## 1 Introduction  
Sustainable development has recently become an unavoidable trend in variable disciplines, including civil engineering and architecture. Therefore, the development and use of sustainable materials, which are energy-efficient and low-cost, has attracted increased interest. The building envelope separates the conditioned interior environment from the unconditioned exterior. Thus, the energy efficiency of the envelope directly affects the efficiency of the entire building system [1]. Furthermore, if the envelope can capture more daylight for the building, the electrical lighting load will be reduced and further energy savings will be achieved [1]. Compared to a traditional electrical lighting system, daylight is more beneficial for a healthy environment, as well as for human productivity and comfort, as it contains the full spectrum of sunlight [1]. The translucent concrete panel (TCP) system is a multi-functional facade system with an emphasis on light transmission and thermal efficiency without sacrificing load-bearing capacity. In 2001, the first commercially available form of TC was invented by [PERSON] [2]. It was composed of glass optical fibers and fine concrete which were combined in such a way that the material was both internally and externally homogeneous. It was manufactured in blocks and panels for decoration. At the Shanghai 2010 EXPO, Italy took the opportunity to build its pavilion out of TC using about 4000 i.light(r) blocks, with each block measuring \(100\times 50\times 5\) cm [3,4]. In the standard products, there are also \(120\times 60\) cm panels with thicknesses of 1.5 or 3 cm [5]. Another product features plastic fibers arranged in a perfect grid--namely Pixel Panels--which were developed by [PERSON] [6]. These panels transmit light from one surface of a wall to the other, but in a pattern whereby the light that shines through the panel resembles tiny stars in a night sky. The University of Detroit-Mercy also developed a process to produce translucent panels made of Portland cement and sand and reinforced them with a small amount of chopped fiber glass [6]. The primary focus of the TC technology has previously been on its esthetic appeal and its application in artistic design; few researchers have investigated its multi-physical properties. [PERSON] et al. (2011) [7] published a study on smart TC and its light-transmitting, mechanical and self-sensing properties, including the long-term durability of the material. [PERSON] and [PERSON] (2015) [8] manufactured TCPs with various densities of optical fibers (OFs), and a series of tests were conducted to understand their multi-physical properties. To investigate the energy consumption savings of TCPs in a building envelope, [PERSON] et al. (2015) [9] and [PERSON] and [PERSON] (2017) [10] performed computational modeling and analysis; the results showed that a TCP facade can cut down energy expenditure by 18% with a fiber volumetric ratio of 5.6%, which made the fabrication process practical. However, a comprehensive experimental study of TCP has not yet been developed to address the issue of structural performance and energy efficiency. Compared to a traditional glass curtain wall, a facade with TCPs has higher durability but can be heavier and thicker. In this paper, a group of formworks made of acrylic sheets was fabricated. OF cages were constructed using perforated steel sheets, meaning that the OFs could be easily inserted into the perforations of these sheets and subsequently placed in the formwork. This was followed by the inclusion of a lightweight mortar consisting of sand, cement, silica fume, super-plasticizer, etc. to reduce the self-weight of the TCPs. For comparison, several TCPs with different volumetric ratios (VRs) of OFs were cast in light-weight and normal-weight mortar panels.