GB/T 20311-2021 in English
VALIDBuilding components and building elements—Thermal resistance and thermal transmittance—Calculation methods
- Issued on:2021-08-20
- Implemented on:2022-03-01
- File Format:PDF
- Delivery:Via email within 5 business days
$388.00
《GB/T 20311-2021建筑构件和建筑单元 热阻和传热系数 计算方法》由TC191（全国绝热材料标准化技术委员会）归口，主管部门为中国建筑材料联合会。
Introduction
Core changes in the standard revision
| Revision dimensions | 2006 edition | 2021 edition |
|---|---|---|
| Terminology system | Undefined EPB standard | Added 3.6 EPB standard definitions |
| Calculation method | Simplified algorithm principle | Added 5 chapters on detailed algorithms and 6.5.1 specific procedures |
| Appendix structure | 4 appendices | Added Appendix A/B input tabulation specifications, and adjusted CF to a normative appendix |
Key technical implementation points
Correction calculation of metal fasteners
When the insulation layer is penetrated by metal fasteners, the correction amount must be calculated according to formula (F.5):
ΔUf = α·(λf·Af·nf/d1)·(R1/Rtot)2
Wherein, the value of α is as follows:
- Full penetration: 0.8
- Embedded: 0.8×(d1/d0)
Guidelines for applying the standard
Simplified algorithm selection conditions
When the following situations occur, the detailed algorithm in Chapter 5.3 should be used instead:
- Maximum/minimum thermal resistance ratio＞1.5
- Metal thermal bridges exist in the insulation layer
- Surface temperature for condensation risk needs to be assessed
EPB standard system positioning
This document corresponds to ISO6946:2017 and belongs to the EPB module structure in the following categories:
- M25 module: Building energy performance calculation
- M4 submodule: Heat transfer coefficient calculation
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