I was lucky enough to attend the Twenty-Third Annual Westford Symposium on Building Science – also known as Summer Camp. It was a truly informative experience and, as the title suggests, it touched on many subjects relating to building science. Plus there is a really great barbecue and picnic at the organizer’s home. But is wasn’t all about R-values and air leakage, though. While the symposium covered many topics I expected; like humidity, air-tightness and unvented roofs, it also touched on several other topics that were unexpected (to me anyway).
The one session that maybe struck me with that “duh, why didn’t I think of that” moment, was called, “Architectural Compactness and Hot Water Systems: Good Design Lowers Cost”. Now, I know what you’re thinking – with a title like this, how could you go wrong? But here’s the thing: I’ve thought about this session every time I touch a sink faucet since.
Whether in public buildings, apartments or houses: the faucet is usually really far away from the hot water source. Your second floor bathroom can be on the far side of the house and the hot water heater is located in the garage or mechanical closet, or even the basement. Even if the hot water source happens to be on the same floor as the faucet, the pipes have to run up in to the floor or ceiling, then run horizontally to the wet wall, then up or down again, before it sees daylight. Prior to any hot water reaching your hands, that pipe has to clear a huge volume of cold water that is already in the trunk and branches.
In the study done by the presenter, it found that 80 to 90 percent of the water draws in a typical residence were from the faucet, so let’s concentrate on that for a moment. In the 1980’s the typical faucet in a home used 3.5 gpm (gallons per minute). Today, the worst you can do by code is 2.2 gpm and most efficient faucets are closer to 1.2 gpm. So even though faucet efficiency has improved drastically since the 1980’s (about 66%), we are still wasting a lot of energy down the drain. We are just waiting for it to get hot!
Everybody washes their hands, right? Well, they should, anyway. The CDC (Center for Disease Control) says you have to wash your hands with soap and water for at least 20 seconds. For the record, the CDC recommends singing the “Happy Birthday” song from beginning to end twice. I wish I had known that earlier, because anyone with kids has probably heard their kids turn on the water long enough to only get through “Happy Birthday to y….” & done. But I digress…
While much of the session was focused on how to keep the “wet” rooms closer to the source. Clearly, we designers can and should learn to do better. But the clearest takeaway for me was this: we wash our hands a lot. Our faucets are usually a single lever, as they are accessible, convenient and easier to change the temperature. If our levers are positions in the “neutral” position (half hot, half cold), and we turn it on 60-100 times a day and run it to wash our hands, we are wasting a lot of hot water!
If we run our faucet for the recommended 20 seconds (minimum, I hope), there is almost no way in most houses (or offices or public restrooms for that matter) that the water will be hot by the time we are done washing our hands. The water already in the pipe is unheated. I know in my house it can take a minute or more for hot water to reach my second story bathroom faucet. An eternity.
But if my faucet is drawing hot water as well as cold when washing my hands, I’ve wasted a lot of energy to heat water that will never touch my hands. By the time the next person touches that faucet, the water I heated in the pipe line will have cooled off because the copper in most houses is not insulated. By simply turning the faucet lever all the way to the right, I use only cold water to wash my hands. No energy wasted.
I came home from Summer Camp all excited about this revelation. There is an obstacle. People (the people I know, anyway) don’t like it when the faucet lever isn’t lined up and nice and straight. My wife, for one, was not impressed. There is a compromise now! In addition to the water efficient faucet, I am told that faucets that will only draw cold water when the lever is straight up and down unless you push it to the left while the water is on are on their way to the market. That way you can leave the lever nice and straight, and not waste that energy.
By the way, the CDC doesn’t care if the water is hot or cold, so unless you have a medical condition, why not use cold?