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Zero-carbon housing is a term used to describe a house that does not release carbon dioxide (CO₂) into the atmosphere. Homes release CO₂ through burning fossil fuels in order to provide heating or while cooking on a gas stove. A zero carbon house can be achieved by either building or renovating a home to be very energy efficient and for its energy consumption to be purely electric.

According to a 2020 UN report, building and construction are responsible for ~38% of all energy-related carbon emissions.^[1] For this reason, the building industry is pushing to find alternative means and methods to reduce the amount of emissions that are associated with both the construction process and the day to day operations to maintain the building.

Definitions

Zero carbon housing:

A home that is designed and implemented in such a way that it does not release any additional carbon emissions into the atmosphere by sustaining itself with clean energy. This means that the energy the house consumes is purely electric.

Zero energy housing:

A home that is designed and built to produce enough of its own renewable energy to sustain itself without needing to rely on the grid. This is different from zero carbon housing because its goal is to produce 100% of its own clean energy.^[2]

Passive house:

A home that focuses of high insulation with an airtight building envelope. High levels of insulation mean the house is able to use less energy for heating and cooling depending on the climate it is in.^[3]

Active house:

A home that focuses on the health and comfort of the occupants. This focus is present in the increased natural lighting and ventilation the house is designed for.^[3]

Goals of Zero Carbon Housing

There are a two main goals to strive for in creating zero carbon homes:

The first goal is to create a passive house which is remarkably well insulated and nearly completely airtight.^[4]
- In constructing a new home, this means windows are placed strategically such that they absorb the heat from sunlight in the winter yet also minimize its heat in the summer.^[4]
- For renovation of existing homes, this requires the building envelop to be upgraded. Caulking areas around the house which are stationary, and weatherstripping areas that move will achieve the airtightness necessary to reduce drafts.^[5]
The second goal is to have no natural gas lines leading into the home and that it gets its energy entirely from electricity or other renewable resources. Electricity generation is continuing to become cleaner as we are finding more ways to utilize renewable resources and transition away from coal and fossil fuels.^[4]

After implementing the methodology of a passive house in addition to being completely shut off to natural gas lines, the house can continue to be improved with various design considerations.

Design Considerations for Zero Carbon Housing

Creating an effective zero carbon house involves multiple levels of consideration stemming from the people who chose to build and/or remodel their home, to the design team in charge of developing the proper design strategies, to the contractors who construct and implement them. It is ultimately a team effort from each contributor to work together to provide the best, most efficient zero carbon house. A few design considerations that can be implemented are outlined below. It is important to note that this is not an exhaustive list but just a few of the most common in practice. These considerations include the orientation of the building itself, incorporating elements such as smart windows, heat pumps, and solar panels, and finally but most importantly installing energy efficient appliances.

Orientation of House

As mentioned above, one main goal of a zero carbon house is to create a passive house. When building a new home, it is very important for the design team to account for orientation of the house in relation to the sun. Sunlight will directly and indirectly effect the heating and cooling of a house based on its orientation, and placement of windows. In the northern hemisphere, the south facing walls come in contact with the sun the most and for the majority of the day time. This wall becomes the most important wall to design to take advantage of when considering a passive solar design. Sunlight will hit the south facing wall and transfer its thermal energy into heat with either direct gain or indirect gain.^[6] Direct gain wall design means that the sunlight enters the house through windows placed along the southern walls and hits the floors and/or other walls. Since windows are made primarily of glass, they have a low thermal conductivity. When the sunlight passes through with its high thermal energy it cannot easily escape due to the glass’s low conductivity and its thermal energy is transferred into heat.^[7] This phenomenon is known as the greenhouse effect. As a result, the house is heated from direct sunlight penetrating through the windows.

Indirect gain wall design uses a Trombe Wall along the southern wall to store thermal energy which can slowly heat up the house.^[6] A Trombe Wall consists of a masonry wall along the southern wall perimeter with a single of double layer of glass along its exterior and about a one inch gap in between the two.^[8] The masonry wall needs to be dark colored to better absorb the sun’s thermal energy and the exterior glass layer creates a greenhouse effect to trap the heat continuously heating up the masonry wall. Over time, the heat in the wall is transferred into the house and will continue warming up the house into the night after the sun has gone down.^[6] This design works well in the northern hemisphere far from the equator because the sun’s position in the sky relative to the house changes. In the winter, the sun is much lower in the sky so it will shine against a larger area of the wall which traps more thermal energy and results in more heat gain inside with less need to use electricity to heat the home. In the summer, the sun is higher in the sky so it can be easier to block the sunlight from hitting the southern wall which doesn’t transfer as much thermal energy meaning it will not heat up as much.^[9]

Both direct and indirect gain take advantage of the sun’s thermal energy to heat up the house in the cold wintery months and through passive solar design ensure that the house does not absorb too much of it during the hot summer months.

Smart Windows

Windows are a huge element in a home. They are great for the occupant to feel connected to the outside environment and allow lots of additional light inside. This is beneficial because the additional lighting provided from the sun means the homes lights do not need to be on as much and can save the homeowner in electricity bills. However, the more sunlight also can cause more heating of the house. Therefore, with additional light comes with additional heat. In the cold winter months, this can actually help the home by providing additional heat so the homeowner can save on heating costs, but in the hot summer months, this can add unwanted additional heat and have an unintended consequence of needing to use more energy to cool the home down.

The use of smart windows in homes can greatly impact the temperature inside by taking advantage of sunlight so that ultimately less energy is used to both heat and cool the building. Approximately 35% of a typical building’s energy is lost through its windows.^[10] There are two types of smart windows that are primarily used to control the temperature on the inside of homes: electrochromic and thermochromic.^[10] Electrochromic glass has been widely used in smart windows. An electrochromic window is able to alter the ability of light and heat to pass through the glass through the use of electrical current. These windows comprise of five layers: two glass layers on the exterior, two layers that serve as electrodes which act as the positive and negative poles in a battery, and a middle electrolyte layer containing ions. When voltage is applied to the window, positively charged ions develop on one side of the window while negatively charged ones move to the other side. This reaction creates a tint to the window which will stay until voltage is again applied to cause a reverse reaction. Electrochromic windows allow the homeowner to decide when they want to allow more sunlight in or block it which gives them more of a sense of control over the amount of energy they use for heating and cooling.^[10] On the other hand, thermochromic windows are windows that change in response to heat. These windows are comprised of less layers than electrochromic windows, typically two layers of glass, with an inner layer of a thermochromic laminate. The thermochromic laminate can be made of various different materials which are temperature responsive and can cause the glass to tint when it reaches high enough temperatures to block heat out, or become more transparent when cool enough to let more light and heat in. Each material has its own threshold temperature where this transition can occur.^[10] Therefore depending on the climate a different smart window could be desired over others.

Heat Pumps

A heat pump can be used in a home as an alternate heating and cooling system in comparison to furnaces and air conditioners. They run on electricity and use the same thermodynamic principles as refrigerators to transfer heat from a cool space to a warm space.^[11] The three types of heat pumps that can be used to heat or cool homes are air-to-air, water source, and geothermal. Each type collects heat from either the air, water, or the ground respectively from outside the house and the heat pump concentrates it for use inside. Heat pumps are such an energy efficient alternative because they do not generate heat like a furnace. Instead, they transfer heat from one source to the other. The heat pump absorbs energy from the outside air and transfer it inside, heating the home up. Additionally, when turned to cooling mode, they act as air conditioners and absorb heat from inside, transferring it outside to cool the home down.^[11]

Air source heat pumps are most commonly used in residential housing. They are so energy efficient that they can reduce electricity bills by about 50%.^[11] Air sourced heat pumps have advanced so much in recent years that they are even suitable for extreme cold weather conditions to provide heat inside the home.

Solar Panels

Solar panels are one of the best ways a home can generate its own electricity. The two main technologies used to harness the suns energy and transfer it into electricity are photovoltaics (PV) and concentrating solar power (CSP). PV are the panels that can be seen on rooftops of residential homes and buildings or even out in fields. They capture the photons from the sunlight and the panels absorb them to create an electric field across its many layers which in turn creates electricity.^[12] CSP is used in very large power plants and therefore is not suitable for residential use.

