Title 24 · California Energy Code

How are additions and alterations modeled for performance compliance?

Q: If I replace a component but leave its performance the same, is that an alteration for modeling?

Yes — a replacement is treated as an altered component for determining the standard‑design altered‑component budget. See the notes to § 180.2(c) .

If you use the performance approach for an addition or alteration, the code requires you to model a standard baseline that keeps unaltered existing components as‑is and sets each altered component to the **more efficient** of (existing condition OR the code altered‑component requirement), then compare that baseline to your proposed design (which uses the actual new features of the addition and altered components). Follow the explicit thresholds and exceptions (e.g., **≤ 300 sq ft** roofing/PV exemptions; **≤ 1,000 sq ft** ventilation exemptions) and always treat replacements as altered components for the baseline. See **§ 150.2** (single‑family) and **§ 180.2** (multifamily) for the controlling rules. file

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Last reviewed: July 6, 2026

What the code requires — plain English

Additions and alterations may comply using the performance approach (energy budgets) or the prescriptive approach; when using the performance approach the model must compare a standard design (a baseline that combines the existing building and code-level altered components) to the proposed design (the actual altered+added components) and show the proposed design meets the energy budget (usually expressed as Long‑Term System Cost, LSC). The controlling rules for single‑family are in § 150.2 and for multifamily in § 180.2.

The operative modeling rule: when you model an addition+alteration under the performance approach, the standard design = existing unaltered components + altered components set to the more efficient of (existing performance OR the code altered‑component requirement); the proposed design = actual existing unaltered components + actual (proposed) altered components + the addition. This is the baseline vs. proposed comparison the code requires.

Requirements in detail

Which projects may be modeled as a standalone addition versus "existing + alteration + addition"

Additions can be modeled either:
- as the addition alone complying with the addition energy budgets; or
- as existing + alteration + addition, in which the standard design combines existing unaltered components with altered components (set to the higher‑efficiency baseline) and the addition energy per code. See § 150.2(a)2 (single‑family) and § 180.1(b) / § 180.2(c) (multifamily).

How the standard design is assembled (decision rule)

For any altered component the standard design uses the more efficient of:
- the existing condition (if that is more efficient), or
- the applicable altered‑component requirement in the code.
For components not altered, the standard design uses the unaltered existing condition (so standard and proposed are identical for those components). This is required language in § 150.2 and § 180.2.

What the proposed design includes

The proposed design model must reflect the actual proposed energy features of the addition and of all altered components (actual insulation, fenestration, HVAC efficiencies, controls, etc.). See § 150.2(a)2 and § 180.2(c).

Ventilation, system expansions, and special verification

Mechanical ventilation requirements for additions/alterations are called out separately (see the whole‑dwelling/unit ventilation thresholds and when full ventilation rates apply). For example, additions increasing conditioned area by more than 1,000 sq ft have whole‑unit ventilation based on total conditioned area. These ventilation rules are in § 150.2(a)C(i–ii) and the parallel multifamily rules in § 180.1/180.2.
When existing HVAC is expanded to serve the addition, the code allows limited relief: existing equipment need not be brought up to full new‑construction requirements provided capacity meets minimums (see the "space‑conditioning system" exceptions in § 150.2(a) and § 180.1).

Table — Decision‑relevant dimensions and code references

Decision dimension	Typical values / thresholds	How it affects modeling	Code Reference
Compliance approach allowed	Performance or Prescriptive	If performance chosen, model standard vs proposed as described below	§ 150.2, § 180.2 file
Model type for addition	Addition alone OR Existing + Alteration + Addition	Determines whether baseline includes existing building components	§ 150.2(a)2; § 180.1(b)2 file
Standard design altered components	Existing condition OR code altered‑component requirement — use the more efficient	Baseline for altered components is the higher‑efficiency case	§ 150.2(a)2B; § 180.2(c)2 file
Proposed design values	Actual proposed component values	Modeled consumption for proposed case	§ 150.2(a)2B; § 180.2(c)3 file
Small addition ventilation exemption	≤ 1,000 sq ft increase (single or multidwelling thresholds shown)	May avoid whole‑unit ventilation recalculation for small additions	§ 150.2(a)C(i); § 180.1(a)2A(i) file
Roofing / PV exceptions	Additions ≤ 300 sq ft (roofing exception)	Some roofing/PV prescriptive rules exempt for very small additions	§ 150.2(a) Exception 1; § 180.1 Exception 2 file
Repairs	N/A	Repairs must not increase preexisting energy consumption	§ 180.3

(References point to the single‑family and multifamily sections that establish the modeling rules.) file

Exceptions & special cases

System expansion exception: If heating, cooling or water heating for an addition is provided by expanding existing systems, the existing equipment need not be upgraded to full Part 6 requirements — but capacity must still meet minimums (see § 150.2(a) Exception 3 and § 180.1 Exception 4). file
Small roofing/PV exemptions: Additions ≤ 300 sq ft may be exempt from certain roofing or solar‑ready requirements. See § 150.2(a) Exception 1 and § 180.1 Exception 2. file
Altered component replacement: If an existing component is replaced it is treated as an altered component for determining the standard‑design altered‑component budget (i.e., it is not silently considered "existing unaltered"). See notes under § 180.2(c).
Minimum existing insulation exception: Some projects where existing framed walls already have at least R‑11 may avoid some additional requirements; the code contains limited exceptions tied to that minimum. See the exception language in § 150.2(a)2B and § 180.1(b)2. file

Common mistakes

Modeling the standard design with code‑only altered components even when the existing component is more efficient: the rule is to use whichever is the more efficient (existing OR code altered requirement) for each altered component. Failing to do so biases the baseline and can invalidate the comparison.
Omitting existing unaltered components from the standard design (or changing their properties): components not altered must be modeled as the existing unaltered condition in both standard and proposed designs.
Forgetting ventilation and whole‑unit airflow thresholds: additions that push conditioned area above the 1,000 sq ft threshold (or create new dwelling units) change required ventilation modeling. Always check the ventilation clauses in § 150.2 / § 160.2 / § 180.1. file
Treating replacements differently: replacing a component counts as an alteration — so it may change the standard design baseline and must be modeled accordingly. See § 180.2(c) Note 1.

Worked example — concrete scenario

Scenario: Existing single‑family house (conditioned area 1,800 ft²) will: (A) replace 200 ft² of windows with new higher‑efficiency glazing; (B) add a 600 ft² conditioned family room addition with an independent new mini‑split heat pump and new lighting.

Choose approach — performance approach allowed under § 150.2.
Decide model scope — because the work includes both an altered component (fenestration) and an addition, model existing + alteration + addition per § 150.2(a)2B.
Assemble the standard design:
- Existing unaltered components (roof, floor, unaltered walls, existing HVAC zones outside of change) are modeled at their current as‑built values.
- For the altered component (the 200 ft² of windows), the standard design uses the more efficient of (a) existing window U‑factor/SHGC or (b) the code altered‑component requirement. If the existing windows are worse than code, standard uses the code requirement; if existing are better than code, standard uses the existing values. This is the baseline rule in § 150.2.
- The standard design includes the addition modeled to meet the code addition energy budgets (or the addition alone approach could be used — but here we picked existing+alteration+addition).
Assemble the proposed design:
- Use the actual proposed new window properties (U‑factor, SHGC) for the 200 ft² replacement.
- Model the 600 ft² addition with the actual proposed envelope, the new mini‑split COP/SEER, and the actual proposed lighting.
Compare LSC (or energy budget) for standard vs proposed. The project passes if the proposed design meets the required energy budget under § 150.1/150.2 performance rules. file

Notes for this example:

Whole‑dwelling ventilation: because the addition is 600 ft² (≤ 1,000 ft²), the smaller‑addition ventilation exemption applies and the whole‑unit ventilation calculation may not change; see § 150.2(a)C(i).
If instead the addition were 1,200 ft², you would model whole‑unit ventilation based on the combined (existing + addition) conditioned area per § 150.0(o) references in § 150.2.

