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IS 16279:2015 is the Indian Standard (BIS) for energy performance of buildings - calculation of energy demand for heating and cooling - general criteria. This standard establishes the general criteria and a calculation methodology for determining the energy demand for space heating and cooling in buildings. It provides a framework for assessing a building's thermal performance by considering factors like heat transfer, ventilation, and internal/solar gains. It is a key document for energy efficiency analysis and green building design.
Establishes general criteria for the calculation of energy demand for heating and cooling of buildings, contributing to energy efficiency assessment.
BIM-relevant code. See the BIM Hub for ISO 19650, IFC, and LOD/LOIN frameworks used alongside it.
Practical Notes
! This code provides the methodology, but actual implementation is almost always done using specialized energy simulation software like EnergyPlus, eQuest, or IES VE.
! The accuracy of the results heavily depends on the quality of input data, particularly climatic data, building envelope properties (U-values, SHGC), and operational schedules.
! This standard is often used in conjunction with the Energy Conservation Building Code (ECBC) and for green building rating systems like GRIHA and IGBC to demonstrate performance.
IEC 62116:2014International Electrotechnical Commission (IEC), International
HighCurrent
Test procedure of islanding prevention measures for utility-interconnected photovoltaic inverters
Provides the foundational test methodology for anti-islanding, which is a core component of IS 16279.
IEC 61727:2004International Electrotechnical Commission (IEC), International
HighCurrent
Photovoltaic (PV) systems - Characteristics of the utility interface
Defines the utility interface requirements (voltage, frequency, harmonics) that IS 16279 provides the test procedures for.
UL 1741Underwriters Laboratories (UL), USA
MediumCurrent
Inverters, Converters, Controllers and Interconnection System Equipment for Use With Distributed Energy Resources
Broader North American standard covering safety and grid interconnection, including tests similar to those in IS 16279.
VDE-AR-N 4105:2018-11VDE (Verband der Elektrotechnik), Germany
MediumCurrent
Power generation systems connected to the low-voltage distribution network - Technical minimum requirements for connection to and parallel operation with low-voltage distribution networks
A comprehensive German application rule with detailed inverter test requirements, especially for advanced grid support functions.
Key Differences
≠Voltage and frequency trip settings in IS 16279 are specified to align with the Indian Central Electricity Authority (CEA) grid code, which may differ from the nominal ranges in European (EN 50549) or US (IEEE 1547) standards to reflect local grid conditions.
≠While IS 16279 introduces the concept, the specific requirements and test procedures for Low Voltage Ride Through (LVRT) are defined by CEA regulations and are tailored to the Indian grid, differing from the specific voltage-time curves mandated in standards like Germany's VDE-AR-N 4105.
≠IS 16279:2015 has a less extensive set of tests for advanced grid support functions (e.g., Volt-VAR, frequency-watt) compared to more recent international standards like UL 1741 Supplement B or IEEE 1547-2018, which mandate more sophisticated inverter behavior.
Key Similarities
≈IS 16279 directly adopts the anti-islanding test methodology from IEC 62116, which involves using a tunable RLC parallel resonant circuit to simulate an island and verifying disconnection within a specified time.
≈A core requirement in both IS 16279 and its international counterparts (like IEC 61727 and UL 1741) is the testing of output current quality, specifically ensuring the Total Harmonic Distortion (THD) remains below 5%.
≈All standards mandate fundamental safety protection tests, including the verification that the inverter automatically disconnects from the grid during abnormal conditions such as over-voltage, under-voltage, over-frequency, and under-frequency.
≈There is a common requirement to limit DC current injection into the AC grid to a very low level (typically less than 0.5% of the rated current) to prevent transformer saturation and ensure safety, with a corresponding test procedure.
Parameter Comparison
Parameter
IS Value
International
Source
Anti-Islanding Detection Time
Must disconnect within 2 seconds
Must disconnect within 2 seconds
IEC 62116:2014
Current Total Harmonic Distortion (THD)
< 5% at rated power
< 5% at rated power
IEC 61727:2004
DC Current Injection
< 0.5% of rated output current
< 0.5% of rated output current
IEC 61727:2004
Over-Voltage Trip Point (continuous)
> 110% of nominal voltage
> 110% of nominal voltage
IEC 61727:2004
Under-Voltage Trip Point (continuous)
< 85% of nominal voltage
< 85% of nominal voltage
IEC 61727:2004
Over-Frequency Trip Point
> 50.5 Hz (for 50 Hz grid)
> 50.5 Hz (for 50 Hz grid)
IEC 61727:2004
Under-Frequency Trip Point
< 47.5 Hz (for 50 Hz grid)
< 47.5 Hz (for 50 Hz grid)
IEC 61727:2004
Power Factor
> 0.9 (lagging) for output > 50% rated
> 0.9 (lagging/leading) for output > 50% rated
IEC 61727:2004
⚠ Verify details from original standards before use
Key Values5
Quick Reference Values
Sensible heat gain from person at rest (seated)75 W
Default lighting heat gain for offices12 W/m²
Default equipment heat gain for offices15 W/m²
Standard indoor design temperature (cooling)25 °C
Standard indoor design temperature (heating)21 °C
Key Formulas
Q_H,nd = Q_H,ht - η_H,gn * Q_H,gn — Annual energy need for heating
Q_C,nd = Q_C,gn - η_C,ls * Q_C,ht — Annual energy need for cooling
Φ_tr = H_tr * (θ_int - θ_ext) — Heat transfer by transmission
Φ_ve = H_ve * (θ_int - θ_sup) — Heat transfer by ventilation
Tables & Referenced Sections
Key Tables
Table B.1 - Metabolic rate of the human body and corresponding sensible and latent heat emission
Table B.2 - Typical internal heat gains from appliances in dwellings
Table B.3 - Conventional occupation density and heat gains in non-residential buildings
Table C.1 - Examples of reference values for frame area fraction of windows
Key Clauses
Clause 5 - Principles of the calculation method
Clause 6 - Division of building into zones
Clause 7 - Calculation of heat transfer by transmission
Clause 8 - Calculation of heat transfer by ventilation
Does this code tell me if my building is energy compliant?+
No, it only provides the method to calculate energy demand. Compliance is checked against benchmarks in other regulations like the Energy Conservation Building Code (ECBC).
What is the main output of calculations based on this code?+
The primary output is the annual energy need for space heating and cooling, typically expressed in kWh/year or kWh/m²/year.
Do I need weather data to use this code?+
Yes, climatic data (like temperature, humidity, solar radiation) for the building's location is a crucial input for the calculations.
Is this code based on an international standard?+
Yes, this standard is technically equivalent to ISO 13790:2008 'Energy performance of buildings — Calculation of energy use for space heating and cooling'.