ISO 16745-1:2017

Sustainability in buildings and civil engineering works — Carbon metric of an existing building during use stage — Part 1: Calculation, reporting and communication

ISO 16745-1:2017 provides requirements for determining and reporting a carbon metric of an existing building, associated with the operation of the building. It sets out methods for the calculation, reporting and communication of a set of carbon metrics for GHG emissions arising from the measured energy use during the operation of an existing building, the measured user-related energy use, and other relevant GHG emissions and removals. These carbon metrics are separated into three measures designated CM1, CM2, and CM3 (see 5.1.1). ISO 16745-1:2017 follows the principles set out in ISO 15392 and those described in Clause 4. Where deviations from the principles in ISO 15392 occur, or where more specific principles are stated, this document takes precedence. The carbon metrics CM1 and CM2 are not quantified based on life cycle assessment (LCA) methodology. Carbon metric CM3 may include partial quantification based on the results of LCA. ISO 16745-1:2017 does not include any method of modelling of the operational energy use of the building but follows the conventions provided by other International Standards, as given in relevant clauses. ISO 16745-1:2017 is not an assessment method for evaluating the overall environmental performance of a building or a building-rating tool and does not include value-based interpretation of the carbon metric(s) through weightings or benchmarking. ISO 16745-1:2017 deals with the application of the carbon metric(s) for an existing building, either residential or commercial, or a building complex. It does not include provisions for regional and/or national building stock.

Développement durable dans les bâtiments et les ouvrages de génie civil — Métrique du carbone des bâtiments existants pendant la phase opérationnelle — Partie 1: Calculs, rapports et communication

General Information

• Status: Published
• Publication Date: 16-May-2017
• ICS: 91.040.01 - Buildings in general
• Technical Committee: ISO/TC 59/SC 17 - Sustainability in buildings and civil engineering works
• Drafting Committee: ISO/TC 59/SC 17/WG 4 - Environmental performance of buildings
• Current Stage: 9093 - International Standard confirmed
• Start Date: 14-Sep-2022
• Completion Date: 13-Dec-2025

Relations

• Revises: ISO 16745:2015 - Environmental performance of buildings — Carbon metric of a building — Use stage
• Effective Date: 05-Nov-2015

Standards Content (Sample)

INTERNATIONAL ISO
STANDARD 16745-1
First edition
2017-05
Sustainability in buildings and civil
engineering works — Carbon metric of
an existing building during use stage —
Part 1:
Calculation, reporting and
communication
Développement durable dans les bâtiments et les ouvrages de génie
civil — Métrique du carbone des bâtiments existants pendant la phase
opérationnelle —
Partie 1: Calculs, rapports et communication
Reference number
©
ISO 2017
© ISO 2017, Published in Switzerland
All rights reserved. Unless otherwise specified, 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
Ch. de Blandonnet 8 • CP 401
CH-1214 Vernier, Geneva, Switzerland
Tel. [phone]
Fax [phone]
[e-mail]
www.iso.org
ii © ISO 2017 – All rights reserved

Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 2
4 Principles . 5
4.1 General . 5
4.2 Completeness . 5
4.3 Consistency . 5
4.4 Relevance . 6
4.5 Coherence . 6
4.6 Accuracy . 6
4.7 Transparency . 6
4.8 Avoidance of double counting . 6
5 Protocol of measuring the carbon metric of a building in the use stage .6
5.1 System boundary . 6
5.1.1 Types of carbon metrics of a building . 6
5.1.2 System boundary for the carbon metrics of a building . 7
5.2 Carbon metric and carbon intensity .10
5.3 Calculation of GHG emissions .10
5.3.1 GHG emissions associated with energy use of a building .10
5.3.2 Measurement of energy carrier .10
5.3.3 Exported energy .11
5.3.4 Energy usage .11
5.3.5 GHG emission coefficients .12
6 Reporting and communication of the carbon metric .14
6.1 General .14
6.2 Reporting of the carbon metric.14
6.2.1 Mandatory requirements .14
6.2.2 Additional information .18
6.3 Communication of the carbon metric.19
6.3.1 Type of communication .19
6.3.2 Provision of information .20
6.3.3 Availability of information .21
6.3.4 Carbon metric disclosure report .21
6.3.5 Explanatory material.22
Annex A (informative) Aim of carbon metric .23
Annex B (informative) Building energy use defined by usage by ISO 12655 .24
Annex C (informative) Types of factors or coefficients by ISO 16346 .27
Annex D (informative) Allocation of emissions related to target energy in combined heat
and power generation by VDI 4660 Part 2 .28
Annex E (informative) Status of ISO 16745 and other documents and concepts related to
the description and assessment of greenhouse gas emissions caused by buildings .35
Bibliography .38
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
through ISO technical committees. Each member body interested in a subject for which a technical
committee has been established has the right to be represented on that committee. International
organizations, governmental and non-governmental, in liaison with ISO, also take part in the work.
ISO collaborates closely with the International Electrotechnical Commission (IEC) on all matters of
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
editorial rules of the ISO/IEC Directives, Part 2 (see www .iso .org/ directives).
Attention is drawn to the possibility that some of the elements of this document may be the subject of
patent rights. ISO shall not be held responsible for identifying any or all such patent rights. Details of
any patent rights identified during the development of the document will be in the Introduction and/or
on the ISO list of patent declarations received (see www .iso .org/ patents).
Any trade name used in this document is information given for the convenience of users and does not
constitute an endorsement.
For an explanation on the voluntary nature of standards, the meaning of ISO specific terms and
expressions related to conformity assessment, as well as information about ISO’s adherence to the
World Trade Organization (WTO) principles in the Technical Barriers to Trade (TBT) see the following
URL: w w w . i s o .org/ iso/ foreword .html.
This document was prepared by Technical Committee ISO/TC 59, Buildings and civil engineering works,
Subcommittee SC 17, Sustainability in buildings and civil engineering works.
This first edition of ISO 16745-1, together with ISO 16745-2, cancels and replaces ISO 16745:2015, of
which it constitutes a minor revision.
ISO 16745:2015, Clause 7 has been transferred to ISO 16745-2 to keep the requirements for the
verification of the carbon metric declaration independent of the requirements for the carbon metric
calculation, reporting and communication, as well as other minor editorial modifications.
A list of all parts in the ISO 16745 series can be found on the ISO website.
iv © ISO 2017 – All rights reserved

