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Building Energy Efficiency Energy Conservation Building Code for Residential Buildings (ECBC-R) Dr Sameer Maithel Indo-Swiss Building Energy Efficiency Project
Building Energy Efficiency
Energy Conservation Building Code for Residential Buildings
(ECBC-R)
Dr Sameer Maithel
Indo-Swiss Building Energy Efficiency Project
Building Energy Efficiency - Overview
• Buildings account for around 33% of the total electricity consumption in India. The electricity consumption in the building sector is rising rapidly primarily as a result of increase in built-up area and increasing penetration of air conditioning.
• The Bureau of Energy Efficiency (BEE) has adopted a multi-pronged approach to conserve energy in building sector:• Energy Conservation Building Code (ECBC) for commercial buildings (2007 & 2017).
• Star rating system for various types of commercial buildings
• Star rating for appliances, which cover air conditioners, fans, lighting, etc.
• BEE now plans to aggressively push for energy efficiency in new housing through the Energy Conservation Building Code for Residential Buildings.
Residential Buildings: Fast Growth in Building Stock & Electricity Consumption
• Residential building stock is expected to double in next 15-20 years• Residential buildings consumes around 255 TWh electricity in 2017, the electricity
consumption in residential buildings is expected to multiply by more than 3X and reach around 850 TWh by 2030.
• Residential buildings will become the largest end-user of electricity in the country accounting for 38% of the total electricity consumption.
• Around 12 million houses being constructed in urban areas for low income and economically weak.
• A significant percentage is in the form of high density, multi-storey residential blocks.
• Very low penetration of air conditioning, though majority have ceiling fans.
• Ensuring thermal comfort to occupants through design is of prime importance.
Affordable Housing Programme in India & Thermal Comfort
Energy Conservation Building Code-Residential: Objective
• Reduces Heat Gains/Loss• Improve Natural
Ventilation & Daylighting Potential
Improved thermal comfort & reduced energy consumption
PROVISIONS FOR BUILDING ENVELOPE
Three Tier Approach to Energy Efficient Building Design
Source: Lechner N. 2015. Heating, Cooling, Daylighting: Sustainable Design Methods for Architects. John Wiley & Sons
ECBC-R (Part I)
Reducing Heat Gains/ Loss from Building Envelope (roof, walls and windows)
Cooling Dominated Climates Heating Dominated Climates
Residential Envelope Transmittance Value (RETV) (W/m2)
• Residential Envelope Heat Transmittance (𝑅𝐸𝑇𝑉) is the net heat gain rate (over the cooling period) through building envelope (excluding roof) divided by the area of building envelope (excluding roof). Its unit is W/m2.
Ist Term
IInd Term
IIIrd Term
Residential Envelope Transmittance Value (RETV)
RETV
Walling material & construction
(U value of walls)
Window to wall ratio
Glass
(U value)
Glass
(SHGC value)
Shading of openings
Direction of wall/openings
Maximum allowable RETV for all climates (except cold climate) is 15 W/m2
Ist Term
IInd TermIIIrd Term
Natural Ventilation Potential
The code defines minimum openable window-to-
floor ratio 𝑊𝐹𝑅𝑜𝑝 for different climate regions.
It is the ratio of openable area to the built-up area
of dwelling units.
𝑊𝐹𝑅𝑜𝑝 =𝐴𝑜𝑝𝑒𝑛𝑎𝑏𝑙𝑒
𝐴𝑏𝑢𝑖𝑙𝑡−𝑢𝑝c
Daylight Potential
The code defines minimum visible light transmittance w.r.t.window-to-wall ratio.
ECBC-R is designed to be a simple code
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• Specify requirements for key elements such as wall and ceiling insulation, window and doors, roofs, etc. Compliance with these codes is commonly assessed by checking project designs and specifications against the list of prescribed requirements.
Prescriptive codes
• Typically allow for trade-offs between similar building components. For example, less efficient insulation for more efficient windows in the building envelope.
Trade-off codes
• Specify a minimum required level of energy consumption or intensity for the whole building. They require energy modelling to be conducted at design stage.
Performance Codes
Outcome-based Codes
• Requires demonstration of buildings achieving code required performance in operation. Compliance is typically possible through energy performance certificates or with energy disclosure policies.
ECBC-R
Increasing Degree of Complexity
Online Compliance Tool (to be made available on launch of ECBC-R)
Example of ECBC -R Compliant Building: SmartGHAR-3, Rajkot
• Pradhan Mantri Awas Yojana (PMAY) project by the Rajkot Municipal Corporation
• Wall made of AAC blocks (light weight and good thermal insulation) to reduce heat gains.
• Roof (insulation) and reflective property (china mosaic) to reduce heat gains
• Adequate window size for natural ventilation
• Proper design and shading of windows to reduce heat gains
Benefits of ECBC-R
• Minimum 20% electricity saving (in cooling) as compared to a typical building and associated reduction in CO2 emissions
• Improved thermal comfort and daylighting for the residents
• Monetary savings due to reduced electricity bills for the residents.
Conclusions• Residential building stock is set to double in next 15-20 years in India and
electricity consumption in residential buildings may increase by three to four times.
• It is imperative that the new residential building stock is Energy Efficient & Thermally Comfortable• Better thermal comfort for occupants
• Lower electricity consumption and bill for the occupants
• Reduction in GHG emissions
• Effective and quick implementation of simple ECBC-R code, with MoP/BEE working closely with the Ministry of Housing & Urban Development & state/cities governments holds the key to mainstream energy efficient and thermally comfortable residential buildings.
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