A new study shows more efficient water heaters can save homeowners money, reduce energy consumption, and help lower carbon emissions.
When you consider that domestic water heating accounts for up to 20% of the household energy usage, and that a conventional water heater loses 57% of the energy before hot water even gets to your shower, tub or kitchen faucet, you have to wonder if there is a better alternative.
So what is the best, most efficient water heating technology available today?
The Wilden Living Lab is a Kelowna-based research project initiated by the Green Construction Research & Training Centre, a partnership between UBC and Okanagan College. Additional partners are AuthenTech Homes, FortisBC and Wilden, Kelowna’s largest master-planned community. The partners recently conducted a study to assess the performance, strengths and weaknesses of energy-efficient water heaters.
The study compared three homes with three different water heating systems. Two of the homes have been built and their energy consumption monitored for three years. The third home, designed to bring energy waste to zero, is currently under construction.
The first home, the Home of Today, has a conventional electric water heater that stores water in an insulated tank. In the second home, called the Home of Tomorrow, the water heater uses a heat pump to extract heat from the surrounding air and stores the water in a tank. According to the U.S. Department of Energy, a heat pump water heater is two to three times more efficient than a standard electric water heater.
Results for the third home or Next Generation Home now being built were modeled on it having a tankless natural gas water heater that heats water instantly on demand. The U.S. Department of Energy reports that a tankless water heater uses up to 34% less energy than a conventional electric water heater.
The table below summarizes the results of the study conducted by UBC Okanagan’s School of Engineering. Under current utility rates, heat pump water heaters offer substantial cost savings and a relatively short payback time of just 2.6 years. The natural gas tankless heater planned for the Next Generation Home offers slightly higher savings but will take 4.1 years to pay back the capital investment. These payback times are very reasonable, making both options a better economic choice than conventional electric water heaters.
Whether you are building from scratch or thinking about upgrading your current water heating system, there are a few other considerations to factor into your decision.
While the cost savings are high for the tankless water heater, it could have a higher operational carbon footprint than an electric storage tank if it was operated with conventional gas. Of course, there is the possibility to operate the tankless water heater with carbon neutral renewable natural gas. FortisBC has a number of renewable natural gas projects underway to provide plenty of this climate-friendly energy.
Space may also be an issue. A heat pump water heater needs a minimum of 28.3 cubic meters of air space to operate and a controlled temperature environment between 4.4 and 32 degrees Celsius. A tankless model, on the other hand, naturally requires much less space.
Pros and cons of different water heating systems:
The Wilden Living Lab is an unprecedented and ongoing research initiative for sustainable homebuilding. Much more research, insight and results to come. Subscribe to the Wilden Living Lab newsletter to stay informed.
Bibliography
[1] “Water heating,” [Online]. Available: https://www.fortisbc.com/services/natural-gas-services/natural-gas-heating-systems-appliances/water-heating. [Accessed 27 September 2021].
[2] “Replacing your Water Heater,” [Online]. Available: https://smarterhouse.org/water-heating/replacing-your-water-heater. [Accessed 2021 September 2021].
[3] “Storage Water Heaters,” [Online]. Available: https://www.energy.gov/energysaver/water-heating/storage-water-heaters.
[4] “Heat Pump Water Heaters,” [Online]. Available: https://www.energy.gov/energysaver/heat-pump-water-heaters.
[5] “Tankless or Demand-Type Water Heaters,” [Online]. Available: https://www.energy.gov/energysaver/tankless-or-demand-type-water-heaters.
[6] “Why You Should Consider Switching to a Heat Pump Water Heater,” [Online]. Available: https://waterheaters.com/heat-pump-water-heater-benefits/#:~:text=Heat%20Pump%20Water%20Heaters%20Last,between%2013%20and%2015%20years.. [Accessed 27 September 2021].
