ISO 50045:2019

Technical guidelines for the evaluation of energy savings of thermal power plants

This document gives general technical guidelines for evaluating energy savings of thermal power plants before and/or after implementing energy performance improvement action(s) (EPIAs). It includes evaluation, unit component efficiency, indexes calculation, analyses and reporting. This document is applicable to existing thermal power generating units (TPGUs), where fossil fuels (e.g. coal, oil, natural gas) are combusted to generate electricity only or to supply thermal energy with the additional production of electricity (i.e. combined cycle power plants). NOTE A typical thermal power plant encompasses at least one TPGU. If there is more than one, the TPGUs can run independently. Results obtained in accordance with this document can be used either to evaluate the potential of energy savings or to determine fulfilment of contract guarantees. They do not provide a basis for comparison of the energy savings between TPGUs. This document does not prescribe performance tests or measurements for TPGU equipment components/systems, the sampling and analysis of the fuels used, substances added for control of emissions (e.g. halide, limestone) and by-products (e.g. ash, gypsum), and instruments to be employed, but it does specify parameters of interest in the determination of energy savings. Applicable procedures can be found in relevant documents (published or to be published).

Lignes directrices techniques pour l'évaluation des économies d'énergie des centrales électriques thermiques

General Information

• Status: Published
• Publication Date: 19-Mar-2019
• ICS: 27.015 - Energy efficiency. Energy conservation in general
• ICS: 27.100 - Power stations in general
• Technical Committee: ISO/TC 301 - Energy management and energy savings
• Drafting Committee: ISO/TC 301 - Energy management and energy savings
• Parallel Committee: ISO/TC 242 - Project Committee: Energy Management
• Current Stage: 9599 - Withdrawal of International Standard
• Start Date: 04-Apr-2025
• Completion Date: 13-Dec-2025

Overview

ISO 50045:2019 - Technical guidelines for the evaluation of energy savings of thermal power plants provides a practical, standards-based framework for assessing energy savings of existing thermal power generating units (TPGUs). Applicable to fossil-fuel-fired boilers, steam turbines, gas turbines and combined-cycle or combined heat-and-power (CHP) systems, the standard covers principles, indexes, component efficiency assessment, analysis procedures and reporting for evaluating energy performance improvement actions (EPIAs). Results can be used to estimate saving potential or to verify fulfilment of energy savings contract guarantees (e.g., energy performance contracting).

Key topics and technical requirements

• Scope and applicability
  • Applies to existing TPGUs burning coal, oil, natural gas or similar fossil fuels for electricity generation or cogeneration.
  • Results are for evaluating potential savings or contractual verification; not intended for inter-TPGU savings comparisons.
• Evaluation principles and indexes
  • Defines evaluation indices and fuel-equivalent accounting concepts to compare energy types consistently.
  • Introduces fuel equivalent consumption rate metrics for generation and supply.
• Unit/component efficiency
  • Guidance on assessing efficiency and energy balance of major components:
    • Boilers: boundaries, energy balance and efficiency calculation considerations.
    • Steam turbine/generator efficiency assessment.
    • Gas turbines: guidance for simple-cycle and combined-cycle systems.
  • Considers auxiliary equipment and pipe/steam transmission efficiency.
• Calculation methods
  • Procedures for calculating fuel equivalent and consumption rates; parameters of interest are specified (the standard does not mandate specific test methods or instruments).
• Analyses, M&V and reporting
  • Stepwise procedure for performance evaluation, determination of energy savings and energy savings income.
  • Reporting structure covering project overview, current equipment status, influencing factors and suggested measures.
• Constraints
  • ISO 50045 does not prescribe sampling, fuel analysis, emissions control additives testing or the precise measurement instruments to be used; it specifies parameters to consider and points to other documents for applicable procedures.

