IS 6670 : 1989Code of practice for thermal insulation of buildings

Link points to Internet Archive / others. Not hosted by InfraLens. Details

ASHRAE 90.1 · ISO 6946 · BS 5250

CurrentSpecializedCode of PracticeBIMArchitectural · Insulation Materials

Link points to Internet Archive / others. Not hosted by InfraLens. Details

IS 6670:1989 is the Indian Standard (BIS) for thermal insulation of buildings. This code of practice provides guidelines for the thermal insulation of buildings to enhance indoor thermal comfort and reduce energy consumption. It details climatic data for India, properties of various insulating materials, and outlines the calculation methodology for thermal transmittance (U-value) for building elements like roofs and walls.

Provides a code of practice for the thermal insulation of buildings.

Overview

Status: Current
Usage level: Specialized
Domain: Architectural — Insulation Materials
Type: Code of Practice

International equivalents

ASHRAE 90.1-2022 · ASHRAE, USA ISO 6946:2017 · ISO, International BS 5250:2021 · BSI, United Kingdom NCC 2022 Vol. One, Section J · Australian Building Codes Board (ABCB), Australia

Typically used with

IS 3346 IS 8183

Also on InfraLens for IS 6670

6Key values 5Tables 4FAQs

BIM-relevant code. See the BIM Hub for ISO 19650, IFC, and LOD/LOIN frameworks used alongside it.

Practical Notes

! While this code provides foundational principles, its requirements and recommendations are now largely superseded and expanded upon by the Energy Conservation Building Code (ECBC) and the National Building Code of India (NBC) 2016.

! The core of this code is the calculation of U-value (Overall Thermal Transmittance) for a composite building element (roof/wall). U-value is the inverse of the sum of all thermal resistances in the assembly.

! Moisture control is crucial. Ensure a proper vapour barrier is designed, especially for cold storage or in humid/cold climates, to prevent condensation and degradation of insulation performance.

Frequently referenced clauses

Cl. 4Climatic Conditions Cl. 5Properties of Materials Cl. 6General Recommendations for Design Cl. 7Insulation of Roofs Cl. 8Insulation of Walls Appendix A - Method for Calculation of Overall Thermal Transmittance (U-Value)

thermal insulationglass woolmineral woolpolystyrenepolyurethane foamcork

International Equivalents

Similar International Standards

ASHRAE 90.1-2022ASHRAE, USA

HighCurrent

Energy Standard for Buildings Except Low-Rise Residential Buildings

Sets minimum energy efficiency requirements, including prescriptive and performance-based insulation levels.

ISO 6946:2017ISO, International

MediumCurrent

Building components and building elements — Thermal resistance and thermal transmittance — Calculation method

Provides the detailed calculation methodology for U-values, a core component of any thermal practice code.

BS 5250:2021BSI, United Kingdom

MediumCurrent

Management of moisture in buildings. Code of practice

Focuses on the critical interaction of insulation, airtightness, and moisture control to prevent condensation.

NCC 2022 Vol. One, Section JAustralian Building Codes Board (ABCB), Australia

HighCurrent

National Construction Code, Volume One, Section J - Energy Efficiency

Defines mandatory energy efficiency measures for commercial buildings, including required insulation R-values.

Key Differences

≠IS 6670 provides general guidance and recommendations, whereas modern standards like ASHRAE 90.1 are mandatory energy codes with multiple, complex compliance paths (prescriptive, performance, trade-off).

≠Modern standards place a strong emphasis on air tightness, requiring air barriers and often mandating whole-building air leakage testing. IS 6670:1989 barely addresses the impact of air infiltration on thermal performance.

≠IS 6670 only qualitatively mentions avoiding thermal bridges. International standards (e.g., ISO 6946) provide detailed quantitative methods to calculate the significant negative impact of thermal bridging through studs, fasteners, and slab edges.

≠Climate zone definitions in IS 6670 are broad and descriptive (e.g., Hot-Dry, Warm-Humid). Modern codes use highly granular, data-driven climate zones (e.g., ASHRAE's 8 zones with A/B/C sub-zones) based on heating and cooling degree days, leading to more tailored requirements.

≠IS 6670's guidance on condensation is a simple rule (vapor barrier on the warm side). Standards like BS 5250 require detailed risk assessments, often using hygrothermal modeling (e.g., Glaser method), to manage moisture.

Key Similarities

≈All standards share the fundamental objective of reducing heat transfer through the building envelope for energy conservation and thermal comfort.

≈The core physical principles are the same: using materials with low thermal conductivity (k-value) to achieve a desired thermal resistance (R-value).

≈All codes recognize the need to insulate the primary elements of the building envelope: roofs, walls, and floors exposed to exterior conditions.

≈They all acknowledge the three modes of heat transfer (conduction, convection, radiation), although the emphasis and calculation complexity for each has evolved significantly over time.

