Electric Retrofits: What You Need to Know

If you own or manage a building with master metered electricity that is not submetered, you are likely getting zapped!

The average monthly cost for an apartment’s electricity usage is approximately $1,419 per year or about $118 per month. That equates to, not including common area expenses, a $23,600 electric bill just on interior usage for a 200 unit community.

If you haven’t considered submetering, now may be a good time to evaluate your options. Submetered apartments save between 15-25% on electricity versus non-submetered apartments. In addition to promoting conservation, many owners see a return on investment in less than 18 months.

Master Metered Electricity
A multifamily building with one master meter installed by the provider, or multiple in the case of garden style buildings, captures both common and interior usage for that particular building’s usage. In this scenario, the owner pays the entire bill directly to the provider.

Submetered Electricity
Submetering measures each individual apartment’s usage. The submeters are installed off the main line in a position that will capture all usage for lighting, appliances and HVAC where applicable (may require separate metering). The resident’s specific usage is billed back and allows for a fair and equitable solution to recoup interior electric expenses.

Is Submetering the Right Choice for You?
The building’s electrical configuration will determine what type of submetering solution you will need so it is critical to know what to look for before investing.

Below are key items to evaluate:

1. Locate the distribution panel. Is it in a common area closet, basement, outside or in each apartment?
2. If the distribution panel is located in a common area closet, does the distribution panel have a circuit breaker for each unit so that each can be turned off by itself at the panel? For example: 12 units per floor or 12 units per building.
   • If each unit can be turned off individually at the panel, it makes sense and is less disruptive and expensive, to submeter at the panel. The submeters are installed either in the distribution panel itself or right next to it.
   • If you can’t turn off one unit at a time, the submeter must go inside the unit next to the distribution panel, usually in or near the kitchen. A flush mount meter is recommended for aesthetics.
   • If the apartment distribution panel is in a closet, a protruding submeter can be used.
3. An outdoor distribution panel follows Steps 1 and 2 but requires a different, weather grade submetering solution. For example: An outside NEMA enclosure to house the meters.
4. Determine the Amp Rating on the main distribution panel: 20, 50, 100, 150, 200 or other.
5. Are the apartments labeled on the distribution panel? If not, this will need to be audited and identified prior to installation.
6. Determine the phasing for the distribution panel: Single-phase, three-phase, Delta phase or other.
7. How many wires feed the distribution panel? 2, 3, 4 or other?
8. The number and location of the building(s) will determine how the electronics needed to read the meters will be installed. A site map is important. Certain topography (mountains and hills) requires careful placement of electronics so reads can be collected. Basements may require more signal strength.
9. Determine where the data collector (a small computer that collects the reads) will go. An interior, dry and sometimes climate controlled space is required.

After conducting the above analysis, you are now ready to choose a submetering solution. A Request for Proposal (RFP) may be the easiest way to gather comparable proposals.  An RFP allows vendors to propose solutions based on your requirements so you can compare hardware specifics, pricing and labor. Remember that a licensed electrician should be included in the labor pricing and a drywall/painter as well if installing within the apartments.

Solutions by Electric Configuration

• Distribution panel: The distribution panel is in a common area or basement and each apartment can be turned off at the panel. Mini meters are the best and least expensive solution. A mini meter is small, designed for residential application and generally works for 100A, 200A, and 400A electric submeters. They are perfect for metering electric consumption or production for nearly any 120V 2-wire or 120/240V 3-wire application.
• Individual unit turn off: The electric for an apartment can only be turned off individually within the unit – A mini meter will still likely work plus an indoor flush mount enclosure. Additional expenses for drywall and paint work will need to be considered.
• Outdoor application: An outdoor rated MMU (Multiple Meter Unit) is typically the best solution. An MMU allows for multiple outdoor submeters to be installed at the exterior distribution panel in a weather grade enclosure. Another option is to use socket style meters. There are pros and cons with these in that they rely heavily on available building space and if meter sockets are already available or would need to be installed.

Be prepared to bring in reliable electricians to help you select the highest quality and most cost effective submetering solution. They will also determine the best configuration for your building type. The payoff is well worth the effort – greatly increasing revenue and property value while also encouraging conservation.

Kate Forsyth
Director of Energy Management for Minol
410.292.7132
kforsyth@minolusa.com

About the Author
Kate joined the Minol USA team in August of 2009. She currently oversees the Energy Management Program with a special emphasis on utility provider bill payment, cost avoidance and green initiatives.

Prior to joining Minol USA, she was employed by REIT AvalonBay Communities, Inc. for more than 20 years. While with AvalonBay, Kate successfully lobbied for the passing of the submetering law in Massachusetts in 2005.