ISO/TR 52016-4:2024

Technical
Report
ISO/TR 52016-4
First edition
Energy performance of buildings —
2024-10
Energy needs for heating and
cooling, internal temperatures and
sensible and latent heat loads —
Part 4:
Explanation and justification of
ISO 52016-3
Performance énergétique des bâtiments — Besoins d'énergie
pour le chauffage et le refroidissement, les températures
intérieures et les chaleurs sensible et latente —
Partie 4: Explication et justification de l'ISO 52016-3
Reference number
© ISO 2024
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Published in Switzerland
ii
Contents Page
Foreword .v
Introduction .vi
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Symbols, subscripts and abbreviations . . 1
4.1 Symbols .1
4.2 Subscripts . .2
4.3 Abbreviated terms .2
5 Description of the method . 2
5.1 Output of the method . .2
5.2 General description of the method .2
5.2.1 General .2
5.2.2 Distinction between ISO 52016-3 and ISO 52016-1 .3
5.2.3 Successive steps in the calculation procedures .3
5.3 Technologies covered in ISO 52016-3 .3
5.3.1 General .3
5.3.2 Building envelope elements with dynamic solar shading .3
5.3.3 Building envelope elements with chromogenic glazing .6
5.3.4 Building envelope elements with an actively ventilated cavity .6
5.3.5 Types of adaptive building envelope elements not covered in ISO 52016-3 .9
5.4 Control scenarios .10
6 Calculation method .11
6.1 Output data .11
6.2 Calculation time intervals .11
6.3 Input data . 12
6.3.1 General . 12
6.3.2 Input data of a simplified adaptive building envelope element . 12
6.3.3 Input data of a detailed adaptive building envelope element . 12
6.3.4 Control related input data . 12
6.3.5 Climatic input data . 13
6.3.6 Constants and physical data . 13
6.3.7 Input data from Annex A and Annex B . 13
6.4 Properties of the adaptive building envelope element . 13
6.4.1 General . 13
6.4.2 Simplified or detailed adaptive building envelope element . 15
6.4.3 Properties of a simplified adaptive building envelope element . 15
6.4.4 Model and properties of a detailed adaptive building envelope element .16
6.5 Connection of the model of the adaptive building envelope element to the model of the
thermal zone of ISO 52016-1 .17
6.6 Selection of control type .17
6.7 Modelling of the control of the environmentally activated adaptive building envelope
element .17
6.8 Modelling of the control scenario for the actively controlled adaptive building envelope
element .18
6.8.1 General .18
6.8.2 Selection of conditions and events .18
6.8.3 Selection of sensors.19
6.8.4 Selection of methods to identify the conditions or events .19
6.8.5 Basic rules for the reference control scenario .21
6.8.6 Modelling of the user behaviour . 22
6.8.7 Reference control scenarios . 22
6.9 Hourly calculation procedures . 25

iii
6.10 Post-processing —Performance characteristics . 25
6.10.1 General . 25
6.10.2 Thermal comfort score . 25
6.10.3 Statistics on the use of the different states of the adaptive building envelope
element . 26
7 Quality control .26
8 Conformity check .26
9 Worked out examples .27
9.1 General .27
9.2 Purpose .27
9.3 Spreadsheet tool .27
9.4 Calculation cases .27
9.4.1 General .27
9.4.2 Building types . 28
9.4.3 Climates . 29
9.4.4 Operation and use profile . 29
9.4.5 Selected adaptive building envelope elements . 30
9.4.6 Control of adaptive building envelope elements . 30
9.5 Overview of selected cases and variants . 30
9.6 Results . .31
9.7 Conclusions . 39
9.7.1 General . 39
9.7.2 Limitations of the spreadsheet tool and example cases . 39
10 Validation of the calculation procedures.40
Annex A (informative) ISO 52016-3 input and method selection data sheet — Template . 41
Annex B (informative) ISO 52016-3 input and method selection data sheet — Default choices .42
Annex C (informative) Reference control scenarios for adaptive building envelope elements
with dynamic solar shading or chromogenic glazing .43
Annex D (informative) Basic study reference control strategies . 74
Annex E (informative) Hourly thermal balance model of ISO 52016-1 and the connected
adaptive building envelope element .82
Bibliography .92

