Sustainable Construction: Green Buildings, Materials, and Envelopes

This report provides a comprehensive overview of sustainability in construction, emphasizing green building principles and practices. It defines sustainability within the context of construction, highlighting the overlap of environmental, economic, and social considerations. The report explores key aspects of sustainable building design, including site selection, water efficiency, energy efficiency, material selection, and indoor environment quality. It examines the benefits of green buildings for building owners, users, and society, such as reduced energy consumption, pollution, and waste. Furthermore, the report delves into the prospects of green buildings and their development, focusing on renewable energy sources, water conservation, and efficient building management systems. It also discusses sustainable materials, emphasizing life cycle stewardship, reuse and recycling, low toxicity, local sourcing, and durability. The report concludes with an explanation of the building envelope, its role in thermal comfort and protection, and its components, including walls, roofs, windows, and doors, which work together to ensure structural integrity and environmental control.

SUSTAINABILITY IN CONSTRUCTION
The terms “sustainability” and “green” that are often used “interchangeably”, have gained
recognition in the architecture, engineering, and construction issues since over the past few
decades. Also, the effort to formulate a definition for sustainability leads to many of the issues
and problems because there are several definitions for sustainability. However, the concept of the
sustainability can be interpreted as the overlap of environment, economy, and society.
Furthermore, sustainable development is not essentially the only a valuable issue, but it can also
serve as excellent vehicles for launching a broader community conversation about economic,
environmental, and social matters in general
The main target of sustainable building design is to develop “environmentally friendly
construction practices” that contribute to save energy, water and raw materials; minimizing water
surplus and greenhouse gas emissions; and consuming reusable and recyclable materials, in order
to create houses that are comfortable, clean, safe, and productive. Due to increasing of new
infrastructural developments in transitional economies of developing countries, and the
insufficient and improper use of existing buildings universally, it is an imperative of the industry
to develop sustainable building technologies. Sustainability in construction engineering is a
philosophy and an integrated design process, not only a building style
Green building is a key architectural concept of the 21st century and it is the technique of
constructing or transforming structures to become environmentally conscientious, sustainable
and resource-efficient throughout their life cycle. The GB (Green building) are capable to have
efficient water use, energy-efficient and eco-friendly environment, use of renewable energy and
recycled/recyclable materials, effectual use of landscapes, effective control and building
management systems and enhanced indoor quality for good health and comfort of the residents
as compared to conventional buildings. The concept of green buildings not only favors human
health, but also safeguards earth from harmful and poisonous effects, fulfilling the accountability
of the concept of sustainable development.
What Makes a Building Green
Green building is interpreted in many different ways, common opinion that they should be
designed and operated to reduce the overall impact of the built environment on human health and
the natural environment by:
 Efficiently using energy, water and other resources
 Protecting occupant health and improving employee productivity
 Reducing waste, pollution and environmental degradation
A green or sustainable building is one which uses less water, optimizes energy efficiency,
conserve the natural resources, generate less waste and provide healthier space for occupants. It
often emphasizes taking advantage of renewable sources.

The specific features of sustainable buildings are as follows
 Site selection with full respect to ecology of the area, existing environment and use of
local materials
 Minimum consumption of energy by the building
 Minimum use of fresh water from external sources
 Maximum use of non-toxic, recycled and renewable material
 Highest indoor air quality without affecting the energy consumption
 Integrated Building Management System for control, monitoring, measurement and
verification
 Innovation in design and construction technique
 Secured power infrastructure
The following are important aspects of green building
A. Sustainable Site
It refers to a site that would have the least environmental threat during construction stage. It has
access to basic amenities like water and sand thereby, reducing pollution caused because of
transportation. It optimizes the use of on-site storm water management and provision for ground
water recharge. Measures are adopted to preserve top soil for absorbing less water through
effective methods
B. Water Efficiency
The main goal here is to increase the effective use of water within the building, thereby reducing
the amount of water needed for specific operations. Some methods which can be adopted for this
include, efficient landscaping techniques and use of innovative wastewater management
technology. Technologies for reuse of water such as Rainwater Harvesting, Wastewater
treatment plant and waterless urinals are installed for conservation of water
C. Energy Efficiency
It involves the installation of various methods of on-site renewable energy production to reduce
the overall energy consumption of the building and other means of using green power (solar,
wind). The optimization of building orientation, shape, design and interior colors and finishes is
done which maximizes the use of natural day lighting. This reduces the dependence on artificial
lighting energy. Window frames, sashes and curtain wall system are so designed to optimize
energy performance.
D. Material Selection
Maximizes the use of recycled content materials, re-usable, renewable, sustainably managed and
bio-based materials. Ways are identified to use high recycled content materials which range from

