,475 30 34,149 59% $30,250 $50,984 ($11,685) $81,234 $74,418

Totals/Max 2,400.0 2,400.0 13,467,496 364 $274,500 $639,104 ($148,415) $913,604 $818,752

ABC Facility

$0$20,000$40,000$60,000$80,000

$100,000

Jan-

99

Feb-

99

Mar

-99

Apr-9

9

May

-99

Jun-

99

Jul-9

9

Aug-

99

Sep-

99

Oct

-99

Nov

-99

Dec

-99

Cost

($)

Energy Cost Demand Cost

Monthly Demand (kW)

0.0

500.0

1,000.0

1,500.0

2,000.0

2,500.0

3,000.0

Daily Energy (kWh/day)

0

10,00020,000

30,000

40,00050,000

Jan-

99

Feb-

99

Mar

-99

Apr-9

9

May

-99

Jun-

99

Jul-9

9

Aug-

99

Sep-

99

Oct

-99

Nov-

99

Dec

-99

9

Monthly Load Factor (%)

78%85% 90%

80%90%

82%76%

81% 84% 83% 86%

59%

0%

20%

40%

60%

80%

100%



Load factor

100#24

(%) xperiodindaysxdayperhrxkWPeak

periodinusedkWhFactorLoad =

Monthly Load Factor (%)

78%85% 90%

80%90%

82%76%

81% 84% 83% 86%

59%

0%

20%

40%

60%

80%

100%

Low load factorsmean excessivedemand for ashort duration -and higher thannecessary cost.



Graphical analysis ofhistorical energy use

Building "A"Gas Space Heat & Gas Domestic Hot Water, Electric A/C

02,0004,0006,0008,000

10,00012,00014,00016,000

Jan Feb Mar Apr May June July Aug Sept Oct Nov Dec

Equi

vale

nt k

Wh

Monthly Electricity Consumption Monthly Gas Consumption

Building "B"Electric Space Heat, Electric A/C, Gas Domestic Hot Water

02,0004,0006,0008,000

10,00012,00014,00016,00018,000


Equi

vale

nt k

Wh


Building "C"Gas Space Heat & Domestic Hot Water, no A/C

0

2,000

4,000

6,000

8,000

10,000

12,000


Equi

vale

nt k

Wh


Building "D"Gas Space Heat & Process Heat, 2 Week August Shutdown

0

2,000

4,000

6,000

8,000

10,000

12,000


Equi

vale

nt k

Wh


28



Calculating degree-days



Correlation of energyconsumption to degree-days


Module 5: EnergyAssessment - DemandAnalysis

Understanding the timepatterns of energy use

29



Learning objectives

Obtain an electrical demand profile,interpret it, and identify possible EMOs;Identify opportunities for power factorcorrection.



Hourly Demand Profile

Hour of the Day1

23

45

67

89

1011

1213

1415

1617

1819

2021

2223

240

20

40

60

80

100

120

140



An ElectricalFingerprint

800

1000

1200

1400

1600

1800

2000

Kilo

wat

ts

Time of Day (00:00 - 24:00)

Peak Day Demand Profile15 minute demand interval

30



Patterns Revealed

Peak DemandNight LoadStart-UpShut-DownWeather Effects

Loads that CycleInteractionsOccupancy EffectsProduction EffectsProblem Areas



Analyzing the Profile

Requires facility operational knowledgeMark scheduled events on the profileCorrelate events with:

Demand increase, decrease, cycling, peaks

Reconcile with demand on utility billsInvestigate unknown patterns

“There’s always a savings opportunity in anew demand profile”



Obtaining a DemandProfile

Periodic utility meter readingsRecording clip-on ammeter measurementsBasic recording power meterMulti-channel recording power metersA Facility energy management or SCADAsystemA dedicated monitoring system

31



Obtaining a demandprofile

DC

AC

START STOP OFFON

CHART POWER

L1

L2

L3

CLIP-ON AMMETER

RECORDER

3 phase power fromsingle phasemeasurement:

kVA = Amps xVolts x 1.73 ÷ 1000



3 phase measurement



Daily or monthly

400

600 800

1000 1200

1400 1600

1800 2000

kilo

wat

ts

Day of the Month

Monthly Demand Profile15 minute demand interval

32



Meter response

Loaddisconnected

Loadconnected



What the demand metersees

20

15

10

5

0



Savings opportunities

Scheduling – reduce startup peaksInfrequent demand peaks – avoidableShift on-peak to off-peak usage patternEquipment loading – consider sequencing

33



Peak demand control

Eliminate accidental peaks Shift activity “off-peak” Peak demand warning for staff Interlock equipment Load shedding system Use generator to “clip” the peak



Power factor correction

Correct power factor – on peakat service entrancein the distribution systemat the point of use power factor



Analyse this!

34


Module 6: EnergyAssessment - Load Inventory

Understanding whereenergy is used



Learning objectives

Create an energy load inventory, andreconcile it to consumption data



Analyse the loadinventory

Where is electricity used?How much - i.e. consumptionHow fast - i.e. demand

35



Lights40.0%

A/C40.0%

Plug Power20.0%

Demand

Lights50.0%

A/C15.0%

Plug Power35.0%

Energy

Why inventory?

Focus your effortsEstablish a basis for savings calculations



Inventory calculations

Item Units Formula

Quantity (a number)

Unit Load kW

Total kW kW Quantity. x Unit Load.

