1. UNIT III
ENERGY EFFICIENCY
1. Environmental Impact of Building Construction
2. Concept of Embodied Energy
3. Operational Energy And Life Cycle Energy
METHODS TO REDUCE OPERATIONAL ENERGY
1. Energy Efficient Building Envelops
2. Solar Heat Gain Coefficient
3. U-Values For Facade Materials
4. Efficient Lighting Technologies
5. Energy Efficient And BEE Rated Appliances For Heating And Air-
Conditioning Systems In Buildings
6. Zero Ozone Depleting Potential (ODP) Materials
7. Wind And Solar Energy Harvesting
8. Energy Metering And Monitoring
9. Concept Of NET Zero Buildings
1.Environmental Impact of Building Construction
There are many societal impacts of construction. Methods, materials, and operations
all contribute to the environmental impact of construction. One of the biggest
environmental problems related to infrastructure development is energy use. In
addition, the environmental impact of construction can also affect wildlife. Roads in
rainforests can cut off migration routes. Dams can divert water from freshwater
habitats. Spills from oil platforms can kill marine organisms and leave the shoreline
polluted.
Construction firm's biggest negative impact on the environment is caused by the
burning of fossil fuels, like gas and diesel. Every construction project results in these
gas emissions of carbon dioxide, methane and other waste products that pollute the
air and are believed to contribute to global warming.
Ecosystem impact
These adverse environmental impacts like waste, noise, dust, solid wastes, toxic
generation, air pollution, water pollution, bad odour, climate change, land use,
operation with vegetation and hazardous emissions. Air emissions are generated
2. from vehicular exhaust, and dust during construction. This emissions include Co2,
No2, and So2. Noise emissions are generated as a result of various construction
equipment's, air compressors and vehicles. The construction equipment's and other
sources will generate noise within the range of 70 to 120 DB within the vicinity of
construction site. Wastes are generated from construction activities, labours camps,
sewage treatment plant, and other sources. The solid waste generated during
operational phase is categorized as biodegradable, recyclable, inert/ recyclable and
hazardous.Waste water is generated from construction activities, sewage,
commercial activities, and other sources.
Natural resources
Various natural resources are used during any typical construction process, this
resources include energy, land, materials, and water. In addition, construction
equipment operations consume a lot of natural resources, such as electricity and/or
diesel fuel. Construction sector is responsible for consuming a high volume of natural
resources and generation a high amount of pollution as a result of energy
consumption during extraction and transportation of raw materials. Construction
sector generate worldwide substantial environmental impacts.
Public impact
Most construction projects are located in a densely populated area. Thus, people
who live at or close to construction sites are prone to harmful effects on their health
because of dust, vibration and noise due to certain construction activities such as
excavation and pile driving . During the construction phase of a project, construction
dust and noise are regarded to be two major factors that affect human health.
2.Concept of Embodied Energy
Embodied energy is the energy consumed by all of the processes associated with
the production of a building, from the mining and processing of natural resources to
manufacturing, transport and product delivery. Embodied energy does not include
the operation and disposal of the building material, which would be considered in a
life cycle approach. Embodied energy is the ‘upstream’ or ‘front-end’ component of
the life cycle impact of a home. A complex combination of many processed materials
determines a building’s total embodied energy. Every building is a complex
3. combination of many processed materials, each of which contributes to the building’s
total embodied energy. Renovation and maintenance also add to the embodied
energy over a building’s life.
Assessing embodied energy
Whereas the energy used in operating a building can be readily measured, the
embodied energy contained in the structure is difficult to assess. This energy use is
often hidden.
It also depends on where boundaries are drawn in the assessment process. For
example, whether to include:
the energy used to transport the materials and workers to the building site
just the materials for the construction of the building shell or all materials used
to complete the building such as bathroom and kitchen fittings, driveways and
outdoor paving
the upstream energy input in making the materials (such as factory/office
lighting, the energy used in making and maintaining the machines that make
the materials)
the embodied energy of urban infrastructure (roads, drains, water and energy
supply).
Gross energy requirement (GER) is a measure of the true embodied energy of a
material, which would ideally include all of the above and more. In practice this is
usually impractical to measure.
Process energy requirement (PER) is a measure of the energy directly related to the
manufacture of the material. This is simpler to quantify. Consequently, most figures
quoted for embodied energy are based on the PER. This would include the energy
used in transporting the raw materials to the factory but not energy used to transport
the final product to the building site.
In general, PER accounts for 50–80% of GER. Even within this narrower definition,
arriving at a single figure for a material is impractical as it depends on:
efficiency of the individual manufacturing process
the fuels used in the manufacture of the materials
the distances materials are transported
the amount of recycled product used.
4. Each of these factors varies according to product, process, manufacturer and
application. They also vary depending on how the embodied energy has been
assessed.
Estimates of embodied energy can vary by a factor of up to ten. As a result, figures
quoted for embodied energy are broad guidelines only and should not be taken as
correct. Consider the relative relationships and try to use materials that have the
lower embodied energy.
Try to use materials that have lower embodied energy.
3. Operational Energy And Life Cycle Energy
The total life cycle energy of a building includes both 'embodied' and
'operational' energy.
Operational energy is the energy required during the entire service life of a
structure such as lighting, heating, cooling, and ventilating systems; and operating
building appliances. Operational energy is associated with relatively longer
proportion of infrastructure's service life and can constitute 80%–90% of the total
energy associated with the structure. Operational energy comprises the energy used
for space heating and cooling, hot water heating, lighting, refrigeration, cooking and
appliance and equipment operation.
Life cycle energy analysis is an approach that accounts for all energy inputs to a
building in its life cycle. The system boundaries of this analysis include the energy
use of the following phases: manufacture, use, and demolition. Manufacture phase
includes manufacturing and transportation of building materials and technical
installations used in erection and renovation of the buildings. Operation phase
encompasses all activities related to the use of the buildings, over its life span.
These activities include maintaining comfort condition inside the buildings, water use
and powering appliances. Finally, demolition phase includes destruction of the
building and transportation of dismantled materials to landfill sites and/or recycling
plants.
Life cycle energy of the building is the sum of the all the energies incurred in its life
cycle. It is thus expressed as sum of Embodied Energy, Operating Energy and
demolition Energy.
