Energy Maintenance Services Group

Every facility should include energy management. Maintenance services that focus on energy management will recommend that you get granular with your energy data. This can be difficult when the best source for data (the utility bill) is often extremely general regarding your facility’s energy consumption.

So what is the best way to get granular? Survey says, “Submeter your energy sources!” Sub metering allows facility managers to isolate energy consumption by sources (e.g., plug loads, HVAC, lighting) and by users (e.g., tenants, departments etc.) to better track and bill for the consumption.

So what is Submetering?

Submetering is installation of additional metering devices to measure energy consumption after the main utility meter.

The benefits are numerous:

• Eliminates inaccurate estimates
• Improved, more accurate billing
• Promotes energy savings
• Concise energy management
• Ease of use and installation
• Compliance with green requirements

Despite the benefits, I saw a recent survey in Building Operating Management that showed only one-third of facility managers use submeters widely and another third do not use them at all. This makes submetering a missed opportunity for facility managers, and the reason for this post. Part of the problem may be that it is more expensive to add a submeter after the facility is constructed.

Top Sources to Submeter

At a minimum, there are three energy consumption sources facility managers should consider adding a submeter to:

1. Plug loads
2. Lighting
3. HVAC systems

1. Plug loads

Plug loads include all electronics in the facility that tap into the building’s plug receptacles (e.g., computers, printers, coffee makers, space heaters etc.) According to Wikipedia, the Commercial Buildings Energy Consumption Survey (CBECS), a national sample survey project of the U.S. Energy Information Administration, reported that based on 2003 data, 19% of the total energy of U.S. office buildings is attributed to plug load energy use (office equipment, computers, and other energy use).

2. Lighting Systems

Most energy consumed in a building comes from lighting. I’ve seen estimates indicating that 20% to 50% of total energy consumption comes from lighting use or misuse. Most importantly, for some buildings, over 90 percent of lighting energy consumed can be an unnecessary expense through over-illumination. The cost of that lighting can be substantial. A single 100 W light bulb used just 6 hours a day can cost over $25 per year to use (.12/kWh).

3. HVAC

HVAC systems are another great source to focus a submeter on. Placing a submeter on your HVAC system can help you determine where spikes occur. Knowing where and when the spikes occur allows facility managers to determine whether the spike was due to a change in the weather or because the HVAC system was operating when it should have been turned off.