Introduction
Buildings contribute approximately one-third of global greenhouse gas (GHG) emissions. With its
high share of emissions, the building and construction sector has the responsibility to take the global
lead in implementing strategies to reduce GHG emissions. The building and construction sector has
more potential and opportunity to deliver quick, deep, and cost-effective GHG mitigation than any
other sectors. Carbon dioxide (CO ) emissions contribute to global warming, which is one of the most
recognized environmental impacts attributable to buildings.
In this context, measurement and reporting of GHG emissions from existing buildings are critical
for enabling significant and cost-effective GHG mitigation. Currently, there has not been a globally
agreed method established to measure, report, and verify potential reductions of GHG emissions from
existing buildings in a consistent and comparable way. If such a method existed, it could be used as a
universal tool for measurement and reporting of GHG emissions, providing the foundation for accurate
performance baselines of buildings to be drawn, national targets to be set, and carbon trading to occur
on a level playing field.
In principle, accurate and precise reporting can only be achieved if GHG emissions (and removals) from
all life cycle stages of buildings are measured and/or quantified. However, not all countries in the world
have sufficient capacity or resources to use and apply life cycle assessment (LCA) methodologies.
Respecting the need for collaboration on a global scale, the need exists for a metric that is usable not
only in countries with sufficient number of experts and a precise database, but also in those countries
where experts’ services are limited and databases have considerable gaps. For instance, with the
potential for global scale carbon trading within building-related sectors, a method that is consistently
usable in both the well-developed and developing world is needed.
Operational energy use in buildings typically accounts for 70 % to 80 % of energy use over the building
life cycle. Therefore, the operating stage of the building’s life cycle is the focus of measurement and
reporting of direct and indirect GHG emissions.
This document aims to set out a globally applicable common method of measuring and reporting of
associated GHG emissions (and removals) attributable to existing buildings, by providing requirements
for the determining and reporting of a carbon metric(s) of a building.
The carbon metric is a measure (a partial carbon footprint) that is based on energy use data and
related building information for an existing building in operation. It provides information related to
the calculation of GHG emissions and can be used as an environmental indicator. Using this approach,
the metric and its protocol can be applied by all stakeholders in both developing and well-developed
countries, where building energy consumption and other relevant data can be retrieved or collected,
making it useful and globally transferable.
This document aims to be practical for many stakeholders (i.e. not only for the building profession), who
are expected to use the carbon metric of a building as reference for decision making in their business
activities, governmental policies, and as a baseline for benchmarking.
The simplicity of approach provides applicability at all scales, ranging from cities and building portfolios
to individual buildings.
INTERNATIONAL STANDARD ISO 16745-1:2017(E)
Sustainability in buildings and civil engineering works —
Carbon metric of an existing building during use stage —
Part 1:
Calculation, reporting and communication
1 Scope
This document provides requirements for determining and reporting a carbon metric of an existing
building, associated with the operation of the building. It sets out methods for the calculation, reporting
and communication of a set of carbon metrics for GHG emissions arising from the measured energy use
during the operation of an existing building, the measured user-related energy use, and other relevant
GHG emissions and removals. These carbon metrics are separated into three measures designated CM1,
CM2, and CM3 (see 5.1.1).
This document follows the principles set out in ISO 15392 and those described in Clause 4. Where
deviations from the principles in ISO 15392 occur, or where more specific principles are stated, this
document takes precedence.
The carbon metrics CM1 and CM2 are not quantified based on life cycle assessment (LCA) methodology.
Carbon metric CM3 may include partial quantification based on the results of LCA.
This document does not include any method of modelling of the operational energy use of the building
but follows the conventions provided by other International Standards, as given in relevant clauses.
This document is not an assessment method for evaluating the overall environmental performance
of a building or a building-rating tool and does not include value-based interpretation of the carbon
metric(s) through weightings or benchmarking.
This document deals with the application of the carbon metric(s) for an existing building, either
residential or commercial, or a building complex. It does not include provisions for regional and/or
national building stock.
2 Normative references
The following documents are referred to in the text in such a way that some or all of their content
constitutes requirements of this document. For dated references, only the edition cited applies. For
undated references, the latest edition of the referenced document (including any amendments) applies.
ISO 6707-1:2004, Buildings and civil engineering works — Vocabulary — Part 1: General terms
ISO 12655, Energy performance of buildings — Presentation of measured energy use of buildings
ISO 14050, Environmental management — Vocabulary
ISO 15392, Sustainability in building construction — General principles
ISO/TR 16344:2012, Energy performance of buildings — Common terms, definitions and symbols for the
overall energy performance rating and certification
3 Terms and definitions
For the purposes of this document, the terms and definitions given in ISO 6707-1, ISO 12655, ISO 14050,
ISO 15392, ISO/TR 16344 and the following apply.
ISO and IEC maintain terminological databases for use in standardization at the following addresses:
— IEC Electropedia: available at http:// www .electropedia .org/
— ISO Online browsing platform: available at http:// www .iso .org/ obp
3.1
building service
service provided by technical building systems (3.19) and by appliances to provide acceptable indoor
environment conditions, domestic hot water, illumination levels, and other services related to the use of
the building
Note 1 to entry: For the purposes of this document, the following terms are used as per their definitions in the
following reference documents: appliances (ISO 6707-1:2004, 5.4.7) and building (ISO 6707-1:2004, 3.1.3).
[SOURCE: ISO 52000-1:2017, 3.3.3, modified – Note 1 to entry has been added.]
3.2
carbon intensity
carbon metric (3.3) expressed in relation to a specific reference unit related to the function of the
building
Note 1 to entry: For the purposes of this document, the following terms are used as per their definitions in the
following reference documents: function (ISO 15686-10:2010, 3.10) and building (ISO 6707-1:2004, 3.1.3).
Note 2 to entry: Examples of reference units may include per unit area, per person, per kilobyte, per unit output,
and per GDP.
3.3
carbon metric
sum of annual greenhouse gas emissions and removals, expressed as CO equivalents, associated with
the use stage of a building
Note 1 to entry: For the purposes of this document, the following terms are used as per their definitions in the
following reference documents: greenhouse gas emissions (ISO 14064-1:2006, 2.5), removals (ISO 14064-1:2006,
2.6), CO equivalents (ISO 14064-1:2006, 2.19) and building (ISO 6707-1:2004, 3.1.3).
3.4
cooling
removal of latent and/or sensible heat
[SOURCE: ISO 16818:2008, 3.47]
3.5
delivered energy
energy (3.6), expressed per energy carrier (3.7), supplied to the technical building systems (3.19) through
the system boundary (3.18), to satisfy the uses taken into account [heating, cooling (3.4), ventilation
(3.20), domestic hot water, lighting, appliances, etc.], or to produce electricity
Note 1 to entry: For the purposes of this document, the term appliances is used as per its definition in
ISO 6707-1:2004, 5.4.7.
Note 2 to entry: Delivered energy can be calculated for defined energy uses or it can be measured.
[SOURCE: ISO/TR 16344:2012, 2.1.33, modified – Note 1 related to active solar and wind energy systems
has been deleted.]
2 © ISO 2017 – All rights reserved

