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Built Green® Star Levels: What Do They Mean?—2021 Versions

Posted on Jan 28, 2022 in:
  • Built Green News

Author: Sonja O'Claire, Built Green Program Manager

All Built Green homes are designed to reach beyond current Washington state building and energy codes—creating greener, healthier, and more equitable homes. However, not all Built Green homes are equal, and building standards and innovations change over time.

In Washington State, the building and energy codes are updated in a 3-year cycle. When the state codes change, typically requiring a higher level of performance and energy efficiency, Built Green must update its checklists to ensure Built Green certifications are representing beyond-code, innovative, and high-performance building practices. Every credit is assigned a point value based on its level of impact, difficulty or cost to implement. Built Green develops its checklist credits with advisory from leading industry professionals to navigate state code changes, technological advancements, and leading-edge best practices. To help distinguish these changes, Built Green checklists are assigned a version number for the year they were implemented. You can see a summary of the previous 2017/2018 version here. In 2021, we released updates for our new construction checklists to respond to code changes.

Regardless of the checklist version, there are four different Built Green certification levels, referred to as star levels, that builders can choose to achieve. This allows builders the flexibility to choose the star level that best matches their experience level with green construction practices, their or their client’s goals, and the project’s site context. The Built Green checklists are designed to encourage green development wherever possible using a holistic approach. This approach goes beyond energy use and takes water use, indoor air quality, site, materials, and community impact into consideration. This post will walk you through the various Built Green certification levels available and help you understand the differences between them.


The first thing many are familiar with when it comes to high performance homes is energy efficiency. Built Green requires notable performance differences for each certification level. The table below provides an overview regarding the energy performance requirements.

Built Green Energy Requirements by Star Level


Performance to be at least 6% improvement above WA State Energy Code


Performance to be at least 12% improvement above WA State Energy Code


Performance to be at least 18% improvement above WA State Energy Code; PLUS pre-wired for any future solar PV installations (single-family) or installed solar PV (multi-family)

Emerald Star

Demonstrate net zero energy performance over the course of a year; PLUS Building is 100% electric, no combustion fuels used inside the building.

Net Zero Energy Label

Any Star level is eligible: Demonstrate net zero energy performance over the course of a year; PLUS building is 100% electric, no combustion fuels used inside the building.


The Built Green checklists provide multiple ways for builders to demonstrate improvements in energy use, but each option is designed to achieve the performance listed in the above table. An example of how a builder can increase performance is a building’s thermal envelope—the wall that provide a physical separation between the exterior environment and the interior of a building. If the thermal envelope is more insulated and air-tight (i.e., less drafty), then the building will require less energy to provide thermal comfort to occupants. Using the Built Green checklist, builders can demonstrate how they have improved the energy performance of the home to provide greater thermal comfort while reducing operational costs to the occupant.

In addition to the home’s design, installing Energy Star rated appliances, heat pump water and space heaters reduce the energy required by the largest energy consumers in a home. Using passive solar design and orientation, light-colored interior finishes, and energy efficient lighting can further improve a home’s performance and comfort. Using a combination of features, builders can achieve high levels of performance, while increasing comfort and decreasing utility bills for occupants.

Targa Homes 5-Star Seattle DADU 1
5-Star, NZE Label homes by Martha Rose Construction

For 5-Star and Emerald Star Built Green homes, additional factors come into play. For example, any Built Green home could be oriented on the lot in a way that will optimize passive solar strategies, but 5-Star single-family homes must provide a designated rooftop location for the wiring and controls for any future solar photovoltaics, while multi-family buildings must have a minimum amount of solar PV installed. Emerald Star is required to achieve net zero energy (NZE)—meaning the building produces as much energy as it consumes in a year. To achieve NZE the building must use clean energy production through wind or solar, with the energy production either on site or within a quarter of mile of the lot.

Site and Water

Energy consumption might be the first thing that comes to mind when people think of high-performance homes, but it isn’t the only aspect. Site requirements ensure the footprint of the house has a minimal environmental impact. For example, one of the requirements for a 4-Star home is planting native, pollinator-friendly, or drought resistant plants, while also limiting thirsty turf grass to 25% or less of landscaped areas. This allows for the homeowner to enjoy beautiful landscaping while saving water and money through lower utility bills. 5-Star homes take stormwater management planning a step further by using pervious paving materials for at least 1/3 of the total area for driveways, walkways, and patios.