At times, solar panel systems are able to produce more energy than the house needs and when this happens, some systems feed into batteries which can store the surplus of electricity. Other systems can wire directly into the home’s grid and allows the homeowner to back feed its excess electricity to the utility company. When this happens, the utility company will often pay the homeowner for the amount of electricity they give back.^[13]

Energy Efficient Appliances

Energy efficient appliances are appliances that are designed and implemented to use less energy compared to their normal everyday household appliance yet provide the same service. Installing energy efficient appliances is one of the easiest ways to reduce energy consumption because after installation, they don’t require the occupant to consciously think about the amount of energy they will expend by turning them on; the appliance simply uses less energy due to the way it was designed.

The United States government has set a certain standard of energy efficiency and created the program Energy Star which provides certifications to consumer products that meet these standards.^[14] Energy Star provides a certified label on products they deem energy efficient and also compiles a list of these appliances, making it easy for the consumer to purchase. Energy Star certified residential homes are at the least 10% and on average 20% more energy efficient compared to homes built to standard code.^[14]

Urbanization

Urbanized and more densely populated communities produce fewer carbon emissions per capita in comparison to suburban or rural communities. While part of this is because in urban settings, people typically are driving less due to the proximity of goods and services, another important factor is that densely populated housing means better insulation because of shared walls and floors and ceilings. With less walls exposed to the outside extreme weathers and more walls being shared, the inside environment is able to remain and maintain more steady temperatures without needing as much cooling or heating.^[15]

Benefits of Zero Carbon Housing

Three important benefits to switching to a zero carbon house involve health, economic, and environmental benefits.

Health

Zero carbon houses offer much cleaner indoor air because they curb fossil fuel combustion which releases volatile gases and pollutants. Appliances such as gas stove, heaters, dryers, and ovens that rely on burning fuel inside the home worsen the air quality indoors and can lead to respiratory issues for the occupants. Not only is the indoor air quality affected, but so is outdoor air quality. Pollution from residential buildings is noted to be responsible for about 15,500 deaths per year in the United States alone.^[16] Replacing appliances that run on fossil fuels can improve indoor air quality and reduce asthma symptoms in children by up to 42%, as well as decrease fire hazards in homes.^[16]

Money

As previously mentioned, energy efficient homes can save the occupant on their utility bills by both replacing their appliances with energy efficient appliances as well as updating their insulation and building envelop. For every $1 invested in improvements towards creating a zero carbon home, approximately $2 are saved in electricity generation and utility costs.^[16]

Climate Change

The most important benefit of zero carbon housing is the reduction in greenhouse gas emissions that are contributing to climate change. Since residential buildings and houses are a major source of greenhouse gas emissions, cities cannot achieve their climate targets without optimizing their energy efficiency.^[17] By reducing the amount of energy houses use and by cleaning up the energy they do use, zero carbon housing can significantly reduce these emissions into the atmosphere to meet the carbon neutral standards many nations are setting.

Challenges associated with Zero Carbon Housing

While all the above examples of how to build and/or renovate a zero carbon house sound great, there are some challenges that come with switching to carbon free. A top concern for most people is the economic factor. On average, zero carbon houses can cost 5% to 15% more than a similar sized regular home.^[4] When seeing this initial increase in price, homeowners often feel discouraged and that the home will not be a good investment. However, looking at the first cost of the home alone without factoring in how much savings the energy efficient home will have is a crucial mistake. When applying the correct design strategies to create a passive, energy efficient home that can generate a significant portion of its own electricity while also being completely carbon neutral, zero carbon homes can end up saving the home homeowner money in the long run.^[4]

However, once a homeowner has invested in a zero carbon house which is completely run on electricity, both self-producing and grid dependent, there arises the issue of electrical grid power outages. While there are measures the design team has taken to help the house generate its own electricity, that does not always mean it can generate enough electricity to sustain normal household activities whereas gas powered stoves would otherwise be able to function. In this instance, it is arguable that the zero carbon house would be preferable to a normal house because while normal household activities are minimized in a power outage, there is still the backup of electricity generated from renewable sources the house has provided as well as the passive design which means the house is well insulated and has measures such direct and indirect gain to help heat it. There additionally are instances where a house is located in an area where solar power is not the most efficient means of electricity generation due to the lack of sunlight available. In this case, the design team will assess whether solar is a good option or if other renewable sources of energy are more suitable.

Finally, a big challenge in the building construction industry is embodied carbon. While the term zero carbon housing insinuates that the house is carbon free, it does not account for the fact that there are carbon emissions associated with the construction of the home, nor the carbon emitted from the materials needed to build it, nor from their transportation from source to site. In fact it is estimated that embodied carbon from new construction will be responsible for nearly half of carbon emissions between now and 2050.^[18] This is a huge consequence that new construction presents which will need to be addressed.

Success with Zero Carbon Housing

There are several examples around the world of individual houses and even communities which have been built to be zero carbon houses and demonstrate that it is possible to live in an energy efficient home that reduces its energy consumption and its greenhouse gas emissions while also providing the occupants with the same functional lifestyle they require. One such community in particular, The Lochiel Park Green Village in South Australia, has proven that with the help of government policy and an ingenious design team, zero carbon housing is possible and practical. The design considerations that the design team implemented increase energy efficiency include solar water heating, a photovoltaic system for each house, high energy star rated appliances, and low energy lighting.^[19] In order to collect data to demonstrate that Lochiel Park was more energy efficient than a similar community of size and climate, appliance and equipment audits were performed, as well as continued energy use and generation monitoring.

As a result of the conducted study, it was concluded that compared to the average of South Australian residential homes, Lochiel Park households used significantly less energy per year per unit floor area. In fact, Lochiel Park homes are so energy efficient that when comparing them to the average of South Australia, the average total annual energy per household consumed less than half the amount of energy.^[19] Not only that but when considering the amount of energy that was delivered to Lochiel Park homes, meaning the total energy consumed minus the amount of energy the homes generated themselves independent of the grid, Lochiel Park was delivered less than a third the amount of energy as the South Australia average.^[19] This is a significant amount in energy reduction which can be attributed to the innovative design team which incorporated a combination of energy efficient technologies and self-sustaining renewable energy electricity generation.

References

^ "Buildings-related carbon dioxide emissions hit record high: UN". phys.org. Retrieved 22 May 2021.
^ "Zero Energy Buildings Resource Hub". Energy.gov. Retrieved 2022-12-15.
^ ^a ^b Saul (2021-11-23). "Passive Homes vs Active Homes". Messana Radiant Cooling. Retrieved 2022-12-15.
^ ^a ^b ^c ^d ^e Roberts, Tobias (2020-06-02). "Zero-Carbon Home: What Is It?". Rise. Retrieved 2022-12-15.
^ "Air Sealing Your Home". Energy.gov. Retrieved 2022-12-15.
^ ^a ^b ^c "Passive Solar Home Design". Energy.gov. Retrieved 2022-12-16.
^ Lu, Shunyao; Li, Zhengrong; Zhao, Qun (2015-01-01). "Thermal Process of Windows in Hot Summer and Cold Winter Climate". Procedia Engineering. 121: 1788–1794. doi:10.1016/j.proeng.2015.09.158. ISSN 1877-7058.
^ "Trombe Walls - an overview | ScienceDirect Topics". www.sciencedirect.com. Retrieved 2022-12-16.
^ "Movement of the Sun | Green Passive Solar Magazine". greenpassivesolar.com. 2010-04-19. Retrieved 2022-12-16.
^ ^a ^b ^c ^d Miller, Brittney J. (2022-06-08). "How smart windows save energy". Knowable Magazine | Annual Reviews. doi:10.1146/knowable-060822-3.
^ ^a ^b ^c "Heat Pump Systems". Energy.gov. Retrieved 2022-12-16.
^ "How Does Solar Work?". Energy.gov. Retrieved 2022-12-16.
^ Scalisi, Tom (2022-11-07). "Are Solar Panels Worth It?". Forbes Home. Retrieved 2022-12-16.
^ ^a ^b "What is ENERGY STAR". www.energystar.gov. Retrieved 2022-12-16.
^ Said, Evana; Rajpurohit, Sujata (2022-09-23). "The Health, Economic and Community Benefits of Zero-carbon Buildings". {{cite journal}}: Cite journal requires |journal= (help)
^ ^a ^b ^c Said, Evana; Rajpurohit, Sujata (2022-09-23). "The Health, Economic and Community Benefits of Zero-carbon Buildings". {{cite journal}}: Cite journal requires |journal= (help)
^ "Why transitioning to zero-carbon buildings is a vital, urgent and rewarding investment for cities". www.c40knowledgehub.org. Retrieved 2022-12-15.
^ Alter, Lloyd. "Architecture 2030 Goes After Embodied Carbon and This Is a Very Big Deal". Treehugger. Retrieved 2022-12-15.
^ ^a ^b ^c Berry, Stephen; Whaley, David; Davidson, Kathryn; Saman, Wasim (2014-07-01). "Do the numbers stack up? Lessons from a zero carbon housing estate". Renewable Energy. Renewable Energy for Sustainable Development and Decarbonisation. 67: 80–89. doi:10.1016/j.renene.2013.11.031. ISSN 0960-1481.

