Green Building and Sustainable Construction

Introduction

The environment has become one of the
most important matters of discussion not only in the United States but around
the world. Sustainable development is the way of the future. The biggest
challenge will be convincing the industry that it must move in this direction. The
environment’s current fragile state increases the need to conserve as much energy
as possible and implement energy efficient practices into our daily lives becoming
more of an obligation rather than a choice. The percentage of people driving
electric and hybrid cars are increasing and people are becoming excited about
recycling, wanting to make a positive impact on the environment through energy
efficient practices. As the conversation continues to spread about the dire
need to protect the environment, these trends will increase in growth and will
become the standard across the globe. One way to move towards a greener planet
is to start with the houses and buildings we live and work in. Three types of
buildings that provide a healthier and greener atmosphere are Passive House,
LEED and the Net Zero standard of building.

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Passive House

            Passive
House is a metric based building energy standard. The Passive House concept was
created in Germany and is often called by the German spelling, Passivhaus. Passive
house is considered to be a more demanding standard for Green Building. HHHHhHowever, it’s demanding standard
and challenging building concept successfully promotes energy efficiency
(“Green Home Building,” 2017). Concrete, bricks and stone are all basic materials
used in building a Passive house because they can absorb the energy from the
sun fully and gradually. As a result of this absorption an occurrence known as
lag takes place. Lag occurs when the flow of heat slows. When the sun strikes a
surface with high thermal capacity, the exterior surface heats quickly storing
as much heat as possible, once the saturation point is reached, heat will then
flow to the inside of the building. This process can last as long as eight or
nine hours depending on the materials used, but for Passive House constructions
where high thermal masses are used often, such as brick or wooden walls, this occurrence
is certainly going to occur at a high rate (“Thermal Properties,” 2017).
Passive House standard is a construction concept geared towards the use of less
energy for heating and cooling than conventional buildings. While, still being significantly
more comfortable and healthier than traditional buildings, this allows for
energy savings of up to 90% (“Passipedia,” 2017). There are three types of
window glass: one pane and two pane, which are commonly used in normal houses,
and three pane windows, which are used in Passive houses. Three pane windows
are preferred over other windows because they are made from three glass panes,
which are split by air or argon gas. Most importantly the U-value of three pane
windows are lower (with argon = 0.36) than two pane windows (with argon = 0.46)
(“ASHRAE Handbook,” 1993). The lower the U-value, the lower the amount of heat
loss which prevents cold air getting in and decreasing the heat getting out.
Another important aspect that Passive house thrives to achieve is a comfy Indoor
Air Quality (IAQ). This is achieved through a ventilation system by
consistently supplying fresh air without causing any unpleasant droughts,
coupled with a highly efficient heat recovery unit that allows for the heat
contained in the exhaust air to be re-used (“Sustainable Architecture,” 2015,).
There are many advantages of building passively: such as increased thermal
comfort and being eco-friendly so it uses much less electricity, which leads to
less consumption of petroleum products, natural gases, coal and wood. It also
improves indoor air quality, the percentage of energy efficiency and
durability. Despite also having superior sound insulation and being low
maintenance, Passive Houses are very affordable. Since Passive homes do not
require heating and cooling systems, money that would be spent on these components
can instead be spent on better windows, insulation and a high efficiency
ventilation system. In Germany the additional cost associated with building a Passive
House as compared to conventional homes is expected to be between 3 to 8% more,
with this cost varying in different countries where components for building a Passive
House is not available (“Passipedia,” 2017)

LEED – Leadership in Energy and Environmental Design

            Leadership
in Energy and Environmental Design (LEED) is a rating system that was developed
by the United States Green Building Council (USGBC). LEED uses a point system
to evaluate the environmental impact of buildings, homes, and other types of
construction. By utilizing a point system, LEED offers points for environmentally
friendly considerations within the building’s design features and will reward
each consideration with a specific amount of points (“Understanding the
Difference,”2017). Additionally, LEED focuses primarily on the materials used
for the project and how well they contribute to the building being as energy
efficient as possible rather than the final energy performance as with Passive
House and Net Zero.

There are four possible LEED scores a
building can receive: Certified, Silver, Gold, and Platinum. The four scores that
can be achieved are as follows:

Certified: Greater than 40 percent of
the total possible points.

Silver: Greater than 50 percent of
the total possible points.

Gold: Greater than 60 percent of the
total possible points.

Platinum: Greater than 80 of the
total possible points (“Leed Certification,” 2015).

 To accumulate credits a building must have certain
standards that benefit the environment. These consist of five main categories:

1.)    Sustainable sites – This category
focuses on the environment surrounding the building and awarding credits for
projects that emphasize the vital relationships among buildings, ecosystems,
and ecosystem services. It focuses on restoring project site elements,
integrating the site with local and regional ecosystems, and preserving the
biodiversity that natural systems rely on (“USGBC,” 2017).

2.)    Water efficiency –This section
addresses water holistically, looking at indoor use, outdoor use, specialized
uses, and metering. The section is based on an “efficiency first” approach
to water conservation (“USGBC,” 2017).

3.)    Energy and atmosphere – This category
approaches energy from a holistic perspective, addressing energy use reduction,
energy-efficient design strategies, and renewable energy sources (“USGBC,”
2017).

4.)    Materials and resources – This
category focuses on minimizing the embodied energy and other impacts associated
with the extraction, processing, transport, maintenance, and disposal of
building materials. The requirements are designed to support a life-cycle
approach that improves performance and promotes resource efficiency (“USGBC,”
2017).

