Net-Zero Case Study, zHome

Kent State University

NET-ZERO ENERGY BUILDINGS

Case Study

Tori Elizabeth Butera Environmental Technology I | Fall 2020 Course Instructor: Adil Sharag-Eldin, Ph.D.

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ABSTRACT This case study examines net-zero building design; net-zero buildings have become increasingly popular as society has become more ecologically conscious of its choices and actions and the impact these have on the environment. Although net-zero building design has grown in popularity, there is not yet a finite definition.

This case study analyzes the four net-zero models utilized by designers today: Net-Zero Site Energy, Net-Zero Source Energy, Net-Zero Energy Cost, and Net-Zero Energy Emissions. Net-zero building design is further examined through a functioning example of a net-zero building, zHome. zHome is a multifamily townhome community located in Issaquah, Washington; Issaquah is located about 20 miles east of Seattle. The zHome project was completed in 2011. The community consists of ten individual townhomes ranging in size from one to three bedrooms. The analysis of the project’s success began with an in-depth analysis of the climate, understanding Issaquah’s environmental needs through the use of Climate Consultant’s data. Next, the design strategies of the project were analyzed and evaluated, and then compared to suggested strategies; the analysis begins with the passive strategies implemented by zHome’s design team. Following this analysis, a brief examination of the townhome’s acoustic environment was completed and is detailed in the report. Lastly, the additional high-performance strategies of the home are analyzed. Upon the completion of this case study, it can be noted that the zHome project is successfully pioneering a greener future in residential living, becoming a model for all builders to follow.

This can’t be a fad or even a trend. This needs to be a fundamental, bedrock change planetwide. zHome is just one small step along the way—I believe we can get there, but the revolution must continue.

-Brad Lilijeuirt, Project Manger

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TABLE OF CONTENTS ABSTRACT

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COUNT DOWN TO ZERO

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zHOME

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A Brief History of the Development of Net-Zero Building Design

Climate Analysis Design Strategy Analysis Passive Design Active Design

Acoustic Environment Additional High-Performance Strategies

CONCLUSION

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REFERENCE

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THE COUNT DOWN TO ZERO

A Brief History of the Development of Net-Zero Building Design

Architects have a responsibility to leave a positive, lasting impact on the world; this includes the environment. In recent years it has been a goal of the government, on local, national, and international levels, to be more conscious of our actions and their effects on the environment. The green movement is becoming a vital part of this goal. All fields and disciples have accepted a role in the mission to care for the environment, undoing the damage current and past generations have created. This study further analyzes architects’ roles and the actions they have taken, fully understanding the influence the discipline’s design has upon the environment starting at the conceptual stage and continuing throughout the building’s lifetime.

As Architects have become more conscious of the impact the discipline has upon the environment, the opportunity has arisen to expand upon the positive impact which their designs can have. A new building classification has developed through this progression and understanding the architect’s ability to impact the environment positively; these buildings are called High-Performance Buildings (HPB). A High-Performance Building is defined as “a building that integrates and optimizes on the lifecycle of the basis of all major high-performance attributes, including energy conservation, environment, safety, security, durability, accessibility, cost-benefit, productivity, sustainability, functionality, and operational considerations.” (Energy Independence and Security Act of 2007, Title IV, Energy Savings in Buildings and Industry, Section 401) Through further research and development, the architects and their teams have invented and mastered techniques to decrease a building’s negative impact on the environment; with some strategies having a positive impact on the environment. A combination of these techniques has led to innovations within buildings, both commercial and residential, that do not negatively impact the environment, some even having a positive impact through design. This innovation is referred to as a Net-Zero Building.

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Net-zero buildings have become increasingly popular as society has become more ecologically conscious of their choices and actions. Although these buildings are growing in popularity, difficulty in establishing the finite definition has arisen. Net-zero’s definition is currently dependent on the project’s goals and values of the design team and building owner. The Steven Winter Associates, Inc. have established four classifications to develop and define what a net-zero building is; these classifications are discussed below:

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Net-Zero Site Energy

A site zero-energy building produces at least as much energy as it uses in a year when accounted for at the site. This approach to net-zero is more conservative than others and easy to implement, encouraging green design. Advantages of this model include its on-site verifiability and its easy performance tracking. The limitation of this model includes the requirement of PV panel exports to offset natural gas use, this model is inconsiderate of the utility cost, and does not differentiate between the nonenergy fuel types.

