Triacta ebook

How to Choose the Right Electrical Submeter

It's well established that the best way to reduce energy consumption and save on building operating expenses is to give tenants full visibility of their electricity use. It's equally well established that the primary instrument for doing that is the electrical submeter.

But how do you choose the right submeter for the job?

What is Electrical Submetering?

Many commercial and residential buildings use a single "master meter." Electricity comes into a building at bulk rate prices from the Utility, and landlords bill tenants for electricity based on flat fees or formulas derived from the space they occupy. Occupants pay for electricity as part of a monthly bill, but their energy use is not individually monitored or tracked.

Electrical submetering  is the measurement of consumption after the master meter. Submeters (also referred to as power meters, electrical meters, and energy monitors) are installed after the master meter to measure individual electrical load.

Graphic of electricity coming into a building's Master meter and then measured after the panel by a multi-unit Sumter
Submeters can measure energy use for tenants, departments, building equipment, or any other electrical load.

The Benefits of Electrical Submetering?

Submeters allow for the granular measurement of energy, right down to the individual circuit. Building owners and property managers can pinpoint energy use, identify failing equipment, and allocate costs fairly by installing submeters. Tenants pay only for the electricity they use, are accountable for their consumption, use less energy, and lower their electricity bills.
Reduce Energy Use, Save Money
There are several strategies for reducing energy costs, but few are as compelling and fundamental as submetering. Many studies have shown that using submeters to allocate charges based on actual energy use is one of the most effective ways to reduce consumption. 

One of the most exhaustive examinations of applying electrical submetering to commercial buildings was undertaken by the U.S. Department of Energy as part of the Federal Energy Management Program (FEMP) in 2007. This study showed that merely installing meters resulted in a 2% reduction in energy use through the Hawthorne Effect. [1]

But that was just the start. FEMP found that submetering aspart of a coherent, continuous commissioning program of benchmarking, analysis, and remediation can result in 15% to 45% savings. [2]
Thinking in Three-Dimensions
Choosing the right type of meter means asking yourself three questions:
  • Do I need single or multi-point meters?
  • Should my meters be networked?
  • Do I need revenue-grade metering ?  

Single or Multi-point Meters ?

Single-point meters are useful for measuring specific points of interest in a building and have long been used in building management applications. But to gain enough knowledge to make successful energy management decisions, more granularity is required.

Doing this using single-point meters would require a tremendous number of them. In these situations, multi-point meters offer several advantages over single-point meters related to hardware cost and deployment.

Multi-point meters have a much smaller footprint than multiple banks of single-point meters, and lower per meter-point deployment and maintenance costs. Additionally, in commercial settings where building configurations often change, tenant moves are more easily accommodated when multi-point meters are deployed. 
One multi-point meter (in yellow circle) replaces multiple, single-point meters.

Networked, Or Not ?

This seems like an easy answer, but many meters are still being deployed today that need manual reading — costing time and money. And “orphaned” meters that have been forgotten completely is not an uncommon story in many facilities. So the answer is networked, of course.

But the question is not just about the absence of networking. It's also about what kind of networking you choose. Integrating with other systems (financial, building operation, IT, energy management, billing, etc.) is critical in today's connected world. Choosing submeters that are local area network-based (ethernet or wireless) and IP-centric allows them to "speak" to other systems and enables integration today and tomorrow.

The language your meters speak is an important consideration too. The free and unobstructed flow of meter information to all stakeholders, systems, and applications with a need to know should be your goal. To ensure that your data remains in your control and can be easily used today and tomorrow, your meters should use open protocol, non-proprietary data formats.
Open protocol + Non-proprietary Data Formats = Free Flow of Information + No Vendor Lock-in

Revenue-grade, or Not ?

There is a growing wave of regulation throughout North America focused on the metering of electrical consumption. Simply put, if money changes hands (as with government incentive programs or tenant billing), certified meters are becoming a legislated requirement.

Regulatory bodies are using the tried and true ANSI c12.20 0.5 accuracy class as the standard meters must meet — and requiring third-party laboratory certification to prove that they do.

To be clear, if a meter is only being used for internal purposes and not to bill tenants or receive financial remuneration, it does not have to be a regulated meter. In fact, there are no such rules for certification in some jurisdictions, even on financial transactions. But this is not a viable approach long-term — and regulation is destined to be introduced across North America.
There is a growing wave of regulation focused on the metering of electrical consumption.

So What's It Going to Be?

When planning a project that requires metering or monitoring, property managers and building owners need to understand current requirements while keeping an eye on what the future holds.

Ask yourself how many meter points you need to measure — today and down the road. If it's just a few, then single-point meters are likely the best route to go. But suppose you have several circuits to measure, and the allocation of those circuits is likely to change over time. In that case you might do better by taking advantage of the lower deployment, integration, and maintenance cost of multi-point meters.

Meters deployed today should be connected to a building's network. The cost-savings gained by avoiding manual meter reads and orphaned meters is reason enough alone. More compelling, however, are the benefits property managers and building owners gain when their energy data can flow freely to all of their building systems.

Benefits that include sending meter reads and pulse collection information to a billing agent while also sharing it with an energy management service for ongoing monitoring. Or being able to trial a new energy management analytics service while continuing to use your current vendor. You can only realize these benefits if you use IP-centric, open systems meters.

Lastly, there are many reasons for property managers and building owners to consider using regulated meters over non-regulated. The primary one being the requirement for an approved instrument of measure when allocating energy costs to building tenants. 

But even if current objectives are not for billing, goals change. With the small total incremental project costs associated with using approved meters versus unapproved — it makes sense to keep your options open.