Does Title 24 Require a Smart Thermostat?
Not in most homes: every heating or cooling system needs a programmable setback thermostat under Sections 150.0(i) and 110.2(c), but a demand responsive thermostat, which Joint Appendix JA5 calls an occupant controlled smart thermostat, is needed only where a project relies on certain exceptions. Some commercial and common-area systems need one too.
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The baseline: a setback thermostat
Section 150.0(i)1 requires every heating or cooling system in a single-family home, heat pumps included, to have a setback thermostat as specified in Section 110.2(c), unless a central energy management control system controls it. A setback thermostat has a clock that lets the occupant program temperature setpoints for at least four periods in 24 hours.
Some heaters are exempt from 110.2(c): gravity gas wall heaters, gravity floor and room heaters, noncentral electric heaters, fireplaces and decorative gas appliances, wood stoves, room air conditioners and room air-conditioner heat pumps.
Replacing equipment brings the thermostat into the job. When an air conditioner or heat pump is altered by replacing refrigerant-containing components such as the compressor, a coil or the metering device, Section 150.2(b)1Fi requires every thermostat on that system to be replaced with a setback thermostat meeting 110.2(c).
Heat pumps with backup heat
A thermostat controlling a heat pump with electric resistance or gas furnace supplementary heat must also take the outdoor temperature from a sensor or an internet weather service, display it, lock out supplementary heat above 35°F except in defrost or emergency heat, and show when backup heat is running (Section 150.0(i)2). The installer certifies the tested setup on the certificate of installation. More on our page on heat pump requirements.
When a smart thermostat is required in a home
The CEC's single-family manual puts it plainly: for residential dwellings, demand responsive controls are "only required as a part of specific Exceptions to HVAC and Solar Ready requirements." The ones you are most likely to meet:
- Refrigerant charge in cold weather. Below 55°F, an installer who charges a system by weight may use an alternative verification procedure if the thermostat meets Section 110.12 (Exception 1 to Section 150.1(c)7Aic, and its counterpart for alterations in 150.2(b)1Fiib). See refrigerant charge verification.
- Low airflow on an altered system. A system that cannot reach the minimum airflow may comply through the procedure in RA3.3.3.1.5 with a thermostat meeting 110.12 (Exception 1 to Section 150.2(b)1Fiia).
- A smaller solar zone. Exception 5 to Section 110.10(b)1A cuts the single-family solar zone from 250 to 150 square feet where all thermostats are demand responsive, and Exception 6 drops the minimum where they are and the home adds one of several listed measures. See solar ready requirements.
What JA5 asks of the thermostat
A demand responsive thermostat must be certified to the Energy Commission as meeting JA5, and its controls must work with OpenADR, either as a certified virtual end node or certified as able to respond to one (Section 110.12(a)1). Among the JA5 requirements, it:
- meets the setback requirement of Section 110.2(c)
- restores its programmed settings and network connection after a power cut
- by default moves the setpoint 4°F on a demand response or price signal: up for cooling, down for heating
- offers fixed event setpoints as an alternative to the offset, defaulting to 82°F for cooling and 60°F for heating, and by default cannot be set remotely above 90°F or below 50°F
- lets the occupant override an event and change any setting at any time
- shows connection status, an active event, the current temperature and the setpoint
The manual adds that demand responsive controls installed voluntarily, which do not contribute to compliance, need not meet these requirements. Whatever thermostat you choose still has to meet the setback requirement.
Apartments and commercial spaces
In apartments, each dwelling unit system needs a setback thermostat; demand responsive thermostats apply to common use areas, as our page on multifamily temperature control explains. In nonresidential buildings, Section 120.2(b)4 requires thermostats for single-zone air conditioners and heat pumps to meet Sections 110.2(c) and 110.12(a); see commercial thermostats and zoning.
Common Title 24 Questions
- What is Title 24?
- Do I need a Title 24 report?
- How much does a Title 24 report cost?
- How long does a Title 24 report take?
- What is included in a Title 24 report?
- What plans do I need to upload?
Frequently Asked Questions
No. A new home needs a setback thermostat for each heating or cooling system, plus the outdoor-temperature features where a heat pump has backup heat. A demand responsive thermostat is needed only where the design relies on an exception that calls for one.
The manufacturer certifies it to the Energy Commission, which lists certified products. A thermostat that has not been certified does not meet JA5, whatever its features.
When refrigerant-containing components are replaced, every thermostat on that system must be replaced with a setback thermostat meeting Section 110.2(c). A demand responsive one is needed only if an exception that requires it is used.
Yes. JA5 requires that occupants can change setpoints and settings at any time, including during an event.