Net-Zero Source Energy

A source zero energy building produces at least as much energy as it uses in a year when accounted for at the source. Source energy refers to the primary energy used to generate and deliver to the site. The source energy of a building is calculated by multiplying imported and exported energy by the appropriate site-to-source conversion multipliers; the site-to-source conversion requires significant amounts of information to be determined. Net-zero source energy buildings are advantageous because of their ability to equate energy values of fuel types used at the site. This model is a more obtainable method for zero-energy buildings. This model is best for analyzing the impact on national energy systems. Struggles of this model include its inability to account for the nonenergy difference between fuel types, such as supply availability, and it does not consider all energy costs. This calculation source is too broad, making this model challenging to account for regional and daily uses.

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Net-Zero Energy Cost

In a cost zero energy building, the owner is paid the amount of the money in which its building exports for the energy services and energy used over the year. This model requires an extensive metering system with capacity limits and buyback rates, causing difficulty calculating total zeroenergy charges and servicings. This model is often chosen because of its easy implementation, its ability to be verifiable from a utility bill, and demand response control. Some difficulties faced when using this model include the requirement of a net meter agreement, high volatile energy rates make it challenging to track over time, and this method does not always reflect the impact to the national grid for demand as extra PV generation can be more valuable for reducing demand with on-site storage rather than exporting.

Net- Zero Energy Emissions

A net-zero emissions building produces at least as much emission-free renewable energy as it uses from emissions- producing energy sources; proper emission factors are required for appropriate use. The advantages of this model include its ability to account for nonenergy differences between fuel types. This model is easier to achieve and encourages the design of zero-energy buildings, becoming a better model for green power.

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While each model takes a unique approach to net-zero building with its own set of advantages and disadvantages, each of these models uses no more energy than it generates over the course of the year. Designing a net-zero building is not a one type fits all solution, but when designing a net-zero building, five common steps are taken throughout the process:

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The Building is Assessed

thoroughly understanding the design and its projected energy use

Performance Goals are Established Scope of Project is Defined

a comparison is made between like buildings, understanding the successes and struggles its design team had faced

Design Is Implemented

understanding what is required of the building

Building Begins to Operate

the building will continue to be evaluated throughout its life cycle to understand its strengths and weaknesses of net-zero design

Net-zero building is achieved through a coalition of passive and active design strategies: the active strategies utilizing renewable technologies on site. Passive and active strategies will be discussed in further detail and examined throughout the case study.

Net-zero developments have seen success in all climates; while struggling in the coldest areas, this climate presented a unique set of challenges that were overcome through research and development. The zero-energy buildings’ initial cost is quite substantial but offers a large return of investment, almost eliminating utility bills. As the government has pushed its green initiatives, these buildings have received tax cuts and incentives, an additional monetary value to a net-zero design.

Net-zero buildings have become increasingly popular as their development progresses. Examples of netzero designs include Rocky Mountain Institute in Colorado, the Discovery Elementary School in Virginia, and zHome in Washington. zHome will be further discussed and analyzed throughout this case study.

Discovery Elementary School, Virginia

Rocky Mountain Institute Center, Colorado

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zHome is a multifamily townhome community located in Issaquah, Washington; Issaquah is about 20 miles east of Seattle, Washington. The townhomes’ construction was completed in 2011; it was about a five-year building process due to the economic recession in 2008.

The project is about 13,400 square feet, resulting in 10 individual townhomes, each about 1,350 square feet, offering a flexible floorplan ranging from one to three bedrooms with one to two bathrooms.

On-site parking and garages are available for residents featuring charging ports for electric cars.

Each townhome offers floor plans that include a kitchen, dining room, living room, sun porches, and bedroom(s)/ loft. Please refer to the plans for additional details regarding the townhome’s layout.

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THE TEAM The team who designed and completed the construction of zHome is composed of builders, engineers, and city members; the list to the right provides each member’s name and role. Brad Lilijeuirt, the Project Manager, documented the construction process in stages, sharing his stories and experiences on Dwell. The blog highlights each struggle and accomplishment of the team. Lilijeuirt states the team’s goal was to create a project for the future residential market by experimenting with sustainable living. zHome is the first of its kind; it has led the way to net-zero residential living, specifically pioneering this movement through townhome design.

