If you’re planning a remodel in California—or you just want smart “upgrade while you’re already in there” ideas—this is the moment to pay attention. The 2025 update to California’s Building Energy Efficiency Standards (Title 24, Part 6) is now in effect for projects with permits applied for on or after January 1, 2026. That matters because many additions and major alterations now get evaluated through a stronger lens: efficiency, indoor air quality/ventilation, and electrification-readiness.
Even if you’re not in CA, the same principles apply anywhere: if you’re opening walls, ceilings, or floors, it’s the best time to improve comfort, reduce operating costs, and future-proof your home for cleaner electric systems.
At Modern Living Real Property, we focus on transformation—turning neglected houses into coveted homes. And one of the smartest renovation strategies is this: use the “walls open” phase to do the upgrades that are painful (and expensive) later.
Quick clarity: “Energy Code” vs. “CALGreen” (and why both come up)
- Energy Code = Title 24, Part 6 (California Building Energy Efficiency Standards). This is the big one for energy performance, HVAC, water heating, envelope, lighting efficiency/controls, and ventilation/IAQ requirements in many cases.
- CALGreen = Title 24, Part 11 (Green Building Standards). This overlaps with energy goals (and sometimes EV readiness / low-emissions / construction practices), and some provisions can apply to additions/alterations depending on the project type.
- Local “reach codes” may go beyond the state minimums (common in many CA cities). Always check your local building department for project-specific requirements.
What the 2025 Energy Code is pushing (in plain English)
California updates its energy code on a “triennial” cycle. The 2025 update continues the direction the state has been moving for years—more efficient equipment and cleaner buildings—with emphasis on:
1) Better efficiency through heat pumps (space and water heating)
Heat pumps are a major focus because they deliver heating (and cooling) efficiently and support building decarbonization. In new construction and many major projects, the “heat pump conversation” comes up fast—either required by the energy model or strongly incentivized by compliance pathways.
Upgrade idea while walls are open: even if you’re not installing a heat pump today, plan for it: electrical capacity, circuits, and the right placement for refrigerant lines/condensate routing.
2) Stronger ventilation and indoor air quality (IAQ)
Newer code cycles keep tightening the expectation that homes should be sealed better (less leakage) while also providing controlled ventilation (fresh air on purpose, not through random cracks). That’s where better bathroom fans, kitchen ventilation, and filtration strategies come in.
Upgrade idea while walls are open: run proper ducting for bath fans, improve kitchen exhaust routing, and plan for better filtration at the HVAC return.
3) “Electrification-readiness” (so the next upgrade is easy, not disruptive)
A lot of “electrification-readiness” is simply planning: making sure future electric upgrades won’t require opening walls again. That can include reserved panel capacity, conduit, and dedicated circuits for likely future loads.
Upgrade idea while walls are open: install conduit paths and/or wiring capacity for high-demand electrification items (heat pump water heater, induction range, EV charging, etc.).
4) Better building envelope performance (comfort + lower bills)
Envelope improvements (insulation, air sealing, windows/doors where applicable) are a core lever for compliance—especially because they reduce the load your HVAC system has to handle.
Upgrade idea while walls are open: air sealing + insulation details are usually the highest comfort ROI, especially in older homes.
What this means for “major renos/additions” in real life
When your project requires permits and crosses into “addition/alteration” territory, code compliance typically becomes more documentation-driven. Depending on scope, that can include energy forms, equipment requirements, and sometimes field verification (for example, duct sealing/leakage testing triggered by certain HVAC replacements or duct work).
Translation: the more you touch mechanical systems, conditioned square footage, or major envelope elements, the more likely you’ll need to prove compliance—not just “build it.”
The best “while walls are open” upgrades (practical, high-impact)
If you want the most useful checklist for a renovation, here it is—organized by what’s hard (or expensive) to retrofit later.
