2024 City of Boulder Energy Code Update Frequently Asked Questions

The new City of Boulder Energy Conservation Code (CoBECC) took effect Dec. 1, 2024. View the 2024 City of Boulder Energy Conservation Code. Additional information can be found at www.BoulderEnergyCode.com, including documentation requirements and updated checklists that are required at the time of permit application.

All projects applying for a permit after Dec. 1, 2024 must be designed to meet the 2024 City of Boulder Energy Conservation Code (CoBECC). Projects that are in for Site Review prior to the effective date are permitted to proceed under the 2020 CoBECC as long as they permit within three years of the effective date.

The codes are very similar. The new code focuses on electrification, meaning if you have a new construction project and normally utilize natural gas for certain equipment and/or appliances, you will have to reconsider your selections as these are no longer permitted for new construction under the new 2024 CoBECC.

If your new construction projects typically include all-electric equipment and appliances, then you should have an easier time complying and there is not much difference from the 2020 CoBECC. Energy Rating Index (ERI) requirements stay the same for homes 3,000 square-feet and larger as they are still required to be net-zero energy but homes less than 3,000 square-feet will now have to achieve an ERI of no more than 30 with renewables. Smaller new construction projects, Accessory Dwelling Units (ADUs) and additions that are 1,000 square-feet or less, now have the option to follow the code prescriptively (R401.2.1) as written versus doing an energy model (R401.2.2). This was raised from the 500 square-feet threshold in the previous code to recognize most ADUs are 1,000 square-feet or less and to offer a more streamline path for smaller projects general.

For commercial new construction projects, the new energy modeling standard looks to American Society of Heating, Refrigerating, and Air-Conditioning Engineers ( ASHRAE) 90.1-2022 as modified by Appendix CA, Boulder Modified Appendix G Protocol of the 2024 CoBECC. New construction commercial projects that are all-electric will need to be 10% better than ASHRAE 90.1-2022, while projects that are permitted to rely on mixed-fuel energy sources per Section C403.3 of the 2024 CoBECC will need to be 15% better.

As for alterations, the requirements are in some cases less stringent. This approach acknowledges the age of our existing building stock and seeks to encourage community members to preserve, update and enhance their properties. Rather than imposing stricter standards, which might lead to more scrapes and rebuilds, when the goal should be to support renovation and improvement efforts. The requirements for building renovations were relaxed in both the residential and commercial provisions of the new 2024 CoBECC.

Commercial projects shall be all-electric or utilize other non-fossil fuel-based energy sources. There are exceptions for commercial cooking, hospitals, labs, large S-1 occupancies with constant vehicle traffic and emergency generators (C403.3). 100% of natural gas usage in the exceptions aforementioned would have to be fully offset through on-site renewables. Commercial cooking, emergency generators and lab and industrial process loads are exempt from the renewable offset requirement.

Even though these are exceptions where natural gas can be used, space and water heating shall be required to be all electric.

There are no exceptions for residential projects or additions, they must be all-electric.

The new 2024 CoBECC has been updated to provide guidance on this. The portion of work that is larger, shall govern the energy code compliance for the project. This means that if there is a Level 3 alteration that is 1,500 square-feet with an addition that is 500 square-feet, the project should proceed as if it were a Level 3 alteration in terms of energy code compliance. Another example is if there were an 850 square-feet Level 2 alteration with a 1,200 square-feet addition, the project should proceed as if it were an addition for energy code compliance. Both additions greater than 1,000 square-feet and Level 3 alterations require the project to achieve an ERI of 50 or less OR improve the home by 30% from the existing ERI.

The updated code removes Level 4 alterations to help eliminate confusion. The Level 4 alteration under the 2020 CoBECC is now a Level 3 alteration that includes substantial alteration to the mechanical system AND substantial alteration to the thermal envelope; substantial being defined as 50% or more. For example, a replacement of an existing furnace, A/C, heat pump, etc. would be considered substantial, or more than 50% of the system. These projects should be treated like a Level 3 alteration (commercial or residential) for energy modeling compliance. The main update here is that if the mechanical equipment being replaced is a natural gas furnace, the new equipment would have to be all-electric or other non-fossil fueled equipment. The existing equipment could remain as backup if desired but could not be replaced like for like.

