Facade of building as seen from the street.

Successful construction depends on clear communications, and this is facilitated by using words with commonly accepted meanings. Language must evolve in response to the changing needs of design and construction, and it is not uncommon for words to take on new meanings. Yet we should resist the urge to redefine a term when an appropriate alternative is already established.

A case in point is, "facade." The word derives from Latin for “face” and refers to what can be seen of or experienced on the exterior surface of a building. Here are several definitions:

• The face or front of any considerable building to a street, court, garden, or other place. Rudimentary dictionary of terms used in architecture, civil, architecture..., John Weale 1850

• A face of a building, usually the front. Dictionary of Architecture, Henry H. Saylor, Wiley, 1994

• The main exterior face of a building, particularly one of its main sides, almost always containing an entrance and characterized by an elaboration of stylistic details.” Illustrated Dictionary of Architecture, Ernest Burden, McGraw-Hill 2002

When architects design facades, we are concerned about the organization of shapes, color, massing, texture, ornament, and fenestration, and the experience of the public seeing the building.

"Facade" may be acquiring another definition, however.

I realized this while attending a "Facade Tectonics" conference at University of Southern California. They use the term to mean the materials, systems, and processes that relate to a building's exterior surfaces and appurtenances thereto, including the effect upon the spaces and occupants on both sides of the surfaces. Conference participants delivered papers about the thermodynamics, weather enclosure, and other performance considerations of facades, but scarcely used the word in it established meaning relating to the appearance of a building.

The is no justification for using "facade" in this new way, since there are already preferable terms, including:

• Enclosure: Used in ASTM E1557 - Standard Classification for Building Elements and Related Sitework-UNIFORMAT II, and in the OmniClass international classification system for building elements.

• Envelope: Used by National Institute of Building Science (NIBS), publishers of Building Envelope Design Guide and co-sponsor, along with AIA, of Building Envelope Council.

• Wall and curtainwall are readily understood terms.

There is frequently a connection between a facade and an envelope. Yet the two their meanings are distinct. A structure on Main Street may have the same facade as one on a Hollywood soundstage, but the envelope of one is constructed of hewn limestone while the other is painted plastic foam.