Total water use reduction in Built Green homes is made possible through EPA Water Sense and Energy Star low-flow fixtures and appliances, as well as landscaping that minimizes irrigation needs. Similar to home energy scores, the Water Efficiency Rating System (WERS) and Water Rating Index (WRI) are water efficiency scores that can be used to show a home’s water use reduction. The following is a table that provides an overview regarding Built Green’s water conservation requirements:

Built Green Site and Water Requirements by Star Level


Total water use reduction of at least 30%


Total water use reduction of at least 40%


Total water use reduction of at least 50%; PLUS manage 60% stormwater on-site (multifamily)

Emerald Star

Occupant water use reduction of at least 70%; PLUS manage 100% stormwater on-site (single-family)


Indoor Air Quality

Indoor air quality has an impact on the health of the environment, construction employees, and occupants of a home. All Built Green star levels are required to use materials, sealants, adhesives and finishes that do not emit harmful levels of added formaldehydes and volatile organic compounds that can be detrimental to occupant health.  4-Star homes take it a step further and recommend actions such as separating or air sealing the garage with an automatic exhaust fan to avoid motor exhaust from entering the home. Built Green recognizes another major contributor to poor indoor air quality that often escapes attention – shoes. There are numerous checklist credits (required for 5-Star Homes) dedicated to decreasing the number of pollutants being tracked into Built Green homes by shoes such as designated shoe-removal areas, enclosed vestibules, permanently installed track-off mats, carpets, and/or shoe grates at the principle entryway of a building.

Isola Homes 4-Star
4-Star home by Isola Homes


The materials used in the project and how efficiently they are utilized is also incredibly important and considered when assigning a Built Green star level. Every star level requires builders to post and implement a recycling plan and some form of waste reduction and recycling to ensure materials will not be wasted. 5-star and Emerald Star home require ensuring material sustainability and efficiency by requiring at least 10 materials to include salvaged or recycled content.

Dwell Development Emerald Star
Emerald Star home by Dwell Development

Embodied carbon in buildings is the greenhouse gas emissions associated with building construction that arise from extracting, transporting, manufacturing, and installing building materials on site, as well as the operational an end-of-life emissions associated with those materials. Built Green 5-Star and Emerald Star homes must calculate the embodied carbon through approved methods.

Built Green uses a House Size Matrix to assign increased value to building smaller more resource efficient homes. Smaller than average homes receive additional points added to their final total to achieve a targeted star level. Larger than average homes, regardless of star level, require additional steps to address their increased material usage and environmental impact. Builders can choose between earning additional materials credits or calculate the new building’s embodied carbon baseline and show at least a 10% reduction.

Equity and Social Justice

The three pillars of sustainability are planet, profit, and people. Most often in green construction certifications, the people aspect of sustainability is overlooked. Built Green recognizes as we commit to working for equity and inclusion in housing and the building trades, we must value the voices, experiences, cultures, knowledge, and multi-dimensionality of all people, including community members impacted by discrimination, bias, and systemic barriers. Understanding their perspectives is essential to removing these barriers. Creating these spaces of belonging and centering equity in turn provides economic and growth opportunities, reduction in turnover costs, and increased applicant labor pool for builders to capitalize on. This section is intended to support architects, builders, and developers in their efforts to promote equity and inclusion, one home at a time. With each Built Green star level, the qualitative positive impact on the community increases. As the builder progresses in each star level they must increase their efforts in universal design, community planning, equitable sourcing, and create an equity and social justice plan for each project.

Dwell Development Emerald Star
ANEW PACE Training Program

Why Certify with Built Green?

While an Emerald Star-certified home is greener with a reduced environmental impact than a 3-Star Built Green home, it is important to remember both homes are designed with the environment, community, and the inhabitants in mind. 3-Star certification is a great way for builders new to green building to learn more about the Built Green program and then begin to ramp up the certification levels they aim for.

Every star level builds upon the next to create greener homes. The needs of the builder, the homeowners, the community, and the environment are all considered when any Built Green home is constructed. Providing builders with the flexibility to choose which features to incorporate into the home increases the probability that more builders will choose to build greener homes. The star level tiers help provide clarity on how green each project is.


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