Related provisions

§ 150.1 — Performance & prescriptive approaches for new single‑family (useful reference when modeling addition alone).
§ 140.1 — Performance approach: energy budgets for nonresidential/new construction (baseline methodology parallels).
§ 141.0 — Additions/alterations to nonresidential and hotel/motel buildings (parallel standard‑design rules).
§ 160.2 — Ventilation and indoor air quality mandatory requirements (referenced for whole‑unit ventilation).
§ 170.1 / § 170.2 — Performance and prescriptive approaches for multifamily new construction (background for multifamily additions).

Code references

Grounded in the retrieved California Energy Code — click a citation to read the verbatim passage:

§ 1.88 High relevance — show source text
27|1.88|2.27|1.88|2.27|2.27|2.27|2.27|2.27|2.27|2.27|2.27|2.27|2.85|1.88| |1. NR = Not Required.|1. NR = Not Required.|1. NR = Not Required.|1. NR = Not Required.|1. NR = Not Required.|1. NR = Not Required.|1. NR = Not Required.|1. NR = Not Required.|1. NR = Not Required.|1. NR = Not Required.|1. NR = Not Required.|1. NR = Not Required.|1. NR = Not Required.|1. NR = Not Required.|1. NR = Not Required.|1. NR = Not Required.|1. NR = Not Required.|

NOTE: Authority: Sections 25213, 25218, 25218.5, 25402 and 25402.1, Public Resources Code . Reference: Sections 25007, 25008, 25218.5, 25310, 25402, 25402.1, 25402.4, 25402.8 and 25943, Public Resources Code .

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12 MULTIFAMILY BUILDINGS—ADDITIONS, ALTERATIONS

AND REPAIRS TO EXISTING MULTIFAMILY BUILDINGS

SECTION 180.0—GENERAL

Additions, alterations and repairs to existing attached dwelling units and common use areas in multifamily buildings, existing outdoor lighting for these occupancies, and internally and externally illuminated signs shall meet the requirements specified in Sections 100.0 through 110.10, 160.1, and 160.3 through 170.2 that are applicable to the building project, and either the performance compliance approach (energy budgets) in Section 180.1(b) (for additions) or 180.2(c) (for alterations), or the prescriptive compliance approach in Section 180.1(a) (for additions) or 180.2(b) (for alterations), for the climate zone in which the building is located. Climate zones are shown in Figure 100.1-A.

Covered process requirements for additions, alterations and repairs to existing multifamily buildings are specified in Section 141.1.

Nonresidential occupancies in mixed occupancy buildings shall comply with nonresidential requirements in Sections 120.0 through 141.1.

NOTE: For alterations that change the occupancy classification of the building, the requirements specified in Section 180.2 apply to the occupancy after the alterations.

NOTE: Authority: Sections 25213, 25218, 25218.5, 25402 and 25402.1, Public Resources Code . Reference: Sections 25007, 25008, 25218.5, 25310, 25402, 25402.1, 25402.4, 25402.5, 25402.8 and 25943, Public Resources Code .

SECTION 180.1—ADDITIONS
§ 150.0 High relevance — show source text
MANDATORY FEATURES AND DEVICES. . . . . . . . . . . . . . . 159

150.0 Mandatory Features and Devices. . . . . . . . . . . . . . . .159

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CONTENTS

SUBCHAPTER 8 SINGLE-FAMILY RESIDENTIAL BUILDINGS—

PERFORMANCE AND PRESCRIPTIVE COMPLIANCE

APPROACHES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 177

150.1 Performance and Prescriptive Compliance Approaches for Single-Family Residential Buildings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 177

SUBCHAPTER 9 SINGLE-FAMILY

RESIDENTIAL BUILDINGS—ADDITIONS AND ALTERATIONS

TO EXISTING RESIDENTIAL BUILDINGS . . . . . . . . . . . . . . 187

150.2 Energy Efficiency Standards for Additions and Alterations to Existing Single-Family Residential Buildings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 187

SUBCHAPTER 10 MULTIFAMILY BUILDINGS—MANDATORY

REQUIREMENTS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 199

160.0 General. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 199

160.1 Mandatory Requirements for Building Envelopes . . . 199

160.2 Mandatory Requirements for Ventilation and Indoor Air Quality . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 200

160.3 Mandatory Requirements for Space-Conditioning Systems in Multifamily Buildings. . . . . . . . . . . . . . . 212

160.4 Mandatory Requirements for Water-Heating Systems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 223

160.5 Mandatory Lighting Requirements for Indoor and Outdoor Spaces . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 224

160.6 Mandatory Requirements for Electric Power Distribution Systems . . . . . . . . . . . . . . . . . . . . . . . . . 232

160.7 Mandatory Requirements for Covered

Processes. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 234

160.8 Mandatory Requirements for Solar Ready Buildings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 234
CBC § 301 High relevance — show source text
The IEBC is a model code in the International Code family of codes intended to provide requirements for repair and alternative approaches for alterations, changes of occupancy and additions to existing buildings. A large number of existing buildings and structures do not comply with the current building code requirements for new construction. Although many of these buildings are potentially salvageable, rehabilitation is often cost-prohibitive because compliance with all the requirements for new construction could require extensive changes that go well beyond the value of the building or the original scope of the alteration. At the same time, it is necessary to regulate construction in existing buildings that undergo additions, alterations, extensive repairs or change of occupancy. Such activity represents an opportunity to ensure that new construction complies with the current building codes and that existing conditions are maintained, at a minimum, to their current level of compliance or are improved as required to meet basic safety levels. To accomplish this objective, and to make the alteration process easier, this code allows for options for controlled departure from full compliance with the International Codes dealing with new construction, while maintaining basic levels for fire safety, structural and life safety features of the rehabilitated building.

This code provides three main options for a designer in dealing with alterations of existing buildings. These are laid out in Section 301 of this code:

Option 1: Work for alteration, change of occupancy or addition of all existing buildings shall be done in accordance with the Prescriptive Compliance Method given in Chapter 5. It should be noted that this method originates from the former Chapter 34 of the IBC (2012 and earlier editions).

Option 2: Work for alteration, change of occupancy or addition of all existing buildings shall be done in accordance with the Work Area Compliance Method given in Chapters 6 through 12.

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Option 3: Work for alteration, change of occupancy or addition of all existing buildings shall be done in accordance with the Performance Compliance Method given in Chapter 13. It should be noted that this option was also provided in the former Chapter 34 of the IBC (2012 and earlier editions).

Under limited circumstances, a building alteration can be made to comply with the laws under which the building was originally built, as long as the accessibility requirements are met, there has been no substantial structural damage and there will be limited structural alteration. Flood hazard provisions also must still be addressed where there is a substantial improvement.

Note that all repairs must comply with Chapter 4 and all relocated buildings are addressed by Chapter 14.

