Can I Calculate Plug Load Savings Without an IGA?

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 Yes, it’s possible to calculate potential plug load energy savings without performing an investment grade audit. Most energy managers do not have the tools or enough information to confidently estimate potential plug load savings for their buildings.  This post will explore different methods to calculate potential savings without performing an investment grade audit.

These estimates will be less accurate than an IGA savings estimate, but they are often sufficient to determine whether it makes sense to proceed with a detailed audit. 

Calculate Estimated Plug Load Savings using Rule of Thumb

When specifics about the number and types of loads are unknown, the following rule of thumb can be used to gauge potential energy savings: 

The yearly cost to power an uncontrolled kW load is roughly $1,000. Powering the load off nights and weekends saves nearly $700 each year since commercial buildings are only occupied about 30 percent of the time.

Here’s the math:

Annual Cost Uncontrolled kW MEL at $.11 kWh
Devices are on all day, every day

8,760 hours on x $.11 kWh rate = $ 963.60

Annual Savings Controlled kW MEL at $.11 kWh
Devices turned on weekdays, turned off nights and weekends

6,132 hours off x $.11 kWh rate = $ 674.52

Use Automated Plug Load Energy Savings Calculator

A more accurate and detailed plug load energy savings estimate can be created with an automated savings calculator like Bert’s Preliminary Savings Sheet (PSS). The PSS estimates the number of common plug loads for each building based on the type of building and its size.  It also includes potential kWh and dollar savings for the project by device type and building.  

Bert uses exclusive data about the number of devices per square foot and average hourly standby loads from earlier projects to estimate savings. The following data is needed for Bert’s model: building types, square footages and kWh rates.  

Contact Bert for a Preliminary Savings estimate.

Audit Buildings For Most Accurate Plug Load Energy Savings Calculations

A detailed physical inventory is the most accurate way to estimate savings. Without this level of detail, it is simply not possible to accurately calculate plug load energy savings.

Record the location, quantity and device type of all plug loads electronically. This makes the savings estimate more accurate.  In addition, ESCOs, installation partners, and the end user can all easily access the data. At the same time, determine the standby load for each device type. Run the IGA saving model using actual audit counts and standby loads.

Compare Measured Overnight Load to Savings Estimate to Verify Energy Savings

Once control and measurement devices, such as the Bert Smart Plug and Inline Series, are installed the savings model should be run again using the ‘as-built” quantities and measured standby loads. Compare KWh and dollar savings to the earlier savings estimates.

Calculate the Reduction in Baseline Load Percentage

Finally, compare the proportion of the Overnight Load to the Baseline Load to calculate the energy savings as a percentage of the total Baseline Load. In most projects, Overnight Load represents somewhere between 30% and 50% of the Baseline Load.



This percentage varies greatly between projects, depending on occupancy hours, kinds of devices controlled and the daytime energy usage patterns. In buildings with heavy daytime device usage, the daytime load represents a larger proportion of the overall load, so reduction in baseline load will be closer to 30%. In buildings where devices are used less frequently during the week, the daytime and overnight loads will be closer in size.  In these cases, baseline load reduction could be close to 50 percent.

As you look at the percentage, keep in mind that the percentage reduction is not directly related to the project’s kWh or dollar savings.  A lower percentage does not mean that a project is saving less money or fewer kilowatt hours than a project with a higher percentage. It just means that, on a relative basis, the projects with the smaller  reduction percentage has larger daytime loads. 

Breakdown of the Baseline Load

Baseline Load: kWh recorded during baseline data collection
Includes all devices and circuits that will be controlled. Devices operate without schedules, collecting hourly measurement data. Baseline Load is split into two categories for savings calculations: Daytime Load and Overnight Load.

Daytime Load: kWh while the building is occupied
This load varies from week-to-week and can differ from the load recorded during baseline data collection. Devices are scheduled on. 

Building operators seeking detailed information about daytime device usage should use an administrative dashboard like Bert Analysis to analyze and compare daytime energy usage.

Overnight Load: kWh while the building is empty
Also called Standby Load. This load is eliminated once devices are scheduled. Total kWh savings and dollars are equal to the size of this load.

Bert Plug Load Solution Delivers Missing Energy Management Piece

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Welcome to Bert’s new blog about plug load solutions for commercial buildings. We plan to cover a variety of topics – potential energy savings from managing loads, various plug load control options, implementation strategies and more.

Bert’s Plug Load Solution for “Everything Else” in the Building

Bert’s plug load solution delivers the missing energy management puzzle piece; control and management for small electric loads not connected to Building Automation Systems (BAS). These loads have many names: plug loads, hardwired loads, commercial miscellaneous electric loads, plug and process loads (PPLs). While individual loads are small, plug loads are actually the fastest growing source of energy usage in commercial buildings.  In addition, plug loads are also frequently the largest source of energy usage.

The BAS handles HVAC, lighting and mechanical systems, but doesn’t address plug loads. Bert describes these loads – which are outside of a building’s core functions – as “everything else” in commercial buildings. Typical devices include printers, copiers, classroom electronics, vending machines, exhaust fans, break room equipment, window AC units, electric hot water heaters and air handling units. 

Plug loads run 24/7 because they are not managed or controlled. Buildings waste money powering devices in empty buildings. Bert’s plug load management solution uses the existing wireless network to turn devices off when buildings are empty. At the same time, Bert collects and stores real-time granular device, measurement and temperature data for increased efficiency and comfort. As a result, building operators save money and gain valuable insight into building operations. Bert can either be installed as a standalone solution or integrated into the existing BAS.

Bert controls everything else

Plug Load Data from 40,000 Loads

Bert is the leading wireless Plug Load Solution supplier, with over 40,000 smart plugs and inline units installed. Bert controls devices in school districts, colleges, local governments, office buildings, and sporting venues. In each project, Bert inventories the number and types of plug and hardwired loads by building. Data is entered into Bert’s proprietary data model.

In short, we crunch the numbers to calculate the average number of devices – printers, vending machines, charging carts etc. – found per square foot in particular building types. Bert maintains density factors for elementary schools, middle schools, high schools, college academic buildings, academic labs, administrative/office buildings and public assembly buildings.

Bert collects baseline measurement data from loads each device after the plug load control hardware is installed.  The data is analyzed to determine average standby loads and energy usage patterns for various devices.

How Much Energy Do Plug Loads Use Each Year?

To put plug loads into context:

According to the Department of Energy, devices with non-traditional end uses consumed over 7 quadrillion BTU in 2012. That’s a big number.  In fact, it’s equivalent to the amount of dynamite needed to carve Mount Rushmore 135,800,000 times, according to the Department of Energy’s Direct Currents Energy Unit Calculator .  The calculator uses alternative energy units to make energy consumption easier to understand.

The Energy Information Administration Annual Energy Outlook (AEO) 2015 forecasts that primary energy consumption from plug loads will grow 27% from 2016 to 2030 and the contribution of these loads to total building energy consumption increases from 36% in 2016, to 43% in 2030 under its business-as-usual scenario.

Standby or overnight loads associated with MELs account for more than 100 billion kWh and $ 11 billion in annual energy costs in the United States alone, according to Energy Star®. In case you’re wondering – that’s the same amount of energy needed for 6,116 Moon Landings.