Existing buildings undergoing a repair, alteration, addition, and/or change of occupancy or use must follow the requirements of Chapter 5 [RE] of the Denver Energy Code (DEC). A given project may need to follow the requirements of more than one section, depending on the existing conditions and scope of work for each area of the building. Chapter 5 [RE] also covers work on historic buildings. The sections below outline the requirements for each type of project and provide example scenarios to help clarify the options for compliance.
To see more about the prescriptive and performance compliance options, visit 2022 Denver Energy Code Resources for Residential Buildings.
Project Types
Work Category |
Definition |
Repair |
The reconstruction or renewal of any part of an existing building for the purpose of its maintenance or to correct damage. |
Alteration |
Any construction, retrofit or renovation to an existing structure other than repair or addition. Also, a change in a building, electrical, gas, mechanical, or plumbing system that involves an extension, addition or change to the arrangement, type, or purpose of original installation. |
Addition |
An extension or increase in the conditioned space floor area, number of stories, or height of a building or structure. |
Change of Occupancy or Use |
A change in the occupancy classification of a building or a change in the use of a building or portion of a building that involves a change in the application of the requirements of this code. |
Considerations Before Starting a Project on an Existing Residential Building
- Does your project scope fall into more than one work category (addition, alteration, repair, or change of occupancy)?
- If so, you must follow the requirements of each applicable section.
- For additions: What is the increase in conditioned floor area as a percentage of the total existing above grade conditioned floor area?
- Additions that do not exceed a 20% increase or 300 sq. ft. (whichever is less) are not required to provide air barrier details or heating and cooling equipment sizing calculations.
- For additions following the prescriptive path: Is unconditioned space being changed to conditioned space?
- If so, air leakage testing is required both to baseline the existing building and confirm that the completed project has an air leakage rate less than or equal to the baseline.
- New envelope assemblies for other additions are exempt from air leakage testing, but third-party inspection of the building envelope may still be required.
- Does the project qualify as a historic building?
- If one of the following conditions is met, the historic building is exempted from provisions of the 2022 Denver Energy Code relating to the construction, repair, alteration, restoration, and movement of structures, and change of occupancy:
- Report submitted/signed by a registered design professional demonstrating compliance with a provision of the building code would impact the historic character/form/function
- Letter from the Colorado State Historic Preservation Officer
- Documentation from the Denver Landmark Preservation Commission or Lower Downtown Design Review Commission
- For repairs: Is additional work on nondamaged components required?
- If the work is necessary for the required repair of damaged components, it is not subject to the requirements for alterations.
- If it is additional scope beyond the repair, it is subject to the requirements of Chapter 5 [RE].
- Does your alteration include replacing or installing space or water heating equipment?
Additions must follow the requirements of the Denver Energy Code Section R502. Additions satisfy the Denver Energy Code requirements when one of the following conditions is met:
- The addition alone complies with the prescriptive requirements
- The existing building and addition comply as a single building
- The building with the addition does not use more energy than the existing building
Unaltered portions of the existing building or building systems do not need to meet any provisions of the Denver Energy Code.
This section considers two separate types of additions:
- Changes In Space Conditioning: where unconditioned or low-energy space is changed to conditioned space (e.g., finishing an existing attic or basement, turning an unconditioned garage into a new bedroom)
-
All Other Additions: where the addition is comprised of all new, added conditioned space.
The code outlines options for both types:
Change in Space Conditioning
If the addition changes unconditioned or low-energy space to conditioned space, the project must meet all the requirements for new construction. DEC Section R502.2 offers some exceptions that recognize that full compliance for existing buildings is difficult and allows some flexibility for compliance through several pathways:
- Total UA Alternative
- Total Building Performance
- Energy Rating Index pathways
If your project follows the prescriptive compliance path, air leakage testing is required to show that the air leakage rate of the existing building with the addition is less than or equal to the air leakage rate of the original existing building.
All Other Additions
Additions that are comprised of all new space may select either:
- Prescriptive compliance path
- One of the performance compliance paths
- Total Building Performance (DEC R405)
- Energy Rating Index (ERI) (DEC R406)
If you choose a performance compliance path, the addition must meet all the requirements of either DEC Sections R405 or R406 as they relate to new construction.
If you choose the prescriptive path, you must meet the requirements outlined in DEC Section R502.3.
New building envelope assemblies that are part of the addition may either:
- Meet the prescriptive insulation and fenestration criteria of DEC Table R402.1.2 or DEC Table R402.1.3
- Select the Total UA alternative option (DEC Section R402.1.5).
Addition building envelope assemblies must also meet all other requirements of DEC Sections R402.1 through R402.4. While new envelope assemblies are exempt from air leakage testing, third-party inspections of the air barrier, air sealing, and insulation installation may still be required.
New ducts installed as part of the addition must meet the requirements of DEC Section R403 (ducts from an existing heating and cooling system that are extended to an addition are exempt).
New service hot water systems and new lighting systems that are part of the addition must follow the requirements in DEC Sections R403.5 and R404.1, respectively.
