The PSHC panels in our daylighting system are thin, planer, sawtooth made of clear acrylic material, and consists of an array of acrylic prisms with one surface of each prism forming a plane surface as the prism backing, ша 42cJeBIBe

There are two refracting angles, 42° and 5° ‘ ‘

(Fig.1). For deep penetration of sunlight, these prismatic panels accommodate a wide range of _

solar altitudes. The occurrence of refraction due Fig-1- A prism geometry for PSHC
to these panels is used to change the direction of transmitted light rays (Daylight in Buildings, Program Annex 29, July 2000). In winter, direct solar radiation penetrates the system at a high degree, which creates a temperature difference after passing through the glazing area. This effect produces good thermal conditions inside the room or a building.

A typical PSHC unit installation has more than one-prismatic glazing module consisting of thin planer sawtooth transparent sections made of acrylic material. For this experimental work, these panels are obtained from “SITECO” Beleuchtungstechnik, (Germany) with prismatic elements integrated inside the intermediate space. Unit dimensions are 1190mmx790mm. The details of construction of the panels are, (1) external sheet: clear glass, approx-5mm, (2) internal sheet: laminated safety glass, approx-6mm, (3) intermediate space: width approx-34mm, with two prismatic elements and (4) total thickness: approx-45.5mm. The prismatic elements are composed of square surfaces of approx 205mmx205mm.

These panels have a total solar energy transmission coefficient, which is composed of the coefficients of direct solar transmission and of secondary heat transfer. The direct solar transmission coefficient specifies that part of solar radiation incident on the glazing surface that is directly transmitted inside. The secondary heat transfer coefficient signifies the part of incident solar radiation, which is transferred inside by convection and longwave IR-radiation through the individual glass sheets and prisms, which produces heat inside the room (Table1).

The panels are fixed on a small window (the dimensions of window were 2m long and 0.6m wide) of the south facing wall of the target room. The target room building is of rectangular style with dimensions of 2.4m high, 2m wide and 3.9m long. The target room has been developed by keeping in view the concepts of reflecting sunlight to the ceiling, to improve the visual comfort by increasing ceiling luminance levels across the depth of the room, and to produce uniforms glare-free illuminance and better thermal conditions across the room (Fig2.a). A small fan is fixed just below the entrance of target room in the south­facing wall in order to circulate the warm air inside the room during winter. The whole daylighting system is designed for latitude 36.5o (Dejeon, Korea). The design of the target and reference rooms is shown in Fig.2b.

Fig.2b. PSHC twin test cells in KIER.