Energy Conservation Building Code

Table of Contents

Energy conservation aspect has not been a factor in building design in India. Buildings has been designed for its aesthetics, cost, uniqueness and saleability. This has resulted into tremendous increase in operating energy cost. Energy Ceonservation Building Code (ECBC) is a step forward for energy efficient buildings.

ECBC have had a long and proven history of inproving energy performance of buildings and yielding significant savings. ECBC has been used as one of the most effective tools for reducing energy use in buildings. The ASHRAE standard in the US, for example has resulted in over 60 % reduction in energy use in typical building. In developing countries, a typical saving of 20 % to 35 % can be expected.

The ECBC has been finalized after extensive consultation with all stakeholders by a commitee of experts constituted by BEE for this purpose. The ECBC has been developed to cater to 5 different climatic zones in the country as in NBC. These climatic regions are: composite, hot and dry, warm and humid, moderate, and cold.

Broadly ECBC:

A widespread awareness and support is required for its effective implementation and eventual enforcement. Presently, compliace to ECBC is voluntary.

Provisions in Energy Conservation Act, 2001

Energy Conservation Building Code (ECBC) is one of the important provision of Energy Conservation Act, 2001.

The Code defines norms and standards of energy consumption expressed in terms of per square meter of area wherein energy is used and includes location of building. The BEE is mandated to take suitable steps to prescribe guidelines on ECBC.

In addition, the Central Government including the State Governments can amend ECBC to suit regional and local climatic conditions. State government may specify and notify ECBC with respect to use of energy in the buildings. Central government and state government can direct every owner or occupier of building or building complex, being designated consumer, to comply with the provision of ECBC for efficient use of energy and its conservation.

Further, the Central Governments and State Governments can direct, any designated consumer, if considered necessary for efficient use of energy and its conservation, to get energy audit conducted by an accredited energy auditor is such manner and at such intervals of time as may be specified by regulation.


To provide minimum requirements for the energy efficient design and construction of buildings.


The code is applicable to new commercial buildings having a connected load of 100 kW or greater or a contract demand of 120 kVA or greater.

This code would become mandatory as and when it is notified by the central and state government under Energy Conservation Act, 2001

Applicable Building Systems:The provision of this code applies to:

  1. Building envelopes, except for unconditioned storage spaces or warehouses,
  2. Mechanical systems and equipments including HVAC,
  3. Service hot water and pumping,
  4. Interior and exterior lighting, and
  5. Electrical power and motors.

The provisions of this code do not apply to:

  • Buildings that do not use either electricity or fossil fuel,
  • Equipment and portions of building system that use energy primarily for manufacturing processes, and
  • Where this code is found to conflict with safety, health, or environment codes.
  • Reference Standards: National Building Code, 2005 is the reference document.

    Administration and Enforcement

    Compliance with the requirements of this energy code shall be mandatory for all applicable buildings as and when it is notified in the official gazette.

    New buildings: 

    New buildings shall comply with the provisions of applicable building system of the code or the Energy Budget Method.

    Addition to existing building:

    If the addition plus existing building exceeds the threshold, compliance may be done either (i) the addition alone, or (ii) addition together with existing building.

    Alteration to existing building:

    Where the existing building exceeds the threshold, the portion being altered shall meet the compliance requirements.


    Mandatory Requirements

    Fenestration: U-factor and Solar Heat Gain Coefficient (SHGC) shall be determined as per ISO-15099. Air leakage for glazed swinging entrance doors and revolving doors shall not exceed 5.0 l/s⋅m2. Air leakage for other fenestration and doors shall not exceed 2.0 l/s⋅m2

    Opaque construction: U-factor to be determined as per the procedure of ASHRAE fundamentals 2005.

    Building envelope sealing: The following areas of the enclosed building envelope shall be sealed, caulked. gasketed or weather-stripped to minimize air leakage:

    1. Joints around fenestration and door frames,
    2. Openings between walls and foundations and between walls and roofs and wall panels,
    3. Opening at penetrations of utility services through roofs, walls and floors,
    4. Site-built fenestration and door,
    5. Building assemblies used as ducts or plenums, and
    6. All other openings in the building envelope.