Hrs/Period hours

kWh/Period kWh Total kW x Hrs/Period Diversity Factor (Div’ty Factor) 0 - 100%

Peak kW kW kW x Diversity Factor



Demand breakdown

Demand Breakdown

Lighting50%

Motors25%

Other25%

Demand Breakdown

Lighting50%

Motors25%

Other25%

36



Peak demandbreakdown

Peak Demand Breakdown

Lighting45%

Motors27%

Other28%

Peak Demand Breakdown

Lighting45%

Motors27%

Other28%



Energy breakdown

Energy Breakdown

Lighting52%Motors

35%

Other13%

Energy Breakdown

Lighting52%Motors

35%

Other13%



Sample inventory

Loads QtyUnit KW

Total KW

DiversityFactor

PeakKW Hours KWH

Fluorescent F96 4 0.165 0.66 1 0.7 300 198Incandescent 100 w 24 0.1 2.4 0.9 2.2 100 240400w MH Lights 21 0.465 9.765 1 9.8 420 4,101Compressor.(60HP) 1 50 50 1 50.0 400 20,000Pump (20 HP) 1 16 16 0.75 12.0 400 6,400Micro-Wave 1 0.75 0.75 0.1 0.1 2 2Coffee Machine 2 1.5 3 1 3.0 200 600

Total 83 77.7 31,541

37



Energy flow diagram

Oil or Na tural Gas

Energy Inflow

Boiler Stack L oss

Exhaust

W arm F lu id to DrainDoor Heat Loss

W all Heat Loss

W indo wHeat Loss

Ventilat ion

Process Exhaust

Electric ity

Energ y Inflow

SolarEnergy Inflow

E nergy S ystem B oundary



Thermal energyinventory

Energy Flow Type Example Equipment/Functions

Conduction Wall, windows Building structure.

Air Flow - Sensible General exhaust Exhaust and makeup air systems,combustion air intake.

Air Flow - Latent Dryer exhaust Laundry exhaust, pool ventilation,process drying equipment exhaust.

Hot or Cold Fluid Warm water to drain.Domestic hot water, process hot water,process cooling water, water cooled aircompressors.

Pipe Heat Loss Steam pipeline. Steam pipes, hot water pipes, any hotpipe.

Tank Heat Loss Hot fluid tank. Storage and holding tanks.Refrigeration systemoutput heat Cold storage. Coolers, freezers, process cooling, air

conditioning.

Steam Leaks and Vents Steam vent Boiler plant, distribution system,steam appliance.


Module 7: EnergyAssessment - EMOs

Finding energymanagement opportunities

38



Learning objectives

Systematically identify EMOs;Describe the factors that need to beconsidered in assessing costs andbenefits.



Finding opportunities:Start at the end-use

1st Analyze Present Usage

2nd Identify and Quantify the Savings Opportunities

Meter

End-Use



Start at point of end-use

PipingNetwork

DistributionSystem

Motor

Bearings

Pump

FlowControlValve

Utility Meter

End-Use HeatExchanger

Other HeatExchanger

39



Component efficiencies

PipingNetwork

60%

DistributionSystem

96%

Motor85%

Bearings98%

Pump60%

FlowControlValve70%

Utility Meter 100%

End-Use HeatExchanger

Other HeatExchanger



System efficiency

Distribution

Meter Motor Pump

ValvePiping

Bearing

Energy In

Energy Out

Only 20%



Component and systemefficiencies

20%Overall60%Piping70%Valve60%Pump98%Bearing85%Motor96%Distribution

100%MeterTypical EfficiencyComponent

40



Three simple steps

Start with a valid needWaste-loss analysis

i.e. match and maximize

Optimize the supply



Why this order?

End-use actions influence all other partsof the system – do this firstLower cost actions are operational – atend-useHigher cost actions are technological –higher efficiency componentsEnd-use determines supply requirement



Match the requirement

Setback temperaturesTurn-off lights in unoccupied areasProvide task—rather than general — lightingAvoid dampers / throttling – match flows by:

Resizing the fan/pumpInstalling a variable speed drive on fan/pump motor

Provide ventilation on demand

41



Maximise efficiencies

Reduce ventilation duct flowrestrictionsClean air filters regularlyKeep heat exchange surfacescleanUse a higher efficacy light sourceInstall a high efficiency motor



Assessing the costsand benefits

Benefits:direct energy savingsindirect energy savingscomfort/productivityincreasesoperating and maintenancecost reductionsenvironmental impactreductionO&M savings

Costs:direct implementationcostsdirect energy costsindirect energy costsO&M cost increase



More about savingsEnergy Savings: energy saved x incremental energy rateDemand Savings: kVA saved x incremental demand rateThermal Fuel Savings: Fuel Energy Saved = Point of Use Energy Saved÷ Heating Plant Efficiency

Fuel Cost Saved = Fuel Energy Saved x Incremental Cost of Fuel ÷Energy Content of Fuel

Indirect electrical savingse.g. reduced A/C loads due to more efficient lighting:

A/C kWh Saved = Lighting kWh saved ÷ COPLess re-lamping labour and lamp cost from switching to a longer-lifelamp typeIncrease in employee productivity from converting to a higher quality,higher efficiency fixture type.

42



More about costs

Initial cost of implementing the retrofitDecrease in lamp life - increased re-lamping costs

Decrease in lamp life due to increase in switching

Any increase in maintenance costs such as higher costlamps and ballastsHigher cost of repairs or lower life of any replacementenergy-efficient equipmentIndirect energy costs:

Increase in heating costs due to more efficient or switchedlighting


Module 8: Energy Efficiencyin Building Electrical Systems

Electrical energymanagement opportunities



Learning objectives

Describe building performance standardsIdentify and assess energy efficiencyopportunities for lighting systems;miscellaneous plug loads; motors, drives,fans and pumps.