BUILDER: LAND:

Port Blakely Communities

ARCHITECT:

Vandervort Architects David Vandervort Mark Weirenga

The team designed a townhome community centered around energy efficiency, water usage reduction, locally sourced materials, and recycling systems by establishing an aggressive benchmark focused on net-zero energy at a specific size and price point.

ENERGY ENGINEER: Stantec

In his blog on Dwell, Lilijeuirt interviewed the architects of zHome, close collages of his, David Vandervort and Mark Weirenga of Vandervot Architecture. During this interview, both architects expressed their passion for green design and excitement for this project as an opportunity to holistically fulfill many of their firm’s goals through this project.

STRUCTURAL ENGINEER: Harriot Smith Valentine

LOW IMPACT DEVELOPMEOPMENT: CIVIL:

In the 19th century, we devoted our best minds to exploring nature. In the 20th century, we devoted ourselves to controlling and harnessing it. In the 21st century, we must devote ourselves to restoring it.

-Stephen Ambrose

Howland-Ichijo USA

2020 Engineering Core Design Inc.

LANDSCAPE ARCHTECT: Dar Webb Landscape Architects

INTERIOR DESIGN:

LH Design

PROJECT MANAGER:

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Brad Liljequist

The community is designed centrally around a sun courtyard with gardens and vegetation. Multiple passive and active design strategies have been incorporated into each townhome. These strategies include but are not limited to the use of clerestory windows, manual shading devices, PV panels, and cisterns; these will be further analyzed and discussed throughout this case study.

AWARDS:

Emerald Star The highest Leadership in Energy and Environmental Design (LEED)

Materials for the project were chosen for the zHome community for the advantages they provide in creating a net-zero home. The townhomes feature bamboo flooring, double pane windows, and VOC paint.

The material will be further analyzed and discussed throughout this case study.

Certification by the U.S. Green Building CouncilBuilt Green Hammer Award (King and Snohomish Counties) Good Design Award from Japanese Institute of Design Promotion Development of the Year Award 2011

Through my analysis, I can confirm that zHomes has established a new way of living, introducing the opportunity to live a net-zero energy lifestyle. zHome has become an example for all to follow, winning multiple awards through its design, construction, and completion phases.

Design & Build Award from Forest Stewardship Council (FSC) 2012 U.S. Department of Energy Builder’s Challenge 2012 Northwest Energy Star Project of the Year 2011 Residential Project of the Year in North America

zHome is a competitivity priced for the real estate market in Seattle, Washington. Below is a comparison between the zHome’s townhouse and a typical townhouse of comparable size and amenities. The townhomes are close in cost, with a significate difference in the cost of amenities. This comparison reinforces that net-zero living is affordable for all.

2009 Smart Partnership Award

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WHY zHOME I chose to research and analyze the zHome project for many reasons, the prominent being because the pioneering this project has led. Today more than ever, Americans are spending close to all their time at home. During the period before Covid, it was concluded through research that Americans spent 93% of their time indoors, this number only increasing as work from home initiatives grew and social gatherings and public spaces have diminished. Through this research, I wanted to learn if it was possible to turn these negatives into positives, especially for the environment; we have the opportunity to create a green future, creating hope for the future through these times that seem so bleak.

As my research progressed, I became more invested in this project, especially after reading Brad Liliquist’s blog with Dwell. His passion for this project and the joy he wrote only inspired me more for my career. This research has excited me about my responsibilities and duties to leave a lasting and positive impact on the world through my designs.

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CLIMATE ANALYSIS Seattle Region Before the analysis of the zHome can be completed, the climate of Issaquah, Washington, must be understood. The following data was generated through the use of Climate Consultant. Note, Seattle was chosen because of its proximity to Issaquah.

TEMPERATURE RANGE

Seattle, and Issaquah, is a reasonably cool region with temperatures ranging from approximately 40 degrees Fahrenheit to 60 degrees Fahrenheit. The warmest months are those in the summer- May through September; July and August the warmest of these. The coldest months are those in winter- October- April; December and January being the coldest of these.

MONTHLY DIURNAL AVERAGES

The analysis of the Monthly Diurnal Average parallels the data analyzed in the Average Temperature graph; warmest in the summer months of July and August while the coldest are December and January. Based on the data in this chart, it can be noted that Seattle is rarely in a range of thermal comfort; the few months that naturally can obtain thermal comfort are July and August.

The relationship between the dry bulb and wet bulb temperature indicates that Seattle is the most humid in December and January.

