Energy Efficient Buildings : Status, Challenges and

Opportunities in Indian Scenario

Dr. Ranjana Jha and Nikhil JindalNSIT, Faculty of Technology

University of Delhi

• In India, 30-40% of all primary energy is used in buildings.

• In high and middle income regions, the requirement of this energy is achieved with fossil fuels.

• In low income regions, biomass is still the main source of energy.

• These both patterns of energy consumption are environmentally intensive and contributing to global warming.

• Without proper policy interventions and technological improvements, the use of fossil fuels and biomass is not expected to change in near future.

• The construction, operation and demolition of building generate substantial social and economic benefits to the society, but it has serious negative impacts on the environment.

• Energy use associated with greenhouse gas emissions, waste generation, construction material use and recycling, water use and discharge and integration of building with other infrastructure and social systems is considerable.

Energy utilized over the life cycle of building

For commercial buildings For residential buildings

• Most of the energy used in buildings is due to the acclimatization systems (space heating, ventilation and air conditioning) followed by water heating and lighting.

• Lowering overall consumption has a direct impact on environment such as increase in indoor air quality, decrease in natural resources use and improved comfort due to improved energy efficiency in buildings.

• The pattern of different energy use of a building depends upon the building type and the climate zone where it is located.

• The type of the buildings set different requirements for indoor climate and internal loads such as cooling, ventilation, lighting, space heating, water heating and others for different climate zones.

• Lighting energy demand remains the same for all climate zones.

• Focus for energy efficient measures are different in different climate zones.

• Focus must be given on cooling and heating energy reduction in both residential as well as commercial buildings.

Opportunities for energy efficiency in buildings

• The diversity of buildings and their different use imply major differences for the adoption of energy conservation models.

• The energy sources used, methods applied and equipments added need to be tailored according to individual needs.

• For heating and cooling of building, the renewable energy sources such as solar heat or bio fuels should be preferred.

• Heat pumps based on outdoor air heat source can be a efficient way to heat a building.

• Raw materials for building sector are extracted, processed, transported, added in consumption phase and finally disposed.

• All these stages imply a number of environmental impacts.

• Embodied energy can be saved through the right selection of building materials.

• Light weight building materials such as timber frames usually have lower embodied energy compared to heavy weight construction.

• The building should be designed with due consideration to the facts such as local climate, transport distance, availability of materials and budget.

Building Envelope

• A well insulated thermal envelope without thermal bridges is a passive way to obtain a low heat/cool demand and improve thermal comfort.

• High level of insulation is accomplished by constructing a thicker than normal wall and filling it by a insulating material.

• Windows are still the least insulating part of the building envelope with a heat loss coefficient that is typically 4-10 times higher than one of the other envelope elements.

• Windows are built up of a number of components such as glass, gas filling, spacer, frame etc. that can be combined so that in each case, the window meets the requirements for insulation properties, day lighting and solar shading.

Energy Efficient Models

• There are different views in order to promote the energy efficient buildings which include low and zero energy buildings, passive house design, energy plus buildings, eco-cities etc.

Low Energy Building

• In low energy buildings, the energy consumption is based on an increased level of thermal insulation, high performance windows, air tight structural details, ventilation and heat recovery systems.

• Heat recovery from exhaust air in the ventilation system is common in this type of building.

• The different energy efficient measures should be considered as energy conservation technologies and passive and solar active technologies.

• In this type of building, the energy consumption is strongly influenced by construction practice.

Zero Energy Building

• Zero energy buildings are the buildings that produce as much as energy as they consume over a full year.

• This solution minimizes the impact of building on the environment and does not reduce the indoor comfort of the user. They are seen as a potential solution of mitigating global warming and other environmental problems.

• For individual house, a number of micro generation technologies can be applied to provide heat and electricity. These can include solar cells and small scale wind turbine for electricity and bio fuels or ground source heat pumps, solar thermal collectors and micro combined heat and power installation for heating.

Passive House

• A passive house is a building in which a comfortable interior climate can be maintained without active heating and cooling systems. The house maintains the comfortable indoor room temperature itself.

• A passive house is cost effective when combined with capitalized cost (construction, design, installed equipments and operating cost).

• Hot water supply using regeneration energy source

should use solar collector or heat pumps. There should be controlled ventilation and heat recovery of the exhaust air.

Recommendations

• There is a need of policies that encourage for more energy efficient buildings, policies regarding energy pricing and taxation, awareness, education, technology access and building safety norms.

• Regularities must provide a necessary framework for energy efficient buildings under different conditions and different climate zones. Such regularities should cover the energy use over the entire life span of buildings.

ITC Green Building, Gurgaon

CII Godgej Green Building, Hyderabad

Thank you