Practical applications and users

• Energy managers and plant engineers assessing retrofit or optimization projects
• ESCOs and auditors performing measurement and verification (M&V) for energy performance contracting
• Consultants and financiers evaluating project viability and guaranteed savings
• Regulators and policy makers establishing evaluation frameworks for thermal power plant efficiency
• Useful for planning EPIAs, benchmarking component-level improvements and preparing verification reports

Related standards and references

• ISO 17741, ISO 17743, ISO 2314, ISO 10987, ISO 14452 and other ISO/IEC terminologies cited in the document inform terms, heating value definitions and related procedures.
• ISO 50045 complements national and industry test standards by specifying evaluation parameters and reporting requirements while pointing to applicable measurement procedures elsewhere.

Keywords: ISO 50045:2019, thermal power plants, energy savings evaluation, TPGU, boiler efficiency, turbine efficiency, gas turbine, combined cycle, fuel equivalent, energy performance improvement (EPIA), measurement and verification (M&V).

Standards Content (Sample)

INTERNATIONAL ISO
STANDARD 50045
First edition
2019-03
Technical guidelines for the
evaluation of energy savings of
thermal power plants
Lignes directrices techniques pour l'évaluation des économies
d'énergie des centrales électriques thermiques
Reference number
©
ISO 2019
© ISO 2019
All rights reserved. Unless otherwise specified, or required in the context of its implementation, no part of this publication may
be reproduced or utilized otherwise in any form or by any means, electronic or mechanical, including photocopying, or posting
on the internet or an intranet, without prior written permission. Permission can be requested from either ISO at the address
below or ISO’s member body in the country of the requester.
ISO copyright office
CP 401 • Ch. de Blandonnet 8
CH-1214 Vernier, Geneva
Phone: [phone]
Fax: [phone]
Email: [e-mail]
Website: www.iso.org
Published in Switzerland
ii © ISO 2019 – All rights reserved

Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Symbols, units and abbreviations . 4
5 Evaluation of energy savings . 5
5.1 General . 5
5.2 Principles . 6
5.3 Evaluation indexes . 7
6 Unit component efficiency . 8
6.1 Boilers . 8
6.1.1 Boundary . 8
6.1.2 Boiler energy balance . 8
6.1.3 Boiler efficiency calculations .11
6.1.4 Others .12
6.2 Steam turbine/generator efficiency .12
6.3 Gas turbine efficiency .13
6.3.1 General.13
6.3.2 Simple cycle gas turbine systems .14
6.3.3 Combined cycle power plants.14
7 Calculation of evaluation indexes .16
7.1 Fuel equivalent .16
7.2 Fuel equivalent consumption rate .16
8 Analyses and performance evaluation .16
8.1 Procedure for evaluation .16
8.2 Evaluation of energy savings .18
8.2.1 Determination of energy savings income .18
8.2.2 Analyses for financial benefits .19
9 Reporting .20
9.1 Project overview .20
9.2 Current status and energy consumption of equipment .20
9.3 Analysis of influencing factors .21
9.4 Analysis of energy-savings potential .21
9.5 Suggestions and measures for energy-savings .21
Bibliography .22
Foreword
ISO (the International Organization for Standardization) is a worldwide federation of national standards
bodies (ISO member bodies). The work of preparing International Standards is normally carried out
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electrotechnical standardization.
The procedures used to develop this document and those intended for its further maintenance are
described in the ISO/IEC Directives, Part 1. In particular, the different approval criteria needed for the
different types of ISO documents should be noted. This document was drafted in accordance with the
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This document was prepared by ISO/TC 301, Energy management and energy savings.
Any feedback or questions on this document should be directed to the user’s national standards body. A
complete listing of these bodies can be found at www .iso .org/members .html.
iv © ISO 2019 – All rights reserved

