New federal regulations beginning in mid-April 2015 will require that larger electric water heaters be heat-pump models. It’s time to pay attention to this option.

The GE GeoSpring heat-pump water heater is the quietest model I could find and the only one that's made in America.
Photo Credit: GE Appliances

Last week I wrote about “hybrid” water heaters, a relatively new type of water heater that includes features of both storage and tankless models. This week I’ll cover another type of water heater that is also (confusingly) referred to as “hybrid”: heat pump water heaters. These produce over twice as much hot water for each unit of electricity consumed as any other type of electric water heater (storage or tankless).

You’re going to be hearing a lot about heat-pump water heaters over the next few years, because new federal regulations that take effect in 2015 will require heat pump functionality for larger electric water heaters—more on that below.

A relatively new type of water heater combines features of both tankless and storage water heaters.

A.O. Smith's NEXT Hybrid water heater.Click to enlarge.
Photo Credit: A.O. Smith

In last week’s blog I compared tankless and storage water heaters and explained why tankless water heaters often don’t make that much sense.

This week I’ll describe a newer type of water heater that has some features of both storage and tankless designs and solves several problems that are common with tankless models. While these are referred to as hybrid water heaters, they are quite different from heat-pump water heaters, which are also often referred to as hybrid. I’ll cover heat-pump water heaters next week.

Phobia or fatigue? When it comes to toxic chemicals, we all have our own way of coping with information overload. A free webcast helps you sort it all out.

Do you know where the most toxic chemicals are in building products? Vinyl sheet flooring is a top hazard, but far from the only one.
Photo Credit: DIYadvice.com

Even if we try to ignore it, we are constantly barraged with information about dangerous chemicals in our food, our water, our dust, our air…even our grocery receipts.

The information is often sensationalized, always incomplete, and sometimes downright contradictory from one day to the next.

You can’t “go organic” at work

It’s hard enough to make choices about everyday things like organic food, antibacterial soap, or vinyl flooring in your own home.

As a building professional, your clients look to you to help them make solid, science-based decisions about even more complex products and materials. Decisions about a school, a multifamily building, or a commercial office space can affect a lot of people. Do you have enough information to answer the questions of concerned clients?

Other clients may be skeptical about the dangers of certain materials or worried that alternatives will cost too much, even if they’re interested in healthier materials. How do you cope with that?

Flashing and air barrier seam tapes get buried deep in our walls where we rely on long-term performance without monitoring them. Are they doing their jobs?

Companies do their own more sophisticated testing, like this tensile test on ZIP Tape. The company has a whole video on its testing procedures, but it's more fun to try this at home!
Photo Credit: Screen shot from ZIP System video

NOTE: Read this whole series here.

Service life of tapes can determine the service life of an entire high-performance building assembly.

Performance testing of adhesives and sealants used in our weather barriers is improving due to new field-testing research, as we’ve written about before. However, the improvements in testing haven’t reached a critical product area: pressure-sensitive adhesive (PSA) tapes used for sealing seams in flashing, housewrap, and generally creating continuity in air and weather barriers. “I am unaware of any work being done on this issue, either laboratory or field tests,” says Christopher White, of the National Institute of Standards and Technology (NIST).

The most commonly cited adhesion tests for pressure-sensitive adhesive (PSA) tapes are as follows:

• ASTM D3330 – Standard Test Method for Peel Adhesion of Pressure-Sensitive Tapes
• ASTM D903-98-04 – Standard Test Method for Peel or Stripping Strength of Adhesive Bonds
• ASTM D1876-01 – Standard Test Method for Peel Resistance of Adhesives
• ASTM D3654 – Standard Test for Shear Adhesion of Pressure-Sensitive Tapes
• ASTM D3330 – Standard Test Method for Peel Adhesion of Pressure-Sensitive Tapes

But none of these tests is ideally suited for lab-testing high-stretch construction flashing tapes, and none go anywhere near testing under field conditions. And since just about all tapes are used in concealed weather and air barrier systems, we really need a field-service-life prediction test.

 “Workbench tests” of flashing tapes

So we took matters into our own hands—or rather, our own workbench. Lately I have been just sticking a slew of tapes on different building materials and gauging how hard it is to pull them apart.

Those ubiquitous exit signs use a huge amount of electricity; a little-known alternative to conventional LED products offers surprising savings.

An exit sign at Yale's LEED-Platinum Kroon Hall. Click to enlarge.
Photo Credit: Alex Wilson

In the years that I’ve been writing about energy and energy conservation (longer than I really want to admit), I’ve reported on several dramatic transitions in how we illuminate the exit signs in commercial buildings. For an energy geek, it’s been an exciting technology to watch.

Why care about exit signs?

Why do we even pay attention to exit signs—those ubiquitous red or green illuminated signs that direct our escape from a building should the need arise? They can’t use very much energy, can they?