[1] "Buildings-related carbon dioxide emissions hit record high: UN". phys.org. Retrieved 22 May 2021.

[2] "Zero Energy Buildings Resource Hub". Energy.gov. Retrieved 2022-12-15.

[:0-3] Saul (2021-11-23). "Passive Homes vs Active Homes". Messana Radiant Cooling. Retrieved 2022-12-15.

[:1-4] Roberts, Tobias (2020-06-02). "Zero-Carbon Home: What Is It?". Rise. Retrieved 2022-12-15.

[5] "Air Sealing Your Home". Energy.gov. Retrieved 2022-12-15.

[:3-6] "Passive Solar Home Design". Energy.gov. Retrieved 2022-12-16.

[7] Lu, Shunyao; Li, Zhengrong; Zhao, Qun (2015-01-01). "Thermal Process of Windows in Hot Summer and Cold Winter Climate". Procedia Engineering. 121: 1788–1794. doi:10.1016/j.proeng.2015.09.158. ISSN 1877-7058.

[8] "Trombe Walls - an overview | ScienceDirect Topics". www.sciencedirect.com. Retrieved 2022-12-16.

[9] "Movement of the Sun | Green Passive Solar Magazine". greenpassivesolar.com. 2010-04-19. Retrieved 2022-12-16.

[:4-10] Miller, Brittney J. (2022-06-08). "How smart windows save energy". Knowable Magazine | Annual Reviews. doi:10.1146/knowable-060822-3.

[:5-11] "Heat Pump Systems". Energy.gov. Retrieved 2022-12-16.

[12] "How Does Solar Work?". Energy.gov. Retrieved 2022-12-16.

[13] Scalisi, Tom (2022-11-07). "Are Solar Panels Worth It?". Forbes Home. Retrieved 2022-12-16.

[:6-14] "What is ENERGY STAR". www.energystar.gov. Retrieved 2022-12-16.

[15] Said, Evana; Rajpurohit, Sujata (2022-09-23). "The Health, Economic and Community Benefits of Zero-carbon Buildings". {{cite journal}}: Cite journal requires |journal= (help)

[:2-16] Said, Evana; Rajpurohit, Sujata (2022-09-23). "The Health, Economic and Community Benefits of Zero-carbon Buildings". {{cite journal}}: Cite journal requires |journal= (help)

[17] "Why transitioning to zero-carbon buildings is a vital, urgent and rewarding investment for cities". www.c40knowledgehub.org. Retrieved 2022-12-15.

[18] Alter, Lloyd. "Architecture 2030 Goes After Embodied Carbon and This Is a Very Big Deal". Treehugger. Retrieved 2022-12-15.

[:7-19] Berry, Stephen; Whaley, David; Davidson, Kathryn; Saman, Wasim (2014-07-01). "Do the numbers stack up? Lessons from a zero carbon housing estate". Renewable Energy. Renewable Energy for Sustainable Development and Decarbonisation. 67: 80–89. doi:10.1016/j.renene.2013.11.031. ISSN 0960-1481.

