# Experimental Investigation and Optimization of a Glazed Transpired Solar Collector  
[PERSON]  
1 CAMBI Research Center, Technical University of Civil Engineering Bucharest, 021414 Bucharest, RomaniaFurthermore, the heating and cooling of buildings in the EU benefitted from the greatest growth RES share (reaching 23.6%) in 2021 [4]. In this context, it is worth mentioning that buildings and the construction sector are still responsible for 36% of the global final energy consumption and 37% of energy-related CO\({}_{2}\) emissions in 2021 [11]. These figures explain the major interest regarding the implementation of energy efficiency solutions and the usage of RES in the building sector. Concerning the RES for heating and domestic hot water, the latest data show that the solar thermal market witnessed a 3% growth in 2021 after seven years of market declines [12]. This increase corresponds to the following numbers (at the end of 2021): 746 million square meters of collector area; 522 GW--cumulated capacity in operation; and 425 TWh energy produced per year (2021), meaning savings of 45.7 million tons of oil and 147.5 million tons of CO\({}_{2}\)[12]. Certainly, most of the solar thermal applications are based on solar water collectors. Nevertheless, solar air systems almost reached 1.5 million square meters of collectors' area (glazed and unglazed air collectors) in operation worldwide--nearly 1 GW installed capacity by the end of 2020 [12]. This expansion of solar air collectors is mainly explained by the following considerations: no risk of frost [13], cost-effective solution [14], supply of high-temperature air [15], high potential in reducing the energy consumption of buildings [16], multiple applications (e.g., space heating [17; 18], preheating of fresh air--ventilation [19], and the drying agricultural food products [20]), and reduced operating costs [16]. On the other hand, solar air-heating technology is based on several types of solar collectors: bare plate, back-pass, glazed, unglazed, covered, uncovered, perforated, un-perforated, single pass, double pass, etc. [21]. In addition, numerous modifications have been investigated to improve the performance of all these types of solar air collectors [22]: modified absorber plate (e.g., sinusoidal corrugations on absorber plate, curved absorber plate, and arched absorber plate with equilateral triangular turbulator and dimply turbulator); integration of a porous medium (e.g., wire mesh and metal scraps); and the implementation of energy storage solutions (e.g., phase-changing materials and plastics). Among these types and improved models of solar air collectors, the ones with a perforated absorber element (called \"Transpired Solar Collectors\"--TSCs) have been analyzed for almost 40 years [23]. Studies have shown that the heat lost through convection and radiation at the surface of the plate can be recovered by manufacturing perforations in the absorber, as in the case of TSCs [24; 25]. Consequently, compared to unperforated (flat absorber element) solar collectors, TSCs are 28-50% more efficient under the same climate conditions [25; 26]. Therefore, TSCs have been successfully employed in buildings [16; 18; 27]. For instance, the use of TSCs for fresh air heating has led to excellent results: more than 70% efficiency [19] and almost 75% energy saving [28]. In addition, according to [PERSON] et al. [29], the use of TSCs has resulted in the best performances for school classroom ventilation in winter, considering energy saving, environmental protection, and economic impact, compared to other solutions for air heating (air conditioners or electric heaters). [PERSON] et al. [30] also revealed that TSCs represent interesting solutions for regions with reduced solar radiation. On the other hand, the efficiency of TSCs is strongly influenced by the wind [19]. [PERSON] and [PERSON] [24] experimentally investigated the performance of TSCs depending on the wind.