## 1 Introduction  
Currently, the \"blue deal\" (a term proposed by the authors to address water-related challenges) is as complex and demanding as the energy deal. The two topics are strictly interconnected, given that energy production requires huge quantities of water and water management depends heavily on energy [1]. Due to the world's population growth and economic development trends, the demand for both water [2] and energy [3] is expected to increase meaningfully. Additionally, climatic changes, driven by global warming, are contributing to the exacerbation of the water crisis [4], whose impact already heavily affects two billion people [5]. One of the major means to address the energy deal on a sustainable basis, beside renewable sources enhancement, is energy efficiency improvement [6]. The latter can be pursued using an integrated approach [7], which means designing and assembling combined multipurpose systems to deliver the same useful effects with less energy and fewer raw materials [8]. Conversely, the \"blue deal\" requires the exploitation of non-conventional water sources [9], along with better management of traditional ones [10]. Among the various non-conventional solutions, atmospheric water could be one of the means to improve water supply [11]. Interest in the atmosphere as a source of fresh water, in the last few years, has notably risen, as demonstrated by the increased number of scientific paper publications [12] and supported by the newly created International Atmospheric Water Harvesting Association (IAWHA) [13]. It is worth noting that in February 2024, the IAWHA organised its first international summit [14] and an international webinar [15], all focused on atmospheric water topics. Nevertheless, atmospheric water capturing can be affected by three main issues. The first two, which are interconnected, pertain to water production quantity and the associated energy consumption, while the third concerns water quality, as highlighted in [16]. This issue can be effectively resolved through a proper design of the Atmospheric Water Generator (AWG) and its treatment unit [16]. It is worth noting that the term AWG identifies all the devices designed to capture atmospheric water, regardless of the specific technology employed. As for the quantities, it should be highlighted that meaningful yields, from tens to several thousand litres per day in a comparatively small space, can be achieved by employing AWGs encompassing Vapour Compressor Refrigeration Cycles (VCRCs) [17]. The drawback of such a technology is the energy consumption [17], which, in adverse environmental conditions, can be on the order of some kWh per litre of produced water. Such a consumption can lead to high costs in atmospheric water production [12]. Embracing an integrated approach, the energy consumption issue can be bypassed, as demonstrated in a hotel case study [18], where an advanced integrated AWG was employed not only to provide water but also heating and cooling fluxes to enhance the existing plant performances. The advanced AWG, pointedly designed to produce drinking-quality water, was based on VCRC, enabling it to function simultaneously as a water provider, a heat pump for domestic water heating, and an air cooling system for primary air. The device gave three useful effects with almost the same energy consumption required by only one of them, due to the smart design. Actually, integrated AWG machines have the same approach as the advanced air conditioning systems that employ condensation heat for domestic water or area heating [19]. When a multi-purpose system is employed instead of a traditional one, the overall energy efficiency increases, giving environmental advantages [20]. Moreover, economic advantages can be achieved too, as demonstrated in [18], where the annual saving related to energy savings was calculated to be USD 80,000.