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@@ Line 1: / Line 1: @@
 {{essay|date=January 2012}}
+'''Zero-carbon housing''' is a term used to describe a house that does not release [[carbon dioxide]] (CO<sub>2</sub>) into the [[atmosphere]]. Homes release CO<sub>2</sub> through burning [[Fossil fuel|fossil fuels]] in order to provide heating or while cooking on a [[gas stove]]. A zero carbon house can be achieved by either building or renovating a home to be very energy efficient and for its energy consumption to be purely electric.
-'''Zero-carbon housing''' and '''zero-energy housing''' are terms used interchangeably to define [[Single-family detached home|single family dwellings]] with a very high [[Efficient energy use|energy efficiency]] rating.  Zero-energy housing requires a very low amount of energy to conduct the daily activities performed by the occupying family.<ref>"Energy Performance of Buildings Directive", Zero Carbon Hub, April 2011, [https://web.archive.org/web/20120426053918/http://www.nhbcfoundation.org/LinkClick.aspx?fileticket=vuga43X50g0=&tabid=458&mid=848] Retrieved 2011-12-14</ref>
+According to a 2020 UN report, [[Greenhouse gas emissions#Buildings and construction|building and construction]] are responsible for ~38% of all energy-related [[carbon emission]]s.<ref>{{cite news |title=Buildings-related carbon dioxide emissions hit record high: UN |language=en |work=phys.org |url=https://phys.org/news/2020-12-buildings-related-carbon-dioxide-emissions-high.html |access-date=22 May 2021}}</ref> For this reason, the building industry is pushing to find alternative means and methods to reduce the amount of emissions that are associated with both the construction process and the day to day operations to maintain the building.
-The term [[carbon footprint]], at present, does not have a concrete and universal definition. Thomas Wiedmann proposed a well received and generally accepted definition that defines carbon footprint as a measure of the total amount of carbon dioxide emissions directly and indirectly caused by an activity or accumulated over the life stages of a product. A carbon footprint can be divided into 4 levels: personal, product, organizational, and country.<ref>{{cite journal |last1=Gao |first1=Gao |last2=Qing Liu |first2=Liu |last3=Jianping |first3=Wang |title=A comparative study of carbon footprint and assessment standards |journal=International Journal of Low-Carbon Technologies |date=1 September 2014 |volume=9 |issue=3 |pages=237–243 |doi=10.1093/ijlct/ctt041 |doi-access=free }}</ref> A personal carbon footprint is a measure of [[greenhouse gas emissions]] that are a result of daily life. Examples of contributors to personal carbon footprint are clothing, food, housing, and traffic. The emissions from the entire life of a product, extraction of raw materials and manufacturing, and recycling or disposal contribute to product carbon footprint. Greenhouse gas emissions from energy used in buildings, industrial processes, and company vehicles account for organizational carbon footprints. An entire country collectively generates a carbon footprint from carbon dioxide emissions generated by the consumption of materials and energy, vegetations and other carbon sequestrations, as well as the indirect and direct emissions caused by import and export activities.<ref>{{cite journal |last1=Gao |first1=Gao |last2=Qing Liu |first2=Liu |last3=Jianping |first3=Wang |title=A comparative study of carbon footprint and assessment standards |journal=International Journal of Low-Carbon Technologies |date=1 September 2014 |volume=9 |issue=3 |pages=237–243 |doi=10.1093/ijlct/ctt041 |doi-access=free }}</ref> Zero carbon housing is a result of the building sector being one of the largest contributors to greenhouse gas emissions in urban areas.<ref>{{cite journal |last1=Wei |first1=Huang |last2=Fei |first2=Li |last3=Sheng-hui |first3=Cui |last4=Fei |first4=Li |last5=Leizen |first5=Huang |last6=Jian-yi |first6=Len |title=Carbon Footprint and Carbon Emission Reduction of Urban Buildings: A Case in Xiamen City, China |journal=Procedia Engineering |date=2017 |volume=198 |pages=1007–1017 |doi=10.1016/j.proeng.2017.07.146 |doi-access=free }}</ref>
-The calculation of the carbon footprint becomes detailed when considering secondary factors.  Secondary factors involve the home's occupant lifestyle such as diet, foods are consumed (example organic vs. non organic), frequency of yearly air travel, commuting mileage to and from work, school, etc., use of public transportation, and number, type, and use of private vehicles. Secondary factors also include fashion or type of clothes purchased and worn, frequency of [[recycling]], recreational activities and use of financial and other services throughout a given year. The frequency of [[airline]] flights in a year is considered due to the amount of fuel consumption and other energy usage and emissions generated by one flight. A person that travels frequently may have a significantly bigger carbon footprint than someone who flies once a year for a vacation.<ref>"Carbon Footprint Calculator", Carbon Footprint, [http://www.carbonfootprint.com/calculator.aspx] {{Webarchive|url=https://web.archive.org/web/20111216164306/http://www.carbonfootprint.com/calculator.aspx|date=2011-12-16}} Retrieved 2011-12-15</ref> The emissions for an individual flight are calculated by using the greater circle method. First, the distance between [[airport]]s is determined. Then calculations are completed to account for indirect distances and by an emissions factor in relation to the type of flight (international or a short flight, and what class seating the person is in).<ref>"Help and Information for the Carbon Footprint Calculators", Carbon Footprint, [http://www.carbonfootprint.com/calculatorfaqs.html] {{Webarchive|url=https://web.archive.org/web/20120101160315/http://www.carbonfootprint.com/calculatorfaqs.html|date=2012-01-01}} Retrieved 2011-12-15</ref> Another contributing factor to a person's carbon footprint is their personal vehicle which includes the type of car driven, the efficiency or [[miles per gallon]] (MPG) rating, and the number of miles driven each year.  The frequency of public transportation used by an individual, miles traveled on public transportation and the type of public transportation used such as bus, train, or subway contributes to their carbon footprint as well. Other factors, as trivial as they might seem, are included in the calculation of a person's carbon foot print to include things such as the type of diet.  A vegetarian compared to a person that eats a lot of [[red meat]] will have a lower carbon footprint. All factors being the same except diet, a [[vegetarian]] secondary carbon footprint averages three metric tonnes of CO<sub>2</sub>, one tonne less than the individual who consumes meat.<ref>Carbon Footprint Calculator", Carbon Footprint, [http://www.carbonfootprint.com/calculator.aspx] {{Webarchive|url=https://web.archive.org/web/20111216164306/http://www.carbonfootprint.com/calculator.aspx|date=2011-12-16}} Retrieved 2011-12-15</ref> Other factors include the purchase of local and /or organically grown produce vs. imported items, the latest clothes fashions vs. more conventional purchases, buying individually packaged products vs. buying in bulk, recycling activities, and the types of recreation such as carbon-free activities like hiking and cycling or [[emission intensity|carbon-intensive]] activities like [[skydiving]] or [[boating]].
 == Definitions ==
@@ Line 36: / Line 34: @@
 Creating an effective zero carbon house involves multiple levels of consideration stemming from the people who chose to build and/or remodel their home, to the design team in charge of developing the proper design strategies, to the [[General contractor|contractors]] who construct and implement them. It is ultimately a team effort from each contributor to work together to provide the best, most efficient zero carbon house. A few design considerations that can be implemented are outlined below. It is important to note that this is not an exhaustive list but just a few of the most common in practice. These considerations include the orientation of the building itself, incorporating elements such as smart windows, [[Heat pump|heat pumps]], and [[Solar panel|solar panels]], and finally but most importantly installing energy efficient appliances.
-== Benefits of Zero Carbon Housing ==
+=== Orientation of House ===
+As mentioned above, one main goal of a zero carbon house is to create a passive house. When building a new home, it is very important for the design team to account for orientation of the house in relation to the sun. Sunlight will directly and indirectly effect the heating and cooling of a house based on its orientation, and placement of windows. In the [[Northern Hemisphere|northern hemisphere]], the south facing walls come in contact with the sun the most and for the majority of the day time. This wall becomes the most important wall to design to take advantage of when considering a passive solar design. Sunlight will hit the south facing wall and transfer its thermal energy into heat with either direct gain or indirect gain.<ref name=":3">{{Cite web |title=Passive Solar Home Design |url=https://www.energy.gov/energysaver/passive-solar-home-design |access-date=2022-12-16 |website=Energy.gov |language=en}}</ref> Direct gain wall design means that the sunlight enters the house through windows placed along the southern walls and hits the floors and/or other walls. Since windows are made primarily of glass, they have a low [[thermal conductivity]]. When the sunlight passes through with its high [[thermal energy]] it cannot easily escape due to the glass’s low conductivity and its thermal energy is transferred into heat.<ref>{{Cite journal |last=Lu |first=Shunyao |last2=Li |first2=Zhengrong |last3=Zhao |first3=Qun |date=2015-01-01 |title=Thermal Process of Windows in Hot Summer and Cold Winter Climate |url=https://www.sciencedirect.com/science/article/pii/S1877705815029860 |journal=Procedia Engineering |language=en |volume=121 |pages=1788–1794 |doi=10.1016/j.proeng.2015.09.158 |issn=1877-7058}}</ref> This phenomenon is known as the [[greenhouse effect]]. As a result, the house is heated from direct sunlight penetrating through the windows.
-Three important benefits to switching to a zero carbon house involve health, [[Economy|economic]], and environmental benefits.
+[[File:Day time.jpg|thumb|Trombe Wall during the day.]]
+[[File:Trombe Wall-Night time.jpg|thumb|Trombe Wall at night.]]