3.6
energy
capacity for doing work; having several forms that may be transformed from one to another, such as
thermal (heat), mechanical (work), electrical, or chemical
[SOURCE: ISO 16818:2008, 3.74]
3.7
energy carrier
substance or phenomenon that can be used to produce mechanical work or heat or to operate chemical
or physical processes
Note 1 to entry: For the purposes of this document, the term heat is used as per its definition in
ISO 16818:2008, 3.117.
Note 2 to entry: The energy content of fuels (3.10) is given by their gross calorific value (ISO/TR 16344:2012,
2.1.78).
[SOURCE: ISO/TR 16344:2012, 2.1.46]
3.8
energy source
source from which useful energy (3.6) can be extracted or recovered either directly or by means of a
conversion or transformation process
EXAMPLE Oil or gas fields, coal mines, sun, wind, the ground (geothermal energy), the ocean (wave energy,
ocean thermal energy), forests, etc.
[SOURCE: ISO 52000-1:2017, 3.4.15]
3.9
exported energy
energy (3.6), expressed per energy carrier (3.7), delivered by the technical building systems (3.19)
through the system boundary (3.18) and used outside the system boundary
Note 1 to entry: It can be specified by generation types [e.g. combined heat and power (CHP), photovoltaic (PV)]
in order to apply different weighting factors.
[SOURCE: ISO/TR 16344:2012, 2.1.72, modified – Note 2 has been deleted.]
3.10
fuel
material that can be used to produce heat or generate power by combustion
Note 1 to entry: For the purposes of this document, the term heat is used as per its definition in
ISO 16818:2008, 3.117.
[SOURCE: ISO/TR 16344:2012, 2.1.74]
3.11
functional equivalent
quantified functional requirements and/or technical requirements for a building or part thereof for use
as a reference basis for comparison
Note 1 to entry: For the purposes of this document, the term building is used as per its definition in
ISO 6707-1:2004, 3.1.3.
[SOURCE: ISO 21931-1:2010, 3.7, modified – a reference to part of a building has been added.]
3.12
greenhouse gas emission coefficient
coefficient that describes the amount of a specific greenhouse gas that is released from doing a certain
activity, such as burning one tonne of fuel (3.10) in a furnace
Note 1 to entry: For the purposes of this document, the term greenhouse gas is used as per its definition in
ISO 14064-1:2006, 2.1.
Note 2 to entry: In general, GHG emission coefficients from specific energy consumption (ISO 50001:2011, 3.7) are
quantified based on GHG emission factors (ISO 14064-1:2006, 2.7) for use of the energy (3.6).
Note 3 to entry: Greenhouse gas emission coefficients can differ by year.
3.13
greenhouse gas reservoir
physical unit or component of the biosphere, geosphere, or hydrosphere with the capability to store
or accumulate a GHG removed from the atmosphere by a greenhouse gas sink (3.14) or a GHG captured
from a greenhouse gas source (3.15)
Note 1 to entry: For the purposes of this document, the term GHG is used as per its definition in
ISO 14064-1:2006, 2.1.
Note 2 to entry: The total mass of carbon contained in a GHG reservoir at a specified point in time could be
referred to as the carbon stock of the reservoir.
Note 3 to entry: A GHG reservoir can transfer greenhouse gases to another GHG reservoir.
Note 4 to entry: The collection of a GHG from a GHG source before it enters the atmosphere and storage of the
collected GHG in a GHG reservoir could be referred to as GHG capture and storage.
[SOURCE: ISO 14064-1:2006, 2.4]
3.14
greenhouse gas sink
physical unit or process that removes a GHG from the atmosphere
Note 1 to entry: For the purposes of this document, the term GHG is used as per its definition in
ISO 14064-1:2006, 2.1.
[SOURCE: ISO 14064-1:2006, 2.3]
3.15
greenhouse gas source
physical unit or process that releases a GHG into the atmosphere
Note 1 to entry: For the purposes of this document, the term GHG is used as per its definition in
ISO 14064-1:2006, 2.1.
[SOURCE: ISO 14064-1:2006, 2.2]
3.16
gross floor area
sum of the floor areas of the conditioned spaces within the building, including basements, mezzanine
and intermediate floor tiers, and penthouses, of headroom height 2,2 m or as specified in national or
regional codes and standards
Note 1 to entry: For the purposes of this document, the following terms are used as per their definitions in the
following documents: conditioned spaces (ISO 16818:2008, 3.38) and building (ISO 6707-1:2004, 3.1.3).
Note 2 to entry: It is measured from the exterior faces of exterior walls or from the centreline of walls separating
buildings, but excluding covered walkways, open roofed-over areas, porches and similar spaces, pipe trenches,
exterior terraces or steps, chimneys, roof overhangs, and similar features.
[SOURCE: ISO/TR 16344:2012, 2.1.79]
4 © ISO 2017 – All rights reserved

