ISO/TR 16344:2012

Energy performance of buildings - Common terms, definitions and symbols for the overall energy performance rating and certification

ISO/TR 16344:2012 provides a coherent set of terms, definitions and symbols for concepts and physical quantities related to the overall energy performance of buildings and its components, including definitions of system boundaries, to be used in all standards elaborated within ISO on energy performance of buildings. These terms and definitions are applicable to energy calculations in accordance with the Technical Report and standards on the overall energy performance of buildings and their components, to provide input to the Technical Report or using output from the Technical Report. They are based on existing terms and definitions from standards and other documents referenced in the bibliography.

Performance énergétique des bâtiments — Termes, définitions et symboles communes pour l'évaluation de la performance et la certification énergétique

General Information

• Status: Withdrawn
• Publication Date: 11-Oct-2012
• Withdrawal Date: 11-Oct-2012
• ICS: 91.120.10 - Thermal insulation of buildings
• Technical Committee: ISO/TC 163 - Thermal performance and energy use in the built environment
• Drafting Committee: ISO/TC 163/WG 4 - Joint ISO/TC 163 - ISO/TC 205 WG: Energy performance of buildings using holistic approach
• Parallel Committee: ISO/TC 205 - Building environment design
• Current Stage: 9599 - Withdrawal of International Standard
• Start Date: 21-Jun-2017
• Completion Date: 13-Dec-2025

Relations

• Revised: ISO 52000-1:2017 - Energy performance of buildings - Overarching EPB assessment - Part 1: General framework and procedures
• Effective Date: 14-Nov-2015

Standards Content (Sample)

TECHNICAL ISO/TR
REPORT 16344
First edition
2012-10-15
Energy performance of buildings —
Common terms, definitions and
symbols for the overall energy
performance rating and certification
Performance énergétique des bâtiments — Termes, définitions
et symboles communes pour l’évaluation de la performance et la
certification énergétique
Reference number
©
ISO 2012
© ISO 2012
All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized in any form or by any
means, electronic or mechanical, including photocopying and microfilm, without permission in writing from either ISO at the
address below or ISO’s member body in the country of the requester.
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Published in Switzerland
ii © ISO 2012 – All rights reserved

Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Terms and definitions . 1
2.1 Terms . 1
2.2 Proposed groupings of terms .19
3 Symbols and abbreviations .25
3.1 General .25
3.2 Principal symbols .25
3.3 Subscripts .26
3.4 More details and examples .29
Annex A (normative) Symbols and abbreviations — Further details and examples .30
Annex B (informative) Translation of symbols and subscripts into French and German .36
Bibliography .40
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.
International Standards are drafted in accordance with the rules given in the ISO/IEC Directives, Part 2.
The main task of technical committees is to prepare International Standards. Draft International
Standards adopted by the technical committees are circulated to the member bodies for voting.
Publication as an International Standard requires approval by at least 75 % of the member bodies
casting a vote.
In exceptional circumstances, when a technical committee has collected data of a different kind from
that which is normally published as an International Standard (“state of the art”, for example), it may
decide by a simple majority vote of its participating members to publish a Technical Report. A Technical
Report is entirely informative in nature and does not have to be reviewed until the data it provides are
considered to be no longer valid or useful.
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.
ISO/TR 16344 was prepared by Technical Committee ISO/TC 163, Thermal performance and energy use
in the built environment, in conjunction with TC 205, Building environment design.
iv © ISO 2012 – All rights reserved

Common terms, definitions and symbols
Introduction
This Technical Report is one of three closely linked documents dealing with definitions and general
procedures for overall building energy performance rating and certification (see also Figure 1):
— ISO/TR 16344, Energy performance of buildings — Common terms, definitions and symbols for the
overall energy performance rating and certification;
— ISO 16343, Energy performance of buildings — Methods for expressing energy performance and for
energy certification of buildings;
— ISO 16346, Energy performance of buildings — Assessment of overall energy performance.
Their development greatly benefited from similar CEN documents (viz. CEN/TR 15615, EN 15217
and EN 15603, respectively) developed to support the European Energy Performance of Buildings
Directive (EPBD).
The main differences between this Technical Report (i.e. ISO/TR 16344) and CEN/TR 15615 are:
— this Technical Report covers only the subjects covered in CEN/TR 15615:2008, Annex C (Definitions)
and Annex D (Common symbols and subscripts);
— this Technical Report includes specific definitions added from other sources without jeopardizing
the consistency and integrity of the document;
— some editorial changes have been made.
Note that a revision of the set of CEN documents to support the EPBD is anticipated in the near future.
Issuing the corresponding ISO documents aims to bring the key subject of building energy performance
assessment to the fore at the global level.
Given the strong demand for these documents at ISO level, it was decided not to delay the advancement of
the ISO documents by waiting for these CEN developments. However, it is expected that a future revision
of the ISO documents will be carried out in collaboration with CEN under the Vienna Agreement.