ARRANGEMENT AND FORMAT OF THE 2025 CEBC

The format of the CEBC allows each chapter to be devoted to a particular subject. The following table shows how the CEBC is divided. The subsequent table shows CEBC requirements that are correlated with other California Codes. The chapter synopses detail the scope and intent of the provisions of the CEBC.
§ 140.6 High relevance — show source text
140.6 Prescriptive Requirements for Indoor Lighting. . . .130

140.7 Prescriptive Requirements for Outdoor Lighting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .138

140.8 Prescriptive Requirements for Signs . . . . . . . . . . . . .141

140.9 Prescriptive Requirements for Covered

Processes. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .141

140.10 Prescriptive Requirements for Photovoltaic and Battery Energy Storage Systems . . . . . . . . . . . . . . .145

SUBCHAPTER 6 NONRESIDENTIAL AND

HOTEL/MOTEL OCCUPANCIES—ADDITIONS, ALTERATIONS

AND REPAIRS. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 149

141.0 Additions, Alterations and Repairs to Existing Nonresidential and Hotel/Motel Buildings, to Existing Outdoor Lighting, and to Internally and Externally Illuminated Signs . . . . . . . . . . . . . . . . . . .149

141.1 Requirements for Covered Processes in Additions, Alterations to Existing Nonresidential and Hotel/Motel Buildings. . . . . . . . . . . . . . . . . . . . . . . . .157

SUBCHAPTER 7 SINGLE-FAMILY RESIDENTIAL BUILDINGS—

MANDATORY FEATURES AND DEVICES. . . . . . . . . . . . . . . 159

150.0 Mandatory Features and Devices. . . . . . . . . . . . . . . .159

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CONTENTS

SUBCHAPTER 8 SINGLE-FAMILY RESIDENTIAL BUILDINGS—

PERFORMANCE AND PRESCRIPTIVE COMPLIANCE

APPROACHES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 177

150.1 Performance and Prescriptive Compliance Approaches for Single-Family Residential Buildings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 177

SUBCHAPTER 9 SINGLE-FAMILY

RESIDENTIAL BUILDINGS—ADDITIONS AND ALTERATIONS

TO EXISTING RESIDENTIAL BUILDINGS . . . . . . . . . . . . . . 187

150.2 Energy Efficiency Standards for Additions and Alterations to Existing Single-Family Residential Buildings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 187

SUBCHAPTER 10 MULTIFAMILY BUILDINGS—MANDATORY

REQUIREMENTS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 199
§ 141.0 High relevance — show source text
Notes to Section 141.0(b)3:
1. If an existing component must be replaced with a new component, that component is considered an altered component for the purpose of determining the energy budget and must therefore meet the requirements of Section 141.0(b)3.
2. The standard design assumes the same geometry and orientation as the proposed design.
3. The “existing efficiency level” modeling rules, including situations where nameplate data is not available, are described in the Nonresidential ACM Reference Manual.
Exception 1 to Section 141.0(b): When heating, cooling or service water heating for an alteration are provided by expanding existing systems, the existing systems and equipment need not comply with Sections 110.0 through 120.9 and Section 140.4 or 140.5.

Exception 2 to Section 141.0(b): When existing heating, cooling or service water heating systems or components are moved within a building, the existing systems or components need not comply with Sections 110.0 through 120.9 and Section 140.4 or 140.5.

Exception 3 to Section 141.0(b): Where an existing system with electric reheat is expanded when adding variable air volume (VAV) boxes to serve an alteration, total electric reheat capacity may be expanded not to exceed 20 percent of the existing installed electric capacity in any one permit and the system need not comply with Section 140.4(g). Additional electric reheat capacity in excess of 20 percent may be added subject to the requirements of Section 140.4(g).

Exception 4 to Section 141.0(b): The requirements of Section 120.2(i) shall not apply to alterations of space-conditioning systems or components.

(c) Repairs. Repairs shall not increase the preexisting energy consumption of the repaired component, system or equipment.

(d) Alternate method of compliance. Any addition, alteration or repair may comply with the requirements of Title 24, Part 6 by meeting the applicable requirements for the entire building.

Note: Authority: Sections 25213, 25218, 25218.5, 25402 and 25402.1, Public Resources Code . Reference: Sections 25007, 25008, 25218.5, 25310, 25402, 25402.1, 25402.4, 25402.5, 25402.8, 25910, and 25943, Public Resources Code .

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NONRESIDENTIAL AND HOTEL/MOTEL OCCUPANCIES— ADDITIONS, ALTERATIONS AND REPAIRS

SECTION 141.1—REQUIREMENTS FOR COVERED PROCESSES IN ADDITIONS, ALTERATIONS TO EXISTING NONRESIDENTIAL AND HOTEL/MOTEL BUILDINGS

Covered processes in additions or alterations to existing buildings that will be nonresidential and hotel/motel occupancies shall comply with the applicable Subsections of Section 120.6 and 140.9.

(a) Lab and Process Facility Exhaust Systems. Additions and alterations to existing laboratories and factories shall meet the requirements of Section 140.9(c).

(b) Computer Rooms. All newly installed computer room cooling systems and uninterruptible power supply systems in additions/alterations shall meet the requirements of Sections 120.6(j), 140.9(a)2 and 140.9(a)4 and comply with Item 1 below.
§ 301.3.2 High relevance — show source text
301.3.2 Work area compliance method. A lterations, additions and changes of occupancy complying with the applicable requirements of Chapters 6 through 12 of this code shall be considered in compliance with the provisions of this code.

301.3.3 Performance compliance method. Alterations, additions and changes of occupancy complying with Chapter 13 of this code shall be considered in compliance with the provisions of this code.

Note: [HCD 1 & HCD 2] The provisions contained in Chapter 13 are not adopted by HCD, but may be available for adoption by a local ordinance. (See Section 1.1.11.)

301.4 Relocated or moved buildings. Relocated or moved buildings shall comply with the requirements of Chapter 14.

SECTION 302—GENERAL PROVISIONS

302.1 Dangerous conditions. The code official shall have the authority to require the elimination of conditions deemed dangerous.

302.1.1 Dangerous conditions. [BSC] Regardless of the extent of structural or nonstructural damage, the code official shall have the authority to require the elimination of conditions deemed dangerous.

302.2 Additional codes. Alterations, repairs, additions and changes of occupancy to, or relocation of, existing buildings and structures shall comply with the provisions for alterations, repairs, additions and changes of occupancy or relocation, respectively, in this code and the California Energy Code, California Fire Code, California Mechanical Code, California Plumbing Code, California Residential Code and California Electrical Code . Where provisions of the other codes conflict with provisions of this code, the provisions of this code shall take precedence.

302.2.1 Additional codes in health care. In existing Group I-2 occupancies, ambulatory health care facilities, outpatient clinics and hyperbaric facilities, alterations, repairs, additions and changes of occupancy to, or relocation of, existing buildings and structures shall also comply with NFPA 99.

302.3 Existing materials. Materials already in use in a building in compliance with requirements or approvals in effect at the time of their erection or installation shall be permitted to remain in use unless determined by the code official to be unsafe.

302.4 New and replacement materials. Except as otherwise required or permitted by this code, materials permitted by the applicable code for new construction shall be used. Like materials shall be permitted for repairs and alterations, provided that unsafe conditions are not created. Hazardous materials shall not be used where the code for new construction would not permit their use in buildings of similar occupancy, purpose and location. [HCD 1] Local ordinances or regulations shall permit the replacement, retention and extension of original materials, and the use of original methods of construction, for any building or accessory structure, provided such building or structure complied with the building code provisions in effect at the time of original construction and the building or accessory structure does not become or continue to be a substandard building. For additional information, see Health and Safety Code Sections 17912, 17920.3, 17922(d), 17922.3, 17958.8 and 17958.9.

Exception: No replacement residential garage door shall be installed to connect the replacement door to an existing residential automatic garage door opener that does not have a battery backup function designed to keep the garage door operational without interruption during an electrical outage. See Health and Safety Code Section 19892.

§ 5.106.5.6.3 High relevance — show source text

5.106.5.6.3 EVCS alternative compliance. In lieu of compliance with Section 5.106.5.6.2, EVCS shall be provided with Level 1, low power Level 2, or Level 2, or any combination of Level 1, low power Level 2 or Level 2 EVSE such that the total power supplied by the combination of EVSE meets the minimum power indicated in Table 5.106.5.6.3, based on the total number of actual parking spaces in each parking facility.