3.17
renewable energy
energy (3.6) from an energy source (3.8) that is not depleted by extraction
[SOURCE: ISO/TR 16344:2012, 2.1.123, modified – specific reference to energy source has been added
and the examples and explanatory note have been removed.]
3.18
system boundary
boundary that includes within it all areas associated with a building (both inside and outside the
building) where energy (3.6) is consumed or produced
Note 1 to entry: For the purposes of this document, the term building is used as per its definition in
ISO 6707-1:2004, 3.1.3.
Note 2 to entry: Inside the system boundary, the system losses are taken into account explicitly, while outside the
system boundary, they are taken into account in the conversion factor.
[SOURCE: ISO/TR 16344:2012, 2.1.142]
3.19
technical building system
technical equipment for heating, cooling (3.4), ventilation (3.20), humidification, dehumidification,
domestic hot water, lighting, building automation and control and electricity production
Note 1 to entry: A technical building system can refer to one or to several building services (3.1) [e.g. heating,
heating and domestic hot water, and indoor transportation (e.g. escalator, elevator)].
Note 2 to entry: A technical building system is composed of different sub-systems.
Note 3 to entry: Electricity production can include cogeneration (ISO 52000-1:2017, 3.3.5), wind power and
photovoltaic (PV) systems.
[SOURCE: ISO 52000-1:2017, 3.3.13, modified – indoor transportation has been added to Note 1 to entry.]
3.20
ventilation
process of supplying or removing air by natural means or mechanical means to or from a space for the
purpose of controlling air contaminant levels, humidity, odours, or temperature within the space
[SOURCE: ISO 16818:2008, 3.242]
4 Principles
4.1 General
The application of the following principles is fundamental to ensuring that GHG-related information
presented through the carbon metric represents a true and fair measure. These principles provide
the basis for the application of the requirements in this document by the organization or individual
determining the carbon metric.
4.2 Completeness
Include all relevant GHG emissions and removals (see 5.1) that provide a significant contribution to the
carbon metric.
4.3 Consistency
Apply assumptions, methods, and data in the same way throughout the carbon metric determination to
arrive at conclusions in accordance with the needs of the intended user and intended use (see 5.1).
4.4 Relevance
Select the GHG sources, GHG sinks, GHG reservoirs, data, and methodologies appropriate to the needs of
the intended user and the intended use (see 5.3.4).
4.5 Coherence
Select methodologies, standards, and guidance documents already recognized and adopted for energy
measurement and consumption to enhance comparability between common carbon metrics (see 5.3.2)
4.6 Accuracy
Ensure that the carbon metric quantification and communication are accurate, verifiable, relevant, and
not misleading and that bias is avoided and uncertainties are minimised (see 5.3.4).
4.7 Transparency
Address and document all relevant issues in an open, comprehensive, and understandable presentation
of information.
Disclose any relevant assumptions and make appropriate references to the methodologies and
data sources used. Clearly explain any estimates and avoid bias so that the carbon metric faithfully
represents what it purports to represent.
Ensure that the carbon metric communication is available to the intended audience and its intended
meaning is presented in a way that is clear, meaningful, and understandable. Include information on the
functional equivalent, data assumptions, calculation methods, and other characteristics to make the
limitations in the comparisons of carbon metrics transparent and clear to the target group (see Clause 6).
4.8 Avoidance of double counting
Avoid counting of greenhouse gas emissions and removals that have already been allocated within
other carbon metrics (see 5.3).
NOTE This list of principles has been adapted based on the principles described in ISO/TS 14067:2013,
Clause 5.
5 Protocol of measuring the carbon metric of a building in the use stage
5.1 System boundary
5.1.1 Types of carbon metrics of a building
A carbon metric shall be measured by quantifying the direct and indirect GHG emissions and removals
associated with a building in use.
The three types of carbon metrics of a building are defined as follows:
a) Carbon metric 1 (CM1) is the sum of annual GHG emissions, expressed as CO equivalents, from
building-related energy use (see 5.3.4.1);
b) Carbon metric 2 (CM2) is the sum of annual GHG emissions, expressed as CO equivalents, from
building- and user-related energy use (see 5.3.4.2);
c) Carbon metric 3 (CM3) is the sum of annual GHG emissions and removals, expressed as CO
equivalents, from building- and user-related energy use, plus other building-related sources of GHG
emissions and removals.
6 © ISO 2017 – All rights reserved