43



Building performancestandards - SAEDES®

Intended to:Minimise ODS useMinimise GHGemissionConserve non-renewable energyresourcesOptimise buildingperformance toachieve the economicbenefits

Provisions:Minimum demand andenergy efficiency ofnew buildingsBuilding performanceparametersClimate dataApplication of otherstandardsDetailed technicalcriteria



SAEDES performancestandards

Area

Lux

W/m2 General Office Space Computer Rooms & Drafting Areas Public Areas (Foyer & Corridors) Stairs Kitchen Toilets Car Park Plant Rooms Retail

400 600

200 - 400 50 - 100 200-300

100 50 - 100

100 - 200 400 - 800

17 26

7 - 17 3 - 5

10 - 16 5

3 - 5 5 - 10 8 - 25



. . . And climate data

SI Units (EC)

City

Latitude

Longitude

Elev (m)

HDD

CDD

Win. Des. 99%

Summer

DB 2,5%

WB 2,5%

CapeTown/ D F Malan

33,97S

18,60E

46

936

2474

22

72

53

Johannesburg

26,13S

28,23E

1694

1066

2362

13

65

51

Pretoria

25,73S

28,18E

1330

639

3,238

14

69

51

44



SABS 0400-1990 –ventilation rates

Minimum Air Requirement, l/s (per person except

where noted)

Occupancy Smoking Non-smoking

Educational Buildings Classrooms Laboratories

Libraries

- - -

7,5 7,5 6,5

Shops Malls, arcades, warehouses

Sales floors, showrooms, dressing rooms

7,5 7,5

7,5 7,5

Garages Parking garages

Ticket kiosks

per m2 floor area 7,5 5,0

per m2 floor area 7,5 5,0

Libraries General

Bookstock

- -

6,5 3,5

Offices General

Meeting and waiting spaces Conference and board rooms

Cleaner’s rooms

7,5 7,5

10,0 1,0

5,0 5,0 5,0 1,0



The building as an energysystem

What are theinteractions?

Heat from lightsHumidityreduction by ACIncreased freshair requirementfrom reductionof infiltrationOthers?



Other impacts of energyreduction

Power quality – introduction ofharmonics?Indoor air quality – changes withventilation/infiltration ratesGreenhouse gas emissions – CO2 emissionreduction has monetary value

45



Lighting system

Ceiling Fixture

Lamps (light source)Ballast

Lens or Diffuser

Floor

Switch

Work SurfaceThe Requirement

Walls



Lighting considerations

Minimise operating time Ensure appropriate levels and quality Maximise efficiency of delivery Maximise the source efficiency

Lamp efficiency = efficacy



Lighting quality

Illumination level Uniformity Absence of glare Colour temperature Colour rendition index (CRI)

46



Colour renderingindex (CRI)

Light Source CRI RenderingIncandescent lamps 97 ExcellentFL, full spectrum 7500 94 ExcellentFL, cool white deluxe 87 ExcellentCompact Fluorescent 82 ExcellentFL, Warm White deluxe 73 GoodMH (400 W clear) 65 GoodHPS (250 W deluxe) 65 GoodFl, Cool White 62 GoodFL, Warm White 52 FairMV (phosphor-coated) 43 PoorHPS (400 W diffuse coated) 32 PoorMV (clear) 22 PoorLow Pressure Sodium --- Impossible



Light source efficacy

Lamp Type Lumens/Watt Incandescent 10 - 18 Mercury Vapour 20 - 50 Fluorescent 40 - 100 Metal Halide 60 - 100 High Pressure Sodium 60 - 120 Low Pressure Sodium 90 - 200



Some questions

Are lights on when the space is unoccupied?Are lights on in an area served by daylight?Is lighting switched from breakers?Is there sufficient and convenient switchingavailable?Is the level of light appropriate for the task athand?Is regular maintenance performed?

47



Summary of lightingopportunities

Lower Cost – match the requirement Better switching - more switches & levels Occupancy sensors & timers Reduce overall level & use task lights

Higher Cost – improve the efficiency Upgrade to a more efficient fixture Use a more effective fixture layout Use a more efficient light source



EMOs for lighting

Switch off unnecessary lightsRemove redundant fixturesDelampingRelampingModifications or replacement

Remove or replace fixture lensesRetrofit the existing lighting system with a moreefficient systemReplace inefficient ballasts

Clean light fixtures, lamp reflectors and roomsurfaces



Plug loads

Plug loads add upTurn them offSelect high efficiencymodels

48



Electric motors

First, reduceunnecessary useEnsure properoperating conditionsProvide goodmaintenanceConsider an energyefficient motor

The motor is not the end-use; consider what is beingdriven.



Imbalance =Inefficiency!

0

20

40

60

80

100

0 2 4 6 8 10

Voltage Imbalance (%)

Incr

ease

in L

osse

s (%

)



Match the motor to theload

Motor Loading

Effi

cien

cy (%

)

0% 25% 50% 75% 100%

0%

25%

5

0%

75%

10

0%

49



Operating conditions

Leading cause of motor failure is heat 10% temperature increase = ½ life Clean air vents Balance voltages Avoid too many starts



Motor rewinding

Could reduce efficiency by 5%Depends upon rewind shopSpecify motor iron core test after rewindIt is realistic to expect minimal reductionin efficiency after a rewind



Energy efficient motors

Loading (%) 100% Load 75% Load 50% LoadHP Type Eff'y P.F. Eff'y P.F. Eff'y P.F.11

EEStd

84.072.0

80.578.0

84.072.0

74.070.0

81.568.0

62.058.0

1010

EEStd

90.284.0

88.085.5

90.284.0

85.080.5

90.281.5

77.075.0

5050

EEStd

92.891.7

84.584.0

93.091.7

81.081.

91.790.2

73.071.5

100100

EEStd

93.591.7

91.583.5

94.091.7

91.080.5

93.890.2

87.073.0

200200

EEStd

94.893.0

90.588.5

95.093.0

88.586.5

94.691.7

83.080.0

50



Watch your speed!