+Indirect gain wall design uses a [[Trombe wall|Trombe Wall]] along the southern wall to store thermal energy which can slowly heat up the house.<ref name=":3" /> A Trombe Wall consists of a [[masonry]] wall along the southern wall perimeter with a single of double layer of glass along its exterior and about a one inch gap in between the two.<ref>{{Cite web |title=Trombe Walls - an overview {{!}} ScienceDirect Topics |url=https://www.sciencedirect.com/topics/earth-and-planetary-sciences/trombe-walls |access-date=2022-12-16 |website=www.sciencedirect.com}}</ref> The masonry wall needs to be dark colored to better absorb the sun’s thermal energy and the exterior glass layer creates a greenhouse effect to trap the heat continuously heating up the masonry wall. Over time, the heat in the wall is transferred into the house and will continue warming up the house into the night after the sun has gone down.<ref name=":3" /> This design works well in the northern hemisphere far from the [[equator]] because the sun’s position in the sky relative to the house changes. In the winter, the sun is much lower in the sky so it will shine against a larger area of the wall which traps more thermal energy and results in more heat gain inside with less need to use electricity to heat the home. In the summer, the sun is higher in the sky so it can be easier to block the sunlight from hitting the southern wall which doesn’t transfer as much thermal energy meaning it will not heat up as much.<ref>{{Cite web |date=2010-04-19 |title=Movement of the Sun {{!}} Green Passive Solar Magazine |url=https://greenpassivesolar.com/passive-solar/scientific-principles/movement-of-the-sun/ |access-date=2022-12-16 |website=greenpassivesolar.com |language=en-US}}</ref>
+Both direct and indirect gain take advantage of the sun’s thermal energy to heat up the house in the cold wintery months and through [[Passive solar building design|passive solar]] design ensure that the house does not absorb too much of it during the hot summer months.
-'''Health:'''
+=== Smart Windows ===
-* Zero carbon houses offer much cleaner [[Indoor air quality|indoor air]] because they curb fossil fuel [[combustion]] which releases [[Volatiles|volatile gases]] and [[Pollutant|pollutants]]. Appliances such as gas stove, heaters, dryers, and ovens that rely on burning fuel inside the home worsen the air quality indoors and can lead to respiratory issues for the occupants. Not only is the indoor air quality affected, but so is outdoor air quality. Pollution from [[Residential area|residential buildings]] is noted to be responsible for about 15,500 deaths per year in the United States alone.<ref name=":2">{{Cite journal |last=Said |first=Evana |last2=Rajpurohit |first2=Sujata |date=2022-09-23 |title=The Health, Economic and Community Benefits of Zero-carbon Buildings |url=https://www.wri.org/insights/health-economic-and-community-benefits-zero-carbon-buildings |language=en}}</ref> Replacing [[Home appliance|appliance]]<nowiki/>s that run on fossil fuels can improve indoor air quality and reduce [[asthma]] symptoms in children by up to 42%, as well as decrease [[fire hazards]] in homes.<ref name=":2" />
+Windows are a huge element in a home. They are great for the occupant to feel connected to the outside environment and allow lots of additional light inside. This is beneficial because the additional lighting provided from the sun means the homes lights do not need to be on as much and can save the homeowner in electricity bills. However, the more sunlight also can cause more heating of the house. Therefore, with additional light comes with additional heat. In the cold winter months, this can actually help the home by providing additional heat so the homeowner can save on heating costs, but in the hot summer months, this can add unwanted additional heat and have an unintended consequence of needing to use more energy to cool the home down.
+The use of smart windows in homes can greatly impact the temperature inside by taking advantage of sunlight so that ultimately less energy is used to both heat and cool the building. Approximately 35% of a typical building’s energy is lost through its windows.<ref name=":4">{{Cite journal |last=Miller |first=Brittney J. |date=2022-06-08 |title=How smart windows save energy |url=https://knowablemagazine.org/article/technology/2022/how-smart-windows-save-energy |journal=Knowable Magazine {{!}} Annual Reviews |language=en |doi=10.1146/knowable-060822-3}}</ref> There are two types of smart windows that are primarily used to control the temperature on the inside of homes: [[Electrochromism|electrochromic]] and [[Thermochromism|thermochromic]].<ref name=":4" /> Electrochromic glass has been widely used in smart windows. An electrochromic window is able to alter the ability of light and heat to pass through the glass through the use of electrical current. These windows comprise of five layers: two glass layers on the exterior, two layers that serve as electrodes which act as the positive and negative poles in a battery, and a middle electrolyte layer containing [[Ion|ions]]. When voltage is applied to the window, positively charged ions develop on one side of the window while negatively charged ones move to the other side. This reaction creates a tint to the window which will stay until voltage is again applied to cause a reverse reaction. Electrochromic windows allow the homeowner to decide when they want to allow more sunlight in or block it which gives them more of a sense of control over the amount of energy they use for heating and cooling.<ref name=":4" /> On the other hand, thermochromic windows are windows that change in response to heat. These windows are comprised of less layers than electrochromic windows, typically two layers of glass, with an inner layer of a thermochromic laminate. The thermochromic laminate can be made of various different materials which are temperature responsive and can cause the glass to tint when it reaches high enough temperatures to block heat out, or become more transparent when cool enough to let more light and heat in. Each material has its own threshold temperature where this transition can occur.<ref name=":4" /> Therefore depending on the climate a different smart window could be desired over others.
-'''Money:'''
+=== Heat Pumps ===
-* As previously mentioned, energy efficient homes can save the occupant on their [[utility bill]]<nowiki/>s by both replacing their appliances with energy efficient appliances as well as updating their insulation and building envelop. For every $1 invested in improvements towards creating a zero carbon home, approximately $2 are saved in electricity generation and utility costs.<ref name=":2" />
+[[File:Outunit of heat pump.jpg|thumb|200x200px|Heat Pump]]
+A [[heat pump]] can be used in a home as an alternate heating and cooling system in comparison to furnaces and air conditioners. They run on electricity and use the same thermodynamic principles as refrigerators to transfer heat from a cool space to a warm space.<ref name=":5">{{Cite web |title=Heat Pump Systems |url=https://www.energy.gov/energysaver/heat-pump-systems |access-date=2022-12-16 |website=Energy.gov |language=en}}</ref> The three types of heat pumps that can be used to heat or cool homes are air-to-air, water source, and geothermal. Each type collects heat from either the air, water, or the ground respectively from outside the house and the heat pump concentrates it for use inside. Heat pumps are such an energy efficient alternative because they do not generate heat like a furnace. Instead, they transfer heat from one source to the other. The heat pump absorbs energy from the outside air and transfer it inside, heating the home up. Additionally, when turned to cooling mode, they act as air conditioners and absorb heat from inside, transferring it outside to cool the home down.<ref name=":5" />
+Air source heat pumps are most commonly used in residential housing. They are so energy efficient that they can reduce electricity bills by about 50%.<ref name=":5" /> Air sourced heat pumps have advanced so much in recent years that they are even suitable for extreme cold weather conditions to provide heat inside the home.
-'''Climate Change:'''
+=== Solar Panels ===
-* The most important benefit of zero carbon housing is the reduction in greenhouse gas emissions that are contributing to climate change. Since residential buildings and houses are a major source of greenhouse gas emissions, cities cannot achieve their climate targets without optimizing their energy efficiency.<ref>{{Cite web |title=Why transitioning to zero-carbon buildings is a vital, urgent and rewarding investment for cities |url=https://www.c40knowledgehub.org/s/article/Why-transitioning-to-zero-carbon-buildings-is-a-vital-urgent-and-rewarding-investment-for-cities?language=en_US |access-date=2022-12-15 |website=www.c40knowledgehub.org}}</ref> By reducing the amount of energy houses use and by cleaning up the energy they do use, zero carbon housing can significantly reduce these emissions into the atmosphere to meet the [[Carbon neutrality|carbon neutral]] standards many nations are setting.
+[[File:Installation of solar PV panels - panels in place - geograph.org.uk - 2624288.jpg|thumb|Solar panels installed on the roof]]
+[[Solar panel|Solar panels]] are one of the best ways a home can generate its own electricity. The two main technologies used to harness the suns energy and transfer it into electricity are [[photovoltaics]] (PV) and concentrating solar power (CSP). PV are the panels that can be seen on rooftops of residential homes and buildings or even out in fields. They capture the [[Photon|photons]] from the sunlight and the panels absorb them to create an [[electric field]] across its many layers which in turn creates electricity.<ref>{{Cite web |title=How Does Solar Work? |url=https://www.energy.gov/eere/solar/how-does-solar-work |access-date=2022-12-16 |website=Energy.gov |language=en}}</ref> CSP is used in very large [[Power station|power plants]] and therefore is not suitable for residential use.
+At times, solar panel systems are able to produce more energy than the house needs and when this happens, some systems feed into batteries which can store the surplus of electricity. Other systems can wire directly into the home’s grid and allows the homeowner to back feed its excess electricity to the utility company. When this happens, the utility company will often pay the homeowner for the amount of electricity they give back.<ref>{{Cite web |last=Scalisi |first=Tom |date=2022-11-07 |title=Are Solar Panels Worth It? |url=https://www.forbes.com/home-improvement/solar/are-solar-panels-worth-it/ |access-date=2022-12-16 |website=Forbes Home |language=en-US}}</ref>
-== Challenges associated with Zero Carbon Housing ==