Parameter Comparison

Parameter	IS Value	International	Source
Roof U-Value (Air-Conditioned)	0.4 W/m²K (for hot-dry/warm-humid zones)	0.27 W/m²K (U-0.048)	ASHRAE 90.1-2022 (non-residential, insulation entirely above deck, Climate Zone 3A)
Wall U-Value (Air-Conditioned)	0.6 W/m²K (for hot-dry zones)	0.55 W/m²K (U-0.097)	ASHRAE 90.1-2022 (mass wall, Climate Zone 3A)
Climate Zone Basis	Qualitative classification into 5 zones based on temperature and humidity (e.g., Hot-Dry, Warm-Humid).	Quantitative classification based on Heating Degree Days (HDD) and Cooling Degree Days (CDD).	ASHRAE 90.1-2022
Treatment of Thermal Bridging	Qualitative advice: 'discontinuities... should be avoided.' No calculation method provided.	Mandatory correction factors (ΔU) and detailed calculation procedures for metal studs, fasteners, and slab edges.	ISO 6946:2017
Focus Unit	Primarily recommends maximum U-values (W/m²K).	Primarily prescribes minimum R-values (m²K/W) for insulation components and maximum U-values for assemblies.	NCC 2022 (Australia)
Air Barrier Requirement	Not specified as a mandatory continuous system.	Continuous air barrier is mandatory, with specific requirements for material properties and joint sealing.	ASHRAE 90.1-2022

⚠ Verify details from original standards before use

Key Values6

Quick Reference Values

Thermal conductivity of common brick (k-value)0.72 W/m·K

Thermal conductivity of dense concrete (k-value)1.44 W/m·K

Thermal conductivity of glass wool (k-value)0.034 - 0.040 W/m·K

Internal surface resistance for walls (horizontal heat flow)0.12 m²·K/W

External surface resistance for walls (sheltered)0.08 m²·K/W

Internal surface resistance for roofs (upward heat flow)0.10 m²·K/W

Key Formulas

U = 1 / R_T — Overall heat transfer coefficient

R_T = R_si + R_1 + R_2 + ... + R_n + R_so — Total thermal resistance

R = t / k — Thermal resistance of a material layer

Tables & Referenced Sections

Key Tables

Table 1 - Mean Monthly Maximum and Minimum Temperatures for Some Stations in India

Table 2 - Thermal Conductivity of Building Materials (k-value)

Table 3 - Thermal Conductivity of Insulating Materials (k-value)

Table 4 - Thermal Resistance of Air Spaces

Table 5 - Surface Resistances

Key Clauses

Clause 4 - Climatic Conditions

Clause 5 - Properties of Materials

Clause 6 - General Recommendations for Design

Clause 7 - Insulation of Roofs

Clause 8 - Insulation of Walls

Appendix A - Method for Calculation of Overall Thermal Transmittance (U-Value)

Frequently Asked Questions4

How do I calculate the U-value of a wall?+

U-value is the reciprocal of Total Thermal Resistance (RT). RT is the sum of internal and external surface resistances plus the resistance of each material layer (R = thickness/conductivity). See Appendix A for the detailed method.

Where can I find the thermal conductivity (k-value) of brick or insulation?+

Table 2 provides k-values for common building materials like brick and concrete, while Table 3 lists k-values for various insulating materials like glass wool and polystyrene.

Is this code still current?+

This code is foundational but for new projects, you must refer to the mandatory Energy Conservation Building Code (ECBC) and the National Building Code (NBC) which have more updated and comprehensive requirements.

What is surface resistance?+

It's the thermal resistance of the thin layer of air on the inner and outer surfaces of a building element. Values are given in Table 5 and depend on the surface orientation and exposure.

QA/QC Inspection Templates

📋

QA/QC templates coming soon for this code.

Browse all 300 templates →

IS 6670 : 1989Code of practice for thermal insulation of buildings

PDF Google Compare BIS Portal

Link points to Internet Archive / others. Not hosted by InfraLens. Details

ASHRAE 90.1 · ISO 6946 · BS 5250

CurrentSpecializedCode of PracticeBIMArchitectural · Insulation Materials

PDF Google Compare BIS Portal

Link points to Internet Archive / others. Not hosted by InfraLens. Details

Provides a code of practice for the thermal insulation of buildings.

Overview

Status: Current
Usage level: Specialized
Domain: Architectural — Insulation Materials
Type: Code of Practice

International equivalents

ASHRAE 90.1-2022 · ASHRAE, USA ISO 6946:2017 · ISO, International BS 5250:2021 · BSI, United Kingdom NCC 2022 Vol. One, Section J · Australian Building Codes Board (ABCB), Australia

Typically used with

IS 3346 IS 8183

Also on InfraLens for IS 6670

6Key values 5Tables 4FAQs

BIM-relevant code. See the BIM Hub for ISO 19650, IFC, and LOD/LOIN frameworks used alongside it.

Practical Notes

! Moisture control is crucial. Ensure a proper vapour barrier is designed, especially for cold storage or in humid/cold climates, to prevent condensation and degradation of insulation performance.

Frequently referenced clauses

thermal insulationglass woolmineral woolpolystyrenepolyurethane foamcork

International Equivalents

Similar International Standards

ASHRAE 90.1-2022ASHRAE, USA

HighCurrent

Energy Standard for Buildings Except Low-Rise Residential Buildings

Sets minimum energy efficiency requirements, including prescriptive and performance-based insulation levels.