Example Scenarios
Change in Space Conditioning
Project scope: The unconditioned attic of an existing detached single-family dwelling is being converted to a vaulted ceiling over the existing living space. New lighting systems will also be installed.
Since this addition converts existing unconditioned space to conditioned space, it must meet the requirements outlined above for a “Change in Space Conditioning.”
The addition may follow any of the compliance pathways:
- Prescriptive
- Total Building Performance
- Energy Rating Index (ERI)
The exceptions of DEC Section R502.2 allow relaxed requirements for the performance-based compliance paths.
Since the building thermal envelope must be extended around the new conditioned space of the addition, the existing roof is considered a new envelope assembly and must meet the requirements of the selected compliance path. If the prescriptive path is selected, air barrier testing is required for the addition per DEC Section R502.3.1.
All new lighting systems installed in the addition must meet the requirements of DEC Section R404.1.
New Addition with Alteration
Project Scope: An existing one-story (2,200 sq. ft.) detached single-family dwelling is undergoing both a renovation and the construction of a new addition. The renovation includes:
- Lighting updates
- HVAC system replacement
- Window replacements.
The addition creates 750 sq. ft. of new single-story space.
Because this project scope falls into two different work categories (Alteration and Addition), each part of the project must follow the requirements for the applicable section.
The addition creates new space and does not involve previously unconditioned space, so it must meet the requirements for “All Other Additions.”
The addition may follow any of the compliance pathways:
- Prescriptive
- Total Building Performance
- Energy Rating Index (ERI)
The addition must meet all applicable requirements of the selected pathway as they relate to new construction.
The addition increases the conditioned floor area by more than 20% (750 sq. ft. is 34% of the original 2,200 sq. ft.) so air barrier details must be provided for new building envelope assemblies.
Since the HVAC system is being replaced as part of the renovation, newly installed ducts into the addition must meet the requirements of DEC Section R403. The addition increases the conditioned floor area by more than 20%, so ACCA Manual J, Manual S, and Manual D calculation packages must be provided for sizing the new HVAC equipment and systems.
All new lighting systems installed in the addition must meet the requirements of DEC Section R404.1.
Alteration
This alteration does not impact the building envelope assemblies beyond the window replacements.
- The new windows must meet the U-factor SHGC specified in DEC Table R402.1.3.
- An area-weighted average of all the replacement windows may be used instead.
The replacement HVAC system must meet the code requirements for new construction. We encourage project teams to consider electric equipment or appliances when feasible.
All new lighting systems installed as part of the renovation must meet the requirements of DEC Section R404.1.
Regardless of the compliance path, the Denver Energy Code requirements apply only to altered portions of the existing building. Unaltered portions of the existing building or building systems do not need to meet any provisions of the DEC.
Alterations must follow the requirements of 2022 Denver Energy Code Section R503. Alterations that meet all the following conditions satisfy the requirements of the Denver Energy Code:
- Altered and/or new components of the building meet all applicable requirements of the code as they apply to new construction
- The altered building is not less conforming to the code than the original existing building
- The alterations do not lead to unsafe or hazardous conditions, or overload the existing building systems
Unaltered portions of the existing building or building systems do not need to meet any provisions of the 2022 Denver Energy Code.
Alterations must meet the prescriptive requirements outlined in sections R503.1.1 through R503.1.4.
- The performance compliance paths (R405 Total Building Performance and R406 Energy Rating Index) are not available for this project type.
If the alteration project scope includes any building envelope assemblies, the alterations must meet the prescriptive insulation and fenestration criteria of DEC Tables R402.1.2 or R402.1.3.
- The Total UA alternative (DEC Section R402.1.5) is not available for alterations.
- Replacement fenestration may use an area-weighted average U-factor and SHGC to meet the prescriptive values specified in DEC Table R402.1.3.
- Altered building envelope assemblies must also follow the prescriptive insulation requirements outlined in DEC Sections R402.2.1 through R402.2.12.
While altered assemblies are exempt from many of the air leakage requirements, they must meet provisions for:
- Fenestration air leakage (DEC Section R02.4.3)
- Recessed lighting (DEC Section R402.4.5)
Certain alterations (such as storm windows over existing fenestration and roof recover projects) are exempted from meeting the prescriptive requirements due to their limited scope.
New ducts installed as part of the alteration must meet the requirements of DEC Section R403
- Ducts from an existing heating and cooling system that are extended to an addition are exempt).
New service hot water systems and new lighting systems that are part of the alteration must follow the requirements in DEC Sections R403.5 and R404.1, respectively.
- There is no exception for lighting compliance in the Denver Energy Code, regardless of the percentage of luminaires replaced.
Example Scenarios
Interior Only Alteration
Project Scope: A kitchen remodel in an existing detached single-family dwelling where the work is contained to the interior of the building. The project includes:
- New lighting
- New ductwork routed from an existing HVAC system.
Since the exterior envelope and service water heating systems are not being altered, they are not required to be brought up to code for new construction.
All new lighting installed as part of the renovation must meet the requirements of DEC Section R404.1.
