Building Product Durability–and Denial

The rate at which materials age and fail should factor into every building—and manufacturing—decision.

Is it any wonder that many of us struggle to do the right thing—and spend less money over the long term—operating, maintaining and replacing parts and products in our homes?

My six-year-old electric resistance hot water tank is failing. As I explore possible replacements, I have to factor in and compare a whole range of variables, not the least of which is the probable lifespan of each technology. Let’s look at just the uninstalled costs.

Comparing Types of Water Heaters

To replace my old 30-gallon electric resistance tank with another of its ilk, I’d spend about $450, with a probable lifespan of 6-10 years. Some product reviewers, however, suggest that I might replace the heating element and anode, and get a few more years out of the tank. At least one manufacturer, Rheem, offers a Marathon model, which has a plastic tank with a lifetime warranty, at two to three times the cost of a standard unit.

Replacing old hot water tanks with new technology is not as straightforward as it should be. Why can’t we have products that are efficient and extremely durable?

Alternatively, I could go solar, switching to a 40-gallon, roof-mounted solar hot water system with a 240 volt backup, at a cost of about $2,000. These tend to last 20 years or more and save somewhere between 25 percent to 85 percent over conventional tanks, depending on where you live.

A third option would be a hybrid heat pump water heater. They pay for themselves quickly in energy savings, typically in five years or less, saving 30 percent to 40 percent on heating bills. I’ve installed two of these this year myself. But their lifespan is an open question. Reviews of their reliability from Consumer Reports are mixed, as you need repair people with HVAC and plumbing skills to fix one. Most units carry a 10-year warranty.

As for wall-hung hot water heaters, reviews of on-demand systems put the payback time for upgrading from a storage tank gas water heater to a gas tankless unit at 22½ years to 27½ years. I’m not a fan of gas dependency, but the same study puts electric wall-hung replacements at a 12- to 20-year payback. 

In my experience, most wall-hung units need repeated repairs and regular maintenance, and at least one major repair within five or six years. Most will be lucky to last 10 years without an overhaul.

Given these durability wild cards, solar would appear to be the best long-term investment. In Florida, solar could supply about 85 percent of my hot water, with a stainless storage tank. I could save about $350 a year in heating costs, enabling me to pay it off in less than 10 years, with another 10 years of “free” hot water still to come. But that efficiency drops to only about 25 percent in a Northeast winter.

For my location in Maine, then, I’d have to choose between a standard efficiency—but durable—plastic or stainless tank with no real efficiency gain over my old unit, other than the fact that I wouldn’t replace it twice if I lived there 20 years. Or, I roll the dice on a more-efficient heat pump model with a shorter lifespan.

Durability for Water Heaters and Beyond

My point is that durability (or the lack thereof) is the missing link in high-performance products. Efficiency rebates might shorten the payoff somewhat, but what about the hassle and environmental impacts of product replacement?

Hot water equipment is just the proverbial tip of the iceberg. Every product we put in a house begins to “age out” the moment it’s installed. Each choice casts a much longer shadow than merely weighing the embodied energy of the house as it’s being built.

As you enjoy this year’s top-shelf selection of the Green Homes of the Year, put on your building science hat, and think about durability. How have these builders struck a balance between beauty and durability? Which homes will operate with the greatest efficiency, with the least service calls?

Vinyl gets brittle. Wood degrades and grays. Window seals fail. Ferrous tanks rust. Grout sealant washes away. Driveways crack. Foundations shift. Roof shingles degrade. Nails rust.

Great builders and manufacturers do their best to make the long process from creation to demolition (and reuse) as smooth and low impact as possible.