ISO 6946:2017ISO, International

MediumCurrent

Building components and building elements — Thermal resistance and thermal transmittance — Calculation method

Provides the detailed calculation methodology for U-values, a core component of any thermal practice code.

BS 5250:2021BSI, United Kingdom

MediumCurrent

Management of moisture in buildings. Code of practice

Focuses on the critical interaction of insulation, airtightness, and moisture control to prevent condensation.

NCC 2022 Vol. One, Section JAustralian Building Codes Board (ABCB), Australia

HighCurrent

National Construction Code, Volume One, Section J - Energy Efficiency

Defines mandatory energy efficiency measures for commercial buildings, including required insulation R-values.

Key Differences

Key Similarities

≈All standards share the fundamental objective of reducing heat transfer through the building envelope for energy conservation and thermal comfort.

≈The core physical principles are the same: using materials with low thermal conductivity (k-value) to achieve a desired thermal resistance (R-value).

≈All codes recognize the need to insulate the primary elements of the building envelope: roofs, walls, and floors exposed to exterior conditions.

≈They all acknowledge the three modes of heat transfer (conduction, convection, radiation), although the emphasis and calculation complexity for each has evolved significantly over time.

Parameter Comparison

Parameter	IS Value	International	Source
Roof U-Value (Air-Conditioned)	0.4 W/m²K (for hot-dry/warm-humid zones)	0.27 W/m²K (U-0.048)	ASHRAE 90.1-2022 (non-residential, insulation entirely above deck, Climate Zone 3A)
Wall U-Value (Air-Conditioned)	0.6 W/m²K (for hot-dry zones)	0.55 W/m²K (U-0.097)	ASHRAE 90.1-2022 (mass wall, Climate Zone 3A)
Climate Zone Basis	Qualitative classification into 5 zones based on temperature and humidity (e.g., Hot-Dry, Warm-Humid).	Quantitative classification based on Heating Degree Days (HDD) and Cooling Degree Days (CDD).	ASHRAE 90.1-2022
Treatment of Thermal Bridging	Qualitative advice: 'discontinuities... should be avoided.' No calculation method provided.	Mandatory correction factors (ΔU) and detailed calculation procedures for metal studs, fasteners, and slab edges.	ISO 6946:2017
Focus Unit	Primarily recommends maximum U-values (W/m²K).	Primarily prescribes minimum R-values (m²K/W) for insulation components and maximum U-values for assemblies.	NCC 2022 (Australia)
Air Barrier Requirement	Not specified as a mandatory continuous system.	Continuous air barrier is mandatory, with specific requirements for material properties and joint sealing.	ASHRAE 90.1-2022

⚠ Verify details from original standards before use

Key Values6

Quick Reference Values

Thermal conductivity of common brick (k-value)0.72 W/m·K

Thermal conductivity of dense concrete (k-value)1.44 W/m·K

Thermal conductivity of glass wool (k-value)0.034 - 0.040 W/m·K

Internal surface resistance for walls (horizontal heat flow)0.12 m²·K/W

External surface resistance for walls (sheltered)0.08 m²·K/W

Internal surface resistance for roofs (upward heat flow)0.10 m²·K/W

Key Formulas

U = 1 / R_T — Overall heat transfer coefficient

R_T = R_si + R_1 + R_2 + ... + R_n + R_so — Total thermal resistance

R = t / k — Thermal resistance of a material layer

Tables & Referenced Sections

Key Tables

Table 1 - Mean Monthly Maximum and Minimum Temperatures for Some Stations in India

Table 2 - Thermal Conductivity of Building Materials (k-value)

Table 3 - Thermal Conductivity of Insulating Materials (k-value)

Table 4 - Thermal Resistance of Air Spaces

Table 5 - Surface Resistances

Key Clauses

Clause 4 - Climatic Conditions

Clause 5 - Properties of Materials

Clause 6 - General Recommendations for Design

Clause 7 - Insulation of Roofs

Clause 8 - Insulation of Walls

Appendix A - Method for Calculation of Overall Thermal Transmittance (U-Value)

Frequently Asked Questions4

How do I calculate the U-value of a wall?+

Where can I find the thermal conductivity (k-value) of brick or insulation?+

Table 2 provides k-values for common building materials like brick and concrete, while Table 3 lists k-values for various insulating materials like glass wool and polystyrene.

Is this code still current?+

What is surface resistance?+

It's the thermal resistance of the thin layer of air on the inner and outer surfaces of a building element. Values are given in Table 5 and depend on the surface orientation and exposure.

QA/QC Inspection Templates

📋

QA/QC templates coming soon for this code.

Browse all 300 templates →

IS 6670 : 1989Code of practice for thermal insulation of buildings

Overview

International Equivalents

Key Values6

Tables & Referenced Sections

Related Resources on InfraLens

Frequently Asked Questions4

QA/QC Inspection Templates

IS 6670 : 1989Code of practice for thermal insulation of buildings

Overview

International Equivalents

Key Values6

Tables & Referenced Sections

Related Resources on InfraLens

Frequently Asked Questions4

QA/QC Inspection Templates