Introduction
This document provides a general and practical framework for evaluating energy savings of thermal
power plants, including steam power plants based on the Rankine cycle, gas turbine plants and
combined cycle systems. These power plants mainly comprise one or several thermal power generating
units (TPGUs) to produce electricity only or both electricity and heat (i.e. cogeneration facilities and
combined heat and power systems) by burning coal, oil products, natural gas and/or other fuels.
This document covers principles, procedures, evaluation indexes and calculation methods when
determining the potential of energy savings of an existing TPGU before (an) energy performance
improvement action(s) (EPIAs) or evaluating the contract guarantees of its energy savings after the
EPIA(s) (e.g. energy performance contracting).
This document can be used by any interested party that intends to evaluate energy savings of a thermal
power plant.
The relationship of this document with related standards and the Plan-Do-Check-Act cycle is shown in
Figure 1.
Figure 1 — General process for iterative improvement
INTERNATIONAL STANDARD ISO 50045:2019(E)
Technical guidelines for the evaluation of energy savings of
thermal power plants
1 Scope
This document gives general technical guidelines for evaluating energy savings of thermal power plants
before and/or after implementing energy performance improvement action(s) (EPIAs). It includes
evaluation, unit component efficiency, indexes calculation, analyses and reporting.
This document is applicable to existing thermal power generating units (TPGUs), where fossil fuels (e.g.
coal, oil, natural gas) are combusted to generate electricity only or to supply thermal energy with the
additional production of electricity (i.e. combined cycle power plants).
NOTE A typical thermal power plant encompasses at least one TPGU. If there is more than one, the TPGUs
can run independently.
Results obtained in accordance with this document can be used either to evaluate the potential of
energy savings or to determine fulfilment of contract guarantees. They do not provide a basis for
comparison of the energy savings between TPGUs.
This document does not prescribe performance tests or measurements for TPGU equipment
components/systems, the sampling and analysis of the fuels used, substances added for control of
emissions (e.g. halide, limestone) and by-products (e.g. ash, gypsum), and instruments to be employed,
but it does specify parameters of interest in the determination of energy savings. Applicable procedures
can be found in relevant documents (published or to be published).
2 Normative references
There are no normative references in this document.
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
ISO and IEC maintain terminological databases for use in standardization at the following addresses:
— ISO Online browsing platform: available at https: //www .iso .org/obp
— IEC Electropedia: available at http: //www .electropedia .org/
3.1
energy savings
ΔE
reduction of energy consumption compared to an energy baseline
Note 1 to entry: Energy savings can be actual (realized) or expected (predicted).
Note 2 to entry: Energy savings can be the result of implementation of an EPIA (3.4).
[SOURCE: ISO 17743:2016, 3.8, modified — “or autonomous progress” has been deleted from Note 2
to entry.]
3.2
fossil fuel
organic material, other than biomass, used as fuel
Note 1 to entry: In this document, the term fossil fuel primarily refers to coal, oil and natural gas used for
electricity generation (3.11) or both electricity generation and heating supply.
[SOURCE: ISO 6707-3:2017, 3.5.8, modified — Note 1 to entry has been added.]
3.3
thermal power generating unit
TPGU
facility that consists of all the equipment necessary for the production of electricity or heat energy, or
both, by combusting fossil fuels (3.2)
Note 1 to entry: In a typical fossil fuel-fired thermal power plant, for example, a TPGU would normally consist
of one or more boilers, where coal, oil or natural gas is burned to create steam, one or more turbine generators,
which convert the steam's heat energy into electricity, and other plant equipment, which supports both boiler
and turbine generators.
Note 2 to entry: A TPGU usually operates independently and can be brought online or taken offline as demand
fluctuates.
3.4
energy performance improvement action
EPIA
action or measure (or group of actions or measures) implemented or planned within a project intended
to achieve energy performance improvement through technological, management, behavioural,
economic or other changes
[SOURCE: ISO 17741:2016, 3.8]
3.5
combined heat and power
CHP
system that uses waste heat associated with electricity production, to provide heat for industrial,
building space or other uses such as hot water and space heating for neighbouring buildings
[SOURCE: ISO 14452:2012, 2.16, modified — “associated with” has replaced “from” and “heat for
industrial, building space or other uses such as” has been added.]
3.6
steam generating unit
furnace, boiler or heat recovery steam generator used to produce steam in the process of combusting
fossil fuels (3.2) or waste heat
3.7
gas turbine generating unit
system combined with a gas turbine and all the essential equipment necessary for producing electricity
or/and both electricity and useful heat
3.8
energy efficiency
effectiveness of converting chemical energy into electric energy or heat energy into electric energy, or
both
[SOURCE: ISO 10987:2012, 3.11, modified — “chemical energy” has replaced “energy” and “electric
energy or heat energy into electric energy, or both” has replaced “useful work”.]
2 © ISO 2019 – All rights reserved