    Prescriptive Requirements

    This deals with maximum assembly U-factor or the minimum insulation R-value for roofs, opaque walls and vertical fenestration. Skylight area is limited to a minimum of 5 % of gross roof area.

    Heating, Ventilation & Air Conditioning

    Mandatory Requirements

    Minimum Equipment Efficiencies: 

    Unitary Air Conditioners
    Equipment classMinimum COPMinimum IPLV
    Air cooled: ≥ 19 kW and < 40 kW3.08 
    Air cooled: ≥ 40 kW and < 70 kW3.08 
    Air cooled: ≥ 70 kW2.932.99
    Water cooled: < 19 kW4.10 
    Water cooled: ≥ 19 kW and < 40 kW4.10 
    Water cooled: > 40 kW3.223.02

    Coeficient of Performance (COP): Ratio of rate of heat removal (heat delivery for heating units) to rate of energy input; Integrated Part-Load Value (IPLV): A single number figure of merit on part-load EER, COP or kW/TR expressing part-load efficiency for air-conditioning and heat pumps on the basis of weighted operation at various load capacities.


    1. All mechanical cooling systems ≥ 28 kW and heating systems ≥ 7 kW shall be controlled by a timeclock.
    2. All heating and cooling equipments shall be temperature controlled. Where a unit provides both heating and cooling, controls shall be capable of providing a temperature dead band of 3 °C.

    Piping and Ductwork: All pipes / ducts to be insulated.

    System Balancing: 

    1. Air system to be balanced to minimize throttling losses. For fans ≥ 0.75 kW, fan speed to be adjusted to meet the design flow.
    2. Hydraulic system to be balanced to minimize throttling losses.For pump ≥ 7.5 kW, pump impeller shall be trimmed or pump speed shall be adjusted to meet the design flow.

    Prescriptive Requirements

    Air Side Economizer: Each individual cooling fan system of design supply capacity of over 1200 LPS and a total mechanical cooling capacity over 22 kW shall include either: (a) an aireconomizer capable of modulating outside-air and return-air dampers to supply 100 % of the design supply air quantity as outside air, or (b) A water economizer capable of providing 100 % of the expected system cooling load at outside air temperature of 10 °C. Not applicable for projects in hot-dry and warm-humid climate zones.

    Variable Flow Hydronic System: Chilled or hot water system shall be designed for variable fluid flow.

    Service Hot Water and Pumping

    Mandatory Requirements

    Solar Water Heating: Residential facilities, hotels and hospital with a centralized system shall have solar water heater for at least 20 % of design capacity.

    Also, where gas is available, not more than 20 % of the heating shall be met from electrical heating.

    Equipment efficiency: The performance and efficiency of service water heating system shall meet or exceed requirements as per IS.

    Supplementray Water Heating System: These shall be designed to maximize the energy efficiency and incorporate following design feature in cascade: (a) maximum heat recovery from hot discharge of condenser of air conditioning units, (b) use of gas fired heater whereever gas is available, and (c) electric heaters as last resort.

    Piping insulation: The pipeline of entire hot water system shall be insulated.


    Mandatory Requirements

    Lighting Control: 

    1. Automatic Lighting Shutoff: Interior lighting systems in buildings larger than 500 m² shall be equiped with an automatic control device. Within these buildings, all office areas less than 30 m², all meeting and conference rooms, all school classrooms and all storage spaces shall be equipped with occupancy sensors. For other spaces, this automatic control device shall function on either: (a) a schedule basis at specified programmable times. An independent programme schedule shall be provided for areas of no more than 2500 m, or (b) occupancy sensors that turn the lighting off within 30 minutes of an ocupant leaving the space. Light fixtures controlled by occupancy sensors shall have a wall-mounted, manual switch capable of turning off lights when the space is occupied.
    2. Space Control: Each enclosed space shall have at least one control device to independently control the general lighting within the space. Each control device shall: (a) control a maximum of 250 m² for a space less than 1 000 m² and a maximum of 1 000 m² for bigger spaces, (b) be capable of overriding the shutoff control, and (c) be readily accesible and located so that occupant can see the control.
    3. Control in Daylighted Areas: Luminaires in daylighted area greater than 25 m² shall be equiped with either a manual or automatic device that: (a) is capable of reducing the light output of the luminaire in the day lighted areas by at least 50 %, and (b) controls only the luminaries located entirely within the day lighted area.
    4. Exterior Lighting Control: Lighting for all exterior applications, not exempted, shall be controlled by a photo sensor or astronomical time switch.