-While all the above examples of how to build and/or renovate a zero carbon house sound great, there are some challenges that come with switching to carbon free. A top concern for most people is the economic factor. On average, zero carbon houses can cost 5% to 15% more than a similar sized regular home.<ref name=":1" /> When seeing this initial increase in price, homeowners often feel discouraged and that the home will not be a good [[investment]]. However, looking at the first cost of the home alone without factoring in how much savings the energy efficient home will have is a crucial mistake. When applying the correct design strategies to create a passive, energy efficient home that can generate a significant portion of its own electricity while also being completely carbon neutral, zero carbon homes can end up saving the home homeowner money in the long run.<ref name=":1" />
+=== Energy Efficient Appliances ===
-However, now that the homeowner has invested in a zero carbon house which is completely run on electricity, both self-producing and grid dependent, there arises the issue of the electrical grid [[Power outage|power outages]]. While there are measures the design team has taken to help the house generate its own electricity, that does not always mean it can generate enough electricity to sustain normal household activities whereas gas powered stoves would otherwise be able to function. In this instance, it is arguable that the zero carbon house would be preferable to a normal house because while normal household activities are minimized in a power outage, there is still the backup of electricity generated from renewable sources the house has provided as well as the passive design which means the house is well insulated and has measures such direct and indirect gain to help heat it. There additionally are instances where a house is located in an area where solar power is not the most efficient means of electricity generation due to the lack of sunlight available. In this case, the design team will assess whether solar is a good option or if other renewable sources of energy are more suitable.
+Energy efficient appliances are appliances that are designed and implemented to use less energy compared to their normal everyday household appliance yet provide the same service. Installing energy efficient appliances is one of the easiest ways to reduce energy consumption because after installation, they don’t require the occupant to consciously think about the amount of energy they will expend by turning them on; the appliance simply uses less energy due to the way it was designed.
+[[File:Energy Star logo.svg|thumb|127x127px|Energy Star Label]]
+The United States government has set a certain standard of energy efficiency and created the program [[Energy Star]] which provides certifications to consumer products that meet these standards.<ref name=":6">{{Cite web |title=What is ENERGY STAR |url=https://www.energystar.gov/about |access-date=2022-12-16 |website=www.energystar.gov |language=en}}</ref> Energy Star provides a certified label on products they deem energy efficient and also compiles a list of these appliances, making it easy for the consumer to purchase. Energy Star certified residential homes are at the least 10% and on average 20% more energy efficient compared to homes built to standard code.<ref name=":6" />
+=== Urbanization ===
-Finally, a big challenge in the building construction industry is embodied carbon. While the term zero carbon housing insinuates that the house is carbon free, it does not account for the fact that there are carbon emissions associated with the construction of the home, nor the carbon emitted from the materials needed to build it, nor from their transportation from source to site. In fact it is estimated that embodied carbon from new construction will be responsible for nearly half of carbon emissions between now and 2050.<ref>{{Cite web |last=Alter |first=Lloyd |last2= |last3= |first3= |title=Architecture 2030 Goes After Embodied Carbon and This Is a Very Big Deal |url=https://www.treehugger.com/architecture-goes-after-embodied-carbon-and-very-big-deal-4852211 |access-date=2022-12-15 |website=Treehugger |language=en}}</ref> This is a huge consequence that new construction presents which will need to be addressed.
+[[Urban area|Urbanized]] and more densely populated communities produce fewer carbon emissions per capita in comparison to [[Suburb|suburban]] or [[Rural area|rural]] communities. While part of this is because in urban settings, people typically are driving less due to the proximity of goods and services, another important factor is that densely populated housing means better insulation because of shared walls and floors and ceilings. With less walls exposed to the outside extreme weathers and more walls being shared, the inside environment is able to remain and maintain more steady temperatures without needing as much cooling or heating.<ref>{{Cite journal |last=Said |first=Evana |last2=Rajpurohit |first2=Sujata |date=2022-09-23 |title=The Health, Economic and Community Benefits of Zero-carbon Buildings |url=https://www.wri.org/insights/health-economic-and-community-benefits-zero-carbon-buildings |language=en}}</ref>
+== Benefits of Zero Carbon Housing ==
-== Determining a zero-carbon home ==
+Three important benefits to switching to a zero carbon house involve health, [[Economy|economic]], and environmental benefits.
-According to a 2020 UN report, [[Greenhouse gas emissions#Buildings and construction|building and construction]] are responsible for ~38% of all energy-related [[carbon emission]]s.<ref>{{cite news |title=Buildings-related carbon dioxide emissions hit record high: UN |url=https://phys.org/news/2020-12-buildings-related-carbon-dioxide-emissions-high.html |access-date=22 May 2021 |work=phys.org |language=en}}</ref> Required emissions until the finished building exists may therefore be a major part of the definition of a "zero-carbon" home.
+=== '''Health''' ===
-* '''Energy efficiency''': Homes have to be energy efficient and minimize the energy demand that is generated daily from a home. New homes will be required to have sufficient [[Building insulation|insulation]] installed and be "adequately airtight." The installation of 180mm (or more depending on climate) thick insulation, [[Water recycling|recycling]] of [[gray water]], replacement of appliances with an energy efficiency rating of "A" and insulation of hot [[water heating|water heaters]] all contribute to qualifying the degree of energy efficiency.
+Zero carbon houses offer much cleaner [[Indoor air quality|indoor air]] because they curb fossil fuel [[combustion]] which releases [[Volatiles|volatile gases]] and [[Pollutant|pollutants]]. Appliances such as gas stove, heaters, dryers, and ovens that rely on burning fuel inside the home worsen the air quality indoors and can lead to respiratory issues for the occupants. Not only is the indoor air quality affected, but so is outdoor air quality. Pollution from [[Residential area|residential buildings]] is noted to be responsible for about 15,500 deaths per year in the United States alone.<ref name=":2">{{Cite journal |last=Said |first=Evana |last2=Rajpurohit |first2=Sujata |date=2022-09-23 |title=The Health, Economic and Community Benefits of Zero-carbon Buildings |url=https://www.wri.org/insights/health-economic-and-community-benefits-zero-carbon-buildings |language=en}}</ref> Replacing [[Home appliance|appliance]]<nowiki/>s that run on fossil fuels can improve indoor air quality and reduce [[asthma]] symptoms in children by up to 42%, as well as decrease [[fire hazards]] in homes.<ref name=":2" />
-* '''Carbon compliance''': The onsite contribution to zero carbon includes low onsite carbon usage and zero carbon energy such as a community heating network. A community heating network or "[[district heating]]" is a system that distributes heat for residential and commercial water and [[Space heater|space heating]] needs usually from a central location. This dramatically reduces the carbon footprint of individual homes. Which type of heating fuel/system used further impacts on the carbon footprint.
-* '''Allowable measures''': Any type of approved carbon-saving measures that could be used on homes consisting of on-site, near-site, and off-site options. On-site options include installation of [[smart appliance]]s, use of grid-injected bio-methane, installation of site-based [[Thermal energy storage|heat storage]], etc. Near-site options include local micro-hydro schemes, communal [[waste management]] solutions, and local [[energy storage]] solutions. Off-site options include the investment in plants that turn waste into energy, investment of renovating with low carbon technologies, and investment of low carbon cooling, etc.<ref>"Allowable Solutions for Tomorrow's New Homes", Zero Carbon Hub, July 2011, http://www.zerocarbonhub.org/definition.aspx?page=4 {{Webarchive|url=https://web.archive.org/web/20120129171245/http://www.zerocarbonhub.org/definition.aspx?page=4 |date=2012-01-29 }},  Retrieved 2011-12-14</ref> Other alternative solutions include the development of alternative projects such as [[reforestation]], solar, hydro, and wind power. This is known as [[carbon offset]]ting.<ref>{{cite web|title=What is a carbon footprint? |url=http://www.carbontrust.co.uk/solutions/CarbonFootprinting/what_is_a_carbon_footprint.htm |access-date=2016-02-18 |url-status=dead |archive-url=https://web.archive.org/web/20080516071225/http://www.carbontrust.co.uk/solutions/CarbonFootprinting/what_is_a_carbon_footprint.htm |archive-date=May 16, 2008 }}</ref> These projects are considered carbon offsetting because they either prevent the burning of fossil fuels (solar, hydro, wind) or they utilize CO<sub>2</sub> from the atmosphere (reforestation) resulting in offsetting the amount of carbon released into the atmosphere by conventional fossil fuel burning methods.
+=== '''Money''' ===
-Various private entities and government agencies are beginning to promote the concepts of zero-carbon homes and zero-carbon footprints. In the [[United Kingdom]] the Zero Carbon Hub helped the building of zero-carbon housing become a more common practice. The Zero Carbon Hub existed from the summer of 2008 until 31 March 2016 when the government closed it.<ref>{{Cite web|url=http://www.zerocarbonhub.org/news/zero-carbon-hub-close|title=ZERO CARBON HUB TO CLOSE {{!}} Zero Carbon Hub|website=www.zerocarbonhub.org|access-date=2016-04-27|archive-date=2016-05-03|archive-url=https://web.archive.org/web/20160503235011/http://www.zerocarbonhub.org/news/zero-carbon-hub-close|url-status=live}}</ref> The Zero Carbon Hub was a public/private partnership working together with the private industry and the government to help reach the government's energy consumption reduction goals set by the [[European Union]] under the [[Kyoto Protocol]] of 1997.<ref>"Energy performance of Buildings Directive", Zero Carbon Hub, April 2011, [https://web.archive.org/web/20120426053918/http://www.nhbcfoundation.org/LinkClick.aspx?fileticket=vuga43X50g0=&tabid=458&mid=848] Retrieved 2011-12-14</ref> In the European Union, buildings are responsible for 40% of the total amount of energy needed by the European Union.  This percentage is expected to rise with an increase in future building construction.<ref>"Energy performance of Buildings Directive", Zero Carbon Hub, April 2011, [https://web.archive.org/web/20120426053918/http://www.nhbcfoundation.org/LinkClick.aspx?fileticket=vuga43X50g0=&tabid=458&mid=848] Retrieved 2011-12-14</ref>