Energy efficient motors tend to havehigher rated/operating speeds.

1-3% higher rated speeds.

When driving a centrifugal load:A 1% speed increase = 3.5% power increase.



Fans & pumps

Comprise significantload in buildingsTypically oversizedMisapplication iscommonProper flow controlcan yield largesavings



Assessing fans &pumps

Match the need - make sure thefan/pump size matches the need for flowEnsure that the pump or fan is operatingat close to optimal conditions - if notreconsider the pump/fan selectionReduce resistance to flow in thedistribution systems - flow resistance,fittings, pipe/duct sizing

51



Powerful laws

Q2

Q1

'N2

N1

P2

P1

'N2

N1

2 kW2

kW1

'N2

N1

3

Affinity laws for centrifugal fans and pumps.

N = speed, Q = flow, P = pressure, kW = power



Efficiency optimisation

Capacity (litres/sec)

Head -Capacity

Efficiency

MaximumEfficiency atthis Point

SimilarCurve for

Fans



Fan/Pump savingsstrategy

MaximizeEfficiency

Technological Operational

Match theRequirement

2

1

4

3Apply avariablespeed drive

Maintain &operate atbest point.

Turn it offor reducevolume.

Replacepump ormotor.

52



Assessment questions

Is the fan/pump being throttled at thedischarge?Is the fan/pump doing a meaningful job?Is the fan/pump correctly sized?Check fan/pump curves; is fan/pumpoperating efficiently?Does the requirement for air/liquid vary?



More fan/pumpquestions

Can the fan/pump be slowed down?Can the system head be reduced,ducts/pipes cleaned?Is the fan/pump excessively noisy, hot orvibrating?Are there leaks in the air distributionsystem?Is the fan being throttled at the inlet?



Fan/pump EMOs

Clean and balance air distribution systemsCheck overall fan/pump sizing andefficiencyEliminate air flow reduction with dampers,fluid flow control with valvesUse a booster fan/pumpReduce fan/pump speed

53



The advantage ofvariable speed

0

20

15

5

25

10

40% 60% 80% 100% FLOW

VariableSpeedMethod

ThrottlingMethod

PowerSaving!

HP


Module 9: Energy Efficiencyin Building Thermal Systems

Thermal energymanagement opportunities



Learning objectives

Assess the heating and cooling load of abuilding;Identify and assess energy efficiencyopportunities for building envelope; HVACsystems including boilers, steam and hotwater distribution systems, air distributionsystems; and the application of buildingcontrol systems.

54



Heating/cooling loads andthe “comfort zone”



Heat loss and gain – basicrelationship

Q U A T T= × × −( )2 1

Q = Heat loss rate (W)U = 1 / R-value = Heat transfercoefficient (W/m2.oC)A = Surface area (m2)T2 = Indoor Temperature (oC)T1 = Outdoor Temperature (oC)



Insulation EMOs – reduceheat loss/gain

Maintenance:Repair damagedinsulationRepair damagedcoverings and finishesMaintain safetyrequirements

Low-cost:Insulate non-insulatedpipes & fittingsInsulate non-insulatedvesselsAdd insulation toreach therecommended level

55



Insulation EMOs

Retrofit:Upgrade existinginsulation levelsReview economicthickness requirementLimited budgetupgrade

New construction:High R materialsBuilding orientationHigh efficiency glazingWindow shadesFloor plans



Infiltration/ExfiltrationEMOs

Caulk all cracksCaulk around all pipes,louvers, or other openings thatpenetrate the building skinRepair windowsWeatherstrip exterior doorsand windowsCover window air conditionersduring off seasonsInstall revolving doors,vestibule and automatic doorclosers

Q F T TA= × × −1232 2 1. ( )



Solar gain – radiationheat load

30° South Latitude Total(Wh/day)

Time of Day 6 7 8 9 10 11 12 13 14 15 16 17 18 S 131 115 71 56 56 56 56 56 56 56 71 115 131 1,024SE 417 552 516 385 218 75 56 56 56 56 48 40 20 2,493E 429 619 639 568 389 175 56 56 56 56 48 40 20 3,148

NE 167 298 357 357 290 175 67 56 56 56 48 40 20 1,985Dec N 20 40 48 56 60 75 83 75 60 56 48 40 20 679

NW 20 40 48 56 56 56 67 175 290 357 357 298 167 1,985W 20 40 48 56 56 56 56 175 389 568 639 619 429 3,148

SW 20 40 48 56 56 56 56 75 218 385 516 552 417 2,493Hor 75 242 520 715 861 953 993 953 861 715 520 242 75 7,726S 87 79 56 52 56 56 56 56 56 52 56 79 87 826SE 369 520 488 353 183 64 56 56 56 52 48 36 16 2,295E 397 615 651 576 393 175 56 56 56 52 48 36 16 3,124

Jan NE 167 326 397 397 330 210 87 56 56 52 48 36 16 2,176& N 16 36 48 56 79 107 119 107 79 56 48 36 16 802

Nov NW 16 36 48 52 56 56 56 210 330 397 397 326 167 2,144W 16 36 48 52 56 56 56 175 393 576 651 615 397 3,124

SW 16 36 48 52 56 56 56 64 183 353 488 520 369 2,295Hor 60 262 488 699 850 937 977 937 850 699 488 262 60 7,567S 22 30 41 48 48 52 52 52 48 48 41 30 22 534SE 204 401 371 245 100 52 52 52 48 48 41 30 7 1,651E 245 545 612 549 378 171 52 52 48 48 41 30 7 2,779

Feb NE 137 364 471 479 416 304 145 56 48 48 41 30 7 2,545& N 7 30 48 100 174 215 234 215 174 100 48 30 7 1,384

