Overview

Historic Background
Double-hung windows were introduced by the English scientist and inventor Robert Hooke in the second half of the eighteenth century and became widely used soon after. The beautiful buildings in Scotland and London designed by Robert Adam have them, the neoclassical style of American architecture has them. They were used in large numbers ever since in the US, UK, Canada, Australia and New Zealand in colonial-style single and multi-family residences and high-rise apartment and office buildings.

They are still manufactured, even as “energy saving windows”, despite two serious shortcomings.

1. At most half of the window can be opened to the external environment reducing the cross section for natural ventilation.
2. When closed the sashes are not in the same plane, which is esthetically not pleasing and also increases air leakage.

The Invention
We have invented an improved double-hung window, which eliminates these shortcomings. The window can be opened completely to the outside doubling the rate of natural ventilation thereby reducing or eliminating the need for air conditioning; when closed, the sashes are in the same plane improving appearance and reducing air leakage. This is achieved as follows:

There is a breast cavity under the window; the two sashes have guiding pins and slide on two parallel vertical grooves located on both sides of the window frame which extends into the breast cavity. Guided by a horizontal connecting section and a crossing section the two sashes can be either in the same groove, or in parallel grooves. For the complete opening of the window, after opening the breast cavity, the two sashes are stored parallel to each other with the aid of a branching section and a horizontal section within the breast cavity. A more detailed description and drawings are to be found in the enclosed patent while the video shows the window in operation. The unique and facile manner in which the window operates makes its use like play. Remote control is an option. We have a working model in Budapest, Hungary.

Marketing
With the current interest in green building, enhanced by government-sponsored consortia, we believe this window would have an important contribution to energy savings by reducing the need for air conditioning particularly in low humidity geographic areas and where the nights are cool and there are regular breezes.

Application
Applications would include new colonial style single and multi-family residences, particularly upper floor bedroom and bath-room windows. Application in high-rise residential and office buildings seems particularly advantageous due to the prevailing higher winds at higher altitudes, and may be considered instead of fixed windows. It is important to note that these improved double-hung windows keep the advantages of traditional double-hung windows, namely in not taking up inner or outer space and being wind resistant when partially open.