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Energy Monitoring and Code Q&A

A guide to help you understand energy monitoring and metering code requirements and best practices.

Electrical room with multiple smart meters, cabinets, wiring and fire extinguisher.

As buildings become more sophisticated, building owners have gained the ability to have more insight over how building systems operate. Energy monitoring systems track energy usage in near real-time, and new advances in technology have made this effort easier and less expensive.

Advances in energy codes in the District have created a need for energy monitoring systems in new construction and substantially renovated projects. At the same time, DC Benchmarking Regulations and Building Energy Performance Standards create compelling use cases for better understanding how energy is being used in an existing building.

This post uses a Q&A format to help explain code-based metering requirements for new buildings in the District and best practices around how to apply metering to existing buildings and using data.

First off: What’s a Meter?

In simple terms, a meter is simply a device for recording usages of a connected load across a period of time. Think of a meter as a measurement device. Most buildings will have utility meters (which measure the amount of energy used at a building provided by the utility company). These utility meters are used by utility companies to track the energy used at a building. Utility companies then use this recorded usage to bill buildings.

In addition to utilities, submeters are common. These meters are installed downstream from the utility meter, so submeters serve part of a building load. Submeters are typically provided by private companies, and newer central electrical equipment like switchgearz allow for submetering to occur easily.

What Does Code Require?

The 2017 DC Energy Conservation Code’s Commercial Provisions includes requirements for energy metering and monitoring in two areas: Chapter 8 and Chapter 10. (Residential buildings are generally exempted from these requirements.)

Chapter 8, specifically Section 8.4.3, describes what sort of building loads need to be metered or sub-metered and applies to new buildings and buildings that are getting entirely new electrical systems, while Chapter 10, specifically Section 10.4.5, is focused on whole-building energy monitoring and applies to only new buildings. (You don’t need to commit those sections to memory, but this post references those sections regularly.)

Section 8.4.3 of the DC Commercial Code: Building and Component Loads

Section 8.4.3 covers both whole-building metering requirements and sub-metering requirements for newly constructed non-residential buildings and those undergoing a complete electrical system replacement.

Whole-Building Metering Requirements

Code says all energy delivered, produced, or reclaimed at a building level must be metered. This can be broken into two components: the form of energy and the type of energy. Energy forms include the following:

  • Energy delivered to the building. This includes electricity from the grid, pipeline gas, wood pellets for stoves, or coal for fancy pizza ovens.
  • Energy produced at the building site. Forms of energy produced on-site could include solar PV systems, biogas, electricity produced by engine generators like combined heat and power systems.
  • Energy reclaimed at the building site. This is uncommon but could include applications like large-scale heat recovery.

Energy types include the following:

  • Electricity
  • Natural gas
  • Fuel oil
  • Propane
  • Steam
  • Chilled water
  • Hot water

This applies to both buildings served by campus district energy plants and buildings served by pipeline gas.

These forms and energy types must be metered and monitored, usage and peak demand recorded, and these values must be stored for at least 36 months. What does that mean?

  1. Metering is what we talked about earlier, so that’s easy. (Remember: a meter is just a measurement device).
  2. Monitoring means a meter is required. (Monitoring is just that: keeping track of something.)
  3. Recording and reporting means that raw consumption data is stored and capable of being analyzed. The reporting system must “be capable of showing hourly, daily, monthly, and annual energy consumption and demand.” Note that the code also requires connection to a data acquisition system, although the code is silent on what this system entails. Some best practices on this system are later in this post!
  4. Most utility level meters and building management systems (BMS) today can report usage at a granularity greater than hourly—for example, 15 minutes.

Sub-metering: when is it needed, and how is it set up?

Sub-metering key building loads is required If a non-residential building is greater than 25,000 square feet. These key loads are broken into end uses:

  • HVAC system total energy use.
  • Lighting system total energy use.
  • Plug loads (loads connected to typical receptacles).
  • Process loads, best described as any single load that exceeds 5% of connected loads of the building. Think data centers, manufacturing equipment, or commercial kitchens.
  • Building operations and miscellaneous loads. This is a catch-all category for loads that don’t fit into the categories above. Think of this like “other.” (Elevators are the most common inclusion here.

This setup includes both designing space to put a sub-meter in any connecting that meter to a data acquisition system, as we described above. A few other cases apply:

  • For non-residential buildings smaller than 25,000 SF, sub-meters are not required – but space to install them in the future is.
  • For multi-tenant buildings, the code requires the metering described in the previous paragraph be provided for each floor in the building. This delineation is made on a per-floor basis.
  • Individual unit metering where the resident pays electricity bills directly to PEPCO is not the same thing as sub-metering.

The below graphic shows an example of all of these items in practice.

Wait, I thought sub-metering was banned in the district by the Public Service Commission’s Order 737 in 1928?

You are correct. However, title seven of the Clean and Affordable Energy Act of 2008 overturned the ban – but only for non-residential buildings.

Section 10.4.5 of the DC Commercial Code: New Building Whole-Energy Metering

Section 10.4.5 requires that every new building above a certain size is constructed with whole building energy metering for a specified set of energy sources and meter data acquisition. This section only applies for brand new construction and effectively copies the requirements in Section 8.4.3 with a few exceptions:

  • Buildings or additions less than 25,000 square feet
  • Individual tenant spaces less than 10,000 square feet
  • Individual dwelling units
  • Residential buildings with less than 10,000 square feet of common area
  • Fuel used on-site for emergency equipment.