iv
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 document 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).
ISO draws attention to the possibility that the implementation of this document may involve the use of (a)
patent(s). ISO takes no position concerning the evidence, validity or applicability of any claimed patent
rights in respect thereof. As of the date of publication of this document, ISO had not received notice of (a)
patent(s) which may be required to implement this document. However, implementers are cautioned that
this may not represent the latest information, which may be obtained from the patent database available at
www.iso.org/patents. ISO shall not be held responsible for identifying any or all such patent rights.
Any trade name used in this document is information given for the convenience of users and does not
constitute an endorsement.
For an explanation of 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 www.iso.org/iso/foreword.html.
This document was prepared by ISO Technical Committee ISO/TC 163, Thermal performance and energy
use in the built environment, Subcommittee SC 2, Calculation methods in collaboration with the European
Committee for Standardization (CEN) Technical Committee CEN/TC 89, Thermal performance of buildings
and building components, in accordance with the Agreement on technical cooperation between ISO and CEN
(Vienna Agreement).
A list of all the parts in the ISO 52016 series can be found on the ISO website.
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.

v
Introduction
0.1 Set of EPB standards and supporting tools
This document gives guidance to a set of international standards that is used to collectively assess the overall
energy performance of buildings (EPB). Throughout this document, this group of standards is referred to as
the “set of EPB standards”.
All EPB standards follow specific rules to ensure overall consistency, unambiguity and transparency (see
ISO 52000-1 , CEN/TS 16628 and CEN/TS 16629).
All EPB standards provide a certain flexibility with regard to the methods, the required input data and
references to other EPB standards, by the introduction of a normative template in Annex A and Annex B with
informative default choices.
One of the main purposes of the set of EPB standards is to enable laws and regulations to directly refer to
the EPB standards and make compliance with them compulsory. This requires that the set of EPB standards
consists of a systematic, clear, comprehensive and unambiguous set of energy performance procedures. The
number of options provided is kept as low as possible, taking into account national and regional differences
in climate, culture and building tradition, policy and legal frameworks (subsidiarity principle). For each
option, an informative default option is provided (see Annex B).
0.2 Rationale behind the set of EPB technical reports
There is a risk that the purpose and limitations of the EPB standards will be misunderstood, unless the
background and context to their contents, and the thinking behind them, is explained in some detail to
readers of the standards. Consequently, various types of informative contents are recorded and made
available for users to properly understand, apply and nationally or regionally implement the set of EPB
standards.
If this explanation were attempted in the standards themselves, the result is likely to be confusing, especially
if the standards are implemented or referenced in national or regional building codes.
Therefore, each EPB standard is accompanied by an informative technical report, e.g. this document, where
all informative content is collected, to ensure a clear separation between normative and informative content
(see CEN/TS 16629 for a more detailed explanation):
— to underscore the difference between the normative and informative content;
— to reduce the page count of the actual standard;
— to facilitate understanding of the set of EPB standards.
0.3 This document
This document gives guidance on ISO 52016-3. The role and the positioning of ISO 52016-3 in the set of EPB
standards is defined in the introduction of ISO 52016-3. A brief article on the subject can be found in the
[21]
REHVA Journal .
To fully understand this document, it is intended to be read in close conjunction, clause by clause, with
ISO 52016-3. Essential information provided in ISO 52016-3 is not repeated in this document. References to
a clause can refer to the combined content of that clause in both ISO 52016-3 and this document.
0.4 Accompanying spreadsheet
[35]
An extensive spreadsheet has been prepared to test and demonstrate ISO 52016-1. For the purpose of
testing and demonstrating ISO 52016-3, this spreadsheet has been extended with an (optional) sheet to
cover adaptive building envelope elements with different states and different control scenarios according to
ISO 52016-3.
Examples of calculations with adaptive building envelope elements are found in this document.

