When you replace a furnace, an air conditioner or a heat pump in California, the job has to meet Title 24, the state’s Building Energy Efficiency Standards. Many people think of the energy code as a rule for new houses, but replacing heating or cooling equipment counts as an alteration, so it applies to an ordinary change-out too. What it requires depends on the job and on the code in effect when the work is permitted. Your installer confirms the requirements for your specific home; this guide explains what they generally cover.
What Title 24 is
Title 24 is the part of California’s regulations that holds the state’s building standards. Its energy standards, developed by the California Energy Commission and updated periodically, set efficiency rules for new homes, additions and alterations. For an HVAC replacement they touch four areas: the efficiency of the new equipment, the ducts, independent verification of some of the work, and the documents that prove compliance. Because the rules are revised from time to time, what applied to a neighbour’s replacement a few years ago may not match what applies to yours.
Minimum equipment efficiency
New equipment has to meet the minimum efficiency for its type and size. These are the ratings to look for:
| Equipment | What is rated |
|---|---|
| Central air conditioner | SEER2 (seasonal cooling efficiency) and EER2 (efficiency at peak outdoor heat) |
| Heat pump | SEER2 for cooling and HSPF2 for heating |
| Gas furnace | AFUE (how much of the fuel’s energy becomes heat for the house over a season) |
Federal standards set most of these minimums. California is in the federal region where central air conditioners must meet an EER2 minimum as well as a SEER2 minimum, so a model sold for colder states may not be allowed here. A rating also belongs to a matched system: an outdoor unit paired with a different indoor coil or air handler can carry a different rating, so the installer checks the exact combination going into your home.
A minimum is a floor, not a recommendation. Our efficiency ratings guide explains how to weigh a higher rating against what it costs.
Duct leakage testing
Ducts are where Title 24 most often changes a replacement job. Ducts in attics, crawlspaces and garages lose heated and cooled air through loose joints, torn connections and gaps at the registers. On many change-outs of ducted systems, and when ducts are added or replaced, the code calls for:
- A leakage test. The registers and returns are sealed off, a calibrated fan pressurizes the duct system, and the instrument measures how much air escapes.
- Sealing and retesting if the leakage is above the allowed limit.
- Insulation on new or replaced ducts in unconditioned spaces such as the attic, to the level the code sets.
There are exceptions, and they depend on the job and the current code. Ask before the work starts whether duct testing is part of your project, so it is in the quote rather than a surprise later. A failed first test does not mean the new equipment is wrong. It means air you pay to heat or cool is escaping before it reaches the rooms, and sealing it can help the rooms at the far end of the duct runs.
Third-party HERS verification
On many replacements, some of the installer’s work has to be confirmed by a HERS rater. HERS stands for Home Energy Rating System. The rater is independent of the installer, works through a HERS provider approved by the California Energy Commission, and visits the home to run or witness the required tests. Duct leakage is the most common one. Depending on the equipment and the job, other field checks, such as airflow across the indoor coil or the refrigerant charge, can also be on the list.
The rater’s results are recorded with the rest of the compliance documents, and the building department looks for them before it signs off. You do not normally hire the rater yourself; the installer schedules the visit. Your part is giving access to the attic, the registers and the equipment.
Sizing and thermostats
When the whole system is new, ducts included, the code expects the equipment to be sized from a heating and cooling load calculation for the house. Even on a simple change-out, a load calculation is the sound way to size the new unit, rather than copying the old unit’s size or adding capacity to be safe. An oversized system tends to short-cycle and remove less humidity.
A replacement also brings the thermostat into the picture: the energy code generally expects a programmable setback thermostat on a system whose heating or cooling equipment is replaced. If your home still has an old dial thermostat, plan on a new one as part of the job.
The paperwork, and why the installer handles it
Title 24 compliance is documented on standard forms:
- a certificate of compliance, which describes the work and how it meets the energy code;
- an installation certificate, signed by the installer, recording the equipment and the installer’s own test results;
- a verification certificate from the HERS rater, where verification applies.
You may see them called CF1R, CF2R and CF3R. The installer handles them because the installer has the model numbers and ratings, runs the tests, signs the installation certificate, books the rater and holds the permit the forms belong to. The building department generally will not close the permit until the required documents are complete. For how the permit itself works, from application to final inspection, see our guide to permits for HVAC work.
Testing, sealing and the rater’s visit add time and cost to a replacement. A complete quote includes them, so compare quotes on the same scope of work. Once the job is done, ask for copies of the finished certificates.
A Hayward note: original ducts
A lot of Hayward homes built between the 1950s and the 1970s still run on their original ductwork, mostly in the attic and, in some slab homes, under the floor. After decades, joints loosen and old tape lets go, so a leakage test on one of these systems can find a lot of leakage. Attic ducts can usually be sealed or replaced; ducts in a slab are much harder to reach. If testing turns up a duct problem, ductwork repair becomes part of the plan, and it is better to know that before the new equipment goes in.
Getting quotes for an AC installation, a furnace installation or a move to a heat pump? Ask each installer how Title 24 testing and verification will be handled for your home.