Each one uses relatively little electricity, but they are on all the time. And we have a lot of them in our schools, factories, and office buildings. The U.S. Environmental Protection Agency estimates that there are more than 100 million exit signs in use today in the U.S., consuming 30–35 billion kilowatt-hours (kWh) of electricity annually.

An update on getting the global warming potential (GWP) out of insulation materials.

Today's closed-cell SPF has a global warming potential of 1,430, but if producers adopt new HFO blowing agents, it will drop to close to zero. Click to enlarge.
Photo Credit: John Straube

I’ve been pretty vocal about a big problem with some of our most common insulation materials: that they are made using blowing agents that are highly potent greenhouse gases.

All extruded polystyrene (XPS) and most closed-cell spray polyurethane foams (SPF) are made with HFC (hydrofluorocarbon) blowing agents that have global warming potentials (GWPs) many hundreds of times greater than that of carbon dioxide. (My apologies for contaminating this column with so many acronyms!)

Insulation: good news, bad news

Exterior adhesives and sealants are formulated for performance, but some contain chemicals that pose risks to unprotected workers or the environment

The silicone found in many window caulks is not much of a health risk to onsite workers, but the chemicals used to produce silicon are coming under greater scrutiny.
Photo Credit: ArmaCo Construction

 NOTE: Read this whole series here.

As discussed throughout this series, adhesives and sealants used outside the building envelope have to adhere to the substrate and seal gaps, and they often need to be as durable as the building itself. Performance is the primary concern, and the chemical constituents often take a back seat. Unlike products used on the interior—where VOCs and other potentially hazardous chemicals can concentrate to create indoor air quality problems for occupants—for exterior products, exposure risk is mostly limited to workers who manufacture and apply the products.

Compressible gaskets keep air and water barriers continuous without liquid sealants or adhesive tapes. But they don’t all last equally well.

This Holst Architecture-designed Passive House project, Karuna House, includes gasketing on the sill plate—common in Northern Europe for decades but fairly new to the U.S.
Photo Credit: Hammer & Hand

NOTE: Read this whole series here.

In the U.S., we tend to put a lot of faith in caulks, tapes, and wet-applied sealants. But in Europe it’s a different story.

Some Gaskets can be used in place of tapes or liquid sealants, mainly as part of residential air barrier systems. According to Lee Jaslow of Conservation Technologies, a leading U.S. distributor of high-performance gaskets and one of the high-performance gasket listings in GreenSpec, the market for gaskets in residential construction is small but growing, with increased interest due to high-performance rating systems such as Passive House.

Caulk joint sealants can be a major deciding factor in how long your building envelope lasts. Is there a better way to predict how long they last?

Mounted on the roof at NIST, this "weathering engine" tests sealant durability.
Photo Credit: National Institute of Standards and Technology

NOTE: Read this whole series here.

Durability, or service life, is critical to the overall performance of liquid caulk joint sealants in the water and air barriers in our buildings.

If we can figure out how long sealants actually last then we can come up with a prudent inspection schedule—and have a good idea of how they’ll fail and how to replace them. The good news about sealants is that they are generally exposed to view—unlike flashing tapes, which are generally buried and inaccessible. (More on tapes in a future post.)

Fairly assessing durability or service life

We are always hoping for that one magic test that fairly, accurately, and realistically portrays one or more performance attributes of our building materials.

The trouble is that, while field tests can be more realistic, they tend to introduce many uncontrolled or non-measurable conditions. And the trouble with laboratory tests is that they set, control, and measure many conditions, making them often far from what actually goes on in the field.

It turns out that we have plenty of useful standardized laboratory tests for both liquid sealants and tapes that we use in our weather and air barriers. That’s the good news. The bad news is that we haven’t had useful tests for the field service life prediction of those same sealants and tapes—until recently.

Introducing all-natural expanded cork boardstock insulation to the North American market.

Expanded cork insulation is available up to 12 inches thick and can be used much like polyiso. Click to enlarge.
Photo Credit: Amorim Isolamentos

I’m always on the hunt for the latest, most interesting, and most environmentally friendly building materials, and I have particular interest in insulation products—partly because many conventional insulation products have significant environmental downsides. (See “Avoiding the Global Warming Impact of Insulation” and “Polystyrene: Does it Belong in a Green Building?”)

So I was thrilled to learn about expanded cork boardstock insulation made by the Portuguese company Amorim Isolamentos and just now being introduced into the North American market. Francisco Simoes, of Amorim, visited our office in Brattleboro in June and told us all about it.

Familiar to wine drinkers as the traditional bottle-stopper, cork is a natural product made from the outer bark of a species of oak tree that grows in the western Mediterranean region of Europe and North Africa. The bark is harvested after trees reach an age of 18–25 years and it regenerates, allowing harvesting every nine years over the tree’s 200-year life.