Energy Performance (EP)
ISO TR 16344
EP
Overall Energy
Performance of the EP
ISO 16343
building includingits expressions
technicalbuilding
ISO 16346
systems
EP aggregation
Boundaries, classification
Collect all energy elements
Building energy needs
and system energy losses
Component input data
Boundaryconditions
Figure 1 — Flow diagram illustrating the successive elements of the general procedures
The difference between this Technical Report and ISO 16818, Building environment design — Energy
efficiency — Terminology, is that ISO 16818 gives terms and definitions for use in the design of energy-
efficient buildings, while this Technical Report provides an unambiguous and consistent common set of
terms, definitions and symbols for all elements of the assessment of the overall energy performance of
buildings. The unambiguous and consistent use of terms, definitions and symbols is essential when the
energy performance is assessed in the context of national or regional building regulations, e.g. to check
compliance with minimum energy performance requirements and/or to produce energy performance
certificates for a building.
vi © ISO 2012 – All rights reserved

TECHNICAL REPORT ISO/TR 16344:2012(E)
Energy performance of buildings — Common terms,
definitions and symbols for the overall energy
performance rating and certification
1 Scope
This Technical Report provides a coherent set of terms, definitions and symbols for concepts and
physical quantities related to the overall energy performance of buildings and its components,
including definitions of system boundaries, to be used in all standards elaborated within ISO on energy
performance of buildings.
These terms and definitions are applicable to energy calculations in accordance with this Technical
Report and standards on the overall energy performance of buildings and their components, to provide
input to this Technical Report or using output from this Technical Report. They are based on existing
terms and definitions from standards and other documents referenced in the bibliography.
NOTE Slightly different definitions might be applicable to other situations, e.g. design of installations.
2 Terms and definitions
For the purposes of this Technical Report, the terms and definitions given in ISO 7345 and the
following apply.
2.1 Terms
2.1.1
air-conditioned floor area
area equipped with air-conditioning equipment, measured at floor level from the interior surfaces of the
walls
NOTE See also “gross floor area”.
2.1.2
air-conditioning system
combination of all components required to provide a form of air treatment in which maximum or
minimum temperature is controlled, possibly in combination with the control of ventilation, humidity
and air cleanliness
2.1.3
auxiliary energy
electrical energy used by technical building systems for heating, cooling, ventilation and/or hot domestic
water to support energy transformation to satisfy energy needs
NOTE 1 This includes energy for fans, pumps, electronics, etc. Electrical energy input to a ventilation system
for air transport and heat recovery is not considered as auxiliary energy, but as energy used for ventilation
(see 2.1.156).
NOTE 2 In ISO 9488, the energy used for pumps and valves is called “parasitic energy”.
2.1.4
building
construction as a whole, including its envelope and all technical building systems, for which energy
is used to condition the indoor climate and to provide domestic hot water and illumination and other
services related to the use of the building
NOTE The term can refer to the building as a whole or to parts thereof that have been designed or altered to
be used separately.
2.1.5
building area
greatest horizontal area of a building above grade within the outside surface of the exterior walls or
within the outside surface of the exterior wall and the centrelines of the fire walls
2.1.6
building automation and control
products, software and engineering services for automatic controls, monitoring and optimization,
human intervention and management to achieve energy-efficient, economical and safe operation of
building services equipment
2.1.7
building calculation model
mathematical model of the building, used to calculate its energy use
2.1.8
building energy cost
calculated annual energy cost of all purchased energy for the building
2.1.9
building heat transfer coefficient
sum of the transmission and ventilation heat transfer coefficients
2.1.10
building services
services provided by technical building systems and by appliances to provide indoor climate conditions,
domestic hot water, illumination levels and other services related to the use of the building
2.1.11
building type
classification of a building by usage as given in definitions 2.1.11.1 to 2.1.11.9
2.1.11.1
assembly
building or structure for the gathering together of persons, such as auditoriums, churches, reception
halls, gymnasiums, theatres, museums, passenger depots, sports facilities and public assembly halls
2.1.11.2
health and institutional
building or structure for the purpose of providing medical treatment, confinement or care, and sleeping
facilities such as hospitals, sanatoriums, clinics, orphanages, nursing homes, mental institutions,
reformatories, jails and prisons
2.1.11.3
hotel or motel
building or structure for transient occupancy, including not only hotels and motels but also resorts,
barracks and dormitories
2 © ISO 2012 – All rights reserved