Do these metering systems need to be commissioned?

Yep! As with many complex systems, a commissioning process is critical to getting a system that works. Metering and monitoring must be included in the project commissioning process. There are five main steps to successfully commissioning a metering system:

  • Define requirements – include energy metering, monitoring, and reporting in the Owner’s Project Requirements (OPR) document.
  • Review drawings – confirm that the devices and configuration shown on the drawings and specifications can satisfy the OPRs.
  • Install equipment and integrate metering devices data acquisition system.
  • Verify configuration of data acquisition – test the metering devices against known loads.
  • Training and turnover – the owner and operator of the system needs to know how to use it and the specific location of all the metering devices.

I have a campus. What should I do?

In the context of a campus with a central physical plant, the approach is straightforward:

  1. Include energy meters on chilled water, hot water, and steam lines (if applicable) to a new building
  2. Integrate these meters to the new building’s BMS.

Great, so I meet code. Now what?

While code requirements give building owners a base for tracking where energy is used at a building, it falls a bit short of providing useful data to building owners. To collect actionable data for a building, you’ll typically need more granularity than whole-building data or even energy data by end-use. Buildings should pair code-required energy monitoring with more granular data, including things that might come from a BMS.

This integrated system should be included in a project’s commissioning process. A commissioning report, as-built documents, and training material should be expected of energy monitoring system installations.

Can I get help from the local utilities?

Yep. Local utilities have the ability to provide pulse outputs to their buildings; these pulse outputs can be easily tied into a BMS.

Wait! What’s a pulse output?

Good question. Pulse generators or pulsers can be fitted to mechanical gas meters. Pulsers generate a pulse based on the movement of a crank and tangent assembly inside the meter. These pulses can be read by a data acquisition device like a field controller typical for a BMS.

For natural gas, in most cases, data acquisition equipment can be integrated onto utility provided energy meters. Typically, these meters measure uncorrected volumetric flow rates.

Similarly, for electricity, data acquisition equipment can be integrated onto utility provided energy meters—and it also uses a pulse output. These pulse outputs record electricity use per pulse (although the weight of the pulse varies by meter), and these pulses can also be read by a data acquisition device. In order to correctly read the amount of energy used onsite, the pulse weight must be known. The local utility will provide this pulse weight, usually written on the outside of the junction box containing the pulse output.

Can I use a BMS to help with this?

Sure, and if you read the previous section you saw how it can come in handy. Most new commercial buildings have a BMS that controls key energy-using equipment like central heating, cooling, ventilation, and domestic hot water systems. This equipment can provide detailed information on energy performance, but also requires a bit of additional programming of the BMS to effectively display key performance data like energy input and output.

Can I tie my BMS data in with my power monitoring data?

One awkward reality of smarter buildings: there are now a lot of different control systems for different equipment with different ways of handling data. Ideally, building operators would be able to see all building information in a single location, which means that different systems like a BMS and power monitoring system would be accessible via the same platform. This is accomplished through the use of communication protocols, or the language that building systems talk to each other.

Communication protocols are necessary in order to integrate different building systems—that’s how building systems “talk” to each other. Some protocols are “open” protocols, which means they use publicly available, standardized data tables. These systems are typically easier to integrate, allowing programmers to know what to expect from an otherwise unfamiliar system.

Other protocols are “closed,” meaning you can only get information from the manufacturer of that particular piece of equipment. Getting information out of these systems can be tricky, incomplete, and unclear to programmers.

Can you give more specific energy monitoring best practices?

Sure can.

  • Start by identifying your major mechanical energy users. Monitor the input and output energy of these systems. In most cases, this will include major HVAC equipment at a minimum; domestic hot water systems would also be reasonable for multifamily, hotel, or other building types with large DHW loads.
  • Tie your power monitoring system to your BMS. ‘Power monitoring system’ is a loose term. While offices, hotels, and other larger, central systems might have an actual power monitoring system, other building types like multifamily housing may be just as well served by installing pulse outputs on their utility services and tying those into the BMS. This is especially true in more unitized multifamily applications where it could be difficult to get effective sub-metered information on end uses.
  • Identify if you need to integrate end use platforms. Complex lighting systems may have their own controls. HVAC systems can sometimes come with their own controls. Neither of these systems may originally be seen as connected to a power monitoring systems. Instead, tie these systems together with a common, open protocol so anyone reviewing the collected information can view it from the same platform.
  • Display obtained data in ways that make sense for building occupants and operators. Setting up good reporting and good alarming capabilities is important. Alarms are used to help alert operators when a piece of equipment fails, a sensor goes out of calibration, or other issue comes up. While most BMS have operating and diagnostic alarms as part of their normal development process, performance alarms—such as “are we using too much energy?”—tend to either not be set up or set to a lower priority compared to alarms about equipment or sensors as noted above. Performance-based alarms are key for helping building operators stay proactive about energy use in the building.
  • Graphics and trending functions are helpful to assess performance quickly. Good, effective graphics take some time to develop but allow operators to figure out what’s happening at a glance. Trending is similar but allows you to figure out how a system has been operating over time.
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