Domestic Hot Water Recirculation Part 1: What’s The Point?

Lake Mead.jpg

Declining water levels in Lake Mead. ©iStock.com/ artiste9999

By Chad Edmondson

Domestic hot water recirculation systems serve two purposes.  They provide comfort and convenience and help conserve water.  They maintain sufficiently heated water closer to tap so we waste less water and time before we shower, bathe, wash dishes, etc. 

It’s not often in the modern world that human comfort and conservation of a precious natural resource go hand in hand but this is one of them. 

Hot water recirculation systems are also part of the building code now that most states soon or will be adhering to ASHRAE 90.1 - 2010.  Therefore, it is important that anyone involved in the design or installation of commercial plumbing systems understand how these systems work. 

Why We Must Design to Save Water

What could have led ASHRAE, and subsequently building codes all over the U.S., to require domestic hot water recirculation systems in non-residential buildings?  This relatively bold stance on water conservation is quite simply a reaction to profound water shortages throughout the U.S. – shortages that will only get worse as the population continues to increase.

There are some rather alarming facts about the fresh water supply that tend to go unnoticed or unacknowledged by the average U.S. citizen – particularly those of us in the southeast where we’ve been less affected by water shortages.  Here are a just a few:

  • As of the end of May 2014, severe to extreme drought has affected about 20% of the contiguous U.S., which includes all states but Alaska and Hawaii.
  • About 34 percent of the contiguous U.S. fell in the moderate to extreme drought categories at the end of May 2014.
  • The year 2013 closed as the driest year in recorded history for many areas of California, and the drought is continuing this year.
  • According to a Scripps Institution of Oceanography study there is a 10% chance that Lake Mead, largest water reservoir in the United States, could be dry by 2014.

Globally speaking, the numbers are more disturbing:

  • More than 1 billion people worldwide lack adequate access to clean drinking water
  • 2.7 billion people find water scarce for at least one month of the year.
  • One in five people in the developing world lacks access to sufficient water to meet even the most basic requirements for wellbeing and child development.
  • According to the United Nations, water use has grown at more than twice the rate of population increase in the last century.
  • By 2025, an estimated 1.8 billion people will live in areas plagued by water scarcity, with two-thirds of the world's population living in water-stressed regions as a result of use, growth, and climate change.

Meanwhile, in the US we use an average of 151 gallons of water per person per day.  In the southeast the number is closer to 182 gallons per day. 

Since water is a necessity for literally everything we hold dear, from life to the production of food and energy, the implications of the global water crisis are far reaching.  Powerful arguments exists that water scarcity alone represents one of the greatest threats to global economies and even international security.  After all, the population and our need for fresh water continue to grow while the amount of fresh water we have on earth stays the same.

Domestic hot water recirculation systems save water – lots of water.  That’s why ASHRAE 90.1-2010 is onboard and why contractors and engineers should be onboard as well.  Effective application of such systems involves a careful balance between the additional energy required to drive recirculation systems and the water they save.  Over the next several blogs, we will be going over the finer points of domestic hot water recirculation system design so that you can make the most of this strategy, which will soon be a requirement in your state if it isn’t already.