2.1.11.4
multifamily
building or structure containing three or more dwelling units
NOTE See also “dwelling unit”.
2.1.11.5
office
building or structure for office, professional or service type transactions, such as medical
offices, banks, libraries and governmental office buildings
2.1.11.6
restaurant
building or structure for the consumption of food or drink, including fast food restaurants, coffee shops,
cafeterias, bars and restaurants
2.1.11.7
retail
building or structure for the display and sale (wholesale or retail) of merchandise, such as
shopping malls, food markets, auto dealerships, department stores and specialty shops.
2.1.11.8
school
building or structure for the purpose of instruction such as schools, colleges, universities,
and academies
2.1.11.9
warehouse
building or structure for storage, such as aircraft hangers, garages, warehouses, storage buildings and
freight depots
2.1.12
building envelope
elements of a building that enclose conditioned spaces through which thermal energy may be transferred
to or from the exterior or to or from unconditioned spaces
2.1.13
building envelope, exterior
elements of a building that separate conditioned spaces from the exterior
2.1.14
building envelope, semi-exterior
elements of a building that separate conditioned spaces from unconditioned spaces or that enclose semi-
heated spaces through which thermal energy may be transferred to or from the exterior, or to or from
unconditioned spaces, or to or from conditioned spaces
NOTE 1 Building envelope defines the surfaces that need to be insulated, or weather-stripped. The outer shell
of the building is not necessarily the same as the building envelope, particularly where the building contains semi-
heated or unconditioned spaces.
NOTE 2 In some cases, the designer can determine the location of the exterior building envelope by the location
that they place the insulation. For instance, it is not uncommon for a stairwell to be at the outside edge of the
building. If that stairwell does not have any heating or cooling supply, it could be insulated on the outside edge
or the side adjacent to other heated or cooled spaces. If insulated on the outside, the stairwell becomes indirectly
conditioned, and the outside wall is the exterior building envelope. If insulated on the inside, the inside wall is
likely to become the exterior building envelope (unless the outside exposure is so small that it would still be
indirectly conditioned space).
NOTE 3 Where a building with conditioned space also contains semi-heated spaces or unconditioned spaces,
the building envelope for the conditioned space is the roofs, walls, floors, doors, fenestration, etc., that separate
the conditioned space from the exterior. These elements must comply with the residential or non-residential
conditioned-space requirements.
NOTE 4 For semi-heated spaces, the building envelope includes any roofs, walls, floors, doors, fenestration,
etc., that separate the semi-heated space from conditioned or unconditioned spaces (as well as from the exterior).
These elements must comply with the semi-heated space requirements, as must elements separating conditioned
space from unconditioned space.
2.1.15
building heat transfer coefficient
sum of the transmission and ventilation heat transfer coefficients
2.1.16
calculated energy rating
energy rating based on calculations of the weighted net delivered energy used by a building for heating,
cooling, ventilation, domestic hot water and lighting
NOTE National bodies can decide whether other energy uses resulting from occupants’ activities, such as
cooking, production, laundering, computer equipment, etc., are included or not. If included, standard input data
needs to be provided for the various types of building and uses. Lighting is always included except (by decision of
national bodies) for residential buildings.
2.1.17
calculation step
discrete time interval for the calculation of the energy needs and uses for heating, cooling, humidification,
dehumidification and lighting
2.1.18
calculation period
period of time over which a calculation is performed
NOTE The calculation period can be divided into a number of calculation-step periods
2.1.19
CO emission coefficient
2e
for a given energy carrier, quantity of CO emitted to the atmosphere per unit of delivered energy
NOTE The CO emission coefficient includes the equivalent emissions of other greenhouse gases
2e
(e.g. methane).
2.1.20
cogeneration
simultaneous generation in one process of thermal energy and electrical or mechanical energy
NOTE Also known as combined heat and power (CHP).
2.1.21
cooling
removal of latent and/or sensible heat
2.1.22
commissioning
sequence of events to enable the functioning of a building and its heating, ventilation and air-conditioning
(HVAC) system in accordance with the design parameters
2.1.23
conditioned space
cooled space, heated space or indirectly conditioned space as defined in definitions 2.1.23.1 to 2.1.23.3
2.1.23.1
cooled space
enclosed space within a building that is cooled by a cooling system
4 © ISO 2012 – All rights reserved