3.9
heating value
amount of heat released by the complete combustion in air of a specific quantity of fuel when the
reaction takes place at constant pressure
Note 1 to entry: The heating value may be expressed as higher heating value (also known as gross calorific value
or gross energy) or lower heating value (also known as net calorific value).
[SOURCE: ISO 2314:2009, 3.5, modified — “fuel” has replaced “gas or liquid fuel” and Note 1 to entry has
been replaced.]
3.10
fuel equivalent
accounting unit of the fuel heating value (3.9) that represents the energy released by burning a specified
amount of the fuel (e.g. coal, natural gas, oil)
Note 1 to entry: Fuel equivalent is a reference unit for the evaluation of various energy types.
3.11
electricity generation
process whereby electrical energy is obtained from some other form of energy
[SOURCE: IEC 601-01-06:1985, modified — The term has been changed from “generation of electricity”.]
3.12
internal electricity consumption
amount of electricity consumed by a single TPGU (3.3) itself during the process of generation of
electricity and/or heat over a given period (3.25)
3.13
electric energy supply
Q
amount of electricity exported by a single TPGU (3.3), which is transmitted and distributed to
customers, typically through a power grid over a given period (3.25)
3.14
fuel equivalent consumption rate of electricity generation
amount of fuel equivalent (3.10) consumed by a single TPGU (3.3) for producing a unit of electricity
3.15
fuel equivalent consumption rate of electric energy supply
F
e
amount of fuel equivalent (3.10) consumed by a single TPGU (3.3) for supplying a unit quantity of
electricity to customers
3.16
heat to power ratio
ratio of the heat utilized for purposes (e.g. district heating, water desalination) to the electric energy
supply (3.13)
Note 1 to entry: This is different to “heat rate”, which is the ratio of fuel energy input to electricity output.
3.17
pipe efficiency
η
p
thermal efficiency of a continuous enclosed passageway for the transmission of steam generated from a
boiler to a steam turbine within a single TPGU (3.3), including steam chests, valves, etc.
3.18
reference value
set of parameters that can represent the status of a TPGU (3.3) in a certain operating mode
3.19
measurement and verification
M&V
process of energy measurement to reliably determine data in relation to the performance of energy
savings (3.1) for defined system boundaries
[SOURCE: ISO/IEC 13273-1:2015, 3.3.5, modified — “the performance of energy savings” has replaced
“energy performance”.]
3.20
auxiliary equipment
equipment or devices of a TPGU (3.3) that are typically used for supplementing and assisting unit systems
Note 1 to entry: Typical auxiliary equipment may include boiler cleaning equipment, fuel preparation and burning
equipment, economizers and air heaters, ash handling systems, turbine auxiliaries, turbine cycle equipment and
balance of plant equipment.
3.21
conversion factor
C
f
ratio of two measurement units for quantities of the same kind
[SOURCE: ISO 80000-1:2009, 3.24, modified — “between units” in the term and the examples have been
deleted.]
3.22
energy savings income
income resulting from implementing an EPIA (3.4) over a defined period (3.25)
3.23
rated operating condition
operating condition requiring fulfilment during measurement in order that equipment performs as
designed or determined
[SOURCE: ISO 4064-1:2014, 3.4.4, modified — “equipment performs as designed or determined” has
replaced “a meter perform as designed”.]
3.24
rated operation
operation under rated operating condition (3.23)
3.25
period
time duration where predicting or measuring results can be obtained
4 Symbols, units and abbreviations
For the purposes of this document, the following symbols, units and abbreviations apply.
The user should either adjust all units or adopt suitable conversion factors to ensure unit consistency.
For example, GJ might be used for large plants, kJ for small plants.
C conversion factor
f
ΔE energy savings kJ
F fuel equivalent consumption rate of electric energy supply g/kWh
e
I energy-saving income monetary unit
nc
4 © ISO 2019 – All rights reserved

