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Building automation system uses several networks of sensors for continuous monitoring of building control systems for energy-efficient operation. Physical sensors are costly and need frequent calibration. The accurate measurement of supply air temperature from the air handling units (AHUs) has an important effect on the control of cooling coil, supply air temperature and supply airflow rate delivered to rooms. In the case when such a sensor gives erroneous measurements, a virtual sensor can replace temporarily the faulty sensor, and it can also be used for automated fault detection of HVAC systems. This article proposes two different gray-box (models A and B) for predicting the supply air temperature of air handling units that were developed and tested using the measurements from two buildings. The models require the measurement of three variables (mixed air temperature, cooling coil valve signal, and chilled water inlet temperature). The results of both models are discussed and compared. A sliding window approach for cross-validation of the models was also carried out. The developed grayboxmodels A and B could be integrated into BAS for virtual measurement, virtual calibration, and fault detection in HVAC systems. [ABSTRACT FROM AUTHOR]

Reducing heating cost is a major challenge for greenhouses growers especially those located in cold regions. Several techniques have been applied to reduce greenhouse heating costs in winter season. This study presents a comprehensive review of different energy saving techniques that can be applied to reduce heating costs including energy-efficient greenhouse designs, use of energy-efficient covers, use of thermal curtains, energy-efficient management of indoor microclimates, selection of energy-efficient heating system, and the potential of using alternative energy sources. The energy saving potential of different design parameters (shape, orientation) depends greatly on the location, and the energy-saving potential of most passive heating systems (water tanks, rock bed) may not be feasible for commercial greenhouses production in cold regions. Alternative energy sources such as industrial waste heat, geothermal energy, and wood biomass could be a suitable option to reduce the greenhouse heating cost for large-scale production. However, it is important to consider the trade-offs between the agronomic need of plants and energy-saving potential of various energy-saving techniques, also the economic feasibility of energy saving systems in greenhouses. It can be concluded that this study could be useful for greenhouse growers, researchers, and manufacturer for creating sustainable energy-efficient greenhouse production in cold regions. Highlights • Energy saving potential of construction materials and dimensions of design explored. • Heating efficiency of different environmental control practises explored. • Heating systems, and use of alternative energy explored. • Energy saving could be significantly different based on the greenhouse location. [ABSTRACT FROM AUTHOR]

Cloud cover based solar radiation models are relatively simple and convenient as the models require the input of cloud cover data which are mostly available from the meteorological stations. In this study, the performance of a cloud cover based solar radiation model (Kasten-Czeplak model) with original or locally fitted coefficients was evaluated for estimating the hourly global solar radiation for four different locations in Western Canada. The average value of R2, mean bias error, and root mean square error are 0.69, −61.6, and 157.9 W m−2, respectively, for the model with original coefficients, whereas 0.82, 4.4, 107.1 W m−2 with locally fitted coefficients. Results show that the Kasten-Czeplak model with locally fitted coefficients satisfactorily estimated the hourly solar radiation of four different locations in Western Canada. Also, the results indicate that the model with original coefficients has very limited accuracy under intermediate cloud cover conditions. [ABSTRACT FROM AUTHOR]