2.1.23.2
heated space
enclosed space within a building that is heated by a heating system whose output capacity relative to the
floor area is greater than or equal to the design criteria
2.1.23.3
indirectly conditioned space
enclosed space within a building that is not a heated space or a cooled space but which is heated or cooled
indirectly by being connected to adjacent space(s) provided: (a) the product of the U-factor(s) and surface
area(s) of the space(s) adjacent to the connected space(s) exceeds the combined sum of the product of the
U-factor(s) and surface areas(s) of the space(s) adjoining the outdoors, unconditioned spaces and semi-
heated spaces (e.g. corridors), or (b) that air from heated or cooled spaces is intentionally transferred
(naturally or mechanically) into the space at a rate exceeding three air changes per hour (ACH)
2.1.24
conditioned area
floor area of conditioned spaces, excluding non-habitable cellars or non-habitable parts of a space,
including the floor area on all storeys if more than one
NOTE 1 Internal, overall internal or external dimensions may be used. This leads to different areas for the
same building, however.
NOTE 2 Some services, such as lighting or ventilation, might be provided to areas not included in this definition
(e.g. a car park).
NOTE 3 The precise definition of the conditioned area is given by national authorities.
NOTE 4 Conditioned area can be taken as the useful area unless it is otherwise defined in national regulations.
2.1.25
conditioned zone
part of a conditioned space with a given set-point temperature or set-point temperatures, throughout which
there is the same occupancy pattern and the internal temperature is assumed to have negligible spatial
variations, and which is controlled by a single heating system, cooling system and/or ventilation system
2.1.26
confidence interval
interval that has a high probability (e.g. 95 %) of including the actual value
2.1.27
construction
erection of a new building, or any addition to or alteration of an existing building
2.1.28
construction documents
drawings and specifications used to construct a building, building systems or portions thereof
2.1.29
daylight space
space bounded by vertical planes rising from the boundaries of the daylight area on the floor to the floor
above or to the roof
2.1.30
daylight zone
types of daylight zone are as given in definitions 2.1.30.1 and 2.1.31.2
2.1.30.1
under a skylight
area under a skylight whose horizontal dimension in each direction is equal to the skylight dimension in
that direction plus either the floor to ceiling height or the dimension to an opaque partition, or one-half
the distance to an adjacent skylight or vertical glazing, whichever is least
2.1.30.2
adjacent to vertical glazing
area adjacent to vertical glazing which receives daylighting from the glazing
NOTE For the purposes of this definition and unless more detailed daylighting analysis is provided, the
daylighting zone depth is assumed to extend into the space a distance of 45 m or to the nearest opaque partition,
whichever is less. The daylighting zone width is assumed to be the width of the window plus either 6 m on each
side, the distance to an opaque partition, or one-half the distance to an adjacent skylight or vertical glazing,
whichever is least.
2.1.31
control
action or device to regulate the operation of equipment
2.1.32
dehumidification
process of removing water vapour from air to reduce the relative humidity
2.1.33
delivered energy
energy, expressed per energy carrier, supplied to the technical building systems through the system
boundary to satisfy the uses taken into account (heating, cooling, ventilation, domestic hot water,
lighting, appliances, etc.) or to produce electricity
NOTE 1 For active solar and wind energy systems, the solar radiation incident on solar panels or on solar
collectors or the kinetic energy of wind is not part of the energy balance of the building. It is decided at national
level whether or not renewable energy produced on site is part of the delivered energy.
NOTE 2 Delivered energy can be calculated for defined energy uses or it can be measured.
2.1.34
demand-controlled ventilation
ventilation system in which the room airflow rate is governed by an automatic control depending upon
the levels of occupancy and activity within the space
NOTE Examples are the speed of fans controlled by a presence indicator such as the CO level in the room air,
a presence detector or a timer.
2.1.35
design conditions
specified environmental conditions, such as temperature and light intensity, required to be produced
and maintained by a system and under which the system must operate
2.1.36
design criteria
set of descriptions based on a particular environmental element such as indoor air quality, thermal,
acoustical and visual comfort, energy efficiency and the associated system controls to be used for
assessing the design presented
2.1.37
design documentation
written description of the essential design elements of a plant
2.1.38
design energy rating
calculated energy rating using design data for a building and a standard use data set
NOTE It represents the calculated intrinsic annual energy use of a building design under standardized
conditions. This is particularly relevant in order to obtain a building permit at the design stage.
6 © ISO 2012 – All rights reserved