5.1.2 System boundary for the carbon metrics of a building
5.1.2.1 System boundary for the carbon metrics CM1 and CM2
The system boundary for the CM1 and CM2 of a building is shown in Figure 1. It consists of the
equipment to operate the building fulfilling the demand as energy end use and the technical building
system(s) to deliver, convert, and generate energy for the energy end use.
CM1 and CM2 of a building are determined based on the following:
a) delivered energy for the building and for other energy use within the building’s site (curtilage);
NOTE 1 Delivered energy includes energy provided by the local or national utility supplier and any
remotely generated energy [e.g. from photovoltaic (PV), wind power, or combined heat and power (CHP),
etc.] that is directly connected to the building.
b) total on-site energy generated and used in the building and for other energy use within the
building’s site (curtilage).
NOTE 2 Examples of sources of on-site energy generation can be solar power [photovoltaic (PV) panel],
wind turbine power, biomass fuel, combined heat and power (CHP), fuel cell, and others.
The system boundary shall include all the energy-consuming and -generating systems that are within
the building‘s site (curtilage) and that support the operation of the building.
All building-related energy end use (as indicated in the pale grey boxes in Figure 1) shall be taken
into account for the carbon metric (CM1), even when energy for these building services is separately
measured through sub-metering.
Lighting (including plug-in lighting necessary for the basic function of the building) and controls
(including systems for daylight control) shall be included in the CM1 (see 5.3.4.1).
User-related energy use (as indicated in the dotted box in Figure 1) shall be included in the CM2,
including energy for supplementary lighting installed by building users (see 5.3.4.2).
Figure 1 — Boundary and energy flows — Main energy flows within and crossing the
boundaries for energy use of a building
It is NOT necessary to separately measure the amount of energy generated, converted, or consumed
within the system boundary by each individual system, piece of equipment, or machine.
Exported energy is outside the system boundary but may be reported as additional information where
appropriate (see 6.2.2).
Figures 2, 3, and 4 show examples of the system boundary for CM1.
EXAMPLE 1 Only the energy carrier for the delivered energy and energy generated by the PV panels and used
within the system boundary are required to be measured for CM1.
8 © ISO 2017 – All rights reserved

