You can’t manage what you can’t measure. This basic concept from any entry-level business class is becoming more common in energy codes and standards across the United States. California became the latest to address a building owner’s need for more electricity-use data with the 2013 updates to its state energy code. Though not as prescriptive as some other standards, it does require electrical contractors to reconsider how they specify and install nonresidential electrical panels.

Understanding the basics

The California Energy Commission’s code is formally titled “The Energy Efficiency Standards for Residential and Nonresidential Buildings,” but it is commonly known simply as “Title 24.” It has been a guide for California electrical professionals since 1978, but it has only been two years since the code began addressing power-distribution design, with the 2013 edition that went into effect Jan. 1, 2014. This update included the new Section 130.5, Electrical Power Distribution Systems, which, among other things, calls for new or substantially remodeled commercial buildings to allow for the possibility of submetering by load type and, in some cases, location. On a three-year review cycle, the next edition of Title 24, dated 2016, is set for a Jan. 1, 2017 release.

The standard is as follows: “Electrical power distribution systems shall be designed to permit the aggregated measurement of electrical load energy uses downstream from the service meter according to Table 130.5(b). Additive and subtractive methods may be used to determine aggregate and disaggregated energy use.”

The referenced table identifies the 10 load types to be measured, along with the increased level of disaggregation required at service ratings of 50 kilovolt-amperes (kVA), 250 kVA and 1,000 kVA. Several possible means for meeting disaggregation requirements are outlined, including using separate switchboards, motor control centers or panelboards for each load type or using subpanels (i.e., “split bus” panels) for each load type. However, an important exemption is included that negates the requirement for physical disaggregation in settings where a “complete metering and measuring system” has been installed.

The relatively low service threshold of 50 kVA means ECs working in fast-food restaurants, convenience stores and other such facilities will need to understand what’s required. According to Wayne Stoppelmoor, industry standards manager with Schneider Electric, Des Plaines, Ill., the 50-kVA entry-point was, in general, targeting facilities of 5,000 square feet and larger. However, much smaller projects also can be affected.

“It’s very dependent on the energy intensiveness of the building,” he said. “It really depends on the heating and cooling—and cooking—loads they have.”

Gary Gluck, business development manager at Siemens, Washington, D.C., said that load levels can reach the 130.5(b) threshold in surprisingly small facilities. The intent was to exempt owners of the smallest facilities, such as storefront offices, from any added expense. At 50 kVA, though, energy expenses could be becoming a more important component of ongoing operating costs, so identifying what building systems were having the biggest bottom-line impact could be helpful for those owners.

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“If they made it from the first amp, it would prove an undue burden,” he said, referring to the code’s developers. “They’re trying to deal with an entity that could have an electric bill that could occasionally give them a Maalox moment.”

Weighing the options

Facilities at the lowest level of required disaggregation, between 50 kVA–250 kVA, could face the greatest challenge because the least expensive option—separate panels for each load type—requires a commodity of which most small businesses have all too little: space. Larger facilities, such as supermarkets, usually already feature multiple panels, so disaggregation just means designating those panels and subpanels to specific loads. Small restaurants and gas stations, on the other hand, might not have this flexibility.

“Where it gets tricky is when you have a medium to small facility, where somebody was used to having a single panelboard,” Gluck said. “You’d have some owners or developers freaking out, because now you’re seeing three to four panelboards on the wall.”

In fact, confronting this situation at a number of McDonald’s outlets led Siemens to develop new split-bus products to enable a small facility’s loads to be more easily grouped by type within the same enclosure.

Troy Hull, director of the measurement and verification group for Leviton, Melville, N.Y., said many contractors he has spoken with end up opting for a permanently installed metering and measuring system. These designs generally include a multicircuit monitoring device that collects the required data from multiple circuits through the use of current transformers.

“The fine print says you can meet [the requirement] by installing submetering systems that would meet the intent,” Hull said, adding that many ECs find this to be more cost-effective than installing multiple load-specific panels. “They find it to be cheaper when you look at the total cost, and to be a much more palatable solution.”

The “smart” panels marketed by all the major panel-board manufacturers also qualify for this exemption by providing branch-circuit metering and monitoring from within the panel, itself. This is also the most expensive option, as these units can reach close to triple the cost of a split-bus product, but these units do offer installation savings.

“From the standpoint of labor, it would be almost negligible, because we completely embed the product in our panel,” Gluck said of his company’s version. “It really is transparent.”

Growing awareness

While ECs in California have had a couple years to get used to Title 24’s Section 130.5(b), the requirements did take some getting used to. Contractors, especially, as the point of contact with local electrical inspectors, were faced with a new series of rules in a document with which they’d been familiar for 25 years and not a lot of guidance on how to address them.

“[The 2013 edition] somewhat blindsided some of the industry, because now there was a power-distribution component; from 1978 to 2013, there was nothing about power distribution,” said Don McComas, chief engineer for metering at Eaton Corp., Moon Township, Pa. 

Even ECs who were getting specifications from consulting engineers were left scratching their heads, because those specifications often simply featured boilerplate language requiring panelboards to comply with local codes, without specific design details. As a result, installers brought their questions back to the major panel manufacturers, who then embarked on a major education campaign directed to consulting engineers.

Section 130.5(b) remains unchanged in substance in the 2016 Title 24, though code-writers responded to extensive industry input and made the requirement easier to understand, beginning with the section title. The word “disaggregation” has been replaced, and the title now reads “Separation of Electrical Circuits.”

Similarly, a slight change in the language of the standard itself emphasizes the intent is to simply enable metering by load type, not require it: “Electrical power distribution systems shall be designed so that measurement devices can monitor the electrical energy usage of load types according to Table 130.5-B.”

“They’ve taken out some of the language that made it confusing” Stoppelmoor said. “The 2016 language should make it easier to comply, as long as the panels can be set up to install a meter in the future.”

Coming soon to a jurisdiction near you

The move toward designing systems to enable submetering is becoming more prevalent across the United States. Fred Paul, an application specialist at Eaton Corp., sees the rise in such mandates being driven, at least in part, by the growing integration of renewable—and intermittent—energy sources into utility distribution systems. Many utilities are adopting time-of-use electricity rates to provide incentives to customers to match their demand to the availability of solar- and wind-energy resources.

This is especially true in California, which is committed to the goal of zero-net-energy commercial construction by 2030. However, California is not alone in its call for ever-more-
granular electricity-use data.

“It’s really been kind of a national effort,” Paul said. “You can’t say one state is leading another—they are all borrowing from each other.”

In fact, while Title 24 often garners attention for its frequently ambitious targets, other energy codes have much more stringent power-distribution system requirements, Stoppelmoor said. He cited the 2013 edition of the American Society of Heating, Refrigerating and Air-Conditioning Engineers’ Standard 90.1 and Washington state’s energy code as examples. Both require the installation of submetering equipment, not simply a system designed to accommodate submetering in the future.

“Title 24 stops short of requiring submetering,” Stoppelmoor said. “They’re actually not leading in the energy codes, they’re following.”