HOURLY AVERAGE DAYLIGHT Through the Hourly Average Daylight Hours analysis, it can be inferred the months with more available daylight are in the summer- May through September; the brightest months being May, June, July, and August. These findings follow closely along with the previous analysis, indicating the summer months are the warmest, in part because of the available daylight.

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CLIMATE ANALYSIS Seattle Region Continued

SKY COVERAGE RANGE

The Sky Coverage Range chart provides similar information to that of the Hourly Average Daylight Hours. The months with the most sky coverage or cloudiness are those in the winter, October through April. On average, the Seattle region receives about 70% sky coverage annually.

SUN CHART

The Sun Chart upon analysis indicated that although Seattle receives adequate sunlight, it does not produce a temperature that significantly exceeds the comfort zone. The sun a majority of the year is needed as a source of heat with a minicell time as an exception.

DRY BULB VS RELATIVE HUMIDITY The analysis of the relationship between the dry-bulb temperature and relative humidity indicates an inverse relationship between the two; as one begins to increase, the other decreases, and vice versa. The Seattle region can be referred to as a humid region. This area’s relative humidity ranges from about 50% - 90%; the most humid months are December and January.

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CLIMATE ANALYSIS Seattle Region Continued

WINDWHEEL ANALYSIS

The analysis of the Windwheel data for the Seattle region indicates that the wind levels here are low. The months most windy are those in the winter, still producing a small amount of the wind, typically from the west.

PSYCHOMETRIC CHART

Upon analyzing the Psychrometric Chart, it is established that only about 533 hours in Seattle are naturally thermally comfortable; 533 hours is about 6% of the year. Upon analyzing this chart, it can be assess the passive design strategies implemented in the Seattle region should assist in heat gain.

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CLIMATE ANALYSIS Seattle Region Climate Consultant has highlights ten critical strategies for passive design in the Seattle region:

1 2 3 4 5 6 7 8 9 10

For the passive solar heating face, most of the glass area south to maximize winter sun exposure, but design overhangs to fully shade in the summer.

Provide double pane high-performance glazing windows (Low-E) on west, north, and east, but clear on south for maximum passive gain.

Heat gain from lights, people, and equipment significantly reduces heating needs, so keep home tight, well-insulated (to lower balance point temperature).

Lower the indoor comfort temperature at night to reduce heat energy consumption (lower thermostat heating setback).

Tiles or slate (even on wood floor) or stone- face fireplace provide enough surface mass to store winter daytime solar gain and summer nighttime ‘coolth’.

Traditional passive homes in cool, overcast climates used low mass tightly sealed, well-insulated construction to provide rapid heat buildup in the morning.

Keep the building small (right-sized) because excessive floor area wastes heating and cooling energy

A High-Efficiency furnace (at least Energy Star) should prove cost-effective.

A steeply pitched roof with a vented attic over a well-insulated ceiling works well in cold climates (sheds rain and snow and helps prevent ice dams).

Sunny wind-protected outdoor spaces can extend living areas in cool weather (seasonal sunrooms, enclosed patios, courtyards, or verandahs).

These suggested strategies are compared with the strategies taken by the design team of zHome on the following pages. The images below provide exmaples of the vernacular style seem in this region.

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Headquarters for the Washington Fruit and Produce Company

The Carol Bobo Residence, aka Studio House

DESIGN STRATEGY Passive and Active Strategies The zHome community accomplishes a net-zero energy goal through the use of both passive and active design strategies. This coalition of strategies creates a hybrid model, not exclusively dependent upon one over the other. When designing a home, passive design strategies are analyzed and chosen before active strategies. The active strategies are chosen to fulfill the remaining needs of the building. The following pages first analyze the passive strategies used at zHome and begin to understand the needs fulfilled by the active design strategies.

Passive design strategies use ambient energy sources instead of purchased energy like electricity or natural gas. These strategies are the first to be analyzed and chosen in the design process. Common passive design strategies include daylighting, natural ventilation, and solar energy. These strategies must be included in the design of a net-zero building. The passive design strategies incorporate by the zHome team emphasizes and enhances the sun’s solar power as a source of heat gain.

