Green Building Vocabulary Disputes

Watch out — sloppy terminology may earn you a scolding from the word police

Martin Holladay, GBA Advisor
Green Building Advisor

As any builder knows, construction terms vary from job site to job site; one carpenter’s furring strip is another carpenter’s strapping. Like carpenters, building scientists are inconsistent when it comes to technical terms — in part because building science is a relatively young field.

In new fields of learning (including building science), vocabulary generally wanders at first, and eventually converges once consensus is reached. Reaching agreement on technical terms is useful. It helps achieve a desirable goal: efficient communication.

Some people cling tightly to their favored vocabulary and resent efforts to encourage consensus on technical terms and definitions. That’s fine, as long as no misunderstandings result.

Unless you’re a word junkie, you may roll your eyes at some of the technical disputes listed in the table below. After all, who cares whether WRB stands for “weather-resistant barrier” or “water-resistive barrier”? (Just help me nail up the freakin’ housewrap, okay?)

Other readers will delight in these debates. For interested readers, these disputed terms may be food for thought.

For the record, I’m not necessarily in favor of all of the terms in the “preferred” column. Many of these vocabulary disputes are not yet resolved. In the meantime, the words we choose should communicate our meaning clearly. Adopting an unusual (though technically correct) term doesn’t improve communication if it leaves the listener or reader confused.

Last week’s blog: “One Air Barrier or Two?”

Out-of-favor term Preferred term Comments
Air-to-air heat exchanger Heat-recovery ventilator The industry reached a consensus on “heat-recovery ventilator” two decades ago.
ECM motor ECM “ECM motor” is redundant, since ECM stands for “electronically commutated motor.”
Energy-recovery ventilator Enthalpy-recovery ventilator Enthalpy accounts not only for sensible and latent heat but also mass; however, purists are unlikely to prevail on this one.
Geothermal heat pump Ground-source heat pump The term “geothermal” is best reserved for phenomena like geysers and hot springs.
Green roof Vegetated (or living) roof “Green” has so many meanings that its use in this phrase is imprecise.
Heat exchanger Heat transferer Proponents of this substitution point out that heat is transferred in one direction, not two; however, “heat transferer” has not caught on.
Permeance of a material Permeability of a material “Permeance” is used when discussing a sample of a defined thickness; “permeability” is a material property independent of thickness.
Photovoltaic panel Photovoltaic module A photovoltaic module is made up of a number of photovoltaic cells; a photovoltaic array contains several modules.
Return-air register Return-air grille Registers include dampers, while grilles do not. Of course, return-air grilles do not require dampers.
Sealed crawl space Closed crawl space Consultants from Advanced Energy in Raleigh, NC, prefer “closed crawl space,” since a closed crawl space can work well even without extraordinary air-sealing efforts.
Solar panel Photovoltaic module or solar thermal collector “Solar panel” fails to distinguish between two different technologies.
Solar photovoltaics Photovoltaics In this phrase, “solar” is redundant.
Tankless water heater Instantaneous or on-demand water heater “Tankless” introduces possible confusion with old-fashioned tankless coils.
U-value U-factor Technically (and mathematically) speaking, this number is best described as a factor, not a value; at least the NFRC gets this one right.
Vapor barrier Vapor retarder “Vapor retarder” (or, for the truly precise, “vapor diffusion retarder”) is the best term for materials that slow the passage of water vapor; “vapor barrier” should be reserved for materials with a permeance of 0.1 perm or less.
Vent Grille, register, air intake, exhaust outlet, flue “Vent” is vague, except in phrases like “soffit vent” and “ridge vent”
Weather-resistant barrier Water-resistive barrier The International Code Council Evaluation Service voted that “WRB” shall henceforth stand for “water-resistive barrier.”
This entry was published on July 27, 2010 at 4:07 am. It’s filed under Green Certification, Sustainable Building and tagged , , . Bookmark the permalink. Follow any comments here with the RSS feed for this post.

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