TABLE 5.106.5.6.3	Col2
NUMBER OF PARKING SPACES IN A PARKING FACILITY	MINIMUM TOTAL POWER (KVA) REQUIRED FOR EVCS
0–9	0
10–25	7
26–50	14
51–75	20
76–100	27
101–150	40
151–200	60
201 and over	Total required KVA = P × .05 × 6.6 Where P = Parking spaces in facility

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NONRESIDENTIAL MANDATORY MEASURES

5.106.5.6.4 EVCS for alterations of or additions to parking facilities. Alterations of or additions to parking facilities shall provide EVCS in compliance with Section 5.106.5.6.4. The installation of infrastructure for EV capable spaces required to be provided without EVSE shall not be required.

5.106.5.6.4.1 Alterations of and additions to parking facilities. EVCS shall be provided in accordance with the number indicated in Table 5.106.5.6.1 or minimum power indicated in Table 5.106.5.6.3 when the scope of work includes an increase in power supply to an electric panel serving light fixtures illuminating the parking area or when area containing parking spaces is added to a parking facility. The number of required EVCS shall be based on the total number of existing and new parking spaces in the parking facility.

5.106.5.6.4.2 Alterations consisting of the installation of photovoltaic systems. EVCS shall be provided in accordance with the number indicated in Table 5.106.5.6.1 or maximum power indicated in Table 5.106.5.6.3 when a new photovoltaic system is installed in an existing parking facility.

5.106.5.6.5 Requirement to install EVSE. Level 2 EVSE shall be provided in all existing EV capable spaces to create EVCS when a project is required by California Administrative Code Section 4-309 to be submitted for plan approval to the Division of the State Architect. When EVSE is installed in existing EV capable spaces, accessible EVCS shall be provided in accordance with California Building Code Chapter 11B .

Exception: Projects in which improvements in parking areas consist only of accessibility improvements are not required to comply with Section 5.106.5.6.5.

5.106.6 Reserved.

5.106.7 Reserved.

§ 3-3 High relevance — show source text
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PROVISIONS FOR ALL COMPLIANCE METHODS

members added as part of the alteration shall comply with the California Building Code . This exception shall not apply to the following:
1. Alterations for accessibility required by the California Building Code, Chapter 11A.
2. Alterations that constitute substantial improvement in flood hazard areas, which shall comply with Sections 503.2, 701.3 or 1303.1.3.
3. Structural provisions of Section 304, Chapter 5 or to the structural provisions of Sections 706, 805 and 906.
301.3.1 Prescriptive compliance. Alterations, additions and changes of occupancy complying with Chapter 5 of this code in buildings complying with the California Fire Code shall be considered in compliance with the provisions of this code.

Exception: Hospital buildings removed from acute care service, skilled nursing facilities, intermediate-care facilities, correctional treatment centers and acute psychiatric hospitals [OSHPD 1R, 2, 4 and 5]. The provisions of adopted sections in Chapters 3 through 5 shall control the alteration, repair and change of occupancy or function of existing structures for applications listed in Section 1.10.1, 1.10.2, 1.10.4 and 1.10.5 regulated by the Department of Health Care Access and Information/Office of Statewide Hospital Planning and Development (OSHPD). Refer to Chapter 3A for services, systems and utilities that serve OSHPD 1 buildings.

301.3.2 Work area compliance method. A lterations, additions and changes of occupancy complying with the applicable requirements of Chapters 6 through 12 of this code shall be considered in compliance with the provisions of this code.

301.3.3 Performance compliance method. Alterations, additions and changes of occupancy complying with Chapter 13 of this code shall be considered in compliance with the provisions of this code.

Note: [HCD 1 & HCD 2] The provisions contained in Chapter 13 are not adopted by HCD, but may be available for adoption by a local ordinance. (See Section 1.1.11.)

301.4 Relocated or moved buildings. Relocated or moved buildings shall comply with the requirements of Chapter 14.

SECTION 302—GENERAL PROVISIONS

302.1 Dangerous conditions. The code official shall have the authority to require the elimination of conditions deemed dangerous.

302.1.1 Dangerous conditions. [BSC] Regardless of the extent of structural or nonstructural damage, the code official shall have the authority to require the elimination of conditions deemed dangerous.

302.2 Additional codes. Alterations, repairs, additions and changes of occupancy to, or relocation of, existing buildings and structures shall comply with the provisions for alterations, repairs, additions and changes of occupancy or relocation, respectively, in this code and the California Energy Code, California Fire Code, California Mechanical Code, California Plumbing Code, California Residential Code and California Electrical Code . Where provisions of the other codes conflict with provisions of this code, the provisions of this code shall take precedence.
§ 3.2 High relevance — show source text
301 A .3.2 Nonconforming buildings . Alterations, additions and changes of occupancy to existing buildings or structures designed in accordance with the Pre-1973 building code complying with Section 304A.3.1 and the applicable requirements herein shall be considered in compliance with the provisions of this code.

301 A .3.3 Performance- based method. Alterations, additions and changes of occupancy to existing buildings or structures complying with Sections 304A.3.4 and 304A.3.5 of this code shall be considered in compliance with the provisions of this code.

301 A .4 Moved structures . Structures moved into or within the jurisdiction shall comply with the provisions of the California Building Code for new structures.

301A.5 Reserved.

301A.6 Peer review requirements. Peer review requirements shall comply with California Building Code Section 1617A.1.41.

301A.7 Earthquake monitoring instruments for existing buildings. Earthquake monitoring instrumentation of existing buildings shall comply with Section 313A.

301A.8 Compliance alternatives for services/systems and utilities . Compliance alternatives for services/systems and utilities shall comply with Section 310A.

301A.9 Compliance alternatives for means of egress. Means of egress through existing buildings shall comply with Section 311A.

301A.10 Removal of hospital buildings from general acute care services. Removal of hospital buildings from General Acute Care Services shall comply with Section 312A.

SECTION 302 A —GENERAL PROVISIONS

302 A .1 Dangerous conditions. The code official shall have the authority to require the elimination of conditions deemed dangerous.

302 A .2 Additional codes. Alterations, repairs, additions and changes of occupancy to, or relocation of, existing buildings and struc- tures shall comply with the provisions for alterations, repairs, additions and changes of occupancy or relocation, respectively, in the California Fire Code, California Mechanical Code, California Plumbing Code and California Electrical Code. Where provisions of the other codes conflict with provisions of this chapter, the provisions of this chapter shall take precedence.

302 A .2.1 Additional codes in health care. In existing Group I-2 occupancies, ambulatory health care facilities, outpatient clinics and hyperbaric facilities, alterations, repairs, additions and changes of occupancy to, or relocation of, existing buildings and structures shall also comply with NFPA 99.

302 A .3 Existing materials and equipment. Materials and equipment already in use in a building in compliance with requirements or approvals in effect at the time of their erection or installation shall be permitted to remain in use unless determined by the code official to be unsafe in accordance with California Building Code Section 116.