blended concrete using fly ash, slag, recycled concrete aggregate or other admixtures to
structural steel, ceiling and floor tiles, carpeting, carpet padding etc. Bio-based materials and
finishes such as various types made from agricultural waste and byproducts including straw,
wheat, barley, soy, sunflower shells, peanut shells etc. are used. Reuse of household waste in the
form of biogas is also a feature of this aspect.
E. Indoor Environment Quality
In order to enhance the health of the occupants, buildings should be constructed with materials
having low emissions. Building is designed to maximize the use of natural light for all
occupants. Bio degradable and environment friendly cleaning agents are used, that do not release
harmful agents and residue. There should be a provision for cross ventilation and enhanced
ventilation system
Benefits of Sustainable Building
On a broader scale, design and construction of green buildings will benefit the community at
large with the improvement in environment by reducing GHG (greenhouse gas) emissions,
improving energy saving, and reducing the stress on natural resources. Green concepts and
techniques in the residential sector can help address national issues like handling of consumer
waste, water efficiency, extinction of fossil fuel in nature by increase energy efficiency, conserve
the natural resources. Some of the benefits of a green design to a building owner, user, and the
society as a whole are as follows:
 Reduced energy consumption without sacrificing the comfort levels
 Reduced destruction of natural areas, habitats, and biodiversity, and reduced soil loss
from erosion, etc.
 Reduced air and water pollution (with direct health benefits)
 Reduced water consumption
 Limited waste generation due to recycling and reuse
 Reduced pollution loads
 Increased user productivity
 Enhanced image and marketability
Prospects of Green Buildings and Their Development
The construction of Green Building mainly focuses on reduction of electricity and water
consumption. Lighting loads are biggest consumption points of electricity in buildings. Usage of
Sky lights maximizes the day lighting thereby reduces usage of artificial lighting. Photo Voltaic
cells are to be installed on the roof top of building to generate the electric energy. Rainwater
harvesting and waste water treatment plants are also to be installed within the building to
conserve the water. There are lot of options available to build green homes, a few of those are

energy saving air conditioners (HVACs), high performance glass windows, water saving
solutions, composting toilets, and efficient building management systems.
Green powering resource output and the connected electrical load of the private house spots
including public areas of the small sized Green building, to the extent possible should get
balanced. For huge constructions at least the public walk-a-way area lighting and lift and
pumping loads should be met by the said resource.
Usage of solar window technology could not only generate electricity through Nano PV cells and
miniscule wires, but also illuminates the indoor area spreading the sun light without losing
transparency during day time. However generated electricity can be utilized for illuminating the
same area during night hours. Molten salt storage tanks can be erected on the roof for storing
solar thermal energy for several hours and its fluid can be circulated for heating water instead of
conventional immersion water heaters. Solar water heaters can also be used for serving the above
purpose in small scales.
SUSTAINABLE MATERIALS
The production and use of building materials consumes large quantities of energy and resources
and generates waste. The choice of materials used in a building therefore has important
implications for the environment; wherever possible they should be selected to minimize
negative environment impacts and the consumption of non-renewable resources. A key concept
when thinking about what materials to use is ͚ life cycle stewardship͛. This means that the
consequences and impacts of using materials must be considered from the point at which they
are mined/harvested, through processing and manufacture, to installation, use, reuse/recycling
and disposal. Key considerations regarding sustainable materials include:
 Reused or recycled – where possible reuse materials or use recycled materials instead of
new ones as this cuts out the emissions and energy consumption associated with
producing new materials and reduces waste. For example, where demolition is involved,
identify opportunities for reuse or recycling of demolition materials (e.g. use recycled
aggregates in new concrete)
 low toxicity - use non-toxic materials that are free of harmful chemicals such as CFCs
 local sourcing – sourcing of materials locally may help to reduce the energy use and
environmental impacts associated with transportation
 Responsible sourcing - independent certification schemes exist to confirm that specific
materials comply with responsible sourcing standards. For example, timber from well-
managed forests is certified by the Forest Stewardship Council (FSC).
 maintenance/replacement and durability – using materials that are long lasting and that
are cheap and relatively easy to maintain, adapt and/or replace will ensure that buildings
are flexible and built to last