Since the new ductwork is extended from an existing heating and cooling system, it does not need to meet the requirements of DEC Section R403.
Exterior Only Alteration
Project Scope: An existing detached single-family dwelling is replacing all windows (including frames) and the front door.
The new windows and door must meet the prescriptive values specified in DEC Table R402.1.3. Alternatively, an area-weighted average of all the replacement fenestration may be used to meet the required U-factor or SHGC. The replacement windows and door must also meet the fenestration air leakage requirements of DEC Section R402.4.3.
Repairs must follow the requirements of DEC Sections R501.3 and R504.
- Components of a building or system must be maintained to meet the requirements of the code edition under which they were installed.
- Work on nondamaged components necessary for the required repair or damaged components is considered part of the repair and does not need to meet the requirements for alterations.
The following items are examples of repairs:
- Glass-only replacements in an existing sash and frame
- Roof repairs
- Replacement of only the bulb, ballast, or both within an existing luminaire, provided the installed interior lighting power is not increased
The following items are not subject to the requirements for repairs:
- Routine maintenance
- Ordinary repairs exempt from permit
- Abatement of wear due to normal service conditions
Example Scenario
Project Scope: Glass in an existing window that was broken due to an accident is being repaired without replacement of the sash or frame. The existing window was installed when the building was permitted under the 2015 International Energy Conservation Code (IECC).
The broken pane shall be replaced with a glass that results in a whole window that meets the prescriptive requirements of 2015 IECC Table R402.1.
A project with a change of occupancy or use to residential must follow the requirements of DEC Section R505.1. The requirements depend on the energy-demand categories of the original occupancy and the new occupancy, based on the categories presented in DEC Table R505.1:
Change to an equivalent or higher energy-demand category
- The project must meet all 2022 Denver Energy Code Requirements for new construction unless calculations are provided that show the change will not result in an increase in demand for fossil fuel and electrical energy.
- DEC Section R505 offers some exceptions that recognize that full compliance for existing buildings is difficult and allows flexibility for compliance
- Prescriptive Compliance with Total UA Alternative: If you choose to follow DEC Section R402.1.5 for the building envelope design, the Total UA of the building after the change of occupancy or use is permitted to be 10% higher than the Total UA calculated using the U-factors in Table R402.1.2.
- Total Building Performance: If you choose the Total Building Performance compliance path, the annual energy cost of the proposed design is permitted to be 10% higher than the requirements of DEC Section R405.2.
Change to a lower energy-demand category
- The project must meet all 2022 Denver Energy Code requirements for additions, alterations, or repairs as applicable
Energy Demand Category |
International Building Code Occupancy |
International Residential Code Use |
4 (highest energy demand) |
A, B small assembly space |
|
3 |
B gym, E, I-4, M |
|
2 |
B (except as listed above), I-1, I-2, I-3, R |
All uses permitted in IRC structures |
1 (lowest energy demand) |
F, H, S |
|
Example Scenarios
Lower Demand Category to Higher Demand Category
Project Scope: An existing 1-story textile factory (Energy demand category 1) is being converted to an assisted living facility with less than 16 residents (Energy demand category 2). The project includes:
- HVAC and service hot water heating equipment replacements
- Lighting replacement
- Punched openings for new windows and doors
The occupancy is changing from a lower energy-demand category to a higher category. The change will result in increased energy demand, so the project must meet all the requirements of the Denver Energy Code for new construction.
The project may follow any of the compliance pathways:
- Prescriptive
- Total Building Performance
- Energy Rating Index (ERI)
The exceptions of DEC Section R505.1 allow relaxed requirements for the Total UA alternative and Total Building Performance compliance paths.
The new space heating and service hot water heating equipment must meet all applicable provisions of DEC Section R403, depending on the selected compliance path. We encourage project teams to consider electric equipment or appliances when feasible.
All new lighting installed as part of the project must meet the requirements of DEC Section R404.1.
New fenestration and other alterations to the building thermal envelope must meet all applicable provisions of DEC Section R402, depending on the selected compliance path.
Higher Demand Category to Lower Demand Category
Project scope: An existing 2-story building that was previously used as mercantile space (Energy demand category 3) is being converted to an alcohol and drug center (Energy demand category 2). The project includes:
- HVAC and service hot water heating equipment replacements
- Lighting replacements
- Window replacement
The occupancy is changing from a higher energy-demand category to a lower category, so the project must meet all the requirements for an alteration (DEC Section R503).
The replacement HVAC system must meet the code requirements for new construction (including requirements for newly installed ducts). The new service hot water system must meet the requirements of DEC Section R403.5. We encourage project teams to consider electric equipment or appliances when feasible.
All new lighting installed as part of the alteration must meet the requirements of DEC Section R404.1.
The new windows must meet the prescriptive values specified in DEC Table R402.1.3. An area-weighted average of all the replacement fenestration may be used to meet the required U-factor or SHGC. The replacement windows must also meet the fenestration air leakage requirements of DEC Section R402.4.3.