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PROVISIONS FOR ALL COMPLIANCE METHODS
§ 110.2 High relevance — show source text
Compliance with the cooling-only perfor-
mance is required as defined in Notes b and c of Table 110.2-I.
h. Water-to-water heat pumps with a capacity less than 135,000 Btu/h are included in Table 110.2-B, Heat Pumps—Minimum Efficiency Requirements.
i. Source leaving liquid temperature.
1. The cooling evaporator liquid flow rate used for the heating rating for a reverse cycle air-to-water heat pump shall be the flow rate determined during the full-load cool-
ing rating.
2. The cooling evaporator liquid flow rate for the simultaneous cooling and heating and heat recovery liquid cooled chilling packages rating shall be the liquid flow rates
from the cooling operation full-load rating.
3. For heating-only fluid-to-fluid chiller packages, the evaporator flow rate obtained with an entering liquid temperature of 54°F and a leaving liquid temperature of 44°F
shall be used.
j. NA means the requirements are not applicable.|a. The size category is the full-load net refrigeration cooling mode capacity, which is the capacity of the evaporator available for cooling of the thermal load external to the chill-
ing package.
b. For air source heat pumps, compliance with both the 47°F and 17°F heating source outdoor air temperature (OAT) rating efficiency is required for heating.
c. Heating full-load rating conditions are at standard rating conditions defined in AHRI 550/590 (I-P), Table 4, which includes the impact of defrost for air source heating ratings.
d. For units that operate in both cooling and heating, compliance with both the cooling and heating efficiency is required.
e. For heat recovery heating chilling package applications where there is simultaneous cooling and heating, compliance with the heating performance heat recover COPHR is
only required at one of the four heating AHRI 550/590 (I-P) standard ratings conditions of Low, Medium, Hot-Water 1 or Hot-Water 2. Compliance with the cooling-only perfor-
mance is required as defined in Notes b and c of Table 110.2-I.
f. For liquid source heat recovery chilling packages that have capabilities for heat rejection to a heat recovery condenser and a tower condenser, the COPHR applies to operation
at full load with 100 percent heat recovery (no tower rejection). Units that only have capabilities for partial heat recovery shall meet the requirements of Table 110.2-D, Water
Chilling Packages—Minimum Efficiency Requirements.
g. For heat recovery heating chilling package applications where there is simultaneous cooling and heating, compliance with the heating performance heat recover COPHR is
only required at one of the four heating AHRI 550/590 (I-P) standard ratings conditions of Low, Medium, Hot-Water 1 or Hot-Water 2. Compliance with the cooling-only perfor-
mance is required as defined in Notes b and c of Table 110.2-I.
h. Water-to-water heat pumps with a capacity less than 135,000 Btu/h are included in Table 110.2-B, Heat Pumps—Minimum Efficiency Requirements.
i. Source leaving liquid temperature.
1. The cooling evaporator liquid flow rate used for the heating rating for a reverse cycle air-to-water heat pump shall be the flow rate determined during the full-load cool-
ing rating.
2. The cooling evaporator liquid flow rate for the simultaneous cooling and heating and heat recovery liquid cooled chilling packages rating shall be the liquid flow rates
from the cooling operation full-load rating.
3.
§ 180.0 High relevance — show source text
AND REPAIRS TO EXISTING MULTIFAMILY BUILDINGS

SECTION 180.0—GENERAL

Additions, alterations and repairs to existing attached dwelling units and common use areas in multifamily buildings, existing outdoor lighting for these occupancies, and internally and externally illuminated signs shall meet the requirements specified in Sections 100.0 through 110.10, 160.1, and 160.3 through 170.2 that are applicable to the building project, and either the performance compliance approach (energy budgets) in Section 180.1(b) (for additions) or 180.2(c) (for alterations), or the prescriptive compliance approach in Section 180.1(a) (for additions) or 180.2(b) (for alterations), for the climate zone in which the building is located. Climate zones are shown in Figure 100.1-A.

Covered process requirements for additions, alterations and repairs to existing multifamily buildings are specified in Section 141.1.

Nonresidential occupancies in mixed occupancy buildings shall comply with nonresidential requirements in Sections 120.0 through 141.1.

NOTE: For alterations that change the occupancy classification of the building, the requirements specified in Section 180.2 apply to the occupancy after the alterations.

NOTE: Authority: Sections 25213, 25218, 25218.5, 25402 and 25402.1, Public Resources Code . Reference: Sections 25007, 25008, 25218.5, 25310, 25402, 25402.1, 25402.4, 25402.5, 25402.8 and 25943, Public Resources Code .

SECTION 180.1—ADDITIONS

Additions to existing multifamily buildings shall meet the applicable requirements of Sections 110.0 through 110.9; Sections 160.0, 160.1, and 160.2(c) and (d); Sections 160.3 through 160.7; and either Section 180.1(a) or 180.1(b).

Exception 2 to Section 180.1: Additions of 300 square feet or less are not required to comply with the roofing product requirements of Section 170.2(a)1A.

Exception 3 to Section 180.1: Existing inaccessible piping shall not require insulation as defined under Section 160.4(e).

Exception 4 to Section 180.1: Space-conditioning system. When heating or cooling will be extended to an addition from the existing system(s), the existing heating and cooling equipment need not comply with Part 6. The heating system capacity must be adequate to meet the minimum requirements of CBC Section 1204.1.

Exception 5 to Section 180.1: Space-conditioning system ducts. When any length of ducts are extended from an existing duct system to serve the addition, the existing duct system and the extended ducts shall meet the applicable requirements specified in Sections 180.2(b)2Ai and 180.2(b)2Aii.

Exception 6 to Section 180.1: Photovoltaic and BESS, as specified in Sections 170.2(f) through 170.2(h), are not required for additions.

Exception 7 to Section 180.1 : Dwelling unit space heating system. New or replacement space heating systems serving an addition may be a heat pump or gas heating system.
CRC § 301 High relevance — show source text
This change expands the current process from two independent 1-year cycles to a single continuous 3year cycle. There will be two groups of code development committees and they will meet in separate years. The current groups will be reworked. With the energy provisions of the International Energy Conservation Code ® (IECC®) and Chapter 11 of the International Residential Code ® (IRC®) now moved to the Code Council’s Standards Development Process, the reduced volume of code changes will be distributed between Groups A and B.

Code change proposals submitted for code sections that have a letter designation in front of them will be heard by the respective committee responsible for such code sections. Because different committees hold Committee Action Hearings in different years, proposals for most codes will be heard by committees in both the 2024 (Group A) and the 2025 (Group B) code development cycles. It is very important that anyone submitting code change proposals understands which code development committee is responsible for the section of the code that is the subject of the code change proposal.

Please visit the ICC website at iccsafe.org/products-and-services/i-codes/code-development/current-code-development-cycle for further information on the Code Development Committee responsibilities as it becomes available.

Coordination of the I-Codes

The coordination of technical provisions allows the I-Codes to be used as a complete set of complementary documents. Individual codes can also be used in subsets or as stand-alone documents. Some technical provisions that are relevant to more than one subject area are duplicated in multiple model codes.

INTRODUCTION TO THE INTERNATIONAL EXISTING BUILDING CODE

The IEBC establishes minimum requirements for existing buildings using prescriptive and performance-related provisions. It is founded on broad-based principles intended to encourage the use and reuse of existing buildings while requiring reasonable upgrades and improvements.

The IEBC is a model code in the International Code family of codes intended to provide requirements for repair and alternative approaches for alterations, changes of occupancy and additions to existing buildings. A large number of existing buildings and structures do not comply with the current building code requirements for new construction. Although many of these buildings are potentially salvageable, rehabilitation is often cost-prohibitive because compliance with all the requirements for new construction could require extensive changes that go well beyond the value of the building or the original scope of the alteration. At the same time, it is necessary to regulate construction in existing buildings that undergo additions, alterations, extensive repairs or change of occupancy. Such activity represents an opportunity to ensure that new construction complies with the current building codes and that existing conditions are maintained, at a minimum, to their current level of compliance or are improved as required to meet basic safety levels. To accomplish this objective, and to make the alteration process easier, this code allows for options for controlled departure from full compliance with the International Codes dealing with new construction, while maintaining basic levels for fire safety, structural and life safety features of the rehabilitated building.

