GB/T 39749-2021 English PDF (GBT39749-2021)

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GB/T 39749-2021: Evaluation method and graduation for energy efficiency performance of insulating glass unit
GB/T 39749-2021
GB
NATIONAL STANDARD OF THE
PEOPLE’S REPUBLIC OF CHINA
ICS 81.040
Q 30
Evaluation method and graduation for energy
efficiency performance of insulating glass unit
ISSUED ON: MARCH 09, 2021
IMPLEMENTED ON: FEBRUARY 01, 2022
Issued by: State Administration for Market Regulation;
Standardization Administration of the People’s Republic of
China.
Table of Contents
Foreword ... 3 
1 Scope ... 4 
2 Normative references ... 4 
3 Terms and definitions ... 4 
4 Evaluation method ... 4 
5 Gradation ... 6 
Appendix A (Normative) Characterization method of insulating glass unit ... 7 
Evaluation method and graduation for energy
efficiency performance of insulating glass unit
1 Scope
This Standard specifies the terms and definitions, evaluation methods and
gradation for energy efficiency performance of insulating glass unit.
This Standard applies to single-cavity insulating glass unit, multi-cavity
insulating glass unit, and vacuum composite insulating glass unit for
construction.
2 Normative references
The following documents are indispensable for the application of this document.
For dated references, only the dated version applies to this document. For
undated references, the latest edition (including all amendments) applies to this
document.
GB/T 2680, Glass in building - Determination of light transmittance, solar
direct transmittance, total solar energy transmittance, ultraviolet
transmittance and related glazing factors
GB/T 11944, Insulating glass unit
JC/T 2304-2015, The technical specification of energy efficient glass for
building
JGJ/T 151-2008, Calculation specification for thermal performance of
windows, doors and glass curtain-walls
3 Terms and definitions
Terms and definitions determined by GB/T 2680 and GB/T 11944 are applicable
to this document.
4 Evaluation method
4.1 Evaluation conditions
Appendix A 
(Normative) 
Characterization method of insulating glass unit
A.1 The structure of insulating glass unit is characterized by the thickness and
type of a single piece of glass or material, the film designation of the coated
glass, the location of the film surface, the thickness of the spacer layer, and the
type of spacer layer.
A.2 Each part of the insulating glass unit shall be characterized by the following
methods:
a) The thickness of a single piece of glass or material is expressed in
millimeters;
b) The type of a single piece of glass or material can be divided into colorless
transparent glass, colored glass, Low-E coated glass, sunlight control
coated glass, coated glass, laminated glass, tempered glass, glazed glass,
fireproof glass, polycarbonate, sun shade, which are expressed by the
names of various glasses or materials;
c) The film designation of the coated glass shall be named by the
manufacturer;
d) The locations of the membrane surface from outdoor to indoor are
represented as #1, #2, #3, #4, ...;
e) The types of spacers can be divided into air, inert gas, and vacuum. Air is
represented by Air (abbreviated as A); inert gas is represented by the
molecular formula of inert gases such as Ar and Kr. For inert gas, the gas
composition ratio or content shall be given; vacuum is expressed as V; the
residual gas pressure (indicated by P, in Pascals), the radius of the
support (indicated by R, in millimeters), and the distance between the
supports (indicated by S, in millimeter) shall be given.
A.3 The structure characterization methods of common insulating glass units
are as follows:
a) The structure characterization of single-cavity air-filled insulating glass unit
is:
6 mm Low-E coated glass (×××, #2) + 12 mm A + 6 mm colorless
transparent glass;