vi
0.5 Background of this document and ISO 52016-3
ISO 52016-3 and the supporting technical report (this document) have been developed to respond to a
strong need to include adaptive building envelope elements in the assessment of the energy performance of
buildings. This inclusion aims to create a level playing field for conventional and promising techniques.
More extensive background information and history of the whole set of EPB standards is given in the
introduction to ISO/TR 52000-2, the technical report accompanying the overarching EPB standard. Up-to-
date information on the set of EPB standards can be found in the "public material" section of the ISO/TC 163
1)
page on the ISO website.
0.6 Application area of ISO 52016-3
ISO 52016-3 specifies procedures for the calculation of the energy needs for heating and cooling, internal
temperatures and sensible and latent heat loads of a building according to ISO 52016-1, with additions or
modifications that are needed to incorporate adaptive building envelope elements in the calculation.
The main use of ISO 52016-3 is the assessment of the energy performance of buildings (energy performance
labels and certificates), including comparison between buildings and for checking compliance with minimum
energy performance criteria.
ISO 52016-3 is applicable to buildings at the design stage, to new buildings after construction and to existing
buildings in the use phase.
1) https://www.iso.org/committee/53476.html.

vii
Technical Report ISO/TR 52016-4:2024(en)
Energy performance of buildings — Energy needs for heating
and cooling, internal temperatures and sensible and latent
heat loads —
Part 4:
Explanation and justification of ISO 52016-3
1 Scope
This document provides explanation and justification to support the correct understanding and use of
ISO 52016-3.
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 7345, Thermal performance of buildings and building components — Physical quantities and definitions
ISO 9488, Solar energy — Vocabulary
ISO 52000-1, Energy performance of buildings — Overarching EPB assessment — Part 1: General framework
and procedures
ISO 52016-1, Energy performance of buildings — Energy needs for heating and cooling, internal temperatures
and sensible and latent heat loads — Part 1: Calculation procedures
ISO 52016-3:2023, Energy performance of buildings — Energy needs for heating and cooling, internal
temperatures and sensible and latent heat loads — Part 3: Calculation procedures regarding adaptive building
envelope elements
3 Terms and definitions
For the purposes of this document, the terms and definitions given in ISO 7345, ISO 9488, ISO 52000-1,
ISO 52016-1 and ISO 52016-3:2023 apply.
ISO and IEC maintain terminology databases for use in standardization at the following addresses:
— ISO Online browsing platform: available at https:// www .iso .org/ obp
— IEC Electropedia: available at https:// www .electropedia .org/
4 Symbols, subscripts and abbreviations
4.1 Symbols
For the purposes of this document, the symbols given in ISO 52000-1, ISO 52016-1 and ISO 52016-3:2023 apply.
More information on key EPB symbols is given in ISO/TR 52000-2.

4.2 Subscripts
For the purposes of this document, the subscripts given in ISO 52000-1, ISO 52016-1 and ISO 52016-3:2023 apply.
More information on key EPB subscripts is given in ISO/TR 52000-2.
NOTE 1 ISO 52016-1 uses input data from many technology fields. In the exceptional cases that subscripts in
ISO 52016-1 are different from subscripts in other EPB standards that produce output needed as input to ISO 52016-1,
these differences are reported in a special column in the tables with the overview of input data in 6.3. This can
occur when the source documents use subscripts that are crucial for that specific technology field, but conflict with
subscripts that are crucial for another specific technology field.
EXAMPLE Subscript g used for both "glazing" and for "ground".
NOTE 2 In ISO 52016-3 the subscript w (origin: “window”), used in ISO 52016-1 for transparent construction
elements is also used for the adaptive building envelope element.
NOTE 3 For the solar and daylight properties the subscript gl (origin: “glazing”), is used as a rule to specifically
refer to the projected area of the transparent part of the element.
4.3 Abbreviated terms
For the purposes of this document, the abbreviated terms given in ISO 52016-1 and ISO 52016-3:2023 apply.
More information on key EPB abbreviated terms is given in ISO/TR 52000-2.
5 Description of the method
5.1 Output of the method
The structure of ISO 52016-3:2023, Clause 5 conforms to the common template for the set of EPB standards.
ISO 52016-3:2023, Clause 5 contains a brief (qualitative) description of the method, starting with the main
output from the standard.
ISO 52016-3 covers the calculation of the energy need for heating and cooling and the internal temperature
in case of a building or building zone with one or more adaptive building envelope elements.
The method covers also, as product information, the calculation of some energy performance characteristics
of adaptive building envelope elements, applied in a specific (e.g. reference) building.
NOTE Compare e.g. ISO 18292, that also uses a reference building for comparing the energy performance of
windows.
This includes information on whether the building is smart ready in terms of adaptive building envelope
elements.
5.2 General description of the method
5.2.1 General
The calculation procedures in ISO 52016-3 are an extension of the hourly calculation procedures specified in
ISO 52016-1. ISO 52016-3 contains the additions and modifications that are needed to incorporate adaptive
building envelope elements. Therefore, ISO 52016-1 is referenced accordingly throughout ISO 52016-3.
ISO 52016-1:2017 contains a normative Annex G that provides a framework for calculation procedures
involving adaptive building envelope elements. ISO 52016-3 provides calculation procedures.
ISO 52016-3 fills a gap in the set of EPB standards.
The reasons for choosing an hourly calculation time interval are given in 6.2.