This code provides three main options for a designer in dealing with alterations of existing buildings. These are laid out in Section 301 of this code:

Option 1: Work for alteration, change of occupancy or addition of all existing buildings shall be done in accordance with the Prescriptive Compliance Method given in Chapter 5. It should be noted that this method originates from the former Chapter 34 of the IBC (2012 and earlier editions).

Option 2: Work for alteration, change of occupancy or addition of all existing buildings shall be done in accordance with the Work Area C

§ 150.2 High relevance — show source text

respectively.|HL and CL refer to the design heating load and design cooling load, respectively.|

TABLE 150.2-C—MAXIMUM INFILTRATION AIR CHANGES PER HOUR FOR LOAD CALCULATIONS	Col2	Col3	Col4	Col5	Col6	Col7
FLOOR AREA OF CONDITIONED SPACE	SINGLE-STORY HEATING	SINGLE-STORY COOLING	TWO-STORY HEATING	TWO-STORY COOLING	TOWNHOUSE OR CONDOMINIUM HEATING	TOWNHOUSE OR CONDOMINIUM COOLING
ACH for ≤ 900 ft2	0.61	0.32	0.79	0.41	0.69	0.36
ACH for 901−1,500 ft2	0.45	0.23	0.80	0.30	0.50	0.27
ACH for 1,501−2,000 ft2	0.38	0.20	0.50	0.26	0.43	0.23
ACH for 2,001−3,000 ft2	0.32	0.16	0.41	0.21	0.36	0.19
ACH for ≥ 3,001 ft2	0.28	0.15	0.37	0.19	0.32	0.17
CFM for One Fireplace	20	0	20	0	20	0

Performance approach. The energy budget for additions is expressed in terms of long-term system cost (LSC). Performance calculations shall meet the requirements of Section 150.1(a) through (c), pursuant to the applicable requirements in Items A, B and C below.

A. For additions alone. The addition complies if the addition alone meets the energy budgets as specified in Section 150.1(b). B. Existing plus alteration plus addition. The standard design for existing plus alteration plus addition energy use is the combination of the existing building’s unaltered components to remain; existing building altered components that are the more efficient, in LSC energy, of either the existing conditions or the requirements of Section 150.2(b)2; plus the proposed addition’s energy use meeting the requirements of Section 150.2(a)1. The proposed design energy use is the combination of the existing building’s unaltered components to remain and the altered components’ energy features, plus the proposed energy features of the addition. Exception to Section 150.2(a)2B: Existing structures with a minimum R-11 insulation in framed walls showing compliance with Section 150.2(a)2 are not required to comply with Section 150.0(c). C. Mechanical ventilation for indoor air quality. Additions to existing buildings shall comply with Section 150.0(o) subject to the requirements specified in Subsections i and ii below. i. Whole-dwelling unit mechanical ventilation. a. Dwelling units that meet the conditions in Subsection 1 or 2 below shall not be required to comply with the whole-dwelling unit ventilation airflow specified in Section 150.0(o)1C, 150.0(o)1E or 150.0(o)1F. 1.

§ 150.1 High relevance — show source text
1. Performance approach. The energy budget for additions is expressed in terms of long-term system cost (LSC). Performance calculations shall meet the requirements of Section 150.1(a) through (c), pursuant to the applicable requirements in Items A, B and C below.
A. For additions alone. The addition complies if the addition alone meets the energy budgets as specified in Section 150.1(b). B. Existing plus alteration plus addition. The standard design for existing plus alteration plus addition energy use is the combination of the existing building’s unaltered components to remain; existing building altered components that are the more efficient, in LSC energy, of either the existing conditions or the requirements of Section 150.2(b)2; plus the proposed addition’s energy use meeting the requirements of Section 150.2(a)1. The proposed design energy use is the combination of the existing building’s unaltered components to remain and the altered components’ energy features, plus the proposed energy features of the addition. Exception to Section 150.2(a)2B: Existing structures with a minimum R-11 insulation in framed walls showing compliance with Section 150.2(a)2 are not required to comply with Section 150.0(c). C. Mechanical ventilation for indoor air quality. Additions to existing buildings shall comply with Section 150.0(o) subject to the requirements specified in Subsections i and ii below. i. Whole-dwelling unit mechanical ventilation. a. Dwelling units that meet the conditions in Subsection 1 or 2 below shall not be required to comply with the whole-dwelling unit ventilation airflow specified in Section 150.0(o)1C, 150.0(o)1E or 150.0(o)1F.
1. Additions to an existing dwelling unit that increase the conditioned floor area of the existing dwelling unit by less than or equal to 1000 square feet.
2. Junior accessory dwelling units (JADU) that are additions to an existing building. b. Additions to an existing dwelling unit that increase the conditioned floor area of the existing dwelling unit by more than 1,000 square feet shall have mechanical ventilation airflow in accordance with Section 150.0(o)1C, 150.0(o)1E or 150.0(o)1F as applicable. The mechanical ventilation airflow rate shall be based on the conditioned floor area of the entire dwelling unit comprised of the existing dwelling unit conditioned floor area plus the addition conditioned floor area. c. New dwelling units that are additions to an existing building shall have mechanical ventilation airflow provided in accordance with Section 150.0(o)1C, 150.0(o)1E or 150.0(o)1F as applicable. The mechanical ventilation airflow rate shall be based on the conditioned floor area of the new dwelling unit. ii. Local mechanical exhaust. Additions to existing buildings shall comply with all applicable requirements specified in Sections 150.0(o)1G and 150.0(o)2.
D. Space-conditioning load calculations and system capacity. Additions to existing buildings shall comply with all applicable requirements specified in Section 150.2(a)1E.

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SINGLE-FAMILY RESIDENTIAL BUILDINGS—ADDITIONS AND ALTERATIONS TO EXISTING RESIDENTIAL BUILDINGS
§ 160.2 High relevance — show source text
iii. New dwelling units that are additions to an existing building shall have mechanical ventilation airflow provided in accordance with Section 160.2(b)2Aiv or 160.2(b)2Av as applicable. The mechanical ventilation airflow rate shall be based on the conditioned floor area of the new dwelling unit. B. Local mechanical exhaust . Additions to existing buildings shall comply with all applicable requirements specified in Sections 160.2(b)2Avi and 160.2(b)2B. 3. Water heater. When additional water-heating equipment is installed to serve a dwelling unit as part of the addition, one of the following types of water heaters shall be installed: A. A water-heating system that meets the requirements of Section 170.2(d); or B. A water-heating system determined by the Executive Director to use no more energy than the one specified in Item A above.

(b) Performance approach. Performance calculations shall meet the requirements of Sections 170.0 through 170.2(a), pursuant to the applicable requirements in Items 1, 2 and 3 below.
1. For additions alone. The addition complies if the addition alone meets the energy budgets expressed in terms of long-term system cost (LSC) energy.
2. Existing plus alteration plus addition. The standard design for existing plus alteration plus addition energy use is the combination of the existing building’s unaltered components to remain; existing building altered components that are the more efficient, in LSC energy, of either the existing conditions or the requirements of Section 180.2(c); plus the proposed addition’s energy use meeting the requirements of Section 180.1(a). The proposed design energy use is the combination of the existing building’s unaltered components to remain and the altered components’ energy features, plus the proposed energy features of the addition. Exception to Section 180.1(b)2: Existing structures with a minimum R-11 insulation in framed walls showing compliance with Section 180.1(b) are not required to show compliance with Section 160.1(b).
3. Mechanical ventilation for indoor air quality . Additions to existing buildings shall comply with Section 160.2 subject to the requirements specified in Subsections A and B below. When field verification and diagnostic testing are required by Section 180.1(b)3, buildings with three habitable stories or fewer shall use the applicable procedures in the Residential Appendices, and buildings with four or more habitable stories shall use the applicable procedures in Nonresidential Appendices NA1 and NA2.
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MULTIFAMILY BUILDINGS—ADDITIONS, ALTERATIONS AND REPAIRS TO EXISTING MULTIFAMILY BUILDINGS

