Reclaiming Waste Heat (or What I Learned from the 2010 Olympics)

The 2010 Vancouver Olympics will be starting soon on February 12th, and though the Olympic Cauldron hasn’t yet been lit, there are still a lot of interesting things going on!  This year’s Olympic organizers appear to have put a great deal of thought into improving the sustainability of the event.  From partnering with indigenous peoples to attempting to neutralize the Olympic carbon footprint, organizers have made numerous efforts to green up which you can read about on their Sustainability web page.

One aspect of the operations that I find fascinating, has been the work done to reuse otherwise wasted heat energy.  Several of the sporting arenas and the Olympic village are setup with heat reclamation systems.  For example, at Riley-Hillcrest-Nat Bailey Stadium Parks the waste heat generated by the curling rink refrigeration plant will be used to heat pool water and space at the nearby aquatics center.

Now several of you may be wondering what good this information does the average person.  Not many of us have the budget of a Host Olympic City to spend on sustainability projects.   It turns out that it is quite possible to reclaim wasted water heat in the home.  Here are a few facts from the U.S. Department of Energy’s website on Drain Water Heat Recovery:

• Between 80-90% of the energy used to heat water in the home, goes down the drain with the water.
• Drain water heat recovery systems can capture that energy and use it to pre-heat cold water before it goes to your water heater or other appliance.
• Heat recovery systems cost between $300 – $500, not including installation but will pay off between 2.5 – 7 years pending use.

So how do these heat recovery systems work?  The core concept is simple and relies on heat exchange.  Using a shower as an example, a heat recovery system could work as such:

1. Heated water from the hot water tank gets sent up a pipe to the shower.
2. As the person showers, the still hot waste water goes down the drain pipe.
3. Normally cold water would be piped into the water heater to replenish the hot water supply.  However, in a heat recovery system, the inbound cold water is sent through a pipe that makes multiple curls around the drainage pipe along the way.
4. The heat of the outbound shower water is transferred to the incoming cold water.  Usually these sections of the system are made with copper pipe to assist in the heat transfer.
5. After going through the heat transfer, the inbound water has been pre-warmed before entering the water heater.  This action reduces the amount of energy it will take the water heater to perform its job.

The system I’ve just described is basic and is only useful when doing something that uses hot and cold water at the same time. However, more advanced systems allow the capability to store the recovered heat for later use.  It is an exciting idea for improving energy efficiency that has yet to become popular in the United States, though it appears to be doing quite well in Canada.  So if you are considering some home renovations to improve efficiency or making changes to your plumbing, ask your contractor if they can perform this kind of work.

And next month, as you are happily watching the Olympics, just keep in mind that there’s a lot of green going on behind the scenes.