The United States Department has mandated manufacturers of equipment meet minimum energy standards and physical parameters residential applications (as opposed  to commercial) for Thru-The-Wall (TTW) systems, both air conditioner and heat pump. To assist you in determining whether your application meets the US DOE minimum standards we offer the following DOE specifications (10 CFR 430.2):

(1) Is manufactured prior to January 23, 2010;

(2) Is not weatherized;

(3) Is clearly and permanently marked for installation only through an exterior wall;

(4) Has a rated cooling capacity no greater than 30,000 Btu/hr:

(5) Exchanges all of its outdoor air across a single surface of the equipment cabinet; and

(6) Has a combined outdoor air exchange area of less than 800 square inches (split systems) or less than 1,210 square inches (single packaged systems) as measured on the surface described in paragraph (5) of this definition.

Further, the SEER and HSPF minimum requirements are defined as follows (10 CFR 430.32, page 268):

* SEER= Seasonal Energy Efficiency Ratio

* HSPF= Heating Seasonal Performance Factor

Links to the U.S. DOE specifications...

Through-the-wall TTW definition: 10cfr430-2 pg 104-5.pdf

Through- the-wall efficiency mandates: TTW efficiency (see last page)