5.2.2 Distinction between ISO 52016-3 and ISO 52016-1
The calculation procedures of ISO 52016-3 can be seen as an extension of the procedures given in ISO 52016-1.
The reasons for providing these in two separate documents are:
— If ISO 52016-3 was combined into ISO 52016-1, it can harm the acceptance and roll-out of ISO 52016-1,
e.g. if a legal authority wants to adopt the calculation procedures of the current ISO 52016-1, but has
hesitations to adopt ISO 52016-3.
— Maintenance of ISO 52016-1 would be more difficult and costly if combined with the content of
ISO 52016-3. With a separate ISO 52016-3 it is easier to plan revisions, e.g. based on experiences by users
or developing technologies.
— ISO 52016-3 requires specific expertise on the technologies and control scenarios involved.
— The parties interested in the details of ISO 52016-3 are quite specific. Combining all in one document
would not be efficient from the user perspective.
5.2.3 Successive steps in the calculation procedures
In ISO 52016-3:2023, the actual calculation procedures are given in 6.9. However, that subclause is just one
sentence:
"Apply the hourly calculation procedures according to ISO 52016-1:2017, 6.5, with the additions and
adaptations specified in the previous clauses of this document."
ISO 52016-3:2023, 6.4 to 6.8 contain the procedures needed to prepare the calculation. In ISO 52016-3:2023,
5.4, these preparatory steps are introduced as six successive steps.
5.3 Technologies covered in ISO 52016-3
5.3.1 General
The technologies covered in ISO 52016-3 are selected on the basis of current or promising market share
and distinction in functionality and control scenarios or passive response. Some technologies can be quite
different in appearance but very similar in functionality and in options for control. For the purpose of
ISO 52016-3 these are not categorized separately.
For example, for the purpose of ISO 52016-3 the physical model of a closed (unvented) cavity double skin
façade is quite similar to a multiple glazing unit with integrated solar blinds.
Three main categories of technologies are covered in ISO 52016-3:
— Building envelope elements with dynamic solar shading (see 5.3.2).
— Building envelope elements with chromogenic glazing (see 5.3.3).
— Building envelope elements with an actively ventilated cavity (see 5.3.4).
For the sources used in the selection of technologies, see References 35, 28, 17, 18, 27, 34 and 38.
Examples of types of adaptive building envelope elements that are not covered in ISO 52016-3 are presented
in 5.3.5.
5.3.2 Building envelope elements with dynamic solar shading
A building envelope element with dynamic solar shading can be described as a façade element (usually fitted
to a window, door, curtain walling or façade, with one or more actively operated mobile parts) defined as
the curtain that can (partially) obstruct solar radiation or sunlight. The aim of dynamic solar shading is
to control solar radiation and daylight, to contribute to the thermal insulation, thermal comfort, cooling
savings and visual comfort when combined to glazing.