2.1.39
design parameters
set values of the internal environmental conditions to be achieved regardless of the changing external
environmental conditions
2.1.40
design process
course of purposive actions performed to produce a set of design drawings and specifications in which
a building having the potential to provide the functionalities required is described
NOTE Any changes in the building environment design after iterations of decisions and evaluations of the
design have been made must be analysed until the final design stage is reached.
2.1.41
distribution system
conveying means, such as ducts, pipes and wires, to bring substances or energy from a source to the
point of use
NOTE The distribution system includes auxiliary equipment such as fans, pumps and transformers.
2.1.42
domestic hot water heating
process of heat supply to raise the temperature of cold water to the intended delivery temperature
2.1.43
efficiency
performance at specified conditions for the assessment of the energy performance
2.1.44
efficiency of HVAC system
ratio of the useful energy output (at the point of use) to the energy input in consistent units, for a
designated time period, expressed in percent
2.1.45
energy
capability for doing work; having several forms that may be transformed from one to another, such as
thermal (heat), mechanical (work), electrical or chemical
2.1.46
energy carrier
substance or phenomenon that can be used to produce mechanical work or heat or to operate chemical
or physical processes
[ISO 13600:1997]
NOTE The energy content of fuels is given by their gross calorific value.
2.1.47
energy certification
procedures enabling an energy certificate to be obtained
2.1.48
energy certificate
document, recognized by a member state or a legal person designated by it, which includes the energy
performance of a building
NOTE The meanings of the terms “certificate” and “certification” in this Technical Report differ from those in
ISO/IEC 17000:2004.
2.1.49
energy class
easy-to-understand designation system (e.g. A to G) for indicating the energy performance of a building
2.1.50
energy efficiency ratio
EER
ratio of the net capacity of (cooling or heating) equipment to the total rate of electric input under
designated operating conditions
2.1.51
energy efficiency ratio for buildings
EERB
ratio of energy required (ER) and energy used (EU)
2.1.52
energy management system
control system designed to monitor the environment and the use of energy in a facility and to adjust the
parameters of local control loops to conserve energy while maintaining a suitable environment
2.1.53
energy need for domestic hot water
heat to be delivered to the required amount of domestic hot water to raise its temperature from the cold
network temperature to the prefixed delivery temperature at the delivery point
2.1.54
energy need for heating or cooling
heat to be delivered to or extracted from a conditioned space to maintain the intended temperature
conditions during a given period of time
NOTE 1 The energy need is calculated and cannot easily be measured.
NOTE 2 The energy need can include additional heat transfer resulting from non-uniform temperature
distribution and non-ideal temperature control, if these factors are taken into account by increasing (decreasing) the
effective temperature for heating (cooling) and not included in the heat transfer due to the heating (cooling) system.
2.1.55
energy need for humidification or dehumidification
latent heat in the water vapour to be delivered to or extracted from a conditioned space by a technical
building system to maintain a specified minimum or maximum humidity within the space
2.1.56
energy inspection
examination of heating and/or air-conditioning systems in a building
2.1.57
energy performance indicator
energy rating divided by conditioned area
2.1.58
energy performance of a building
calculated or measured amount of weighted net delivered energy actually used or estimated to meet
different needs associated with a standardized use of a building, which might include, inter alia, energy
used for heating, cooling, ventilation, domestic hot water and lighting
2.1.59
energy rating
evaluation of the energy performance of a building based on the weighted sum of the calculated or
measured use of energy carriers
2.1.60
energy required (ER)
energy demand
total energy required to achieve the building performance and comfort over a given period of time,
including HVAC, lighting, occupancy and domestic hot water
8 © ISO 2012 – All rights reserved