 reusable or recyclable – select materials that can be easily dismantled and reused or
recycled at the end of their useful life
Retaining and re-using existing materials
Embodied energy can be minimized by retaining and re-using existing building structures and
materials, particularly if demolition of existing structures is required. Therefore, consideration
should be made to re-use the existing materials within a new development in either their existing
state or in a revised/renewed state. For example, crushed hard materials such as bricks and
concrete may be re-used as aggregate. But also when building new, future recyclability through
easy disassembly should be considered. Consideration should be given to composite materials
which are more difficult to recycle than raw materials. For example, facade and roof structures
that are easily disassembled are more likely to be reused than those that would be damaged when
taken apart.
WHAT IS A BUILDING ENVELOPE?
By nature, we do not expect our environment to maintain a consistent, 74-Degree-Fahrenheit,
50% humidity, climate. Our perception of comfort is quite adaptive and is based on
circumstance, the expectation of environmental conditionals and activities. We use umbrellas
when it’s raining. We dress in layers when it’s cold. We use sunscreen when exposed to
summer’s intense UV rays. And yet, we expect our homes to provide thermal comfort and
protection from the natural elements, at a consistent 74-degrees, every day. Walls, roofs,
windows, and doors all play a role, but really it’s the building envelope that makes this possible.
At its simplest definition, the building envelope is the exterior or shell of a building that repels
the elements.
At its most complex definition, it’s an engineering system that meshes elements such as
structural integrity, moisture control, temperature control, and air pressure boundaries into a
single design strategy.
It is the physical separator between the conditioned and unconditioned environment of a building
including the resistance to air, water, heat, light, and noise transfer. It’s the part of the house that
you can draw a line around: the roof, the walls, and the foundation. While the building envelope
is an outline of sorts, it’s important to remember that these are compounded layers. Each part of
the building envelope must be thought of as a collection of smaller pieces working together to
provide structural support. The way the foundation and walls are built is essential in creating a
sturdy structure, or a base, for the rest of the building. This is one of the main functions of
construction because a well-constructed envelope is necessary to simply keep the structure
standing.

The building’s design must be measured and carried out meticulously to ensure that there are no
open edges, cracks between the windows and walls and imperfections between the roof and the
walls, or between the walls and the foundation. It is all included within the building envelope
concept.
That said, each part of the enclosure faces different challenges.
 Roofs are bombarded by heat, rain, and hail
 Walls contend with wind and rain
 Foundations are always surrounded by wet, damp earth
On a construction level, the home’s building envelope is a series of composite layers —whether
it be wood, glass, veneer, drywall, etc. — each with their own permeable properties that must be
considered A proper building envelope works together to achieve the same goals of stopping or
slowing the flow of air, water, and heat while still allowing the inevitable intrusion of water as a
way to dry out.
Why Do Building Envelopes Matter?

All told, building envelope components work together to perform four basic, but critical
functions: structural support, moisture management, temperature regulation, and air flow. The
latter three—moisure, air and thermal—characterize the “control” functions of the building
envelope, those aspects that ensure a house is energy efficient, comfortable, and sustainable.
1. Moisture control. The most important element of the envelope’s control is its ability to
regulate the transfer of moisture. Moisture presents a distinct danger to the overall
integrity of a building and must be taken into account. Moisture can and will impact your
building over your head (roof), under your feet (basement/floor), and on your sides
(walls). Each component must be addressed to prevent unwanted transfer from causing
extensive damage. It’s essential in all climates, but cold climates and hot-humid climates
are especially demanding.
2. Air control. Controlling air flow is key to controlling energy consumption, ensuring
indoor air quality, avoiding condensation, and providing comfort. Control of air
movement includes flow through the enclosure or through components of the building
envelope itself, as well as into and out of the interior space. So, for example, when we
talk of a house’s draftiness, we’re talking about the control of air flow.
3. Thermal control. Thermal transfer brings to mind how comfortable we feel inside our
own homes. Is it too hot? Is it too cold? If you want to address this question, it is easiest
to look up. As we learned in elementary school, heat rises, and if you don’t have enough
resistance in the building to prevent heat from rising right through the roof, it is time to
raise your building envelope IQ to prevent heat (and money) from escaping.
Why Do Building Envelope Systems Fail?
When the building envelope system is designed and constructed properly, very few occupants
pay attention. But when the building envelope fails (and even the best-built projects do in time),
everyone notices. Those failures can include aesthetic loss, corrosion, poor indoor air quality,
energy inefficiencies, and, in some cases, life-threatening structural failure and eventual
litigation.
1. Design deficiencies. Architects occasionally specify materials or design systems that are
inappropriate for their intended use. Common mistakes include specifying materials that
are incompatible with materials with which they come into contact or have inadequate
performance criteria for thermal movement, structural capacity, or water penetration
resistance. Issues also arise when subcontractors try to reduce the weight, size, or amount
of building envelope components (aluminum, glass, sealants, flashing, etc.) required on a
project. This can lead to inadequate performance or capacity of the materials specified.
2. Material failure. It’s also common for properly specified materials to fail to meet the
published performance levels. This could be a result of errors in the manufacturing,
handling, or storing of the product or components within the product. Common examples
include degrading sealant adhesion, laminated glass delamination, and metal fatigue.