Oct NW 7 30 41 48 48 56 145 304 416 479 471 364 137 2,545W 7 30 41 48 48 52 52 171 378 549 612 545 245 2,779

SW 7 30 41 48 48 52 52 52 100 245 371 401 204 1,651Hor 22 174 397 597 742 835 872 835 742 597 397 174 22 6,408S 0 19 37 45 48 52 52 52 48 45 37 19 0 453SE 0 275 334 148 56 52 52 52 48 45 37 19 0 1,117E 0 460 586 534 382 178 52 52 48 45 37 19 0 2,393

Mar NE 0 364 486 564 523 419 249 93 48 45 37 19 0 2846

30° South Latitude Total(Wh/day)

Time of Day 6 7 8 9 10 11 12 13 14 15 16 17 18 S 131 115 71 56 56 56 56 56 56 56 71 115 131 1,024SE 417 552 516 385 218 75 56 56 56 56 48 40 20 2,493E 429 619 639 568 389 175 56 56 56 56 48 40 20 3,148

NE 167 298 357 357 290 175 67 56 56 56 48 40 20 1,985Dec N 20 40 48 56 60 75 83 75 60 56 48 40 20 679

NW 20 40 48 56 56 56 67 175 290 357 357 298 167 1,985W 20 40 48 56 56 56 56 175 389 568 639 619 429 3,148

SW 20 40 48 56 56 56 56 75 218 385 516 552 417 2,493Hor 75 242 520 715 861 953 993 953 861 715 520 242 75 7,726S 87 79 56 52 56 56 56 56 56 52 56 79 87 826SE 369 520 488 353 183 64 56 56 56 52 48 36 16 2,295E 397 615 651 576 393 175 56 56 56 52 48 36 16 3,124

Jan NE 167 326 397 397 330 210 87 56 56 52 48 36 16 2,176& N 16 36 48 56 79 107 119 107 79 56 48 36 16 802

Nov NW 16 36 48 52 56 56 56 210 330 397 397 326 167 2,144W 16 36 48 52 56 56 56 175 393 576 651 615 397 3,124

SW 16 36 48 52 56 56 56 64 183 353 488 520 369 2,295Hor 60 262 488 699 850 937 977 937 850 699 488 262 60 7,567S 22 30 41 48 48 52 52 52 48 48 41 30 22 534SE 204 401 371 245 100 52 52 52 48 48 41 30 7 1,651E 245 545 612 549 378 171 52 52 48 48 41 30 7 2,779

Feb NE 137 364 471 479 416 304 145 56 48 48 41 30 7 2,545& N 7 30 48 100 174 215 234 215 174 100 48 30 7 1,384

Oct NW 7 30 41 48 48 56 145 304 416 479 471 364 137 2,545W 7 30 41 48 48 52 52 171 378 549 612 545 245 2,779

SW 7 30 41 48 48 52 52 52 100 245 371 401 204 1,651Hor 22 174 397 597 742 835 872 835 742 597 397 174 22 6,408S 0 19 37 45 48 52 52 52 48 45 37 19 0 453SE 0 275 334 148 56 52 52 52 48 45 37 19 0 1,117E 0 460 586 534 382 178 52 52 48 45 37 19 0 2,393

Mar NE 0 364 486 564 523 419 249 93 48 45 37 19 0 2846

56



Reduce solar gain . . .

In new construction:Glass area and typeBuilding orientation in new constructionOverhangs and shading

In existing buildings:Exterior shading (awnings)Interior shading and blindsRe-glazing (maybe)



Summary of heat loadEMOs

Reduce heat loss/gainby:

Conduction - add insulationConvection - minimize airinfiltrationand radiation - replace orimprove windows, useshading

Strategy:eliminate waste - ensurebuilding need is exactlymet by the energy system;maximize efficiency –select best technology,improve operational andmaintenance practices;optimize energy supply -select most economicalenergy source, utilisewaste heat



Reduce heating energy

Maintain the indoor temperature as low as possibleUse most economical level of insulationEnsure vapour barrier is installed and in good repairUse double or triple glazing for windowsReorganise activities inside the building - separate thebuilding into zones based on specific heating and coolingrequirementsDon’t heat unoccupied areas

57



Reduce cooling energy

Maintain the indoor temperature as high aspossibleUse insulation to reduce heat gain in summerUse double or triple glazing or low-E glass forwindowsReorganize activities inside the building - thedesired configuration is opposite that requiredfor reducing heat lossDon’t cool unoccupied areas



Energy efficient HVAC

Intake (make-up)AirFlow

“Waste Heat”Exhaust Air Flow

Outside (lower)Temperature

Inside (higher)Temperature

(B) Internal Heat Gain Exhaust

(A) CooledVentilation

Exhaust&

Intake

BoilerFuel

ChillerElectricity



Causes of inefficiency

Over/underheating/cooling - set-point or temperaturecontrolOver ventilationSimultaneousheating/coolingInadequate controlsfor range ofconditions

Increased heating orcooling due toinfiltrationStratificationPoor equipmentmaintenanceIncorrect system typeor sizingLack of coordinationin central control

58



Finding HVAC EMOs -some questions

Temperature and ventilation requirements ofthe conditioned space - match of systemcapacity to these needsContainment of contaminants from otherbuilding areasWhat is the accuracy of temperature andhumidity control - more accurate controls?Does the HVAC load vary daily and seasonally -does the system have capacity control toaccommodate these swings?



. . . more questions

Is there a preventative maintenanceprogram for the HVAC systems?Are controls calibrated regularly?Was the existing system designed for thepresent purpose or conditions?Are there more efficient systems for ourapplication?