2.1.61
energy used (EU)
final energy
total purchased energy (fossil, electric) excluding renewables consumed to achieve the required building
performance and comfort over a given period of time
2.1.62
energy source
source from which useful energy can be extracted or recovered either directly or by means of a
conversion or transformation process
NOTE Examples include oil or gas fields, coal mines, the sun and forests.
2.1.63
energy use for lighting
energy consumed by a lighting installation to meet the lighting requirements, which depends on the
installed loading, the hours of use and the control regime
NOTE Energy targets, in kW⋅h per year per unit area or length, should be set to encourage energy efficiency.
2.1.64
energy use for other services
electrical energy input to appliances providing other services
NOTE This refers to services other than heating, cooling, domestic hot water, ventilation and lighting.
2.1.65
energy use for space heating or cooling or domestic hot water
energy input to the heating, cooling or hot water system to satisfy the energy need for heating, cooling
(including dehumidification) or hot water, respectively
NOTE If the technical building system serves several purposes (e.g. heating and domestic hot water), it can
be difficult to split the energy use into that used for each purpose. It can be indicated as a combined quantity (e.g.
energy need for both space heating and domestic hot water).
2.1.66
energy use for ventilation
electrical energy input to a ventilation system for air conveyance and heat recovery (not including the
energy input for preheating the air) and energy input to the humidification systems to satisfy the need
for humidification
2.1.67
equipment
devices for comfort conditioning, electric power, lighting, transportation, or service water heating
including, but not limited to, furnaces, boilers, air conditioners, heat pumps, chillers, water heaters,
lamps, luminaires, ballasts, elevators, escalators and control devices or installations
2.1.68
equivalent internal temperature
constant minimum internal temperature, assumed for the calculation of the energy for heating,
or maximum internal temperature, assumed for the calculation of the energy for cooling, leading to
approximately the same average heat transfer as would apply with intermittent heating or cooling, and
with inaccuracy of room temperature control
2.1.69
external dimension
dimension measured on the exterior of a building
2.1.70
external temperature
temperature of the external air
NOTE 1 For transmission heat transfer calculations, the radiant temperature of the external environment is
assumed to be equal to the external air temperature; long-wave transmission to the sky is calculated separately.
NOTE 2 The measurement of external air temperature is given in ISO 15927-1.
2.1.71
existing building
building that has been erected
building for which actual data necessary to assess the energy use are
known or can be measured
2.1.72
exported energy
energy, expressed per energy carrier, delivered by the technical building systems through the system
boundary and used outside the system boundary
NOTE 1 It can be specified by generation types (e.g. combined heat and power, photovoltaic) in order to apply
different weighting factors.
NOTE 2 Exported energy can be calculated or it can be measured.
2.1.73
fossil fuel
organic material, other than biomass, used as a fuel
2.1.74
fuel
material that can be used to produce heat or generate power by combustion
2.1.75
gain utilization factor
factor reducing the total monthly or seasonal heat gains to obtain the resulting reduction of the energy
need for heating
2.1.76
grid electricity
energy delivered to the building from a public electricity network
2.1.77
gross building envelope floor area
gross floor area of the building envelope, but excluding slab-on-grade floors
2.1.78
gross calorific value
quantity of heat released by a unit quantity of fuel when it is burned completely with oxygen at a constant
pressure equal to 101 320 Pa and when the products of combustion are returned to ambient temperature
NOTE 1 This quantity includes the latent heat of condensation of any water vapour contained in the fuel and of
the water vapour formed by the combustion of any hydrogen contained in the fuel.
NOTE 2 According to ISO 13602-2, the gross calorific value is preferred to the net calorific value.
NOTE 3 The net calorific value does not take account of the latent heat.
10 © ISO 2012 – All rights reserved