While the anticipated performance levels are often based upon measured statistical
performance, the strength of materials varies.
3. Poor workmanship. During construction booms, the problem of poor workmanship is
exasperated as a result of having many inexperienced, unsupervised, and untrained
personnel working on projects. It is common to find building envelope components not
installed per the manufacturing specifications. Putting the right people in the right job
goes a long way toward proper installation and overall profitability.
4. Acts of nature. Even with flawless installations, bad things can happen to good work
when environmental conditions exceed those that were anticipated during design. The
effects of hurricane-force wind loads, driving rain, and extreme temperature fluctuations
can overload a properly designed and constructed building envelope, causing damage to
the system and making it vulnerable to further deterioration or failure. While failures of
this type cannot be stopped, many can be prevented through routine inspection and
maintenance to identify small problems before they become big ones.
PASSIVE ENERGY SYSTEM
A passive design uses several techniques, included in the actual structural design and lot layout,
to significantly reduce the amount of energy needed to heat, cool and light a building and also to
reduce the runoff from the site, thus decreasing pollution and increasing infiltration of
precipitation. Passive methods do not require any mechanical or electronic devices, so after the
design is implemented, minimal additional inputs are required. The costs of passive designs are
usually the same as or only slightly higher than conventional designs, making the payback of
these techniques relatively short
Passive design is the control of ventilation and temperature without using any products that
consume energy or money (such as heaters, dehumidifiers or fires). Good passive design
includes:
 House orientation – positioning the house to allow maximum sun in the winter and
coolness in the summer. This includes deciding which rooms you want to be the sunniest.
 Solar energy – using solar panels for water heating, lightening and power.
 Use of shading elements – for example, wide eaves protect from the sun in summer and
provide increased weather protection in winter.
 Placement and glazing of windows – the larger windows should face the sun to capture
the warmth, use glazing to stop heat escaping, and have shading to limit summer
overheating.
 Ventilation – using window joinery that allows ventilation, such as security catches
allowing windows to remain partially open, or vents in the joinery.
 Insulation – to reduce heat loss.

 Thermal Mass – using heavy building materials to store solar energy and limit
overheating during the day but then release energy during the night to provide heating.
Passive design is based on these simple principles:
 using the sun’s energy (solar gain) to heat the home (space heating & water heating),
 using the sun to provide light in the home,
 using very high levels of insulation to retain the heat (i.e. floors, walls, roof, windows,
doors),
 use a compact design to reduce the surface area to volume ratio,
 airtightness - control air flow to reduce heat loss,
 using the heat produced by people and appliances to heat the home,
 use energy efficient appliances,
In practice, a passive house will have most of the following features:
 rectangular in plan, so the sun can shine deep into the house,
 compact (low surface to volume ratio: not necessarily small) design to reduce surface
area,
 positioned on the site so that one of the main facades is facing south,  south facing
facade will have lots of glazing,
 north facing facade will have very little glazing,
 rooms that are used most (e.g. living room, kitchen will be on the south side,
 rooms that used the least (e.g. utility room, toilets, storage) will be on the north side,
 thermal mass (e.g. concrete floor) to absorb and store solar energy (heat),
 very high levels of insulation to retain heat,
 air tight structure to reduce heat loss through draughts,
 controlled ventilation to provide good indoor air quality,
 Solar collectors for water heating etc.
A rectangular building with one of the longer sides facing south and most of the windows on the
southern wall will allow for maximum solar exposure during the winter months, providing both
heat and light. An open floor plan placing the rooms requiring the most light and heat along the
south face of the building optimizes passive system operation. Garages, storage rooms, and other
such spaces can act as thermal buffers when located on the east and west side of a building