EMOs checklist -ventilation

Shut down ventilation/exhaust systems when notrequiredMaintain dampers to reduce outside air leakage whennot requiredUse correct ventilation/exhaust rates for application &occupancyUtilise systems to destratify ceiling airMinimise the Use of local exhaust

59



EMOs checklist - spaceconditioning

Control temperature and humidity according to comfortzoneMinimize solar gainsRaise thermostats during unoccupied hours during thecooling season, lower during heating seasonAdjust space temperatures in unoccupied or storageareasEnsure automatic controls are operating correctly andare calibrated regularlyUse enthalpy control on HVAC systemsUse filters to remove odours



Boiler plant systems

UsefulHeat

Air

Flue Gas

Fuel

100xEnergyFuelEnergyUsefulEfficiencyBoiler =



Hot water boiler plant

HOT WATER BOILER

CONTROL PANEL

T

BREECHING

T

PT

THWR

DHW HEATER

DCW

DHWT

T

HWS T T ZONE

��T

C

M

1

2

3

45

7

8

9

10

11

13

OPTIONALDHW HEATER

6

BURNER

12

60



Fuel combustion

Fuel - carbon - hydrogen - sulpher

Combustion Air - oxygen - nitrogen

Heat (75- 85%)

Combustion

Flue Gas - CO2, CO - nitrogen, NOx - water - excess air - SOx - VOC



Losses from boilersystems

Combustion by-products – depends on the air-fuel mixtureHeat in the flue gas – depends on the amountof excess combustion air and effectiveness ofheat exchangeBlow-down – hot water removed from theboiler to control accumulation of solidsSkin Loss – heat escaping from the boilerenclosure



Combustion efficiencymeasurement

Flue gas & combustion airtemperatureFlue gas constituents

O2 (indicates CO2 and excessair)CONOx, SOx, etc

Draft and differentialpressureEfficiency is calculated fromflue heat loss

61



Measuring combustionefficiency

Equipment required:Combustion analyzerOr, minimally O2,temperature sensorand efficiency tables

Access required:¼” to 3/8” hole influe close to last heatexchange



Boiler plant EMOs

Adjust fuel/air ratioEnsure boiler temperature set point is OKClean heat transfer surfacesStaging/control of multiple unitsOff cycle heat loss reductionBurner alignment/adjustmentBoiler/pipe insulation



More boiler plant EMOsRelocate combustion air intake to usewaste heatReplace inefficient unitsRight-size boilersSmaller boiler for summer loadsHeat recovery on larger boilers

Reduction of loss is first consideration

62



. . . And more EMOs

Reduce blowdown rate, by managingwater treatment.

Reduction from 10% to 5% saves about 1%of fuel

Reduce steam pressureLower flue, radiation, and leak losses

Reduce venting/leaks if possible



Heat recoveryopportunities

Use economizer to heat make-up waterCombustion air pre-heaterFlue gas condenserBlow down heat recoveryRecover de-aerator steam



Savings example

Preheat combustionair with heat frompower house ceilingCombustion air 20oCto 40oCBoiler efficiencyimprovement of 1.1%

63



Assessment of boilerplant



Steam distribution

Heating Appliance

Kitchen

Steam Trap

Steam Trap

Steam Trap

Main Steam Line

Condensate Return Line

Steam From Boiler

Condensate to Boiler

Drain

Valve Steam Fitting



Assessment of steamdistribution Analyze Steam

Distribution

SteamPressure

Pipe Size

Above userrequirement-

reduce pressure

IncreaseCapacityof Piping

SteamTrapping

FutureExpansion

Excessive Loss -consider smaller

pipes

Survey fordamage incorrect,type position, size.

Repair / replace

CondensateReturned?

CheckInsulation

HeatRecovery Send to Drain

Upgradeor

Replace

Finish

Returned toBoiler?

UsedLocally?

Too High

Undersize

Poor

Correct

No,Uncontaminated

Matched

O.K

Oversize No

Yes

No

YesYes

No,Contaminated

Maximum Return

No

Yes

Yes

No

In-adequate

O.K.

Send to Drain

64



Losses in distributionsystems

Steam leaksExcessive pressure drop in steam lines inundersized linesExcessive standby losses due to oversized linesSteam lost due to failure of steam trapsCondensate sent to drain rather than returnedHeat loss from un-insulated pipes valves andfittings



Losses in domestic hotwater

Leaking faucets/valvesAppropriate temperaturesShut down recirculation duringunoccupied periodsFlow restricting devicesInsulation of equipment

TanksRecirculation lines



Insulation opportunities

Repair damaged insulationInsulate non-insulated pipes and vesselsInsulate valves and flangesPaint/wrap tank/pipe surfaces with low-E/aluminum paint/foilAdd/Upgrade insulation up to theeconomical thickness

65



Cooling plant

PowerRequired

HigherTemperature

LowerTemperature

Condenser

Evaporator



Refrigeration EMOs -some questions

Are the condensing devicesclean and well maintained?Are the evaporator devicesclean and well maintained?How is defrostingaccomplished on freezer units?Are inlet refrigerant linesinsulated properly?Are controls operatingproperly (small and largeunits)?Is there a regular maintenanceprogram for the refrigerationsystems?

Do condensers and coolingtowers have adequate coolair?Does simultaneous heatingand cooling occur?Can evaporator temperaturebe increased?Can condenser temperature bereduced?Are the compressor crankcaseheaters off during the warmermonths of the year?



Refrigeration EMOs - morequestions for the experts

Is the refrigeration unit appropriate to the load?How do the refrigeration systems handle partload conditions?Has the heat load within refrigerated spacesbeen minimised?Can thermal storage avoid peak demand causedby refrigeration systems?

