Rev. Rul. 83-150

ISSUE

Do the glass blocks installed in a taxpayer's principal residence in the manner described below constitute a "storm or thermal window" within the meaning of section 1.44C-2(d) (4)(iv)(A)(2) of the Income Tax Regulations?

FACTS

The taxpayer replaced with a window made of glass blocks, an existing single-pane basement window in a dwelling unit built before April 20, 1977, which is being used as the taxpayer's principal residence. Each glass block, approximately 6x6x2 ' inches thick, is manufactured by fusing together two pieces of pan-shaped glass. The resulting hollow block contains a partial vacuum. The glass blocks are cemented together with mortar in the manner of common bricks to fill the space formerly occupied by the single- pane window. When installed, the glass blocks form two glass surfaces separated by insulating air space.

LAW AND ANALYSIS

Section 44C(a)(1) of the Internal Revenue Code allows a residential energy credit against federal income tax for "qualified energy conservation expenditures."

Section 44C(c)(1) of the Code defines energy conservation expenditures as expenditures made on or after April 20, 1977, by a taxpayer for an "energy-conserving component" installed in or on the taxpayer's principal residence if the construction of that dwelling unit was substantially completed before that date.

Section 44C(c)(4)(A)(iv) of the Code lists as an energy- conserving component a storm or thermal window for the exterior of the dwelling.

Section 1.44C-2(d)(4)(iv)(A)(2) of the regulations defines a storm or thermal window as a window with enhanced resistance to heat flow through the glazed area by multi-glazing, an arrangement in which two or more sheets of glazing material are affixed in a window frame to create one or more insulating air spaces. Multi-glazing can be achieved by installing a preassembled, sealed insulating glass unit or by affixing one or more additional sheets of glazing onto an existing window.

Section 44C(c)(6) of the Code, and underlying regulations, and Rev. Proc. 80-36, 1980-2 C.B. 769, as amended by Rev. Proc. 83-73, page 593, this Bulletin, establish the procedures under which a manufacturer of an item may request certification that the item will be treated as an energy conserving component. Section 3.14 of Rev. Proc. 80-36, as amended, provides that the Service will not certify building materials.

Nevertheless, when installed on the exterior of the dwelling, glass blocks meet the definition of a storm or thermal window. However, these glass blocks can be used other than as a window in an exterior wall. They can, for example, be installed in an interior wall, in a partition, or merely for ornamentation.

When installed in the manner described the glass blocks collectively form the equivalent of a multi-glazed area that qualifies as a storm or thermal window within the meaning of section 1.44C-2(d)(4)(iv)(A)(2) of the regulations.

HOLDING

When installed as described above, the hollow glass blocks constitute a thermal window within the meaning of section 1.44C-2(d)(4)(iv)(A)(2) of the regulations. Because they are susceptible of many non-energy-related uses, glass blocks as a class of building material are not certifiable as energy-conserving components. See Rev. Proc. 80-36, as amended.