ISO 18292:2011

INTERNATIONAL ISO
STANDARD 18292
First edition
2011-04-01
Energy performance of fenestration
systems for residential buildings —
Calculation procedure
Performance énergétique des systèmes de fenêtrage pour les
bâtiments résidentiels — Mode opératoire de calcul

Reference number
©
ISO 2011
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ii © ISO 2011 – All rights reserved

Contents Page
Foreword .iv
Introduction.v
1 Scope.1
2 Normative references.1
3 Terms and definitions .2
4 Symbols and units.3
5 Principle .4
5.1 Introduction.4
5.2 Heating energy performance.5
5.3 Cooling energy performance .5
6 Methodology and basic equations .6
6.1 General .6
6.2 The fenestration energy performance for heating .9
6.3 The fenestration energy performance for cooling .9
6.4 The heat balance elements.10
6.5 Assessment of the solar control potential of the rated fenestration system.12
7 Climate data .13
7.1 Introduction.13
7.2 External air temperature .13
7.3 Solar radiation .13
7.4 Wind speed .13
8 Basic thermal and solar-optical fenestration properties.14
8.1 Introduction.14
8.2 Thermal transmittance, U-value .14
8.3 Total solar energy transmittance or solar factor, g-value.14
8.4 Daylight potential .14
8.5 Air infiltration (air permeability) and ventilation .15
9 Reference building .16
9.1 Introduction.16
9.2 Overview of data.17
10 Assessment report.17
Annex A (informative) Explanation of gain/loss utilization factor method used in ISO 13790 for the
fenestration system energy balance equation .18
Annex B (informative) Assessment of the solar control potential of the rated fenestration system.23
Annex C (informative) Example of the calculation of P and P using a monthly method .26
E, H,w E, C,w
Bibliography.32

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.
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 18292 was prepared by Technical Committee ISO/TC 163, Thermal performance and energy use in the
built environment, Subcommittee SC 2, Calculation methods.
iv © ISO 2011 – All rights reserved

Introduction
This International Standard specifies a procedure for the determination of energy rating of window and door
products and other products that are installed in building envelope openings, also known as fenestration
systems. To enable the fenestration industry and their clients to utilize energy performance instead of thermal
transmittance to assess their products, there is a need for a simple, clear, accurate and transparent procedure
that enables the energy performance of these products to be assessed using national climate data and
nationally selected reference buildings.
This International Standard specifies detailed procedures for calculating the energy performance of
fenestration products. In this International Standard, the energy performance is derived from thermal
transmittance, solar gain, and air infiltration data obtained using standard procedures. Converting that value
into an energy rating for the fenestration system is the responsibility of each country's appropriate national
body. It is intended that the details of that rating system be published in a publicly available document. These
procedures require the use of reference conditions, which differ between countries and can represent
conditions other than actual. Allowing different reference conditions enables each country to determine its own
reference values in accordance with local conditions. As long as these conditions are publicly available and
the calculation is based on standardized procedures as specified in this International Standard, it is possible to
calculate the energy performance of a specific product to the desired national reference conditions.

INTERNATIONAL STANDARD ISO 18292:2011(E)

Energy performance of fenestration systems for residential
buildings — Calculation procedure
1 Scope
This International Standard specifies a procedure for calculation of the energy performance of fenestration
systems used in residential buildings, for rating of fenestration systems, doors and skylights, including the
effects of frame, sash, glazing, and shading components. This International Standard specifies procedures for
the calculation of the heating and cooling energy use in residential buildings, internal and external climatic
conditions, and relevant building characteristics.
These procedures can accommodate all climatic conditions and installation details. It is the responsibility of
the appropriate regulatory authority to identify the clauses of this International Standard to be applied in their
area of jurisdiction and the climatic data and reference building specification(s) to be used.
2 Normative references
The following referenced documents are indispensable for the application 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 6613, Windows and door height windows — Air permeability test
ISO 7345, Thermal insulation — Physical quantities and definitions
ISO 9050, Glass in building — Determination of light transmittance, solar direct transmittance, total solar
energy transmittance, ultraviolet transmittance and related glazing factors
ISO 9288, Thermal insulation — Heat transfer by radiation — Physical quantities and definitions
ISO 10077-1, Thermal performance of windows, doors and shutters — Calculation of thermal transmittance —
Part 1: General
ISO 10077-2, Thermal performance of windows, doors and shutters — Calculation of thermal transmittance —
Part 2: Numerical method for frames
ISO 12567-1, Thermal performance of windows and doors — Determination of thermal transmittance by the
hot-box method — Part 1: Complete windows and doors
ISO 12567-2, Thermal performance of windows and doors — Determination of thermal transmittance by hot
box method — Part 2: Roof windows and other projecting windows
ISO 13790:2008, Energy performance of buildings — Calculation of energy use for space heating and cooling
ISO 15099, Thermal performance of windows, doors and shading devices — Detailed calculations
ISO 15927-1, Hygrothermal performance of buildings — Calculation and presentation of climatic data —
Part 1: Monthly means of single meteorological elements
ISO 15927-4, Hygrothermal performance of buildings — Calculation and presentation of climatic data —
Part 4: Hourly data for assessing the annual energy use for heating and cooling
EN 410, Glass in building — Determination of luminous and solar characteristics of glazing
EN 1026, Windows and doors — Air permeability — Test method
EN 13363-1, Solar protection devices combined with glazing — Calculation of solar and light transmittance —
Part 1: Simplified method
EN 13363-2, Solar protection devices combined with glazing — Calculation of total solar energy transmittance
and light transmittance — Part 2: Detailed calculation method
3 Terms and definitions
For the purposes of this document, the terms and definitions given in ISO 7345 and ISO 9288 and the
following apply.
3.1
solar heat gain
g
total solar energy transmittance (solar factor)
NOTE 1 The solar heat gain of the whole fenestration system, including glazing, frame and solar shading device, is
denoted g .
w
NOTE 2 The total solar energy transmittance is also known as the solar heat gain coefficient with the acronym SHGC.
3.2
daylight potential
DP
τ
DP
potential of a fenestration system to supply a building with daylight
NOTE Daylight potential is not incorporated into the energy performance value.
3.3
thermal transmittance
U
heat flow rate in the steady state divided by area and by the temperature difference between the surroundings
on each side of a system
[ISO 7345:1987, 2.12]
NOTE The thermal transmittance of the whole fenestration system, including glazing, frame and solar shading device,
is denoted U .
...