    Exit Signs: Internally illuminated exit signs shall not exceed 5 W per face.

    Exterior Building Grounds Lighting: Luminaries having lamp of 100 W or more shall have minimum efficacy of 60 lumens per watt unless the luminaire is controlled by a motion sensor.

    Interior Lighting Power: The installed light power density (LPD) calculated either on 'Building Area Method' or 'Space Function Method' shall not exceed the values specified in tables. For office buildings, LPD limit is 10.8 W/m².

    Exterior Lighting Power: The connected lighting power shall not exceed:

    Exterior Building Lighting Power
    ApplicationPower limits
    Building entrance (with canopy)13 W/m² of caopied area
    Building entrance (without canopy)90 W/lin m of door width
    Building exit60 W/lin m of door width
    Building facades2 W/m² of vertical facade area

    Electric Power

    Mandatory Requirements


    1. The selection of rating and design of power transformers shall be done so as to satisfy the minimum acceptable efficiency at 50 % and full load. In addition, the transformer must be selected such that it minimises total of initial cost and present value of costs of its lost energy serving estimated loads during its lifespan.
    2. Transformers of rating more 500 kVA would have additional metering CT / PT than the requirements of utilities.

    Energy Efficient Motors: 

    1. All polyphase motors of 0.375 kW or more and expecting to operate more than 1500 hours per year and all polyphase motors of 50 kW or more and expected to operate more than 500 hours per year, shall be energy efficient motors conforming to IS 12615.
    2. Motor HP shall not exceed 200 % of the calculated maximum load being served.
    3. After rewinding of motors, new efficiency test to be made.

    Power Factor Correction: All electricity supplies exceeding 100 A, 3 phase shall maintain power factor between 0.98 lag to 1 at the point of connection.

    Check Metering and Monitoring: Services exceeding 1000 kVA shall have permanently installed electrical metering to record demand, energy and power factor. The metering shall also display current in each face and neutral, voltage between phases and each phase and neutral, and total harmonic distortion. Services exceeding 65 kVA but up to 1000 kVA, shall have permanently installed electric metering to record demand, energy and power factor. Services not excceding 65 kVA shall have electrical metering to record energy.

    Power Distribution Systems: Power distribution losses not to exceed 1% of total power usage by proper designing of power cables.

    Benefits of ECBC

    ECBC encourages energy efficient design of building or alteration of commercial buildings to reduce energy use without affecting building function, comfort, health or productivity; with appropriate regard for economic considerations. These codes eliminate design practices that lead to high energy use and associated costs. Resulting energy savings directly benefits owners and occupants over the entire life of the building.

    The average energy use for typical commercial building is 200 kW⋅h/m² per annum. Considering 30 % saving by compliance of ECBC, this can be brought to 140 kW⋅h/m² per annum. In 2004-05, residential and commercial construction accounted for 19.25 million m² and 21.50 million m² respectively, and further an increase of 10 % each year is expected. This shows tremendous potential for energy saving.

    Implementation of ECBC

    Harmonization of ECBC with National Building Code is under progress by including a chapter on 'Approach to sustainability' in NBC-2005. Also labelling programme for 3 categories of buildings; office buildings, BPO's, and shopping malls; has been developed.

    Still, at present, the capacity required to implement the ECBC is inadequate in India. To promote, incentives need to be given to the industries for insulators and windows.


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