66



Minimize temperaturelift

Match the requirementSetup space temperatures

Clean heat exchange surfacesReduce condenser temperature

Look at cool air supply

Increase evaporator temperatureChilled water reset



Reduce the cooling load

Building insulationWindow solar radiation controlReduce infiltration

especially warm moist air

Refrigerant line insulation



Maintenance &monitoring

Use the sight glassto check condition ofrefrigerant

Lubricationleading cause offailure

Log operatingconditions

67



Higher costopportunities

Avoid head pressurecontrol

Save 20-40%

Avoid hot gas bypass35-40% power inbypass

Compressor upgradeHigher efficiency orvariable speed



Match the requirement

What are the requirements?Temperature, RH, illumination, ventilation

What energy is being consumed?What energy should be consumed?Why is there a difference?

Eliminate waste



Maximize efficiency

How do operation and maintenance practicesimpact energy use?

SchedulesTemperaturesDamper conditionHeat exchanger fouling

Is more efficient technology available?LightingBoilers & chillersControls

68



Chiller efficiency

Note: ton of refrigeration = 12 000 Btu/hr

Electric Chiller New ChillerkW/ton

ExistingkW/ton

Reciprocating .78 to .85 .90-1.2 or higherScrew .62 to .75 .75-.85 or higherCentrifugal High .50 to .62 NA

Moderate .63 to .70 .70-.80 or higher



Efficiency in airdistribution systems

Match the need - ensure that neither too littlenor too much air is supplied to a given areaEliminate waste - clean filters to prevent highback pressuresClean ventilation ducts to eliminate theadditional flow resistance caused by dirtdepositsOptimise efficiency by using fan speedcontrol to regulate air flow rather than dampers



Waste heat recovery

��

Intake (make-up)Air Flow

Outside (lower)Temperature

Inside (higher)Temperature��

��

(B) Internal Heat Gain Exhaust

Heat Direct from Fuel

(A) HeatedVentilation

BoilerThis is a

recoverableenergy flow.

“Waste Heat”Exhaust Air Flow

Hot Flue Gases

Hot Waterto Drain

This is arecoverableenergy flow.

This is arecoverableenergy flow.

FuelEnergy In

69



Match the source touse

What waste heat sources are available?What quantity of heat is available?At what temperature is the heat available?

Where can the heat be used?How much energy is required and at whattemperature?What is the time coincidence between wasteand use?At what location is the heat required?

What is the practical recovery rate - whatportion of the waste heat may be used?



Simple heat exchange

A

B

C

D

TEM PER ATURE

D ISTAN CE

D

C

B

A



Heat recovery methods

DirectFrom one outflow to another inflowFrom higher to lower temperatureRate depends upon approach temperature

IndirectFrom one energy form to anotherTypically requires outside energy input

70



Direct heat recovery

Regime Exchanger Typical Use

Cross Flow Commercial Air Exchange

Rotary Flue Gas Heat Recovery Gas - Gas

Regenerative High Temp. / Low Volume Exhaust

Shell & Tube Process Water, Oil Coolers

Spiral High Pressure Cooling

Plate & Frame Dairy, Process Water Liquid - Liquid

Heliflow Oil Coolers Recovery Boiler Furnace , Engine Exhaust

Evaporative Water Cooling, Humidification, Exhaust Gas Scrubber Gas - Liquid

Air Cooling Oil Cooler, Space Heating



Gas to gas

HOT EXHAUST AIR

COOLED EXHAUST AIR

COLD FRESH AIR

HEATED FRESH AIR

CROSS - FLOWHEAT EXCHANGER

HOT EXHAUST AIR

COOLED EXHAUST AIR

COLD FRESH AIR

WARM FRESH AIR

ROTARY HEAT EXCHANGER



Liquid to liquid

HEAD

SHELL

TUBE BUNDLE

TUBE & SHELL HEAT EXCHANGER

HOT FLUID

COLD FLUID

INLET

OUTLET

WARMER FLUID

COOLER FLUID

PLATES PLATE & FRAME HEAT EXCHANGER

INLET

OUTLET

SEALS

TRANSITION PIECES

COMPRESSION ROD

SPACERS

SEPARATE

71



Gas to liquid

HOT GAS INLET

SPRAY WATER

SPRAY NOZZLES

WARM (136 F) WATER

SATURATED (COOL) GAS

DIRECT CONTACT HEAT EXCHANGER

AIRFAN / MOTOR

WARM AIRHOT LIQUID

COOLER LIQUID

AIR COOLED HEAT EXCHANGER



Indirect heat recovery

Regime Exchanger Typical Use

Heat Pump Space Heating, Hot Water Production

Absorption Chiller Water Chilling, Space Heating

Flash Tank Boiler Blow down Mechanical

Vapour Recompression

Brewing, Sugar Processing

Thermal - Thermal

Combustion of Waste Gases Sewage Treatment, Foundries

Expansion Turbine Chemical Plants Thermal -

Mechanical / Electrical Rankine Cycle High Temperature Waste Gas



Heat pump

EVAPORATOR(HEAT INPUT FROM COLD SOURCE)

CONDENSER(HEAT LOST TO HOT SOURCE)

COMPRESSOR EXPANSION VALVE

Requires Electricity

72



Flash tank

HIGH PRESSURELIQUID FLOW

LOW PRESSURE VAPOUR

LOW PRESSURE LIQUID

Creates steam from a hot high pressure liquid.



Compressed airsystems

Compressed air isexpensive - typicalefficiency is 5% to20%

Hole Diameter Air Leakage @ 600 kPa(87 psi) (Gauge)

1 mm 1 l/s

3 mm 10 l/s5 mm 26.7 l/s10 mm 105.7 l/s



Compressed air EMOs -some questions

Are you supplying leaks in distribution system/end use?Is the supply pressure higher than required to overcomepipe loss?Can you reduce the requirement for air?Can compressor inlet pressure be raised?Can compressor inlet temperature be dropped?Is compressor drive system efficient?Do screw compressors have proper capacity control?Is storage capacity large enough?