+As previously mentioned, energy efficient homes can save the occupant on their [[utility bill]]<nowiki/>s by both replacing their appliances with energy efficient appliances as well as updating their insulation and building envelop. For every $1 invested in improvements towards creating a zero carbon home, approximately $2 are saved in electricity generation and utility costs.<ref name=":2" />
+=== '''Climate Change''' ===
-Despite UK being involved in pioneering some definitions of Zero Carbon Homes, it now appears that it will become unacceptable to market such homes using the term "Zero Carbon Home", because the UK's Advertising Standards Authority (ASA) have ruled that nothing which is manufactured can be called Zero Carbon.<ref>""Zero Carbon Homes" in UK national ASA ban", April 2012, http://www.solartwin.com/zero-carbon-homes-face-imminent-asa-ban {{Webarchive|url=https://web.archive.org/web/20120329034500/http://www.solartwin.com/zero-carbon-homes-face-imminent-asa-ban |date=2012-03-29 }}, Retrieved 2012-04-25</ref>
+The most important benefit of zero carbon housing is the reduction in greenhouse gas emissions that are contributing to climate change. Since residential buildings and houses are a major source of greenhouse gas emissions, cities cannot achieve their climate targets without optimizing their energy efficiency.<ref>{{Cite web |title=Why transitioning to zero-carbon buildings is a vital, urgent and rewarding investment for cities |url=https://www.c40knowledgehub.org/s/article/Why-transitioning-to-zero-carbon-buildings-is-a-vital-urgent-and-rewarding-investment-for-cities?language=en_US |access-date=2022-12-15 |website=www.c40knowledgehub.org}}</ref> By reducing the amount of energy houses use and by cleaning up the energy they do use, zero carbon housing can significantly reduce these emissions into the atmosphere to meet the [[Carbon neutrality|carbon neutral]] standards many nations are setting.
+== Challenges associated with Zero Carbon Housing ==
-== Prototypes ==
+While all the above examples of how to build and/or renovate a zero carbon house sound great, there are some challenges that come with switching to carbon free. A top concern for most people is the economic factor. On average, zero carbon houses can cost 5% to 15% more than a similar sized regular home.<ref name=":1" /> When seeing this initial increase in price, homeowners often feel discouraged and that the home will not be a good [[investment]]. However, looking at the first cost of the home alone without factoring in how much savings the energy efficient home will have is a crucial mistake. When applying the correct design strategies to create a passive, energy efficient home that can generate a significant portion of its own electricity while also being completely carbon neutral, zero carbon homes can end up saving the home homeowner money in the long run.<ref name=":1" />
-=== Earthship Biotecture ===
+[[File:World PVOUT Solar-resource-map GlobalSolarAtlas World-Bank-Esmap-Solargis.png|thumb|261x261px|PV power potential ]]
-An example of zero-carbon housing is Earthship Biotecture. Developed by [[Mike Reynolds (architect)|Mike Reynolds]], the [[Earthship]] is an environmentally friendly 100% sustainable type of home that can be built anywhere and in fact have been constructed all over the world. They are constructed with materials that would normally be discarded to take up space in a [[landfill]] including old tires, bottles, and cans.<ref>"About Earthships", The Halfmoon Earthship, [https://web.archive.org/web/20120426053915/http://halfmoon.californiadreams.us/Earthships.html] Retrieved 2011-12-15</ref> Reynolds has three requirements for the a [[sustainable architecture]] of Earthships. First, they must utilize only natural (non-manmade) as well as recycled materials.  Second, they must depend only on natural ("[[off-the-grid]]") energy sources. Third, they must be financially feasible as a do-it-yourself concept, such that an average person could build their own Earthship.
+However, once a homeowner has invested in a zero carbon house which is completely run on electricity, both self-producing and grid dependent, there arises the issue of electrical grid [[Power outage|power outages]]. While there are measures the design team has taken to help the house generate its own electricity, that does not always mean it can generate enough electricity to sustain normal household activities whereas gas powered stoves would otherwise be able to function. In this instance, it is arguable that the zero carbon house would be preferable to a normal house because while normal household activities are minimized in a power outage, there is still the backup of electricity generated from renewable sources the house has provided as well as the passive design which means the house is well insulated and has measures such direct and indirect gain to help heat it. There additionally are instances where a house is located in an area where solar power is not the most efficient means of electricity generation due to the lack of sunlight available. In this case, the design team will assess whether solar is a good option or if other renewable sources of energy are more suitable.
-Reynolds's design was fairly simple. A southward-facing slope is used and partially excavated to nestle the back of the house into the earth and provide a [[thermal mass]], and discarded tires and earth are used for the walls. The tires are packed with dirt to make a very dense-like brick. These "tire bricks" are strong enough to support the load of a roof structure and also very resistant to fire. Recycled cans and bottles are used as filler in the walls, sometimes with the bottles placed strategically to give an inlay glass tile look.
-Earthships use water four times before it is discarded. There are cisterns at the roof level to collect rain water or snow melt.  The [[cistern]] for a given Earthship is sized to the local climate. From the cistern, the water is fed into a water-organizing module with a pump and filtering device. The water is pumped into a pressurized tank to meet the building code of required [[water pressure]]. This fresh water is used for bathing, drinking, and activities like washing dishes. The water that flows from these activities is known as "gray water;" it is not sanitary for drinking, but it can be filtered and utilized for other purposes in the Earthship. First, the gray water passes through a grease filter and then collected into an interior botanical cell. A botanical cell is an indoor garden with growing vegetation. Oxygenation, transpiration, filtration, and bacterial cleansing all take place in the closed cell which cleans and filters the water.<ref>Reynolds, Mike. (2000). Comfort In Any Climate, Taos: Solar Survival P. {{ISBN|0-9626767-4-8}}</ref> After the botanical cell the process of filtering the "gray water" is complete and the water is used to flush the toilets.  The state the water is in after being used in the [[toilet]] is known as "[[Sewage|black water]]". "Black water" is not reused inside the Earthship but is transferred to a solar-enhanced [[septic tank]] with [[leach field]]s and used for watering of exterior botanical cells (landscape plantings).
-Earthships also have the capacity to process the wastes (generated daily by a household) in the interior and exterior of the Earthship. The exterior botanical cells reduce the waste volume leaching into the ground and reduce the risk of contaminating an [[aquifer]].  This system eliminates the use of large public sewer systems and treatment facilities that sometimes cannot adequately treat.  The reuse of gray water to produce food allows the Earthships to take sustainability to the next level.<ref>Reynolds, Mike. (2000). Comfort In Any Climate, Taos: Solar Survival P. {{ISBN|0-9626767-4-8}}</ref>
-The placement of the Earthship structure into the side of a slope allows a relatively constant [[climate]] inside the home to be maintained with minimal energy usage. The earthen walls act as a thermal mass soaking up heat during the day and radiating that heat back into the living space at night. This allows the temperature of the inside of the house to stay stable throughout the day and night. Conversely, in warmer ambient temperatures, the earth-bermed house maintains a comfortable indoor temperature assisted by the relatively stable core temperature of the earth.
-Earthships can live "off the grid," meaning they can produce their own electricity instead of having to rely on the current infrastructure for power. A power system that consists of [[photovoltaic cell]]s and a [[wind power]] unit supply the Earthship with enough power for the daily actions/usage within a given household. The power from the wind and the solar system is stored in several deep-cycle batteries that deliver the power to the outlets as well as all of the appliances.
-=== The Citu Home ===
-Citu, a company working to accelerate the transition to zero carbon cities, has developed a zero-emission home in partnership with [[Leeds Beckett University]], in part funded by [[Innovate UK]].<ref>[http://www.leedsbeckett.ac.uk/leeds-sustainability-institute/research-funding/ Leeds Beckett University KTP] {{Webarchive|url=https://web.archive.org/web/20180201192841/http://www.leedsbeckett.ac.uk/leeds-sustainability-institute/research-funding/ |date=2018-02-01 }} Retrieved 2018-01-31</ref> With the goal of creating a system able to be produced at scale to allow mass adoption, the [https://www.citu.co.uk/citu-home/ Citu Home] is built in a factory from timber-framed panels. The factory is located in the 'Climate Innovation District', an area on the outskirts of Leeds City Centre where 500 zero emission Citu Homes will be built.
-The Citu Home was developed using [[Passive House]] tools to create a building so efficient that its heating needs will be on average ten times lower than a conventional house. The home does not have a gas boiler, instead it uses a [[Heat recovery ventilation|MVHR system]] to recycle heat from people and appliances. This means the home's small heating requirements can be satisfied entirely with renewable energy. Citu supply all Citu Homes with [[100% renewable energy]] via [[Good Energy]], one of the UK's leading renewable electricity suppliers.