A. Whole-dwelling unit mechanical ventilation . i. Dwelling units that meet the conditions in Subsection a or b below shall not be required to comply with the whole-dwelling unit ventilation airflow specified in Section 160.2(b)2Aiv or 160.2(b)2Av. a. Additions to an existing dwelling unit that increase the conditioned floor area of the existing dwelling unit by less than or equal to 1000 square feet. b. Junior accessory dwelling units (JADU) that are additions to an existing building. ii.
§ 110.0 High relevance — show source text
(a) Additions. Additions shall meet either Item 1 or 2 below.
1. Prescriptive approach. The envelope and lighting of the addition, any newly installed space-conditioning system, electrical power distribution system, or water-heating system; any addition to an outdoor lighting system; and any new sign installed in conjunction with an indoor or outdoor addition shall meet the applicable requirements of Sections 110.0 through 120.7, 120.9 through 130.5 and 140.2 through 140.9.
2. Performance approach. A. The envelope and indoor lighting in the conditioned space of the addition, and any newly installed space-conditioning system, electrical power distribution system, or water-heating system, shall meet the applicable requirements of Sections 110.0 through 120.7, 120.9 through 130.5; and
B. Either:

i. The addition alone shall comply with Section 140.1; or ii. Existing plus addition plus alteration. The standard design for existing plus addition, plus alteration energy use is the combination of the existing building’s unaltered components to remain, existing building altered components that are the more efficient, in LSC, of either the existing conditions, or the requirements of Section 141.0(b)2, plus the proposed addition’s energy use meeting the requirements of Section 140.1. The proposed design energy use is the combination of the existing building’s unaltered components to remain and the altered component’s energy features, plus the proposed energy features of the addition.

Exception 1 to Section 141.0(a): When heating, cooling or service water heating to an addition are provided by expanding existing systems, the existing systems and equipment need not comply with Sections 110.0 through 120.9 or Sections 140.4 through 140.5.

Exception 2 to Section 141.0(a): Where an existing system with electric reheat is expanded by adding variable air volume (VAV) boxes to serve an addition, total electric reheat capacity may be expanded so that the total capacity does not exceed 150 percent of the existing installed electric heating capacity in any one permit, and the system need not comply with Section 140.4(g). Additional electric reheat capacity in excess of 150 percent of the existing installed electric heating capacity may be added subject to the requirements of Section 140.4(g).

Exception 3 to Section 141.0(a): Duct sealing. When ducts are extended from an existing duct system to serve the addition, the existing duct system and the extended ducts shall meet the applicable requirements specified in Section 141.0(b)2D.

Exception 4 to Section 141.0(a): Additions that increase the area of the roof by 2,000 square feet or less are not required to comply with Section 110.10.

Exception 5 to Section 141.0(a): A gas hot water boiler system with a total system input of at least 1 MMBtu/h but no more than 10 MMBtu/h added to an existing building is not required to comply with Section 140.4(k)8.

Exception 6 to Section 141.0(a): A gas service water-heating system with a total system input of at least 1 MMBtu/h added to an existing building is not required to comply with Section 140.5(c).

Exception 7 to Section 141.0(a) : Section 140.4(a)2 shall not apply to new space-conditioning systems or components.

2025 CALIFORNIA ENERGY CODE 149
§ 1.88 High relevance — show source text
85|1.88| |1. NR = Not Required.|1. NR = Not Required.|1. NR = Not Required.|1. NR = Not Required.|1. NR = Not Required.|1. NR = Not Required.|1. NR = Not Required.|1. NR = Not Required.|1. NR = Not Required.|1. NR = Not Required.|1. NR = Not Required.|1. NR = Not Required.|1. NR = Not Required.|1. NR = Not Required.|1. NR = Not Required.|1. NR = Not Required.|1. NR = Not Required.|

Note: Authority: Sections 25213, 25218, 25218.5, 25402 and 25402.1, Public Resources Code . Reference: Sections 25007, 25008, 25218.5, 25310, 25402, 25402.1, 25402.4, 25402.8 and 25943, Public Resources Code .

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6 NONRESIDENTIAL AND HOTEL/MOTEL OCCUPANCIES—

ADDITIONS, ALTERATIONS AND REPAIRS

SECTION 141.0—ADDITIONS, ALTERATIONS AND REPAIRS TO EXISTING NONRESIDENTIAL AND HOTEL/ MOTEL BUILDINGS, TO EXISTING OUTDOOR LIGHTING, AND TO INTERNALLY AND EXTERNALLY ILLUMINATED SIGNS

Additions, alterations, and repairs to existing nonresidential and hotel/motel buildings, existing outdoor lighting for these occupancies, and internally and externally illuminated signs, shall meet the requirements specified in Sections 100.0 through 110.12, and 120.0 through 130.5 that are applicable to the building project, and either the performance compliance approach (energy budgets) in Section 141.0(a)2 (for additions) or 141.0(b) 3 (for alterations), or the prescriptive compliance approach in Section 141.0(a)1 (for additions) or 141.0(b)2 (for alterations), for the Climate Zone in which the building is located. Climate zones are shown in Figure 100.1-A.

Covered process requirements for additions, alterations and repairs to existing nonresidential and hotel/motel buildings are specified in Section 141.1.

Exception to Section 141.0: Alterations to healthcare facilities are not required to comply with this Section.

NOTES:
1. For alterations that change the occupancy classification of the building, the requirements specified in Section 141.0(b) apply to the occupancy after the alterations.
2. Relocation or moving of a relocatable public school building is not, by itself, considered an alteration for the purposes of Title 24, Part 6.
(a) Additions. Additions shall meet either Item 1 or 2 below.
1. **Prescriptive approach.
§ 141.0 High relevance — show source text
ADDITIONS, ALTERATIONS AND REPAIRS

SECTION 141.0—ADDITIONS, ALTERATIONS AND REPAIRS TO EXISTING NONRESIDENTIAL AND HOTEL/ MOTEL BUILDINGS, TO EXISTING OUTDOOR LIGHTING, AND TO INTERNALLY AND EXTERNALLY ILLUMINATED SIGNS

Additions, alterations, and repairs to existing nonresidential and hotel/motel buildings, existing outdoor lighting for these occupancies, and internally and externally illuminated signs, shall meet the requirements specified in Sections 100.0 through 110.12, and 120.0 through 130.5 that are applicable to the building project, and either the performance compliance approach (energy budgets) in Section 141.0(a)2 (for additions) or 141.0(b) 3 (for alterations), or the prescriptive compliance approach in Section 141.0(a)1 (for additions) or 141.0(b)2 (for alterations), for the Climate Zone in which the building is located. Climate zones are shown in Figure 100.1-A.

Covered process requirements for additions, alterations and repairs to existing nonresidential and hotel/motel buildings are specified in Section 141.1.

Exception to Section 141.0: Alterations to healthcare facilities are not required to comply with this Section.