• • • •

Windows Materials Courtyard and Porches Vegetation

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PASSIVE DESIGN STRATEGIES WINODWS & OVERHANGS

Large clerestory windows were chosen to design the zHome townhomes for multiple reasons, first being its ability to admit large quantities of light to naturally light the space and second because of its ability to absorb a large amount of solar heat, in return naturally heating the space. The windows have been oriented to the south to allow for the optimum amount of light to enter the space, especially during the winter months. This aligns closely with the climate analysis, understand the solar heat is needed during the colder months.

Small overhangs of about two feet have been built above the southward-oriented windows to shade the building from the solar heat gain in the warmer summer months. Upon the construction of the shading device’s mask, the device’s effectiveness was analyzed. By analyzing the solar mask, it can be confirmed that these small overhangs are well designed for the townhomes. The overhang provides shade in the warmest and sunniest months of June through August and allows for light to penetrate the windows and generate heat gain during the cold winter months.

Manually operated screens and shading devices have been incorporated into the townhomes to allow additional shading and privacy for the occupants.

The windows chosen for the design of the townhomes provide insulation while still allowing penetration of light. The townhome features double-paned Low-E windows with argon gas between the panes. The choice to use double-paned windows was made due to the concern that the triple pane window would not allow for solar penetration and heat gain in the winter months when needed.

Through the use of double-paned windows, the energy consumption of the townhome has reduced by five percent. Through this passive design strategy, the zHome townhouse can successfully utilize the available solar heat.

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PASSIVE DESIGN STRATEGIES The design team of zHome understood material's role and benefits it offers to passive design, starting at the impact it would have at the construction level through the building's lifetime. Before the team began selecting the materials, strict guidelines were established; the most important being that the materials must be locally sourced, locally being defined as within 400 miles of zHome's location. This decision was made due to the large amounts of carbon emission that accompanies transportation of the construction materials. The team's goal was to reduce carbon-emissions, which began at the design phase and was carried out throughout; by not achieving this goal at each stage, the team felt the project would not achieve its highest level of potential.

All the material chosen for the zHome project can be dissembled and reused again at the end of its lifetime. This process is known as DfD. DfD is defined as a building design process that allows for the easy recovery of products, parts, and materials when a building is disassembled or renovated. The process is intended to maximize economic value and minimize environmental impacts through reuse, repair, remanufacture, and recycling. A DfD process involves developing the assemblies, components, materials, construction techniques, and information and management systems to accomplish this goal.

The materials chosen for the wall include 2x6" Rockwool insulation, a plywood wall, 3.5 inches of expanded polystyrene insulation between the interior and exterior levels. The wall's combined R-value is 38; the combined total calculations can be seen in the below chart featuring each component and its associated R-value.

An R-38 wall indicates a high insulation level, assisting in the containment of the air within the townhome, both warm and cool, maintaining comfort during each season. The insulation of the ceiling results in an R-value of 60.

Along with high levels of insulations, the builders tightly sealed each crack to avoid the escape of any air from within the building. An escape of air would result in poor insulation and a need to use more energy to create a thermally comfortable environment. The highly insulated walls and ceilings and a tightly sealed barrier between the interior and exterior have resulted in a reduction in energy consumption by 15%.

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MATERIALS

PASSIVE DESIGN STRATEGIES COURTYARD & PORCHES

The designer’s choice to incorporate a courtyard and porch for each townhome prodives two key advantages, first its social and utilitrain puroses and second its advantages to passive design strategies. The courtyard and porches create an expansion of space in the cooler months as warm air is trapped within the courtyard between the buildings. The materials of each are have high levels of absorption, allowing for an internal heat gain creating a thermal mass system; the heat absorbed during the day being released into the air as the evening becomes cooler.

VEGETATION

The incorporation of vegitiation to the design of the zHome community creates a beautiful aesthetic along with an additional level of the insolation. The vegetation chosen for the townhomes are applied to the building at various levels and have been planted in close proximity to the townhomes. Bushes, trees and green walls have been incorporated to the zHome community and its passive design strategy.

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DESIGN STRATEGY Passive and Active Strategies While it is clear that the design team of zHome townhouses exhausted the use and examination of passive design strategies, chooisng those best suited to accomplish the goal of creating a net-zero building, this cannot be accomplished without the incorporation of active design strategies. Active design strategies are defined as using energy to support a wider grid network integrating with renewable energy technologies for heat, power, and transportation.