2.1.79
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 It is measured from the exterior faces of the exterior walls or from the centrelines of the 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.
2.1.80
gross floor area over outside or unconditioned spaces
gross area of a floor assembly separating a conditioned space from the outdoors or from unconditioned
spaces, as measured from the exterior faces of exterior walls or from the centrelines of walls
separating buildings
NOTE The floor assembly is considered to include all floor components through which heat might flow
between indoor and outdoor or unconditioned environments.
2.1.81
gross lighted area
GLA
sum of the total lighted areas of a building, measured from the inside of the perimeter walls for each
floor of the building
2.1.82
gross lighted floor area
gross floor area of lighted spaces
2.1.83
gross semi-heated floor area
gross floor area of semi-heated spaces
NOTE The gross building envelope floor area will usually be only one floor on the bottom, whereas the gross
conditioned floor area might include multiple floors in a building.
2.1.84
heat balance ratio
monthly or seasonal heat gains divided by the monthly or seasonal heat transfer
2.1.85
heat gains
heat generated within or entering into the conditioned space from heat sources other than energy
intentionally utilized for heating, cooling or domestic hot water preparation
NOTE 1 These include internal heat gains and solar heat gains. Sinks that extract heat from the building are
included as gains, with a negative sign. In contrast, with heat transfer, for a heat source (or sink) the difference
between the temperature of the space considered and the temperature of the source is not the driving force for
the heat flow.
NOTE 2 For summer conditions, heat gains with a positive sign constitute an extra heat load on the space.
2.1.86
heat recovery
heat generated by a technical building system or linked to a building use (e.g. domestic hot water), which
is utilized directly in a related system to lower the heat input and which would otherwise be wasted (e.g.
preheating of combustion air by a flue gas heat exchanger)
2.1.87
heat transfer coefficient
heat flow rate divided by the temperature difference between two environments
NOTE It is specifically used for the coefficient of heat transfer by transmission or ventilation.
2.1.88
heated space
room or enclosure which, for the purposes of a calculation, is assumed to be heated to a given set-point
temperature or set-point temperatures
2.1.89
heating or cooling season
period of the year during which a significant amount of energy for heating or cooling is needed
NOTE The season lengths are used to determine the period of operation of technical systems.
2.1.90
humidification
process of adding water vapour to air to increase the relative humidity
2.1.91
inspector
person having appropriate training or practical experience in energy inspection of heating and/or air-
conditioning systems and in associated regulations for energy
2.1.92
intermittent heating or cooling
heating or cooling pattern where normal heating or cooling periods alternate with periods of reduced
or no heating or cooling
2.1.93
internal heat gains
heat provided within the building by the occupants (sensible metabolic heat) and by appliances such as
lighting, domestic appliances, office equipment, other than energy intentionally provided for heating,
cooling or hot water preparation
NOTE This includes recoverable system thermal losses, if the holistic approach for the calculation of the
recovered system losses is chosen.
2.1.94
internal dimension
dimension measured from wall to wall and floor to ceiling inside a room of a building
2.1.95
internal temperature
arithmetic average of the air temperature and the mean radiant temperature at the centre of the
occupied zone
NOTE This is the approximate operative temperature according to ISO 7726.
2.1.96
life cycle cost
total cost of a building or its parts throughout its life, including the costs of planning, design, acquisition,
operation, maintenance and disposal, less any residual value
2.1.97
lighting
process of supplying the necessary illumination
12 © ISO 2012 – All rights reserved