Dynamic solar shading can be positioned at the internal or external side of the façade element or integrated
in between two or more façade elements. These façade elements may form a sealed multiple glazing unit, or
consist of an assembly of multiple glazings, or assembly of partly transparent and partly opaque elements.
If a single façade is doubled inside or outside by a second, essentially glazed façade, it is usually defined as a
double skin façade. The width of the cavity between these two skins can range from several centimetres at
the narrowest to several metres for the widest accessible cavities. As long as such a façade has no intentional
ventilation provisions (“closed cavity façade”) it fits into the description of the dynamic solar shading.
This contrasts with the third category, building envelope elements with an actively ventilated cavity.
The main technologies for the dynamic solar shading elements are:
— Venetian blind: blind where the curtain consists of horizontal slats which can be tilted and where the
curtain may be retracted by accumulating the slats. The slat angle can be tilted in various positions. They
are usually opaque, but can also be partly transparent or translucent.
— Roller blind: blind where the curtain consists of material (e.g. fabric) which is retracted by rolling.
The curtain can be semi-transparent, semi-translucent or opaque, and sometimes thermally insulated
(multilayer).
— Roller shutter: shutter where the curtain is retracted by rolling and consists of interconnected horizontal
laths, that can be tilted or not, which run inside channels.
Examples are shown in Figure 1:

a) Windows with internal roller blinds b) Windows with external venetian blinds.
2)
(Colour) photo by Samuel Zeller, CC0 1.0 DEED
c) Closed cavity façade with integrated venetian d) External folding-sliding shutters, Gerrit Rietveld
blinds Academie / Sandberg Instituut, Amsterdam
Figure 1 — Four examples of building envelope elements with dynamic solar shading
For movable blinds or shutters, a specific terminology is used to avoid confusion between the blind or
shutter movement and other movements, such as slats and louvers:
— Extended/retracted: movement of the blind resulting in an increase/decrease in the surface area covered
(see EN 12216:2018, 5.1)
2) No permission required. Credit: https:// creativecommons .org/ publicdomain/ zero/ 1 .0/

— Open/closed: terms used to describe the increase in light (opening) or reduction of light (closing) in
an extended position for products with laths, slats or louvres which can be tilted or adjusted (see EN
12216:2018, 5.1).
See also examples in EN 12216.
5.3.3 Building envelope elements with chromogenic glazing
Chromogenic glazing can be described as an adaptive technology directly integrated in the glazing itself.
The physical properties can reversibly change according to a specific active or passive trigger, changing
the appearance of the glazing itself: making it more or less transparent, absorbing or reflecting for solar
radiation and daylight.
The main technologies currently available on the market are:
— Thermochromic and thermotropic glazing (passive; based on the glazing temperature changing);
— Photochromic glazing (passive; based on the level of incident solar irradiance changing);
— Electrochromic glazing (active; based on the level of electric power changing);
— Gasochromic glazing (active, based on changing gas mixture in cavity);
— Liquid crystal chromogenic glazing (active; based on the level of electric power changing);
— Suspended particle devices.
However, other smart glazing technologies are being, or may be developed, that can be simulated in the
same way, e.g. electrophoretic, fluidic glass, microshades and micromirror arrays.
Examples are shown in Figure 2:
a) High transmittance b) Low transmittance
Key
SOURCE: Project Hamilton Bonaduz, Switzerland. Electrochromic Glass (SageGlass). Pictures by Ingo Rasp.
Figure 2 — Examples of building envelope with chromogenic glazing
5.3.4 Building envelope elements with an actively ventilated cavity
5.3.4.1 Distinctive feature
A building envelope element with an actively ventilated cavity is similar to a building envelope element with
dynamic solar shading, except for the intentional and possibly controlled (i.e. natural, hybrid or mechanical)
ventilation of the cavity or air circulation via the cavity.