If you only want to replace your existing furnace with a new furnace, as part of a Level 1, 2 OR 3 alteration, you can still do that. IF the scope of work is a Level 3 alteration, the equipment can still be replaced but the space for the equipment must be wired for a future electric appliance/equipment to be installed (electric-ready). IF it is part of a level 3 alteration that includes substantial thermal envelope alteration as well then furnace could be retained as backup, but any new equipment would be all-electric.

The submittal requirements for alterations are similar to the 2020 energy code requirements but will depend on the Level of Alteration. For residential projects that are Level 1 or Level 2 alterations, a completed residential prescriptive checklist OR ERI report and residential performance checklist if ERI path is taken. These can be found at www.boulderenergycode.com under Resources. Level 3 alterations must submit a completed residential performance checklist and either an ERI report showing an ERI of 50 or lower OR two ERI reports, one showing the ERI of the existing home prior to renovations, and another showing the proposed alteration achieves a 30% energy use reduction from the home prior to the renovation. The checklists confirm that all the prescriptive or performance code provisions have been met. One thing to note the ERI of 85 ceiling that the 2020 CoBECC put in place for all Level 3 or higher alterations has been removed. Recognizing some existing homes may not be able to achieve this due to limitations but should still be commended for an increase in energy efficiency let alone a 30% increase that is required instead of a slap on the wrist for a target that might be unrealistic.

For commercial projects that are level 1 or 2 alterations, a completed commercial prescriptive checklist OR commercial energy modeling summary report and commercial performance checklist if performance path is chosen. Level 3 alterations must submit a completed commercial energy modeling summary report and commercial performance checklist. Level 3 alterations are still allowed at 25% allowance above the commercial target for compliance.

All full demolition and deconstruction projects – residential and commercial – shall identify how the project will divert from the landfill 75% of the project’s waste by weight. This material must be reused, donated or recycled. Projects will be required to put a refundable deposit down equivalent to $1/ square-foot (minimum of $1,500). Projects will need to submit documentation within 60 days of rough inspections and prior to final inspection. Reporting shall confirm actual diversion achieved, at which point the deposit will be refunded by the city.

Although an ERI score can be obtained for any size home regardless how small, the home must have a kitchen, bath and dedicated bedroom to be modeled under the RESNET Standard. Projects without these elements are unique and will be exempt from the ERI requirement. Instead, these projects will need to meet the mandatory and prescriptive provisions in the 2024 City of Boulder Energy Conservation Code to comply less section R408. Instead of submitting an ERI report and performance checklist they’ll need to submit the residential prescriptive checklist.

NO. the “preliminary” existing building HERS score does not need to be registered with RESNET. The ‘Final’ HERS score showing the 30% minimum reduction from the existing home would need to be registered.

Projects are required to maximize their roof space for renewables. If it can be demonstrated that additional renewables would need to be needed offsite, and the roof area has been maximized then the city could deem the additional offsite solar not necessary for compliance.

A common concern raised with some renovation projects is that Level 2 Alteration work needs to be limited to 50% of the building area; otherwise, the project will be classified as a Level 3 Alteration and the building will need to be brought up to full compliance with the current code. It is important to know the following three classifications/definitions from the 2018 International Existing Building Code (IEBC):

• A Level 2 Alteration 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 Alterations apply where the work exceeds 50% of the aggregate building area.

To have a Level 3 Alteration, the project needs to have a work scope (consisting of reconfigured spaces) that exceeds 50% of the aggregate building area. A project could have Level 2 Alterations in 100% of the building area and not trigger a Level 3 Alteration. Your project is an example of this where the installation of a new lighting system throughout the building without reconfiguring more than 50% of the space does not trigger Level 3 Alteration requirements.

No. If it is a single trade permit looking to replace equipment, like for like then this would be allowed. As long as there was gas equipment there previously, replacement would be allowed. We understand that equipment sizing changes due to additional updates that can happen (example: LED lighting, lowering internal gains from lighting). We want the equipment to be sized appropriately and an increase in size would NOT require you to install equipment that is electric.

No. In these instances, please demonstrate to the city how much solar can be installed and how much would need to be acquired offsite. The city then could review and deem the additional offsite solar not necessary for compliance.