Figure 2 — Examples of energy flow measuring by energy carriers (Ex.1)
EXAMPLE 2 Only the energy carriers for the delivered energy are required to be measured when a co-
generation system is installed and used within the system boundary for CM1.
Figure 3 — Examples of energy flow measuring by energy carriers (Ex.2)
EXAMPLE 3 The energy carrier for the delivered energy and biomass fuel (wood, waste, etc.) harvested within
the system boundary are measured when biomass cogeneration system is installed and used within the system
boundary for CM1.
Figure 4 — Examples of energy flow measuring by energy carriers (Ex.3)
5.1.2.2 System boundary for the carbon metric CM3
The system boundary for the carbon metric CM3 shall include all the elements within the system
boundary for CM2 plus other processes and activities (including upstream and downstream processes),
causing GHG emissions and removals associated with the use stage of the building and other systems
within the building’s site (curtilage). These shall include, where significant, maintenance, including
cleaning, repair, replacement and refurbishment, water use, waste treatment and disposal, and
emissions of refrigerant from building air cooling systems.
5.2 Carbon metric and carbon intensity
The carbon metric is a measure of total GHG emissions attributed to the use of a building in operation,
over a one year period. For more detailed analysis or comparison, the carbon metric may be denoted
relative to a specific measure of carbon intensity, e.g. per unit area, per person, per kilobyte, per unit
output, and/or per GDP.
5.3 Calculation of GHG emissions
5.3.1 GHG emissions associated with energy use of a building
The emitted mass of GHG, expressed as kg CO equivalent per kg emission, shall be calculated from
the delivered energy for each energy carrier plus the on-site energy, if any, produced without using
delivered energy and used in the building and/or for other energy use within the building’s site,
multiplied by the respective GHG emission coefficient, as given in Formula (1):
 


mE⋅=co ×KE+×K (1)
()
()
∑∑
2eqvd el,cidel,cisite,ci site,ci 
 
where
E is the delivered energy for energy carrier del,ci;
del,ci
E is the energy produced onsite for the energy carrier site,ci;
site,ci
K is the GHG emission coefficient for delivered energy carrier del,ci (see 5.3.5);
del,ci
K is the GHG emission coefficient for on-site energy carrier site,ci.
site,ci
Where the sum of energy produced on-site is estimated to be less than 2 % of the total energy, E
site,ci
should be ignored.
NOTE Energy produced on site does not include co-generation by delivered energy sources.
5.3.2 Measurement of energy carrier
Where the energy carrier(s) provides energy to support the operation of the building and/or other on-
site facilities, measurement of the energy carrier shall take account of all the sources delivered to and
generated within the system boundary including
— electricity,
— fuels (e.g. gas, oil, wood, and other biomass waste), and
— imported coolth/steam/heat.
Data for nominal delivered energy is available from the following sources:
a) utility provider reports and contracts;
b) electricity bills;
10 © ISO 2017 – All rights reserved

c) invoices for fuel deliveries;
d) gas bills;
e) meter readings (estimated from invoices, if meter readings are not available);
f) pipeline measurements;
g) energy management software.
The sum of these data shall include all of the energy usage described in 5.3.4.
Data for the on-site generated energy shall be based on the following:
a) meter readings;
b) measured amount of biomass consumed (kg).
NOTE Further information for the method of measuring and calculation of energy in the use stage of a
building is available from ISO 12655, ISO 16343, and ISO 16346.
5.3.3 Exported energy
Exported energy, i.e. energy produced on-site, but not used for the building or other on-site facilities, is
not included in the carbon metric but can be reported as additional information.
Where exported energy is reported as additional information, the GHG emissions from the exported
energy shall be calculated from the amount of energy generated, multiplied by the respective GHG
emission coefficient, as shown in Formula (2):
mE⋅=co ×K (2)
()
∑
2eqvexp,ciexp,ci
where
E is the exported energy for energy carrier exp,ci;
exp,ci
K is the GHG emission coefficient for exported energy carrier exp,ci.
exp,ci
NOTE Annex D presents examples of allocation rules that can be used for combined heat power.
5.3.4 Energy usage
5.3.4.1 Building-related energy use
For CM1, building-related energy use shall be determined as follows (see Annex B for the classification):
a) Energy for HVAC and domestic hot water:
1) energy for space heating;
2) energy for space cooling;
3) energy for air movement;
4) energy for domestic hot water.
b) Energy for fixed lighting;
c) Energy for plug-in equipment for basic building services:
1) plug-in lighting;
2) plug-in heating;
3) plug-in cooling.
d) Energy for other usage:
1) energy for indoor transportation;
2) energy for building auxiliary devices.
For purposes of determining the carbon metric, all building-related energy use shall be included, even
for building services not typically sub-metered or separately measured.
5.3.4.2 User-related energy use
For CM2, user-related energy use is determined as follows (see Annex B for the classification):
a) energy for lighting and plug-in equipment:
1) energy for supplementary lighting installed by building users;
2) energy for household/office appliances.
b) energy for other special usages:
1) energy for cooking;
2) energy for refrigeration (cooling and storage);
3) energy for devices in data centres;
4) energy for other specific functional devices.
5.3.5 GHG emission coefficients
5.3.5.1 General
The greenhouse gas emissions from energy consumption are quantified by using GHG emission
coefficients. GHG emission coefficients characterize the amount of a specific GHG that is released from
doing a certain activity, such as burning one tonne of fuel in a furnace.
The GHG emission coefficient(s) used is based on the type of delivered energy carrier or exported
energy carrier.
For the purpose of this document, the following information shall be stated regarding the type of GHG
emission coefficient used to determine carbon metric:
— sources of information (e.g. national, international);
— greenhouse gases included in CO equivalent (e.g. following Kyoto protocol, Montreal protocol, or
other protocols);
— included elements in supply chain (e.g. on-site or on-site plus upstream processes);
— time frame of impacts on environment (100 years);
— year of reference of emission coefficient data.
The choice of the source of the GHG emission coefficient used for calculating a carbon metric shall be
appropriate for the intended use of the carbon metric.
12 © ISO 2017 – All rights reserved

