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Crouching Heater, Hidden Pool Pump

This article originally appeared in the May 2-18 issue of Strategies, the magazine of the Association of Energy Services Professionals (AESP.ORG).

Crouching Heater, Hidden Pool Pump

The unintended consequences of missing appliances when analyzing loads

Utilities collect and analyze energy usage data for various purposes such as fine tuning load predictions, designing demand side management programs, and improving rate allocation models. While there are many ways to create usage models, there are two common methodologies. Data-based analysis, such as direct load monitoring and disaggregation, create a per-appliance model by analyzing actual user data. Statistical models, such as fixed allocation and regression analysis, use general assumptions to model usage loads. While statistical models are a common method, they can often miss “hidden” usage loads. These missed usage loads can be significant, leading to unintended consequences for utilities and their customers.

Load Analysis 101

Fixed Allocation Model

Itemizes energy according to “typical” energy usage loads for a given home type and climatic region. Itemization does not vary based on conditions (such as weather) or consumer behavior.

Correlation and Regression Analysis

Itemizes energy usage by statistical modeling against factors such as region/weather, home type, and occupancy. Itemization varies by dynamic conditions such as weather, but does not take into account changes such as vacations or appliance upgrades. Often relies on user input to detect presence of appliances.


Itemizes energy usage by applying machine learning algorithms to  energy usage patterns, typically using AMI data. Provides personalized itemization and identifies loads such as heating, cooling, refrigerator, pool pump, electric water heater, and EV without needing user input.

Electric Water Heater: Wherefore Art Thou?

While water heaters are pretty large appliances, they are very good at hiding. Electric water heater loads are often camouflaged within HVAC load because they don’t have a predictable pattern of their own. It’s difficult to develop a general assumption regarding the presence of an electric water heater based on home type or size. Whether a home has an electric or gas water heater can vary based on regional characteristics, construction standards, and the age of the residence. Simple load analysis will often erroneously attribute the energy used by the water heater to HVAC loads. This can lead to frustration for many customers that are conscientiously managing their heating levels if the utility incorrectly recommends they lower thermostat levels.

Did You Know?

In reviewing disaggregated usage data, we learned that in most of the U.S. there is a 40-50% variation between water heater energy consumption in winter versus summer. This is due to the diversity in weather climates, combined with water infrastructure standards that insulate against seasonal swings in water temperature. In Australia, the variance between summer and winter is lower because because few parts of the country reach below freezing temperatures. Conversely, in Japan we identified a 200-300% difference in energy consumption in winter compared to summer due to a difference in infrastructure standards as well as most regions experiencing freezing temperatures.

By not identifying electric water heaters, utilities miss the opportunities for customer engagement to provide water heater-related recommendations. For instance, if the customer has a timer on the water heater, it could be set for an hour before the morning alarm, eliminating water heater cycles during the night. Alternately, the customer could be advised to turn off the water heater from midnight to 5:00 am.

Pool Pumps: Pay No Attention to that Pump Behind the Cabana

Pool pumps are often excluded from simple load analysis because it is difficult to identify which customers have pools. In hot geographies with very cold winters, many people turn the pool pump off in the winter. The load is often hidden in the summer, when they turn the pump back on, because simple analysis attributes the seasonal usage spike solely to air conditioning. In some regions pools are commonplace, and by omitting the pool pump energy load, utilities can miscategorize a large “pool” (sorry!) of customers. This leads to skewed usage levels, and missed opportunities to educate customers on the best times to cycle pool pumps in order to manage spikes in energy consumption.

When correlating usage against weather, the hidden pool pump load can adversely affect air conditioning sensitivity analysis by overestimating cooling usage. Hence any demand side management program would overstate the savings possible from switching AC off, or from changing the setpoint. Depending on the magnitude of the inaccuracy, summer demand side management and efficiency programs could be less effective and require greater intervention.


Failing to account for pool pumps also affects customer engagement. The increased load caused by a pool pump cycling during the day could lead to an assumption that the customer is home during the day. Utilities that target customers based on usage segmentation would send information that is not pertinent to that customer. Even more detrimental, inaccurate load analysis for a pool customer would make his or her home appear inefficient compared to similar homes within the region. This can lead to customers complaining about being “energy shamed” on their home energy report, a particular concern for many utilities.

Isolating pool pump usage from air conditioning usage also helps to optimize summer demand response programs, as the incremental effect of each air conditioning unit can be more accurately predicted and balanced. The utility can explain to customers that syncing household usage with a timed pool pump schedule can be a big cost saver. In winter, the utility can encourage the customer to run the pool pump during the day, when peak energy loads are lower. In the summer, the pool pump could be run in the evening, avoiding daytime air conditioning peak loads. Residents can also be informed of the inefficiency of old pool pumps, and the savings they could realize by replacing them.

EV Chargers: Now You See Me, Now You Don’t

EV chargers contribute another energy load that often hides within plain sight. After installation of a charger, the customer’s overall usage may increase. Because most electric vehicles are plugged in at night, the utility may incorrectly correlate the increase in load to temperature and time, grouping the usage with either heating or lighting loads. By detecting and separating the EV load, the utility is able to proactively offer a cost effective rate structure or recommendations on managing charging times. This increases customer satisfaction, as the customer feels that the utility is a partner in his or her energy conservation journey.


As technology advances, the ways we use data to understand consumer behavior and make energy saving adjustments will continue to evolve. As an increasing number of utilities turn to data-based disaggregation, they are finding greater accuracy in their usage load models. This identification drives even greater energy efficient behavior, as the utility gains a more clear understanding of which loads are shiftable and reducible. In the long term, a more predictable and stable model of usage will allow the industry to develop more equitable rate structures that charge consumers based on actual energy costs and that truly reward energy conservation practices.


The more utilities engage with customers, helping them to understand their energy billing and control their costs, the greater overall customer satisfaction. If customers feel that utilities truly understand their energy usage and that the information the utility provides is correct for their situation, they are much more likely to approve of the utility. This is reinforced by the recent JD Powers 2017 Energy Utility Products and Services Study that found customer satisfaction is dramatically improved by actively engaging with customers across a number of channels. Developing these lines of communications will enhance customer service, billing and corporate citizenship.