Radiative cooling (RC) is attracting more interest from building engineers and architects. Using the sky as the heat sink, a radiative cooling material can be passively cooled by emitting heat to the sky. As a result of the development of material technology, RC research has been revived, with the aim of increasing the materials’ cooling power as well as finding reliable ways to utilize it in cooling for buildings. This review identifies some issues in the current implementation of RC technologies in buildings from an architectural point of view. Besides the technical performance of the RC technologies, some architectural aspects, such as integration with architectural features, aesthetic requirements, as well as fully passive implementations of RC, also need to be considered for building application. In addition, performance evaluation of a building-integrated RC system should begin to account for its benefit to the occupant’s health and comfort alongside the technical performance. In conclusion, this review on RC implementation in buildings provides a meaningful discussion in regard to the direction of the research.

Crop residues are common in rural Ghana due to the predominant role agriculture plays in livelihood activities in these communities. In this paper we investigate the prospects of exploiting agricultural crop residues for rural development in Ghana through bioenergy schemes. A theoretical energy potential of 623.84 PJ per year, which is equivalent to 19,781 MW was estimated using crop production data from the Food and Agricultural Organization of the United Nations and residue-to-product ratios. Ghana has a total installed generation capacity of 4577 MW which is four times less the energy potential of crop residues in the country. Cocoa pod husks were identified as important biomass resources for energy generation as they are currently wasted. To further assess the energy potential of cocoa pod husks, different cocoa pod husks samples were collected across the six cocoa growing regions in Ghana and thermo-chemically characterised using proximate and ultimate analysis. The low levels of nitrogen and sulphur observed, together with the high heating value, suggest that cocoa pod husks and for that matter crop residues are eco-friendly feedstock that can be used to power rural communities in Ghana.

Thermochemical energy storage materials and reactors have been reviewed for a range of temperature applications. For low-temperature applications, magnesium chloride is found to be a suitable candidate at temperatures up to 100 °C, whereas calcium hydroxide is identified to be appropriate for medium-temperature storage applications, ranging from 400 °C up to 650 °C. For the high-temperature range (750–1050 °C), oxides of cobalt, manganese, and copper are found to have the redox behaviour required for thermochemical heat storage. However, some of these materials suffer from low thermal conductivities, agglomeration, and low cyclability and, therefore, require further improvements. The concept of enhancing thermal conductivities through additives such as nanomaterials has been encouraging. From an operational point of view, fluidized-bed reactors perform better than fixed- and moving-bed reactors due to better particle interactions. There is, however, a need for the reaction bed to be further developed toward achieving optimum heat and mass transfers. Agitated fluidized-bed reactors have shown encouraging results and are suggested for further exploration. A combination of appropriate computational tools can facilitate an in-depth understanding of bed dynamics.

Thermochemical energy storage (TCES) presents a promising method for energy storage due to its high storage density and capacity for long-term storage. A combination of TCES and district heating networks exhibits an appealing alternative to natural gas boilers, particularly through the utilisation of industrial waste heat to achieve the UK government’s target of Net Zero by 2050. The most pivotal aspects of TCES design are the selected materials, reactor configuration, and heat transfer efficiency. Among the array of potential reactors, the fluidised bed emerges as a novel solution due to its ability to bypass traditional design limitations; the fluidised nature of these reactors provides high heat transfer coefficients, improved mixing and uniformity, and greater fluid-particle contact. This research endeavours to assess the enhancement of thermochemical fluidised bed systems through material characterisation and development techniques, alongside the optimisation of heat transfer. The analysis underscores the appeal of calcium and magnesium hydroxides for TCES, particularly when providing a buffer between medium-grade waste heat supply and district heat demand. Enhancement techniques such as doping and nanomaterial/composite coating are also explored, which are found to improve agglomeration, flowability, and operating conditions of the hydroxide systems. Furthermore, the optimisation of heat transfer prompted an evaluation of heat exchanger configurations and heat transfer fluids. Helical coil heat exchangers are predominantly favoured over alternative configurations, while various heat transfer fluids are considered advantageous depending on TCES material selection. In particular, water and synthetic liquids are compared according to their thermal efficiencies and performances at elevated operating temperatures.

Previous research has demonstred that microencapsulated phase change materials (MEPCMs) could significantly increase the energy storage density of solar thermal energy storage (TES) systems. Compared with traditional phase change materials (PCMs), MEPCMs have many advantages since they can limit their exposure to the surrounding environment, enlarge the heat transfer area, and maintain the volume as the phase change occurs. In this study, a new MEPCM for solar TES systems is developed by encapsulation of paraffin wax with poly (urea formaldehyde) (PUF). The experimental results revealed that agglomeration of MEPCM particles occurred during the encapsulation process which affected the uniformity of the particle size distribution profile when sodium dodecyl sulfate was used as an emulsifier. The differential scanning calorimetric (DSC) analysis results showed that the melting temperatures were slightly increased by 0.14–0.72 °C after encapsulation. A thermogravimetric (TG) test showed that the sample weight decreased while the weight loss starting temperature was slightly increased after encapsulation. Overall, the sample UF-2, fabricated with the binary emulsifiers of Brij 35 and Brij 30 and 5% nucleating agent, resulted in good particle dispersion and shell integrity, higher core material content and encapsulation efficiency, as well as improved thermal stability.