GHG emission coefficients shall be obtained from, in the following order of priority:
— nationally agreed data;
— independently provided information;
— internationally agreed data.
NOTE 1 There are some usable databases as officially agreed (approved) GHG emission coefficients (see
References [20], [21] and [22]).
NOTE 2 GHG emission coefficients for each fuel type could be the same as those used under national reporting
for flexible mechanisms for the Kyoto Protocol for the six major greenhouse gases.
NOTE 3 Because some officially agreed (approved) GHG emission coefficients are based on default emissions,
they may not necessarily reflect the specific types of fuel combustion and emissions control technologies at each
building.
NOTE 4 Additional geographically or technologically specific GHG emission factors could result in more
accurate calculations and can be used as long as they are credible and as long as the sources are documented and
reported.
NOTE 5 For certain sources, GHG emissions could be calculated in different ways to accommodate differences
in the type of GHG activity data available to individual reporting offices or to help ensure that the calculations
are as accurate as possible.
For international carbon trading mechanisms (such as the Clean Development Mechanism), it is
recommended that the source of the GHG emission coefficient(s) be the internationally agreed sources
appropriate to the fuel that is being consumed and the technology used for the energy carrier.
NOTE 6 This document includes the principle of avoidance of double-counting. This is considered especially in
some situations where supplier/generator-specific emission factors for electricity are used. For example, where
— the process which used the electricity (or used an equivalent amount of electricity of the same type to that
generated) and another process did not claim the generator-specific emission factors for that electricity; and
— the generator-specific electricity production does not influence the emission factors of any other process or
organization.
— some electricity attributes such as green certificates are sold without direct coupling to the electricity itself.
In some countries, parts of the electricity from renewable energy sources might already be sold/exported as
renewable electricity without being excluded from the supplied mix.
5.3.5.2 Treatment of delivered energy
The GHG emission coefficients associated with the use of delivered energy shall take into account,
where relevant, GHG emissions arising from the energy supply system.
When a supplier of energy delivers a specific energy product with a specific GHG emission coefficient
and guarantees that the energy sale and the associated GHG emissions are not double counted, the GHG
emission coefficient for that specific energy product shall be used. When the supplier of energy does not
provide a specific GHG emission coefficient for the specific energy product delivered, the GHG emission
coefficient associated with the utility (e.g. the national grid for electricity) shall be used.
Where a country does not have a national supply system but has several unconnected supply systems
or several countries share a supply system, the GHG emission coefficient(s) associated with the relevant
system from which the energy is obtained shall be used.
Where the GHG emission coefficient(s) for the energy supply system are difficult to access, GHG emission
coefficients for similar energy
...