The City of Boulder Energy Conservation Code sets minimum energy performance standards for newly constructed and renovated buildings. City Council adopted the current Energy Conservation Code on March 3, 2020. The latest revision was approved by City Council on June 6, 2024 and will go into effect on Dec. 1, 2024.
The overall long-term goal for the city’s energy code is to build high performance, net zero energy (NZE) residential and commercial buildings. The objectives below are designed to support this overarching goal.
Supporting the City’s Climate Commitment
To achieve and sustain significant greenhouse gas (GHG) reductions (80 percent reduction by 2050)
To design and adopt NZE, outcome verified codes for all building types by 2031
To support technologies and practices that will move the community toward local, distributed and renewable energy systems (for both buildings and transportation) that support the goal of 100 percent renewable electricity, economic vitality and community resilience
Promoting High Performance Buildings
To promote sustainable building practices throughout the lifecycle of the building process (e.g., waste management, water management, transportation impacts, etc.)
To promote the development and ongoing maintenance of safe, comfortable and high-performing buildings
To support energy resilience (i.e., the ability to maintain operations during grid failure)
Creating Effective and Viable Codes
To adopt codes that are feasible (e.g., updated regularly, implementable, and enforceable)
To provide building owners and design professionals with viable and economically feasible paths to comply with energy codes that are straightforward and easy to understand
What is Net Zero Energy (NZE)?
While NZE can be defined several ways, in this context, NZE means:
The amount of renewable energy produced on site, plus the amount purchased from approved community energy systems, is equal to or greater than the annual energy consumption of the site.
This definition makes it possible for all buildings to become NZE even with poor solar access or other site constraints. Current conversations among experts and advocates at the national level have introduced alternative terminology, including terms such as “net zero carbon’ codes and ‘net zero emissions’ codes. Staff is engaged in these conversations and may propose updated terminology in future updates.
While the majority of this is addressed within the energy code itself, some key components such as waste, water, and transportation impacts are covered in applicable sections of the International Building Code (IBC) or International Residential Code (IRC).
Energy Code Changes
More stringent Energy Rating Index (ERI) requirements
An ERI score is the same as a Home Energy Rating System (HERS) score. This is a numerical score where 100 equates to the efficiency levels prescribed in the 2006 International Energy Conservation Code and 0 is equivalent to a net-zero-energy home. In the 2020 code, new construction and major alteration projects must demonstrate compliance with Boulder’s energy code by using the prescribed ERI compliance path. In the 2020 code ERI scores are getting more stringent compared to the 2017 code.
This figure illustrates the new ERI scores required by the 2020 code for new construction. Note all new homes over 3,000 square feet are required to achieve net zero.
Envelope Backstop
With the cost of renewables decreasing, some projects simply deploy large solar arrays to achieve building performance requirements instead of investing in basic building efficiency. With this code update, an envelope backstop is being introduced that will ensure all elements of the building enclosure: windows, walls, floor slabs, roof assemblies, and doors are energy efficient. Each project will need to comply with prescriptive building envelope requirements in the energy code.
Renewable Offsets
Similar to requirements that already exist for Boulder County projects, all residential pools, spas, outdoor radiant heating, and snow melt systems will be required to offset 100% of the system’s annual energy use by on-site renewable energy generation.
Construction & Demolition Waste Requirements
For over a decade, Boulder’s codes have included construction and demolition waste requirements for residential projects. With this code update, these requirements are being expanded to commercial projects. Additionally, improvements are being made to the code provisions and enforcement practices, including the addition of a requirement for a refundable deposit at the time of permit application.
Code Provisions for Alterations
The 2017 code required additional energy efficiency improvements be made when renovating homes based on the construction value of the project. The 2020 code continued to require energy efficiency improvements for home renovations; however, the requirements are triggered by the level of alteration as defined in the 2018 Existing Building Code.
Energy Use Index (EUI) Performance Path
The 2020 code introduced an EUI target compliance path that allows Boulder to transition towards outcome-based compliance, which staff and our consultants believe will be necessary to meet the City’s building energy efficiency goals.
Solar Mandate
To meet long-term NZE performance goals, it is necessary to encourage the deployment of renewable energy at the project level. The 2017 code mandated solar-ready requirements and the 2020 code required at least 5% of commercial building energy use be supplied by on-site renewables for new construction.
Pilot for Outcome-Verified Code Path
The 2020 code provided an outcome-verified code compliance path. Ultimately, the 2031 goal of Boulder’s energy code is to set standards that will result in buildings that are NZE, not just in theory and as designed, but verified through metered data once the building is constructed, commissioned, and occupied. The outcome path included in the 2020 code would achieve this goal for projects that opt into this path.
Electric Vehicle (EV) Charging Requirements
In 2017, provisions were added to the code requiring commercial and residential projects provide EV charging infrastructure. Because technology has evolved and the demand for EV charging is better understood, the 2020 code clarified and adjusted these requirements for commercial projects.
Residential Code Compliance Pathways
Alteration Levels
Level 1 Alteration: Alteration with scope that includes the removal and replacement or the covering of existing materials, elements, equipment, or fixtures using new material, elements, equipment or fixtures that serve the same purpose.
Level 2 Alteration: Alteration with scope that includes the reconfiguration of space, the addition or elimination of any door or window, the reconfiguration or extension of any system, or the installation of any additional equipment.
Level 3 Alteration: Alteration where the work area exceeds 50 percent of the building area.
Level 4 Alteration: Alteration alteration where the work area exceeds 50 percent of the building area, mechanical and lighting systems are substantially replaced, and the alteration meets the criteria of substantial structural alteration, including fenestration replacement.
New residential construction projects (less than) < 500 square feet shall comply with the residential energy efficiency mandatory and prescriptive requirements in the City of Boulder Energy Conservation Code. Projects greater than or equal to 500 square feet shall comply with the mandatory requirements and are required to achieve the applicable Energy Rating Index (ERI) . The ERI is the non-trademark equivalent to a HERS score and provides an energy efficiency requirement for your residential construction project. New residential construction is moving toward Net Zero Energy, with all buildings being required to meet that standard by 2031.
The larger the house, the lower the ERI (increased efficiency). Houses larger than 3,000 square feet are required to be NZE in the 2020 energy code. Further explanation can be found in the 2020 City of Boulder Energy Conservation Code, Section R406 .
Level 1 Alteration: Alteration with scope that includes the removal and replacement or the covering of existing materials, elements, equipment, or fixtures using new material, elements, equipment or fixtures that serve the same purpose.
Level 2 Alteration: Alteration with scope that includes the reconfiguration of space, the addition or elimination of any door or window, the reconfiguration or extension of any system, or the installation of any additional equipment.
Level 3 Alteration: Alteration where the work area exceeds 50 percent of the building area.
Level 4 Alteration: Alteration where the work area exceeds 50 percent of the building area, mechanical and lighting systems are substantially replaced and the alteration meets the criteria of substantial structural alteration, including fenestration replacement
CV: Construction Value as determine per City of Boulder Construction Value Guidance Document. A cost estimate must be provided with permit application.
Energy Code Training
Staff is in the process of scheduling training sessions for design professionals and applicants. The COVID-19 crisis may delay scheduling these session.