Q electric energy supply kWh
Q energy at the output of a boiler boundary kJ
o,b
Q energy at the input of a boiler boundary kJ
i,b
Q energy losses at a boiler boundary kJ
l,b
Q electric energy generated at a steam turbine boundary kJ, kWh
eg,st
Q energy entering into the steam turbine from the boiler kJ
s,b
Q energy extracted for heating applications kJ
h
Q electric energy generated by a gas turbine kJ, kWh
eg,gt
Q heating energy of the fuel used kJ
f
Q electricity generation of a TPGU kWh
eg,TPGU
Q internal electricity consumption of a TPGU kWh
iec,TPGU
Q electric energy supply of a TPGU kWh
ees,TPGU
U unit price of the fuel used monetary unit
p
W quantity of the equivalent fuels used by a gas turbine kg
f,gt
W quantity of the equivalent fuels used by a TPGU kg
f,TPGU
η boiler efficiency %
b
η efficiency of the steam turbine %
st
η efficiency for a simple cycle gas turbine unit %
gt
η efficiency for a CCPP %
CCPP
η pipe efficiency %
p
EPIA energy performance improvement action
CCPP combined cycle power plant
CHP combined heat and power
M&V measurement and verification
TPGU thermal power generating unit
5 Evaluation of energy savings
5.1 General
Energy savings evaluation in the TPGU before/after implementing an EPIA can be categorized as:
a) evaluation before implementation of an EPIA;
b) evaluation after implementation of an EPIA.
In a), estimated energy savings can be determined by using historical data before the action, with
modelling as appropriate to reflect changes in equipment and operating conditions once the EPIA is
implemented.
In b), energy savings are determined by measurement and verification (M&V) using measured values
(before and after the actions) or with and without an action. When evaluating a thermal power plant,
the rated operation and plant conditions should be considered.
Energy savings by an EPIA(s) in a TPGU are calculated using Formulae (1) to (5).
Prior to implementation of an action:
DEE=−Ev+ (1)
before pb adj
After implementation of an action:
DEE=−Ev+ (2)
afterr badj
where
ΔE is the energy savings;
E is the energy consumption of the prediction period;
p
E is the energy consumption of the baseline period;
b
E is the energy consumption of the reporting period;
r
v is the adjusted quantity to align the conditions of the prediction (reporting) period and
adj
baseline period.
EC=×FE× (3)
pf ep out
EC=×FE× (4)
bf eb out
EC=×FE× (5)
rf er out
where
F , F and F are the fuel equivalent consumption rate of electric energy supply for the
ep eb er
prediction period, baseline period and reporting period, respectively;
E is the output of electric energy;
out
C is the conversion factor.
f
5.2 Principles
The following principles should be followed.
— The appropriate measurement boundary for the EPIA should be determined, and interactive effects
should be taken into account.
— The relevant variables affecting energy performance should be identified for the equipment involved
in the EPIA.
— The appropriate baseline measurement period should be determined to effectively represent energy
performance under expected operating conditions.
6 © ISO 2019 – All rights reserved

— The appropriate modelling approach (e.g. thermodynamic or statistical) should be determined to
account for changes in relevant variables for the baseline case.
— The appropriate ex-ante modelling approach should be determined for the EPIA during the
reporting period.
— The calculation of ex-ante savings should be informed, appropriate load forecasts and other
operating conditions for the EPIA determin
...