In many cases it is a ventilated double skin façade, but also a ventilated window with the intention to capture
heat from the cavity fits into this category.
In addition to achieving thermal and solar control as in the previous two categories, the technologies under
this category have in common that air is deliberately circulated through the cavity, to gain solar either heat,
increase thermal comfort, or both, when heating is required and to enhance thermal comfort and reject
surplus solar load during warm periods. If this is not the case, then, for the purpose of this document, the
adaptive building envelope element does not belong to this category.
The difference with operable solar shading in 5.3.2 is that the air circulation and ventilation is controlled,
either mechanically or by operable vents, thus adding a dimension to the control strategy.
5.3.4.2 Variety of technologies
A wide variety of technologies exist. Typical examples are:
— Double skin façade
— with integrated solar shading;
— mechanically or naturally ventilated;
— with fixed or adjustable vent openings;
— with narrow or wide cavity.
— Ventilated windows
— with integrated blinds;
— to either harvest or reject solar heat, recover heat from ventilation air, or both.
See more examples below in this subclause such as a simplified façade with air extracted behind an internal
screen instead of glazing.
Active ventilative cooling is outside the scope of ISO 52016-3 if there is no thermal interaction with the
components of the façade, or if it is achieved by other air inlets than the air inlet via (and with thermal
interaction with) the façades.
5.3.4.3 Ventilation modes
[34]
Several ventilation modes can coexist within a single ventilated double façade :
a) Outdoor air curtain:
In this ventilation mode, the air introduced into the cavity comes from the outside and is immediately
rejected towards the outside. The ventilation of the cavity therefore forms an air curtain enveloping the
outside façade.
b) Indoor air curtain:
The air comes from the inside of the room and is returned to the inside of the room or via the ventilation
system. The ventilation of the cavity therefore forms an air curtain enveloping the indoor façade.
c) Air supply:
The ventilation of the façade is created with outdoor air. This air is then brought to the inside of the
room or into the ventilation system. The ventilation of the façade thus makes it possible to supply the
building with air.
d) Air exhaust:
The air comes from the inside of the room and is evacuated towards the outside. The ventilation of the
façade thus makes it possible to evacuate the air from the building.

e) Buffer zone:
This ventilation mode is distinctive inasmuch as each of the skins of the double façade is made airtight.
The cavity thus forms a buffer zone between the inside and the outside, with no ventilation of the cavity
being possible.
Several ventilation modes can coexist within a single ventilated double façade.
Generally, naturally ventilated double façades are those which present several ventilation modes, the shift
[34]
from one ventilation mode to the other being done by motorized ventilation openings . With motorized
openings it possible to shift from one ventilation mode to another as a function of their position (in this case,
from a scenario of outdoor air curtain, when the openings are open, to a buffer zone scenario, when they are
in closed position).
The ventilation makes use of openings in either the inner or outer skin, or both, and can be mechanical or
natural.
In general, mechanically ventilated double façades are not equipped with operable ventilation openings and
are characterized by well-defined ventilation modes. In case of natural ventilation, the operation is (as a
rule: actively) controlled by openable vents in either the inner or outer skin, or both, allowing a shift from
one ventilation mode to another as a function of their position. In that case, determining the precise mode
of ventilation is not always self-evident. Indeed, when an opening is placed in open position, the ventilation
phenomena which take place depend on the pressure conditions inside the cavity. The latter in turn depends
on a multitude of factors, including the climatic conditions, e.g. speed and direction of the wind, temperature
difference, sunshine, mode of working of the building´s mechanical ventilation system or opening of the
inside doors.
5.3.4.4 Façades or windows
The term "ventilated double façades" also covers the concepts of ventilated double windows. The distinction
between these two terms (façade and window) is only made when a proper understanding of the text makes
it imperative.
The ventilation air flow rates are provided by the relevant standard(s) under EPB module M5-5 (ventilation).
5.3.4.5 Double skin façades
A double skin façade can be defined as a traditional single façade doubled inside or outside by a second,
[34]
essentially glazed façade . Each of these two façades is commonly called a skin. A ventilated cavity,
having a width which can range from several centimetres at the narrowest to several metres for the widest
accessible cavities, is located between these two skins.
The main difference between a double skin façade and an airtight multiple glazing, whether or not it
integrates a shading device in the cavity separating the glazings, lies in the intentional and possibly
controlled ventilation of the cavity of the double skin façade.
For that reason, and to be clear in the distinction, in the context of ISO 52016-3 the term "building envelope
element" is used with an actively ventilated cavity, thus expressing the key distinctive physical feature.
There are façade concepts where the ventilation of the cavity is controllable, by either fans or openings or
both, and other façade concepts where this ventilation is not controllable. The indoor and outdoor skins are
not necessarily airtight (see, for example, the "louver" type façades). Automated equipment, such as shading
devices, motorized openings or fans, are most often integrated into the façade.
If the cavity is extended over multiple rooms (horizontally) or floors (vertically) it becomes a more
complicated variant, due to the mixing of the cavity air temperatures and air pressures. For the purpose of
ISO 52016-3, the complication has no significant effect, because it requires “only” that, for each state, the
correct spatially "mi
...