Guest post by Steve Mesh
Guess what time it is? You’re right – it’s time for a new version of California Title 24! Similarly to other “energy” codes, Title 24 is updated every three years. The latest version (Title 24-2019) takes effect on January 1, 2020.
Allowable lighting power densities (LPDs) for both indoor and outdoor lighting are getting lower and lower. For example, the LPD for office lighting using the Complete Building Method was 0.75 Watts/ft2 in the previous code (Title 24-2016). In Title 24-2019, it’s down to 0.65 Watts/ft2. For certain categories, the reduction is actually more than 50%. For example, the LPD for religious buildings dropped from 1.5 to 0.7 Watts/ft2. Considering all building categories, the average reduction in allowable LPD is 37% from the previous (2016) code. In the new code version, it is assumed that any fixtures used in new construction or alteration projects will be LED. They are not required to be LED. However, the assumptions about power usage are predicated on that assumption.
The irony is that as energy used by lighting systems is becoming so low, it almost seems silly to have such a complicated list of requirements for lighting and controls. This viewpoint has some major proponents in the lighting industry. It could also be argued, however, that the stringency of Title 24 over the past few decades has been a major force in moving the needle toward greater lighting efficiency. If you travel around the country, it is clear that California is still a leader in terms of its high expectations about low energy usage, and many other states (and energy codes) are catching up to California’s level of stringency.
As the allowable LPDs get lower and lower, the authors of Title 24 (as is also true with other codes) have to work harder to find things they can still tweak in new code versions. A perfect case in point is that it used to be legal for an occupancy sensor to have a time delay of up to 30 minutes before shutting off lights. In recent code versions, that was reduced to 20 minutes. However, there are some other changes in the 2019 code version that are worth mentioning.
One of the most striking changes to the 2019 code version is the addition of Section 130.1(f)1-130.1(f)7 – “Control Interactions.” Here is the code verbiage in its entirety:
(f) Control Interactions. Each lighting control installed to comply with Section 130.1 shall permit or incorporate the functions of the other lighting controls required by this Section.
1. For general lighting, the manual area control shall permit the level or amount of light provided while the lighting is on to be set or adjusted by the controls specified in Section 130.1(b), (c), (d), and (e).
2. The manual area control shall permit the shutoff control to turn the lighting down or off.
3. The multi-level lighting control shall permit the automatic daylighting control to adjust the electric lighting level in response to changes in the amount of daylight in the daylit zone.
4. The multi-level lighting control shall permit the demand responsive control to adjust the lighting during a demand response event and to return it to the level set by the multilevel control after the event.
5. The shutoff control shall permit the manual area control to turn the lighting on. If the on request occurs while an automatic time switch control would turn the lighting off, then the on request shall be treated as an override request consistent with Section 130.1(c)3.
6. The automatic daylighting control shall permit the multi-level lighting control to adjust the level of lighting.
7. For lighting controlled by multi-level lighting controls and by occupant sensing controls that provide an automatic-on function, the controls shall provide a partial-on function that is capable of automatically activating between 50-70 percent of controlled lighting power.
What in the heck does this new verbiage mean? Well, consider a unit control device such as a wallbox occupancy sensor. These typically have a manual switch(es) below the lens for the sensor. Some (but not all) of these also have a photodiode for sensing ambient light. This one device would meet the code requirements for “Shut-OFF Controls” as well as “Manual Area Controls”. However, wallbox occupancy sensors are not normally installed in large open areas such as open offices, classrooms, etc. Therefore, even if you used a wallbox occupancy sensor with an integral photodiode, the likelihood is that it would not qualify as an appropriate control device for meeting the “Automatic Daylighting Controls” requirement for primary sidelit, secondary sidelit or skylit zones. It also wouldn’t meet the requirement for “Multi-Level Lighting Controls”. Keep in mind that all LED fixtures and lamps must be continuously dimmable from 10-100% if used in any project in California. Most wallbox occupancy sensors are not made with an integral dimming function. Even for those that are, they are not typically designed to respond to a continuously variable signal from an integral photodiode.
What is the takeaway based on that example? What is shows is that Title 24-2019 is almost screaming: “USE NLCs, USE NLCs!!!!!” (networked lighting control systems). If you do, then you automatically have equipment and software which is designed to provide all of those functions – and more. For example, most spaces greater than 10,000 ft2 must have lighting control equipment which is demand response “capable” (whether you connect with a utility demand response program or not). This capability will be tested by a building inspector on-site, so there’s no getting around it. The controls you use on your project must have this capability. There is also greater specificity in the 2019 code version about this demand response function. For example, Section 110.12(a)1:
1. All demand responsive controls shall be either:
A. A certified OpenADR 2.0a or OpenADR 2.0b Virtual End Node (VEN), as specified under Clause 11, Conformance, in the applicable OpenADR 2.0 Specification; or
B. Certified by the manufacturer as being capable of responding to a demand response signal from a certified OpenADR 2.0b Virtual End Node by automatically implementing the control functions requested by the Virtual End Node for the equipment it controls.
Many NLCs have provisions for responding to a demand response signal and then automatically dimming or shutting lights off to meet the minimum 15% reduction code requirement (assuming you actually connect to the demand response signal – this is not yet required because it hasn’t yet met the financial hurdle for the state to insist on it). This can easily be accomplished by programming special “events”. That highlights the beauty of using a modern state-of-the-art NLC. Behaviors are programmed instead of “hard-wired” into the circuitry of a unit device.
In most NLCs, all of the controls requirements in Title 24 (and other codes) are easily met because individual devices are merely parts of a comprehensive system. That includes switches/dimmers, occupancy sensors, photosensors and possibly other devices as well (such as thermostats, etc.). Remember that the new verbiage in the 2019 code says … “Each lighting control installed to comply with Section 130.1 shall permit or incorporate the functions of the other lighting controls required by this Section”. That is exactly what happens in an NLC! Are you required by law to use an NLC to meet these requirements? No. Would it be easy to meet these requirements using unit equipment? No. In the lighting industry, we are not entering the Age of Aquarius – we are entering the Age of Networked Lighting Control Systems.
Here’s a summary of these top-level lighting control requirements for indoor lighting in Title 24-2019:
• 130.1(a) – Manual Area Controls
• 130.1(b) – Multi-Level Lighting Controls
• 130.1(c) – Shut-OFF Controls
• 130.1(d) – Automatic Daylighting Controls
• 130.1(e) – Demand Responsive Controls
The same code language as before still exists regarding specific requirements for each of these. For example, some specific applications require the use of a “partial-ON” or “partial-OFF” strategy where lights either come on to 50-70% of full power upon occupancy, or dim to 20-50% of full power upon vacancy, depending on the application. There are still lots of application-specific exemptions and requirements so you need to read through the actual code to make sure you are complying. All of the applicable documents describing California Title 24-2019 are located here.
Interestingly, the 2019 code now makes explicit reference in various places to not only lighting control “systems”, but even to very new technology such as PoE (Power over Ethernet). So, even if the California Energy Commission and the California Public Utility Commission can’t mandate the use of relatively expensive newer technologies, they know that these technologies are changing the market. The fact that there is at least some mention of these in the 2019 code version means that these technologies are worth considering in your next project – especially Networked Lighting Control systems!