Double Facade

The Double Facade is a large 25” x 58” high x 40” wide wooden-framed box. It is composed of a test cell, a thermal mass (any material which has the ability to store thermal energy, and slowly release it over time such as water, masonry, brick, concrete, etc.) and a piece of glazing (glass). The sheet of glass on the outer wall of the structure is adjacent to the thermal-mass wall.


On each face, other than the face of glazing, the frame is filled with 3” of insulation. The insulation was cocked on all edges, in order to ensure that the box is sealed from airflow. A vent will be placed above and below the thermal mass, to connect the test cell to the air channel and to the outdoors. Thermocouples will be placed inside the test cell, and on the top and bottom of the air channel. The thermal mass installed will have insulation on the side facing the inside of the cell, and will be changeable and removable, enabling alternative thermal masses to be used in the system. A door was installed, so as to enable the changing of the thermal masses.


A small gap exists in between the glass and the thermal mass as an area for air to travel through and heat up throughout the processes, due to solar energy (direct solar thermal energy through the pane of glass, and stored thermal energy within the thermal mass). Depending on if the test cell needs to be heated or cooled, different vents will open or close.





PURPOSE
Similarly to a Trombe Wall or a Solar Chimney, the Double Facade acts to passively heat, cool, or ventilate the test cell. A control system will be implemented so as to keep the test cell at a constant temperate by automatically opening or closing vents to heat, cool, or maintain the temperature of the test cell. After the system is implemented and operable, different thermal masses will be temporarily installed in the Double Facade, and the temperature variations in the cell and in the air channel will be recorded for later analysis.


SIGNIFICANCE
From the testing that will be done with this project, a lot will be learned about thermal masses for heating, cooling and ventilating systems, as well as in other applications. Additionally, with the experience gained by creating this system, the implementation of a similar system into a larger project will be much more successful and intelligent. It will be useful when developing the team’s design for the next Solar Decathlon.