73



Compressed air EMOs

Reduce leaks in air distribution system and at point ofuseReduce compressed air system pressureReduce compressed air requirementsEnsure low inlet restrictions (clean air filter)Reduce inlet air temperature (relocate the intake)Provide sequencing control of air compressorsUse screw compressors with capacity controlConsider two stage compression with cooling



Building controlsystems

Threecomponents

sensorscontrollerscontrol devices Controller

Sensor

Control Device Process

Set Point

Feedback

Controlled

Variable



HVAC control loop

74



Efficiency through control -4 principles

Run equipment only when neededSequence Heating and CoolingProvide only the heating or coolingrequiredSupply heating and cooling from the mostefficient source



Control applications

Programmed Start/StopOptimised Start/StopDuty cyclingDemand controlTemperaturesetback/setupAlarms/monitoringEnergy monitoringOptimised ventilation

Optimisation of supply airtemperatureSupply water optimisationChiller/boiler optimisationOther control options

Interior and exteriorlightingDomestic hot watertemperatureCistern flow optimisation


Module 10: Assessing theBusiness Case

Analysing the costs andbenefits

75



Learning objectives

Do preliminary assessment of proposedenergy management investments



Objectives ofinvestment appraisal

Which investments makethe best use of availablemoney?Ensure optimum benefitsfrom investmentMinimise the riskA basis for subsequentperformance analysis



Investment Criteria

Simple Payback

Return on Investment(ROI) and Internal Rateof Return (IRR)

Net Present Value (NPV)and Cash Flow

( ) SavingsAnnualCostCapital

yearsSPP =

Lifeojectx

CostojectEstimatedCostojectEstimatedojectofLifeForSavingsEnergyTotal

ROIPr

100Pr

Pr)Pr( −=

nixPVFV )1( +=

orni

FVPV)1(

=

76



Simple payback period

Quick and easy wayof assessing financialmerits of measuresDoes not account for:

cost of moneyanything after paybackperiod

( )SavingsAnnualCostCapital

yearsSPP =



Cash flow analysis

0 5 0 5 10 15 Project Life (years) Project Life (years) Project A Project B

Capital costsAnnual cash flows

TaxesAsset depreciation

Intermittent cashflows

Costs

Savings



Cash flow table

Table 7.1: Cash Flow Table for Purchase of new BoilerCapital Expenditure R100,000

Expected Savings R48,000

90% on delivery/commissioning, and 10%performance guarantee due at one year.Half in first year, full amount in all remaining years.

(Values in R’000)Year 0 1 2 3 4 5Costs (90.0) (10.0) 0 0 0 0Savings 0 24.0 48.0 48.0 48.0 48.0Net cash flow (90.0) 14.0 48.0 48.0 48.0 48.0Net Project Value (90.0) (76.0) (28.0) 20.0 68.0 116.0

5 year average ROI = 116 / 100 x 100/5 = 23.2%Lifeoject

xCostojectEstimated

CostojectEstimatedojectofLifeForSavingsEnergyTotalROIPr

100Pr

Pr)Pr( −=

77



Time value of money -discount factors

Discount Factors 1/(1 + i)n Year (n) 0 1 2 3 4 5 Discount Factor 6% 1 0.942 0.888 0.840 0.792 0.747 10% 1 0.909 0.826 0.751 0.683 0.620 20% 1 0.833 0.694 0.579 0.482 0.402 30% 1 0.769 0.591 0.456 0.350 0.270 40% 1 0.714 0.510 0.364 0.260 0.186 45% 1 0.690 0.476 0.328 0.226 0.156 50% 1 0.666 0.444 0.297 0.198 0.132

niFVPV

)1( +=



Net present value

Table 7.3: NPV CalculationYear 0 1 2 3 4 5Net cash flow (R000s) (90.0) 14.0 48.0 48.0 48.0 48.0The discounted cash flow at 10% can be found as follows:

Year 0Year 1Year 2Year 3Year 4Year 5

1 x (90.0)0.909 x 14.00.826 x 48.00.751 x 48.00.683 x 48.00.620 x 48.0

= (90.0)= 12.73= 39.65= 36.05= 32.78= 29.76

NPV = the sum of all these values = 60.97 (compare to net project value = 116.0)



Internal Rate of Return

year net cash flow Discount NPV IRR0 -90000 10% R61,048.67 30.37%1 14000 20% R25,216.052 48000 25% R11,885.443 48000 30% R753.504 48000 31% -R1,250.475 48000 35% -R8,627.04

ExcelSpreadsheet

78



Payback and IRR



Risk and sensitivityanalysis scenarios

Pessimistice.g. much higherinterest rates

RealisticBest guess

Optimistice.g. much higherenergy costs


Module 11: Reporting forImplementation

Getting action on the auditrecommendations

79



Learning objectives

Prepare complete and effective energyaudit reports



Writing good auditreports

Know your readerUse simple, direct language

Use an action-oriented style in the active (rather than passive)voiceAvoid technical jargon

Ensure that your report is grammatically correctPresent information graphicallyMake your recommendations clearExplain your assumptionsBe accurate and consistent



A report template

Executive SummarySummary information onkey audit findingsThe recommended EMOsThe implementation cost,savings, and paybackAny special informationrelated to implementation

Technical Sectiondetails of your auditfindingsAudit mandate, scope, andmethodologyFacility description andobservationsAssumptions andcalculationsAudit recommendationsAppendices

Documents

Building Energy Auditing - Department of Energy