5.)    Indoor environmental quality – This
category rewards decisions made by project teams about indoor air quality and
thermal, visual, and acoustic comfort. Green buildings with good indoor
environmental quality protect the health and comfort of building occupants
(“USGBC,” 2017).

A blower door test is conducted on
each building applying for LEED certification to access the tightness of the
building’s envelope along with a duct blaster test to evaluate the duct
sealing. Additional testing is carried out to generate a Home Energy Ratings Standards
(HERS) index score. The HERS index is a scoring system similar to LEED with a
baseline of 100 which is a standard value based on the 2006 International
Energy Conservation Code. Each point achieved below this baseline constitutes a
1% improvement in efficiency (“LEED Certification,” 2015). Initially to
accomplish a LEED certified project, it is an expensive venture compared to an
average building. For new buildings under 50,000 sq. ft. the minimum cost of
LEED certification is $2,900 and for a new building over 500,000 sq. ft. the certification
fees can start from $20,000 (Vamosi, 2011). However, there are many beneficial
factors that would encourage people to pursue a LEED certified project: tax
benefits, utility savings, and the real estate value is increased for LEED
certified buildings.

Net Zero Building Standard

Net zero energy buildings are highly energy-efficient and are designed
to use, over a period of a year, renewable energy generation to consume only as
much energy as can be produced onsite through renewable energy resources. The
International Living Future Institute (ILFI) provides a certification option
for a Net Zero building (NZEB) under its umbrella of the holistic Living
Building Challenge (LBC) certification. The Department of Energy (DOE) and the
National Renewable Energy Laboratory (NREL) have also spearheaded much of the
work on net zero energy buildings to date.  Utilizing energy efficient
products along with a sustainable infrastructure is the underlying goal of this
type of Green Building concept, ultimately minimizing the amount of energy used. Solar
energy is critical and most important in these types of green structures as solar
energy will be used to produce the majority of the energy used by these
buildings. The National Renewable Energy Laboratory (NREL) presents several
definitions for “net zero energy”, and they encourage building
designers, owners, and operators to select the metric that best fits their
project. It suggests four ways in which net zero energy may be defined:

1.)    Net Zero
Site Energy – Site Energy refers to the energy consumed and generated at a
site regardless of where or how the energy originated. In a net zero site
energy building, for every unit of energy the building consumes over a year, it
must generate a unit of energy (“Net Zero Energy Buildings,” 2017).

2.)    Net Zero
Source Energy – Source Energy refers to primary energy needed to extract
and deliver energy to a site, including the energy that may be lost or wasted
in the process of generation, transmission and distribution (“Net Zero Energy
Buildings,” 2017)

3.)    Net Zero
Energy Costs – It means that the building has an energy utility bill of $0 over
the course of a year. In some cases, building owners or operators may take
advantage of selling Renewable Energy Credits (RECs) from on-site renewable
generation. (“Net Zero Energy Buildings,” 2017).

4.)    Net Zero
Energy Emissions – Many conventional energy sources result in emissions of
carbon dioxide, nitrogen oxides, sulfur dioxide, etc. A Net Zero Energy
Emissions building either uses no energy which results in emissions or
offsets the emissions by exporting emissions-free energy (typically from on-site
renewable energy systems) (“Net Zero Energy Buildings,” 2017).

Most Net
Zero Energy structures are still connected into the electric grid just in case,
which allows for the electricity produced from energy sources such as natural
gas, electric, etc. to be used when renewable energy generation cannot meet the
building’s energy load. When, conversely, on site energy generation exceeds the
building’s energy requirements, the surplus energy should be exported back to
the utility grid. When this excess of energy generation occurs, this offsets
the periods of excess demand, resulting in a net energy consumption of zero (“Steven
Winter Associates,” 2016). The key to designing net zero energy buildings is
first reducing energy demand as much as possible, and then choosing good energy
sources. A simple order of operations is to: 1.) Reduce energy loads 2.)
Optimize design for passive strategies 3.) Optimize design of active systems
4.) Recover energy 5.) Generate energy on-site 6.) Buy energy/carbon offsets (“Net Zero Energy Buildings,”2017). By producing as much energy as is consumed
these structures are extremely economical and will cut energy usage down far
beyond the energy usage of a normal home. Therefore, there is an abundance of potential
to save money as well as have a positive impact on the environment.

Similarities and
Differences

As with
most things there are fundamental differences that distinguish similarities and
differences between them. For instance a Passive house focuses on achieving the
absolute minimum amount of energy use required to heat and cool a building
whereas a net zero building is designed to generate as much energy as it uses
in a year. The Net Zero Building concept differs from LEED which conducts an
assessment by “measuring the amount of renewable energy overtime rather than
giving points to systems that may work, but in the long run will not provide
the same amount of energy savings overtime” (“Understanding the Difference,”2017). However, combining these standards together can produce excellent
results. As an example the Center
for Energy Efficient Design (CEED) designed and built in 2010, received
both Passivhaus and LEED certification (Cohen, n.d.) This combination
demonstrates a perfect harmony by utilizing Passivhaus to gain in certification
level and will also assure the owner of a durable, long term reduction of both
energy and maintenance costs.

Conclusion

            Green
building is a socially, economically, and most importantly environmentally
responsible idea that more persons need to adopt.  The United States Green Building Council
developed LEED along with other standards of energy efficient building design
like the Passive House Standard and the Net Zero Building standard in order to
help the construction industry build as energy efficient buildings as possible
while minimally impacting the environment (“Leed Certification,” 2015). This goes a long way in reducing energy cost and conserving natural
resources.  Through education and making
environmentally sound products more readily accessible, and by providing
government incentives it is possible to encourage more persons to adopt green
building and all of the benefits that come along with it.

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