• Photovoltaic Panels • Cisterns • Heat Recovery Vetilators (HRVS)

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ACTIVE DESIGN STRATEGIES PHOTOVOLATIC (PV) PANELS

The largest source of energy for zHome is the use of photovoltaic panels. Photovoltaic (PV) panels collect solar energy and transfer this energy into usable electrical energy; this energy is transferred and used immediately or stored for later use. The PV panels are installed on top of each townhome, on top of the entryway to the courtyard, and near the car charging port. The panels, similar to the windows, oriented southward for optimal solar absorption. Each unit’s anticipated energy loads determine the panel size, the largest being on top of the townhomes, specifically the three bedrooms. The panels absorb the most sunlight during the summer months; this is aligned with the climate analysis.

These are the months that receive the most sunlight. To ensure the energy is continuously available, even in the cloudier months, the PV panels are connected to a grid that stores the energy, essentially creating a battery of the grid.

Although sunlight levels will always be a concern, specifically during the darkest month of January, 1,213 hours of total sunlight is received in Washington. This produces enough energy for the zHome residents without having to utilize the stored energy in the grid.

When excess energy is produced, Issaquah’s city will purchase the excess energy at a retail price. The typical home in Washington pays an average of $70 per month for electricity; for the residents of the zHome townhouses this bill has been eliminated through the use of the PV panels. The elimination of this bill is an example of the return on investments created through net-zero living.

The designers of this building compared the benefits and generated energy levels of the PV panels to wind turbines. Upon analyzing the climate and its wind levels, it is clear that the choice of the PV panels was the best for this location as the wind-generated in this area is relatively low.

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ACTIVE DESIGN STRATEGIES While the sun is central to the design of Zhome, the designers also utilize water.

Ten cisterns collect the rainwater on the property; each unit has its own cistern for collection. A small cistern decorates the entry to the courtyard from the street, highlighting this design feature. The cisterns range in size from 1,0001,800 gallons, dependent on the townhome's size. The cistern for each townhome is located underground; the ground in this region does not fall below 50 degrees Fahrenheit at all times, making it the optimal location for storage and heating.

CISTERNS

The water collected by the cisterns is used as a water source for sinks, laundries, and flushing toilets and used to heat the homes. As the water is collected, a small portion of the tank is heated using the solar energy collected; once warm enough, the water is pumped through the home in a hydronic system located in the floor.

Each home utilizes a heat recover ventilator located on the top floor of the townhome. It has been confirmed that the installation of the heat recovery ventilators has reduced energy usage by three percent due to its ability to keep the warm air within the home.

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HEAT RECOVERY VENTILATORS (HRVS)

DESIGN STRATEGY Strategy Comparison Upon completion of the zHome’s design strategies, it is essential to discuss the other design choices that could have been incorporated into the townhome’s design. The chart below compares the suggested design strategies from Climate Consultant with those taken by zHome’s design team. If the suggested strategy has been used, a ‘Y’ indicates this, and if the strategy was not used, this is indicated by an ‘N.’

1 2 3 4 5 6 7 8 9 10

For the passive solar heating face, most of the glass area south to maximize winter sun exposure, but design overhangs to fully shade in the summer.

Provide double pane high-performance glazing windows (Low-E) on west, north, and east, but clear on south for maximum passive gain.

Heat gain from lights, people, and equipment significantly reduces heating needs, so keep home tight, well-insulated (to lower balance point temperature).

Lower the indoor comfort temperature at night to reduce heat energy consumption (lower thermostat heating setback).

Tiles or slate (even on wood floor) or stone- face fireplace provide enough surface mass to store winter daytime solar gain and summer nighttime ‘coolth’.

Traditional passive homes in cool, overcast climates used low mass tightly sealed, well-insulated construction to provide rapid heat buildup in the morning.

Y Y Y Y N Y

Keep the building small (right-sized) because excessive floor area wastes heating and cooling energy

Y

A High-Efficiency furnace (at least Energy Star) should prove cost-effective.

N

A steeply pitched roof with a vented attic over a well-insulated ceiling works well in cold climates (sheds rain and snow and helps prevent ice dams).

Sunny wind-protected outdoor spaces can extend living areas in cool weather (seasonal sunrooms, enclosed patios, courtyards, or verandahs).

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Y Y

ACOUSTIC ENVIRONMENT The acoustic environment of the zHome townhomes have been evaluated based upon the materials internally used, not factoring in residents’ addition of furniture. Upon calculation and analysis of the materials used in the townhomes it can be established that the acoustic environment exceeds the average noise reduction coefficient, meaning that these residents live in an environment which is not too loud and will not produce an echo. The residents can live in peace as their neighbors will not be heard through the walls.