-The homes timber framed design allows it to sequester several tonnes of CO<sub>2</sub> in the building's structure, whilst the fact it is powered by 100% renewable energy for all its energy needs (including heating) means people living in it can expect to reduce their carbon footprint by over two tonnes of CO<sub>2</sub> per year, as the average UK household emits 2.3 tonnes of CO<sub>2</sub> heating their home.<ref>[https://www.theccc.org.uk/wp-content/uploads/2016/07/5CB-Infographic-FINAL-.pdf Commission on Climate Change UK Household Energy Consumption] {{Webarchive|url=https://web.archive.org/web/20180201020441/https://www.theccc.org.uk/wp-content/uploads/2016/07/5CB-Infographic-FINAL-.pdf |date=2018-02-01 }} Retrieved 2018-01-31</ref>
-===Tecla===
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-In April 2021, the first [[prototype]] 3D printed house made out of [[clay]] from locally sourced soil and water as well as fibers from rice husks and a binder, [[Tecla house|''Tecla'']], was completed.<ref name="printedclayhouse">{{cite news |last1=Palumbo |first1=Jacqui |title=Is this 3D-printed home made of clay the future of housing? |url=https://edition.cnn.com/style/article/tecla-3d-printed-house-clay/index.html |access-date=9 May 2021 |work=CNN |language=en}}</ref><ref>{{cite news |title=First 3D printed clay house completed |url=https://www.wlns.com/dont-miss/first-3d-printed-clay-house-completed/ |access-date=9 May 2021 |work=WLNS 6 News |date=14 April 2021}}</ref><ref name="housing1">{{cite web |title=Mario Cucinella Architects and WASP creates 3D-printed sustainable housing prototype |url=https://www.dezeen.com/2021/04/23/mario-cucinella-architects-wasp-3d-printed-housing/ |website=Dezeen |access-date=9 May 2021 |language=en |date=23 April 2021}}</ref> The housing is not only very low in carbon emissions, but could also be highly cheap, well-[[Thermal insulation|insulated]], stable and weatherproof, climate-adaptable, customizable, get produced rapidly, [[Automation in construction|require only very little easily learnable manual labor]], [[Environmental impact of concrete|mitigate carbon emissions from concrete]], produce little waste and require little energy. It may therefore reduce [[homelessness]], help enable [[Intentional community|intentional communities]] such as autonomous [[autarky|autark]] [[Ecovillage|eco-communities]], and enable the provision of housing for victims of natural disasters as well as – via [[knowledge transfer|knowledge-]] and technology-transfer to local people – for [[European migrant crisis|migrants to Europe]] near their homes, including as an increasingly relevant political option. It was built in Italy by the architecture studio Mario Cucinella Architects and 3D printing specialists WASP. The building's name is a [[portmanteau]] of "technology" and "clay".<ref name="printedclayhouse"/><ref name="housing1"/>
-== Role in environmental governance ==
-Zero Carbon Homes can play a considerable role in [[environmental governance]].  These structures are capable of serving the same everyday functions of a home against changing environmental conditions and are a form of engineering resilience. Engineering resilience is a part of adaptive governance. Adaptive governance is the idea that [[sustainability]] can be achieved by adapting to changes instead of changing something completely.<ref>J.P. Evans, Environmental Governance, (Abingdon: Routledge, 2012), 172-174.</ref> Zero Carbon homes allow humans to adapt to the increasing global temperature. These types of homes make it possible for people to survive without the use of declining levels of fossil fuels, protects the inhabitants from [[Economic shortage|food shortages]], and [[water contamination]]. Zero carbon homes can provide resilience to the changes from the upset of a tipping point in dynamic stability. In this case "tipping point" represents the dangerous aspects of [[climate change]]. When a tipping point occurs the system would be subjected to a new domain of stability and the characteristics of stability will have changed. The system will have entered into a new "domain of attraction" and the system will be attracted to a new resting place. In the idea of this, the height of the valley that the "domain of attraction" is in determines the amount of stress or disturbances needed to force the system into another valley or "domain of attraction".<ref>J.P. Evans, Environmental Governance, (Abingdon: Routledge, 2012), 172-174.</ref> Zero carbon homes provide engineering resilience to this event because they will be able to cope with the disturbances that occur. Exactly when these "tipping points" are going to occur is almost impossible to know and difficult to predict. They represent non-linear change, making it difficult to predict or prepare for.<ref>J.P. Evans, Environmental Governance, (Abingdon: Routledge, 2012), 172-174.</ref>
+Finally, a big challenge in the building construction industry is [[Embedded emissions|embodied carbon]]. While the term zero carbon housing insinuates that the house is carbon free, it does not account for the fact that there are carbon emissions associated with the construction of the home, nor the carbon emitted from the materials needed to build it, nor from their transportation from source to site. In fact it is estimated that embodied carbon from new construction will be responsible for nearly half of carbon emissions between now and 2050.<ref>{{Cite web |last=Alter |first=Lloyd |last2= |last3= |first3= |title=Architecture 2030 Goes After Embodied Carbon and This Is a Very Big Deal |url=https://www.treehugger.com/architecture-goes-after-embodied-carbon-and-very-big-deal-4852211 |access-date=2022-12-15 |website=Treehugger |language=en}}</ref> This is a huge consequence that new construction presents which will need to be addressed.
-==Possible complications==
-* '''Affordability:''' The Net Zero home, though affordable in the long run, may be quite an investment in the beginning. Much of the equipment used in the production of Net Zero housing is expensive. Aside from the solar panels which are an investment of their own, consumers have often settled for less square footage in an attempt to balance out the overall expenses.<ref>"What Are Zero Energy Homes?" Zero Energy Project, zeroenergyproject.org/buy/zero-energy-homes/.</ref> As far as implementing Net Zero building on a large scale goes, funding will become an issue as building size increases due to cost.
+== Success with Zero Carbon Housing ==
-* '''Energy Production:''' One of the most important factors in the construction a Net Zero structure is the amount of energy it will save in comparison to the previous structure. Any Net Zero building needs to be able to function at the same capacity at which it had prior to the retrofitting. This means that each structure will need to produce enough energy to sustain itself or else it will be pulling energy from the general grid. Net Zero homes are most commonly fitted with solar panels as the main energy production source on the roof of the structure. This means that as the height of a certain structure increases, the surface area on the roof becomes smaller in comparison to the overall volume of the structure.<ref>Malin, Nadav. "The Problem with Net-Zero Buildings (and the Case for Net-Zero Neighborhoods)." BuildingGreen, BuildingGreen, 30 Apr. 2016, www.buildinggreen.com/feature/problem-net-zero-buildings-and-case-net-zero-neighborhoods.</ref> Complications concerning energy production will arise due to the fact that there will not be enough space for solar panels to meet the consumption needs of the structure.
+There are several examples around the world of individual houses and even communities which have been built to be zero carbon houses and demonstrate that it is possible to live in an energy efficient home that reduces its energy consumption and its greenhouse gas emissions while also providing the occupants with the same functional lifestyle they require. One such community in particular, The Lochiel Park Green Village in [[South Australia]], has proven that with the help of government policy and an ingenious design team, zero carbon housing is possible and practical. The design considerations that the design team implemented increase energy efficiency include solar water heating, a photovoltaic system for each house, high energy star rated appliances, and low energy lighting.<ref name=":7">{{Cite journal |last=Berry |first=Stephen |last2=Whaley |first2=David |last3=Davidson |first3=Kathryn |last4=Saman |first4=Wasim |date=2014-07-01 |title=Do the numbers stack up? Lessons from a zero carbon housing estate |url=https://www.sciencedirect.com/science/article/pii/S0960148113006095 |journal=Renewable Energy |series=Renewable Energy for Sustainable Development and Decarbonisation |language=en |volume=67 |pages=80–89 |doi=10.1016/j.renene.2013.11.031 |issn=0960-1481}}</ref> In order to collect data to demonstrate that Lochiel Park was more energy efficient than a similar community of size and climate, appliance and equipment audits were performed, as well as continued energy use and generation monitoring.
+As a result of the conducted study, it was concluded that compared to the average of South Australian residential homes, Lochiel Park households used significantly less energy per year per unit [[floor area]]. In fact, Lochiel Park homes are so energy efficient that when comparing them to the average of South Australia, the average total annual energy per household consumed less than half the amount of energy.<ref name=":7" /> Not only that but when considering the amount of energy that was delivered to Lochiel Park homes, meaning the total energy consumed minus the amount of energy the homes generated themselves independent of the grid, Lochiel Park was delivered less than a third the amount of energy as the South Australia average.<ref name=":7" /> This is a significant amount in energy reduction which can be attributed to the innovative design team which incorporated a combination of energy efficient technologies and self-sustaining renewable energy electricity generation.
-* '''Predictability in Relation to Surrounding Environment:''' As the concept of Net Zero building spreads throughout the world, problems with energy production are becoming present aside from size of the structure. The region in which a certain Net Zero home is built in directly effects its energy production. Complications appear amongst the rural community due to the fact that rural areas are often heavily wooded. In order for a solar panel to function to its full potential, it requires direct sunlight for as many hours out of the day as possible.
 == See also ==