Additions should be treated similarly to new construction in that any new equipment or appliances installed in the addition will need to be electric; the new gas range could not be installed in the addition BUT could be used to replace the existing gas range already in the kitchen. It just cannot be installed in the addition. As for extending radiant tube water lines, or even ductwork for that matter into an addition from then existing home would NOT trigger the equipment to be updated to become electric. Gas service lines cannot be extended into a addition for gas equipment.

Yes. You can still replace a gas range or fireplace in a Level 3 alteration that includes substantial mechanical and envelope alteration.

This project could still be considered a Level 2 alteration as long as the additional work performed is limited to repairing the other parts of the home impacted outside of the original scope, so just replacing the sheetrock and filling any empty or cavities missing insulation with insulation (R503.3). If the work starts to expand beyond that then it would probably move into Level 3 alteration territory.

Error Corrections: 

Delete “(MANDATORY)”, call out no longer necessary (ex. C404 Service Water Heating (MANDATORY)) 

Section C403.3.1 Heating and cooling equipment efficiencies (MANDATORY) --> delete “(MANDATORY)” 
(Page C-27) 

Section C403.3.2 Equipment sizing (MANDATORY) --> delete “(MANDATORY)” 
(Page C-27) 

Section C403.5.5 Economizer fault detection and diagnostics (MANDATORY) --> delete “(MANDATORY)” 
(Page C-51)  

Section C403.5.5 Medium-pressure duct systems (MANDATORY) --> delete “(MANDATORY)” 
(Page C-63) 

Section C404 SERVICE WATER HEATING (MANDATORY) --> delete “(MANDATORY)” 
(Page C-63)  

Table C405.5.2(3), includes duplicate rows - -> Delete the last 4 rows of the table. 
(Page C-83) 

Section C405.13.1, #3 references Table C405.12.1 --> update to Table C405.13.1
(Page C-88)

Section C405.13.2, #2 references Table C405.12.1 --> update to Table C405.13.2
(Page C-88)

Section C406.1.1.1, section 2, Update to read --> “New construction less than 5,000 square feet...” 
(Page C-92) 

Section C502.1, #2 update ‘$500,00...’ to $500,000’.  
(Page C-113) 

Section C503.8, Update to read, “…Level 3 alterations shall also comply with Section C407.3 except that EUI or Performance Index (Site Energy) target shall be not greater than 125 percent of the EUI or Performance Index (Site Energy) otherwise permitted by Section C407.3.” Either modeled baseline or fixed performance target pathways are viable options. 
(Page C-116) 

Section R103.2, Delete #12 and replace with “12. Reserved.”
(Page R-2)

Section R401.2.2, reference Table R406.2 - - > update to correct number, Table R406.1.1.  
(Page R-15) 

Table R402.1.2, Footnote e. references Section R402.2.6 - -> update to correct number, R402.2.5. 
(Page R-16) 

Section R406.1.1, #4 reference Table R406.2 - - > update to correct number, Table R406.1.1. 
(Page R-28) 

Table R408.1, Line R408.5 - - > update 15% value from ‘1‘to ‘2’ to align with rest or credits. 
(Page R-31) 

Table R408.1, Line R408.37 - - > Delete/change ‘Passive House Certification’ to ‘Reserved’. If a project is pursuing ‘Passive House Certification’ then the additional credits wouldn’t be applicable.  
(Page R-31) 

Section R502.3, update to read   - -> “New building envelope assemblies that are part of an addition shall comply with Table R402.1.2. Existing wall, ceiling or floor cavities shall be filled with insulation where such cavities cannot meet the prescriptive R-values of Table R402.1.2. 
Exception: Project pursing the ERI pathway for compliance.” 
(Page R-37) 

Section R503.1, references section C503 - - > Update this to section R503. 
(Page R-38) 

Section R503.2.1.1, #2 --> Delete #2 in its entirety. Existing home blower door testing not required for alterations.
(Page R-39) 

Section title reads R503.25 - - > delete the 2, section should read R503.5.  
Page R-40) 

Section R505.1, exception references section R406.34 - -> delete the 4, it should read R406.3. 
(Page R-41)