Understanding Baseload Energy Usage and Optimizing Water Heaters

In the realm of energy modeling, the term "baseload" refers to energy demands that remain consistent throughout the year, irrespective of seasonal changes. A significant component of baseload energy consumption includes refrigeration, lighting, and entertainment, with water heating contributing approximately eighteen percent of total energy use across the nation. This raises an important question: How can households effectively reduce their energy consumption from domestic hot water?

One of the first steps individuals can take is to explore low-cost and no-cost strategies. Behavioral adjustments can significantly impact energy efficiency. For example, when washing clothes, opting for lower temperature settings can be beneficial since modern laundry detergents perform effectively in cooler water. Additionally, washing full loads in both washers and dishwashers conserves energy and water. Simple habits such as not leaving the tap running while brushing teeth or shaving can also lead to noticeable savings.

Further, minor investments like installing low-flow showerheads and faucet aerators can substantially cut down on water usage. Pipe insulation on hot water lines can minimize heat loss during water distribution, thereby optimizing energy consumption.

While replacing a functioning water heater with a high-efficiency model might not always prove economically viable, certain situations may warrant it. The Office of Energy Efficiency & Renewable Energy provides various resources, including a Solution Center and a suite of tools known as RED Calc. Among these is the Domestic Hot Water (DHW) Systems Comparison tool, which allows users to analyze fuel usage and costs for multiple water heaters simultaneously, aiding homeowners in determining if the initial expense of a Heat Pump Water Heater aligns with their needs.

Another key consideration is water temperature. Many people may wonder how changing the water temperature from 140°F to 120°F could influence energy costs. While 120°F is often promoted for energy efficiency, its primary benefit is safety. Installation manuals for water heaters typically include charts highlighting the risk of burns at various temperatures. Setting the water heater to 120°F offers a safer option.

For those experiencing high peak-hour demand relative to their water heater's capacity, a thermostatic mixing valve could be a valuable addition. By setting the water heater to a higher temperature and using the mixing valve to control the delivered temperature, households can effectively increase the volume of hot water available. For example, if the tank’s temperature is at 140°F but the delivered temperature is regulated to 120°F, the effective capacity of the tank increases by about 25%. This modification can lead to a reduction in hot water needs, potentially impacting annual fuel costs.

The financial implications can vary based on a home's hot water usage. In some cases, a slight increase in fuel cost may be observed due to standby losses; however, this may be offset by decreased hot water production needs in households with higher usage, resulting in overall savings.

I encourage everyone to delve into the Domestic Hot Water tools offered by RED Calc as well as other building science resources, to better understand and enhance their home’s energy efficiency.