2.1.98
lighting system
group of luminaires circuited or controlled to perform a specific function
2.1.99
loss utilization factor
factor reducing the total monthly heat transfer to obtain the resulting reduction of the energy need for
cooling
2.1.100
measured energy indicator
measured energy rating divided by the conditioned area
2.1.101
measured energy rating
energy rating based on the measured amounts of delivered and exported energy
NOTE 1 The measured rating is the weighted sum of all energy carriers used by the building, as measured by
meters or other means. It is a measure of the in-use performance of the building. This is particularly relevant to
certification of actual energy performance.
NOTE 2 Also known as “operational rating”.
2.1.102
net delivered energy
delivered energy minus exported energy, both expressed per energy carrier
NOTE 1 A balance of the delivered and exported energy per energy carrier can be performed only if the same
primary energy factors and/or CO coefficients apply to the delivered and exported amounts of that energy carrier.
NOTE 2 The term “net” can also be applied to quantities derived from net delivered energy, e.g. primary energy
or CO emissions.
2.1.103
net thermal efficiency
ratio between the heat or cooling demand of the distribution system and the fuel heat input energy
requirements for heating or cooling, i.e. the energy to be delivered to the heating or cooling system to
satisfy the heat demand of the building
2.1.104
new building
building at the design stage or under construction
building too recently constructed to have reliable records of energy use
2.1.105
non-renewable energy
energy taken from a source which is depleted by extraction (e.g. fossil fuels)
2.1.106
non-renewable primary energy factor
for a given energy carrier, non-renewable primary energy divided by delivered energy, where the non-
renewable energy is that required to supply one unit of delivered energy, taking account of the non-
renewable energy required for extraction, processing, storage, transport, generation, transformation,
transmission, distribution and any other operations necessary for delivery to the building in which the
delivered energy will be used
NOTE The non-renewable primary energy factor can be less than unity if renewable energy has been used.
2.1.107
occupied zone
that part of a conditioned zone in which persons normally reside and where requirements as to the
internal environment are to be satisfied
NOTE The definition of the occupied zone depends on the geometry and the use of the room and is specified
case by case. Usually the term “occupied zone” is used only for areas designed for human occupancy and is defined
as a volume of air that is confined by specified horizontal and vertical planes. The vertical planes are usually
parallel with the walls of the room. Usually, there is also a limit placed on the height of the occupied zone.
2.1.108
other building services
services supplied by energy-consuming appliances
2.1.109
overall internal dimension
dimension measured on the interior of a building, ignoring internal partitions
2.1.110
part-load operation
operational state of a technical system (e.g. heat pump), where the actual load is below the actual output
capacity of the device
2.1.111
performance indicator
particular quantified aspect of a building
2.1.112
primary energy
energy that has not been subjected to any conversion or transformation process
NOTE 1 Primary energy includes non-renewable energy and renewable energy. If both are taken into account,
it can be called total primary energy.
NOTE 2 For a building, it is the energy used to produce the energy delivered to the building. It is calculated
from the delivered and exported amounts of energy carriers, using conversion factors.
2.1.113
process energy
energy consumed in support of a manufacturing, industrial or commercial process other than for
conditioning spaces and maintaining comfort and amenities for the occupants of a building
2.1.114
qualified person
one familiar with the construction and operation of the equipment and the hazards involved
2.1.115
reasonable cost
cost that is accepted by all parties to reach a given end
NOTE 1 This cost, or a method to assess this cost, should be given at the national level.
NOTE 2 This cost strongly depends on the purpose of the effort. For example, the cost of a rating could be
relatively large if it is to provide an official certificate to put the building on the market or for displaying the
building performance to the public, but reduced if it is simply for statistical purposes.
2.1.116
reasonably possible cost
cost considered reasonably likely to be possible
14 © ISO 2012 – All rights reserved

2.1.117
recoverable system thermal loss
part of a system thermal loss which can be recovered to lower either the energy need for heating or
cooling or the energy use of the heating or cooling system
NOTE This depends on the calculation approach chosen to calculate the recovered gains and losses (holistic
or simplified approach).
2.1.118
recoverable energy
part of the energy losses, from the space and domestic hot water system or lighting, which can be
recovered to lower the energy required
2.1.119
recovered energy
that part of the recoverable energy consisting of energy from an energy utilization system which would
otherwise be wasted (not contributing to a desired end use)
NOTE Recovered energy may contribute to reducing the energy required (ER).
2.1.120
recovered system thermal loss
that part of the recoverable system thermal loss which has been recovered to lower either the energy
need for heating or cooling or th
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