Water, energy, and the potential to save billions
Guest post by by Jerry Callahan
Centralized water heating systems are exceptionally wasteful, regardless of whether the water is heated by electricity or gas, or heated in a storage tank or tankless unit. The entire process of getting hot water through a house from a centralized water heater and the associated plumbing consumes a substantial amount of water and energy.
As the water leaves the heater and travels through a house, cold water must be pushed out of the way in order to deliver the hot water to the source. As a result, each time a homeowner draws water from the tap in a centralized system, 1-2 gallons of water are wasted per minute while waiting for hot water to arrive. Centralized water heating systems waste an estimated 20 percent of water heated daily, or 15-30 gallons. Over the course of a year, more than 5,500 gallons are wasted, enough to fill a small residential swimming pool.
Real opportunities exist for large scale water and energy savings through a distributed water heating architecture. Distributed architecture locates water heaters throughout the home, rather than in one centralized location. When water heaters are distributed throughout the house, the wait time for hot water is reduced or eliminated at points of uses. If the water heater is tankless, rather than a tank-type, then energy is used only when hot water is delivered, yielding significant energy savings.
With the average American consuming 36,500 gallons of water during the year, a distributed water heating architecture in every U.S. home would save over 640 billion gallons annually, or the entire water needs of over 5 million households for a year – more than the entire population of Los Angeles! With 18 percent of the typical water heating bill going towards heating water, a mass conversion would also result in a nationwide savings of money and energy.
On a macro level, the potential savings even extend to utility companies. Utilities are looking for ways to increase efficiencies so that they don’t have to undertake the enormous expense of building new plants. Increasing efficiency at the individual level frees up power generating capacity for existing plants and distribution systems. The use of very efficient water heaters in a distributed architecture not only saves individuals money on power and water bills, but also reduces their kW/hr cost because the power company does not have to build more plants - and finance construction with consumers’ money.
Distributed architecture in new construction
In new construction, the adoption of a distributed architecture provides a number of advantages. It is not necessary to run hot water piping throughout the house, decreasing the cost of labor and materials. In most cases, it is less expensive to construct a decentralized home than a centralized home. Moreover, less hot water piping lowers the home’s environmental footprint since most pipes are made from petrochemicals. During renovation, it is also easy incorporate a distributed architecture. Homeowners can position a tankless water heater closest to points of uses in open areas such as attics, closets, cupboards, and crawl spaces.
During new construction or renovation, homeowners should consider where hot water is actually necessary in the home. For example, running hot water pipes to the outside of a home is generally superfluous, with water being used only to wash cars or perform yard work. The construction industry can help homeowners save energy by being smarter about where hot water is placed and consumed in the home.
The installation of tankless electric water heaters can also reduce energy usage compared to electric tank-type units, primarily because the temperature can be set lower. Tankless water heaters can be set at a temperature where no mixing with cold water is necessary in order to cool the hot water to the desired temperature. In addition, unlike a standard tank-type water heater, a tankless heater isn’t continually warming water that just sits idle waiting to be used.
As both individuals and policy makers explore ways to maximize water and energy savings, a distributed architecture using tankless water heaters possesses game-changing potential.
Jerry Callahan grew up on Cape Cod, Massachusetts, and studied naval architecture at MIT and Stevens Institute of Technology. After studying at MIT and earning his MBA from University of Chicago, Jerry co-founded Blue Rhino, the world’s leading propane cylinder exchange company. Today, as the CEO of Heatworks, Jerry leads a team of heating, technology and plumbing veterans with over 50 combined patents that are revolutionizing the water heating industry.
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