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IS 16429:2016 is the Indian Standard (BIS) for energy efficiency requirements for buildings - code of practice. This code establishes the minimum energy efficiency requirements for the design and construction of new commercial buildings. It covers the building envelope, HVAC systems, lighting, and electrical power to promote energy-efficient design. The code provides both a prescriptive path and a whole-building performance path for compliance.
Specifies minimum energy efficiency requirements for the design and construction of new buildings and major renovations of existing buildings.
BIM-relevant code. See the BIM Hub for ISO 19650, IFC, and LOD/LOIN frameworks used alongside it.
Practical Notes
! This standard is very closely aligned with the Bureau of Energy Efficiency's (BEE) Energy Conservation Building Code (ECBC). Compliance with one often ensures compliance with the other, but version differences should be verified.
! The 'Whole Building Performance' method (Clause 4.3) offers more design flexibility but requires specialized energy simulation software and expertise to demonstrate compliance.
! Early-stage design decisions like building orientation, massing, and window-to-wall ratio (WWR) have a significant impact on energy performance and are crucial for cost-effective compliance.
ASHRAE Standard 90.1-2019American Society of Heating, Refrigerating and Air-Conditioning Engineers (ASHRAE), USA
HighCurrent
Energy Standard for Buildings Except Low-Rise Residential Buildings
Both are comprehensive energy codes for commercial buildings covering envelope, HVAC, lighting, and hot water.
International Energy Conservation Code (IECC) 2021International Code Council (ICC), USA
HighCurrent
International Energy Conservation Code
Both serve as model energy codes for new construction, with prescriptive and performance-based paths.
GB 50189-2015Ministry of Housing and Urban-Rural Development, China
MediumCurrent
Design standard for energy efficiency of public buildings
Defines energy efficiency requirements for public/commercial buildings, but tailored specifically to Chinese climate zones and construction practices.
Building Regulations 2010 Part L, Volume 2 (2021 edition)Ministry of Housing, Communities & Local Government, United Kingdom
MediumCurrent
Conservation of fuel and power, Volume 2: Buildings other than dwellings
Sets mandatory energy performance requirements for non-domestic buildings in the UK, with a strong focus on carbon emissions.
Key Differences
≠IS 16429 is a 'Code of Practice', making it voluntary unless adopted by a local authority. In contrast, ASHRAE 90.1 and the IECC are model codes designed for mandatory adoption by jurisdictions, and the UK's Part L is a mandatory national regulation.
≠Climate zone definitions are different. IS 16429 uses 5 Indian-specific zones (Hot-Dry, Warm-Humid, Composite, Temperate, Cold). ASHRAE/IECC use a numerical system (1-8 with A/B/C sub-zones) based on heating and cooling degree days, which are not directly interchangeable.
≠IS 16429 applicability is triggered by a connected load of 100 kW or a contract demand of 120 kVA. International codes like the IECC and ASHRAE 90.1 generally apply to all commercial buildings by definition, with specific exemptions, rather than an electrical load threshold.
≠While IS 16429 recommends whole-building air leakage testing, it is not mandatory under the prescriptive path. The 2021 IECC and UK Part L mandate building air tightness testing for most new commercial buildings.
Key Similarities
≈All standards offer both a 'prescriptive path' with specific component requirements (e.g., U-values, efficiencies) and a 'whole building performance' path that allows for design flexibility through energy modeling.
≈The fundamental structure is similar, with dedicated sections covering the Building Envelope, Mechanical Systems (HVAC), Service Water Heating, and Lighting systems.
≈All codes utilize the concept of Lighting Power Density (LPD), expressed in W/m² or W/ft², to cap the installed power for lighting in different space types.
≈They all prescribe minimum energy efficiency ratings for mechanical equipment like chillers, boilers, and air conditioners, often by referencing equipment-specific standards (e.g., from AHRI or ISO).
Parameter Comparison
Parameter
IS Value
International
Source
Wall U-Value (Composite Climate)
≤ 0.440 W/m²K
≤ 0.812 W/m²K (for mass wall)
ASHRAE 90.1-2019 (Climate Zone 2B, similar to Warm-Humid)
Roof U-Value (Composite Climate)
≤ 0.261 W/m²K
≤ 0.318 W/m²K (insulation above deck)
ASHRAE 90.1-2019 (Climate Zone 2B)
Fenestration SHGC (Solar Heat Gain Co-efficient)
≤ 0.25 (for all climate zones except Cold)
≤ 0.25 (for vertical fenestration)
ASHRAE 90.1-2019 (Climate Zones 0-3)
Lighting Power Density (LPD) - Open Office
≤ 8.2 W/m²
≤ 7.75 W/m²
ASHRAE 90.1-2019
Chiller Efficiency (Water-Cooled Screw, >1055kW)
≥ 6.10 COP (Path A)
≥ 6.22 COP (for 1055-2110 kW range)
ASHRAE 90.1-2019
Whole Building Air Leakage Test
Recommended, not mandatory in prescriptive path.
Mandatory. Rate not to exceed 2.0 L/s·m² @ 75 Pa.
IECC 2021
⚠ Verify details from original standards before use
Key Values5
Quick Reference Values
Applicability thresholdConnected load of 100 kW or greater, or contract demand of 120 kVA or greater
Max U-factor for Walls (Composite Climate)0.440 W/m²K
Max U-factor for Roofs (Composite Climate)0.261 W/m²K
Max SHGC for vertical fenestration (Composite Climate, WWR <= 40%)0.25
Max Lighting Power Density (LPD) for Office Area10.8 W/m²
Key Formulas
Compliance (Whole Building Performance): Annual Energy Use of Proposed Building <= Annual Energy Use of Standard Building
Tables & Referenced Sections
Key Tables
Table 2 - Climate Zone Classification
Table 3 - Opaque Assembly Maximum U-Factor Requirements
Table 4 - Vertical Fenestration Maximum U-Factor and SHGC Requirements
Table 10 - Interior Lighting Power Densities (LPD)
Key Clauses
Clause 4 - Compliance Approaches (Prescriptive and Whole Building Performance)
Clause 5 - Building Envelope
Clause 6 - Heating, Ventilation, and Air Conditioning (HVAC) System
No, this code is for commercial buildings with a connected load ≥ 100 kW or contract demand ≥ 120 kVA. Residential buildings are covered by the Eco-Niwas Samhita (ECBC-R).
What are the main compliance paths?+
There are two paths: the Prescriptive Method, which specifies minimum standards for each component, and the Whole Building Performance (WBP) Method, which requires an energy simulation to show the building's overall performance is better than a baseline (Clause 4).
What are the climate zones defined in the code?+
The code defines five climate zones based on weather data: Hot-Dry, Warm-Humid, Composite, Temperate, and Cold (Table 2).
What is the maximum Lighting Power Density (LPD) for an open-plan office?+
The maximum LPD for an office area is 10.8 W/m² according to Table 10.