A) Air sealing + insulation (comfort first, savings second)
- Seal big leaks first: top plates, plumbing/electrical penetrations, recessed can lights (if any), attic hatch, rim joists.
- Insulate where access is easiest: exterior walls during remodel zones, attic knee walls, vaulted ceilings when opened.
- Don’t skip the details: a “pretty” insulation job can still perform poorly if air is flowing around it.
Useful reference: CEC: 2025 Building Energy Efficiency Standards
B) Ventilation upgrades that actually improve indoor air
- Bathroom fans: quiet, properly ducted to the exterior (not into attic spaces), and sized for the room.
- Kitchen ventilation: effective range hood and proper duct routing (short, smooth, exterior termination where possible).
- Fresh air strategy: if you’re tightening the home, discuss whole-house ventilation approaches with your pro (common in newer standards).
Where homeowners often source quality fans/vent components: Panasonic ventilation, Broan-NuTone
C) HVAC “future-proofing” (and duct realities)
- Duct sealing: if you’re replacing major HVAC components or adding significant duct runs, plan for sealing and possible leakage testing requirements.
- Return air upgrades: better return placement and filtration access can improve comfort and IAQ.
- Heat pump readiness: plan routing for linesets/condensate, outdoor unit location, and electrical needs.
Compliance resource (California-focused): CEC: Standards resources, forms, manuals
D) Electrical “electrification-ready” moves (cheap now, painful later)
This is where a lot of homeowners miss the moment. If walls are open, you can set yourself up for the next 10–20 years.
- Panel capacity planning: evaluate whether your main panel and service can support future electric upgrades.
- Run 240V circuits (or at least conduit) for:
- Heat pump water heater
- Heat pump HVAC / air handler needs
- Induction range
- Electric dryer
- EV charging (if parking layout supports it)
- Outlet strategy: kitchens, vanities, bidets, and utility zones benefit from thoughtful outlet planning now.
CA note: EV readiness is often discussed under CALGreen and local amendments; it can be relevant for certain project types and parking facility changes. If you want the official CALGreen framework (residential mandatory measures), start here: 2022 CALGreen Residential Mandatory Measures (HCD PDF)
E) Windows/doors only when the “why” is right
Windows are expensive. The best time to upgrade is when you’re already changing openings, repairing water damage, or solving comfort problems (drafts/solar heat gain) that can’t be fixed with sealing and shading.
- Seal + weatherstrip first if the window is basically sound.
- Replace if frames are failing, leaks persist, or you’re redesigning openings anyway.
“If I’m already doing a big remodel, what’s the smartest spend?”
If you want a short list of what’s usually worth spending a little money on during major renos/additions:
- Air sealing + insulation details (comfort and performance foundation)
- Quiet, properly ducted ventilation (bath + kitchen)
- HVAC duct sealing and smart filtration access
- Electrical capacity + circuits/conduit for electrification (heat pump readiness, induction, EV)
- Lighting done right (efficient fixtures + layered lighting + controls)
These choices don’t just “meet code”—they make the house feel better to live in.
Where to start (without getting overwhelmed)
- Ask your contractor/designer: “Which code cycle applies to my permit date?” (2022 vs 2025 standards can depend on when you apply.)
- Ask your HVAC pro: “Will this scope trigger duct sealing/leakage testing or HERS verification?”
- Ask your electrician: “If I want heat pumps and an EV charger eventually, what should I run while walls are open?”
- Ask your building department: “Are there local reach code requirements beyond the state baseline?”
Planning a major renovation or addition?
The smartest projects use code updates as a guide—not a burden. If you’re already investing in a transformation, it’s the perfect time to upgrade efficiency, ventilation/indoor air quality, and electrification readiness so the home is more comfortable now and more valuable later.
Explore real transformations here: Modern Living Real Property – Properties. For more practical homeowner guidance, visit Helpful Tips. When you’re ready to talk next steps, reach out: Contact Modern Living Real Property.