NOTES:
1. For alterations that change the occupancy classification of the building, the requirements specified in Section 141.0(b) apply to the occupancy after the alterations.
2. Relocation or moving of a relocatable public school building is not, by itself, considered an alteration for the purposes of Title 24, Part 6.
(a) Additions. Additions shall meet either Item 1 or 2 below.
1. Prescriptive approach. The envelope and lighting of the addition, any newly installed space-conditioning system, electrical power distribution system, or water-heating system; any addition to an outdoor lighting system; and any new sign installed in conjunction with an indoor or outdoor addition shall meet the applicable requirements of Sections 110.0 through 120.7, 120.9 through 130.5 and 140.2 through 140.9.
2. Performance approach. A. The envelope and indoor lighting in the conditioned space of the addition, and any newly installed space-conditioning system, electrical power distribution system, or water-heating system, shall meet the applicable requirements of Sections 110.0 through 120.7, 120.9 through 130.5; and
B. Either:

i. The addition alone shall comply with Section 140.1; or ii. Existing plus addition plus alteration. The standard design for existing plus addition, plus alteration energy use is the combination of the existing building’s unaltered components to remain, existing building altered components that are the more efficient, in LSC, of either the existing conditions, or the requirements of Section 141.0(b)2, plus the proposed addition’s energy use meeting the requirements of Section 140.1. The proposed design energy use is the combination of the existing building’s unaltered components to remain and the altered component’s energy features, plus the proposed energy features of the addition.

Exception 1 to Section 141.0(a): When heating, cooling or service water heating to an addition are provided by expanding existing systems, the existing systems and equipment need not comply with Sections 110.0 through 120.9 or Sections 140.4 through 140.5.
§ 25218.5 High relevance — show source text
Note: Authority: Sections 25213, 25218, 25218.5, 25402, 25402.1, and 25605, Public Resources Code. Reference: Sections 25007, 25008, 25218.5, 25310, 25402, 25402.1, 25402.4, 25402.5, 25402.8, 25605, and 25943, Public Resources Code.

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9 SINGLE-FAMILY RESIDENTIAL BUILDINGS—ADDITIONS AND

ALTERATIONS TO EXISTING RESIDENTIAL BUILDINGS

SECTION 150.2—ENERGY EFFICIENCY STANDARDS FOR ADDITIONS AND

ALTERATIONS TO EXISTING SINGLE-FAMILY RESIDENTIAL BUILDINGS

(a) Additions. Additions to existing single-family residential buildings shall meet the requirements of Sections 110.0 through 110.9; Sections 150.0(a) through (n), (p) and (q); and either Section 150.2(a)1 or 2.

Exception 1 to Section 150.2(a): Additions of 300 square feet or less are not required to comply with the roofing requirements of Section 150.1(c)11.

Exception 2 to Section 150.2(a): Existing inaccessible piping shall not require insulation as defined under Section 150.0(j)1.

Exception 3 to Section 150.2(a): Space-conditioning system. When heating or cooling will be extended to an addition from the existing system(s), the existing heating and cooling equipment need not comply with Part 6. The heating system capacity must be adequate to meet the minimum requirements of CRC 303.10.

Exception 4 to Section 150.2(a): Space-conditioning system ducts. When any length of duct is extended from an existing duct system to serve the addition, the existing duct system and the extended duct shall meet the applicable requirements specified in Section 150.2(b)1Di and 150.2(b)1Dii.

Exception 5 to Section 150.2(a): Additions 1,000 square feet or less are not required to comply with the ventilation cooling requirements of Section 150.1(c)12.

Exception 6 to Section 150.2(a): Photovoltaic systems, as specified in Section 150.1(c)14, are not required for additions.
1. Prescriptive approach. Additions to existing buildings shall meet the following additional requirements: A. Additions that are greater than 700 square feet shall meet the requirements of Section 150.1(c), with the following modifications:
i. Extensions of existing wood-framed walls may retain the dimensions of the existing walls and shall install cavity insulation of R-15 in a 2 × 4 framing and R-21 in a 2 × 6 framing. ii. The maximum allowed fenestration area shall be the greater of 175 square feet or 20 percent of the addition floor area, and the maximum allowed west-facing fenestration area shall be the greater of 70 square feet or the requirements of Section 150.1(c).
§ 180.1 High relevance — show source text
Exception to Section 180.1(a)1: Additions that increase the area of the roof by 2,000 square feet or less are not required to comply with the solar ready requirements of Section 160.8. 2. Mechanical ventilation for indoor air quality. Additions to existing buildings shall comply with Section 160.2 subject to the requirements specified in Subsections A and B below. When field verification and diagnostic testing are required by Section 180.1(a)2, buildings with three habitable stories or fewer shall use the applicable procedures in the Residential Appendices, and buildings with four or more habitable stories shall use the applicable procedures in Nonresidential Appendices NA1 and NA2.

Exception to Section 180.1(a)2: A dwelling unit air leakage test is not required for additions. A. Whole-dwelling unit mechanical ventilation . i. Dwelling units that meet the conditions in Subsection a or b below shall not be required to comply with the whole-dwelling unit ventilation airflow specified in Section 160.2(b)2Aiv or 160.2(b)2Av. a. Additions to an existing dwelling unit that increase the conditioned floor area of the existing dwelling unit by less than or equal to 1,000 square feet. b. Junior accessory dwelling units (JADU) that are additions to an existing building. ii. Additions to an existing dwelling unit that increase conditioned floor area by more than 1,000 square feet shall have mechanical ventilation airflow in accordance with Section 160.2(b)2Aiv or 160.2(b)2Av, as applicable. The mechanical ventilation airflow rate shall be based on the conditioned floor area of the entire dwelling unit comprising the existing dwelling unit conditioned floor area plus the addition conditioned floor area. Exception to Section 180.1(a)2Aii: Mechanical ventilation systems in additions shall be supply, balanced or the existing ventilation type. iii. New dwelling units that are additions to an existing building shall have mechanical ventilation airflow provided in accordance with Section 160.2(b)2Aiv or 160.2(b)2Av as applicable. The mechanical ventilation airflow rate shall be based on the conditioned floor area of the new dwelling unit. B. Local mechanical exhaust . Additions to existing buildings shall comply with all applicable requirements specified in Sections 160.2(b)2Avi and 160.2(b)2B. 3. Water heater. When additional water-heating equipment is installed to serve a dwelling unit as part of the addition, one of the following types of water heaters shall be installed: A. A water-heating system that meets the requirements of Section 170.2(d); or B. A water-heating system determined by the Executive Director to use no more energy than the one specified in Item A above.

(b) Performance approach. Performance calculations shall meet the requirements of Sections 170.0 through 170.2(a), pursuant to the applicable requirements in Items 1, 2 and 3 below.
1. For additions alone. The addition complies if the addition alone meets the energy budgets expressed in terms of long-term system cost (LSC) energy.
2. Existing plus alteration plus addition. The standard design for existing plus alteration plus addition energy use is the combination of the existing building’s unaltered components to remain; existing building altered components that are the more efficient, in LSC energy, of either the existing conditions or the requirements of Section 180.2(c); plus the proposed addition’s energy use meeting the requirements of Section 180.1(a).

Frequently asked questions

When do I have to model the whole building instead of just the altered portions?

Any addition or alteration may comply by meeting the requirements for the entire building (the code explicitly allows the alternate method of compliance of modeling the whole building). See § 141.0(d) / § 180.4 for that option. file

If I replace a component but leave its performance the same, is that an alteration for modeling?

Yes — a replacement is treated as an altered component for determining the standard‑design altered‑component budget. See the notes to § 180.2(c).

Can I keep older, more efficient equipment as the baseline?

Yes — for an altered component the standard design uses the more efficient of the existing condition or the code altered‑component requirement. If the existing equipment is more efficient, the standard design will reflect that. § 150.2 / § 180.2 require this rule. file

Do small additions trigger solar/PV or roofing requirements?

There are limited exemptions: some roofing/solar‑ready requirements are not required for very small additions (for example ≤ 300 sq ft in certain clauses). See the exceptions in § 150.2(a) and § 180.1. file

What is the single most important modeling error to avoid?

Modeling the standard design incorrectly by changing unaltered existing component properties or by defaulting altered components to the code value when the existing component is actually more efficient — the code clearly instructs the standard design composition and the "more‑efficient" rule for altered components. See § 150.2(a)2B and § 180.2(c)2. file

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