There are a number of water heating solutions available to engineers and designers of commercial buildings, but which is the best?

Water heating can be among the largest utility expenses in a commercial building. If done improperly, heating hot water can not only eat into energy expenditure, but waste water in waiting for it to heat up. As the demand for commercial facilities to become more sustainable continues to grow, many building managers and designers are looking for new solutions to address these issues. Energy efficiency is fast becoming one of the most common types of building upgrades, and by having a thorough understanding of the various types of water heaters on the market, engineers can better prepare facilities for these kinds of sustainability demands.

The types of water heater solutions
At the moment, there are three or four major solutions on the market for commercial facilities – storage, tankless, heat pump and solar. However, because the efficiency of solar water heaters are contingent on the sun shining, they are not always the best option for commercial facilities and often require a back up.

Before one can make a decision about the best water heater for a commercial facility, it is important to understand the advantages and disadvantages of each.

Storage: Storage water heaters work by holding a large amount of water and keeping it at a preset temperature. These are among the cheapest face value solutions and last about 10 to 15 years, according to the Department of Energy. While a tank solution may be inexpensive on the surface, it is also one of the least energy efficient solutions because energy can be wasted when the system is in standby, as it needs to maintain the same temperature around the clock. While insulated tanks can help, standby heat loss is the biggest disadvantage of this solution.

Heat pump: Heat pumps are an energy efficient solution that have a similar life span to storage heating. They work by gathering the hot air in a room and pumping it into a water storage tank. This means that they work best when installed in a room with excess heat, though the DOE noted that they can work in a room that remains between 40 degrees Fahrenheit to 90 degrees Fahrenheit. While they use less energy on average than a storage heater, their performance depends on where they are installed. Also, their exhaust is cold air, which increases strain on the building's heating system during colder months.

Tankless: Tankless water heaters are the longest lasting water heating solutions of the three, with the life expectancy surpassing 20 years. They work by heating the water on the spot, rather than constantly warming the water. As a result, it is about 8 to 34 percent more energy efficient than the tank solution. The price of a tankless water heater is about the same as a heat pump solution.

Making the best choice
No building is the same, but it is safe to say that the most efficient solutions tend to be the best giving the increasing demands and standards for energy efficient buildings. While tank solutions are inexpensive at face value, they do not last nearly as long as a tankless water heater and are far less efficient than the rest of the field.

For the more efficient solutions, there are a number of considerations. Tankless solutions can last much longer, which when considering the installation cost of a heat pump is a great advantage. While heat pumps have the potential to be quite efficient they are also dependent on where they are installed and can create strain on other building systems, like HVAC, that may negate some of the efficiency improvements. Conversely, tankless solutions are about 90 percent smaller than a storage tank, allowing them to be installed almost anywhere.

For commercial buildings, ultimately, the more efficient and logistically sound solution is the tankless water heater.