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ADDITIONAL HIGH-PERFORMANCE STRATEGIES Although zHome utilizes many passive and active strategies throughout its design, the goal of net-zero living could not be achieved without the incorporation of other high-performance strategies. zHome utilizes a vary of high-performance equipment: • • • • •

LEED Lights High-Performance Appliances Low Flow Water Fixtures Electric Car Charging Port Resident Education Sessions and Self-Monitoring System

LEED LIGHTING

LEED lights are utilized in each townhome, powered by the solar energy collected through the PV panels. Research states through the experimental phase of the design process that the LEED lights reduced energy consumption by five percent.

HIGH-PERFORMANCE APPLIANCES

Along with the LEED lights, high-performance appliances have been installed in each townhome. The appliances’ installation has resulted in a reduction of energy consumption by seven percent.

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ADDITIONAL HIGH-PERFORMANCE STRATEGIES Continued

LOW FLOW WATER FIXTURES Each townhome in the zHome community is furnished with low flow water fixtures. The fixtures have reduced the consumption of the water, especially hot water. This decrease in water consumption resulted in a decrease in energy consumption. The water supplied through these fixtures is supplied by the cistern system.

OUTLET SWITCHES zHome is centered around reducing energy consumption, which plays a vital role in the townhome’s design. However, a small amount of electrical energy consumption still occurs when outlets are not in use. To avoid this additional electrical consumption, the team installed electrical outlet switches; the switches allow the outlet to be turned off when not in use, reducing the townhome’s energy consumption further.

ELECTRIC CAR CHARGING PORTS Each garage or carport is supported with the accessory needed for electric cars to charge. The charging station draws its energy from that collected by the PV panels; the carports have their own PV panels for electrical generation.

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RESIDENT EDUCATIONAL SESSIONS & SELF-MONITORING SYSTEMS

Lastly, zHome’s team understands that although they have supplied the residents with many net-zero energy features, it is ultimately up to the resident to reduce their energy consumption. zHome allows its residents to monitor their energy use through a meter in the townhome; this meter includes a breakdown of energy consumption, allowing residents to see where improvement can occur. zHome also offers informational sessions on energy consumption techniques, supplying residents with the knowledge they need to further reduce their energy consumption. zHome is proud to say that its consumers use on average about 276 kWh of renewable energy each month in each townhome.

LESSONS LEARNED Lessons learned through the construction and implementation of the net-zero project in Issaquah’s zHome community:

1 2 3 4 5

Establishing project goals early in the design phases is crucial for success. These goals will guide the project, assisting in making difficult decisions.

Embrace and analyze each available passive design strategy. Understanding each’s advantages and disadvantages will help decide if this strategy is best suited for the project.

Begin the design process by choosing passive design strategies and allow for the active strategies to fill the project’s remaining needs.

A knowledgeable design team is necessary for success; a knowledgeable team will allow for the incorporation of the emerging technologies appropriately.

Education is key. Once people are made aware of their energy consumption and provided with the knowledge needed to reduce their consumption, a positive change can occur.

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CONCLUSION zHome has pioneered net-zero residential living. The design time and residents understand their role and accept their responsibility to leave a positive, lasting impact on the environment. Through the use of the hybrid design system of both passive and active design strategies used to achieve the goal of net-zero living, additional education provided to the residents allows for the zHome community to go above and beyond their goal. zHome has reduced the energy consumption of its residents by about 2/3. The graphics below highlighting and outlining this success. zHome has inspired and revolutionized net-zero living; its desgin inspiring builders to implentent net-zero strategies.

Zhome's design team and residents have defined a new way of life that will positively impact the environment.

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REFERENCE /author/david-Hill. “What It Takes to Go Net-Zero.” Architect, 5 Oct. 2017, www.architectmagazine.com/practice/what-it-takes-to-go-net- zero_o.

Associates, Steven Winter. “Net Zero Energy Buildings .” WBDG, 8 Feb. 2016, www.wbdg.org/resources/net-zero-energy-buildings.

Emerson, Joe. “Zero Energy Multifamily Buildings: Three Case Studies.” Zero Energy Project, 21 Aug. 2018, zeroenergyproject. org/2015/11/12/zero-energy-multifamily-buildings-three-case-studies/.

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