Indoor vertical farming (IVF) has expanded exponentially over the last couple of years and is expected to have a compound annual growth rate (CAGR) of 25.9% from 2022 to 2029. IVF has enormous potential to ensure food security for the increased world population and other socio-economic benefits than traditional agricultural systems. However, the high energy demand, capital costs, and limitation in crop variety to be grown are major challenges to achieving the triple pillars (planter, people, and profit) of sustainability. The scholarly article comprehensively analyzes the current technologies, methodologies, and challenges in indoor thermal environment control (temperature, humidity, lighting, air circulation) and their integration with sustainability objectives. Space conditioning is achieved using heating, ventilation, air conditioning, dehumidification (HVACD), artificial lighting, and air circulation, which are energy-intensive due to the sealed envelope of IVF. Previous studies indicate energy consumption for lighting and space conditioning is the primary barrier to achieving sustainability. Minimal research activities have been reported for investigating the pathway to reduce the energy costs for lighting and HVACD systems for IVF. Integrating the air-side economizer and localized air supply for indoor climate control could save a significant amount of energy. The shifting electric demand and dynamic control also have enormous potential to reduce energy costs for lighting and HVACD. Integrating the transient model for heat gain/loss from plants and lighting heat gain is essential for precise energy simulation, which is critical for designing and sizing the right HVACD equipment and completing energy analysis. The research also shows that integrating green energy sources for HVACD and lighting reduces the environmental impacts on a large scale. Therefore, future research should focus on integrating renewable energy (geothermal, solar, wind, hydro) for HVACD, energy-efficient lighting technologies, and digital twin platforms for precision controls to reduce the energy and labor costs for thermal environmental controls in IVF. • A critical analysis is presented on efficient thermal environment controls for sustainable indoor vertical farming. • Appropriate energy-efficient and green energy-based solutions are still lacking in vertical farming operations. • Precision modeling tools need to develop for efficient thermal environment controls and equipment design. • Digital twins-based decision support platforms have potential for minimizing energy and labor costs. • Future research directions are presented for net-zero indoor food production. [ABSTRACT FROM AUTHOR]

Highlights • One-parameter-at-a-time (OAT) approach was used for the sensitivity analysis. • Default values of the CSHHEAT model are reasonably acceptable. • Heating demand is highly sensitive to the thermal properties of cover, thermal blanket, and greenhouse perimeter. • Small change of indoor temperature and RH have significant effects on the heating demand for the coldest months. Abstract The sensitivity of a heating simulation model (CSGHEAT) was performed for estimation of the time-dependent heating requirement in a Chinese-style solar greenhouse in cold region. Results showed that the constant value of air thermal conductance is the main default parameter of the model that significantly affected the model output. The results also indicated the heating requirement is highly sensitive to the greenhouse design parameters including the thermal properties of cover, thermal blanket, and greenhouse perimeter. The thermal blanket is the most important design parameter for the Chinese-style solar greenhouse, and the heating requirement could be increased between 32 and 41% during the coldest three months (January, February, and December) for changing the thermal conductivity from 0.01 to 0.05 W/m K. Increasing daytime indoor set-point temperature from 19 to 23 °C would increase the heating demand between 13 and 20%, whereas the heating demand could be increased by 9–18% for increasing the night-time temperature from 16 to 20 °C. Results also indicate the heating demand could be reduced up to 20% during the coldest period for increasing the indoor relative humidity from 70 to 90%. The results from this study could be useful for understanding the energy saving management of greenhouse operations and for designing the energy-efficient Chinese-style solar greenhouses in cold regions. [ABSTRACT FROM AUTHOR]

The simulation model CSGHEAT has been developed to estimate the hourly heating requirements in a Chinese-style solar greenhouse. The heating model was developed based on the heat balance of greenhouse air. With the set indoor temperatures, the surface temperatures of the floor and north wall were estimated by solving ordinary differential heat balance equations. The model is relatively easy to use because the model does not need to input measured data such as solar radiation like other models, and most of the heat sources and sinks in the Chinese-style solar greenhouse are included in the model. The model was validated with experimental data, and the predicted result was found to be in good agreement with the measured data. The mean difference between the measured and the estimated ground temperature is about 1.4 °C, and 1.8 °C for the north wall. The average percent error and relative root means square error (rRMSE) value for hourly heating prediction are 8.7%, and 11.5%, respectively. Therefore, the CSGHEAT model is considered to be sufficiently accurate and a reliable tool for researchers and others in the greenhouse industry to assist in designing and analyzing supplemental heating requirements in Chinese-style solar greenhouses. [ABSTRACT FROM AUTHOR]

Summary: Greenhouses in northern climates require a large amount of supplemental heating for growing crops in winter seasons, so energy‐efficient design of greenhouses based on local climate is important to minimize the heating demand. In this study, greenhouse design parameters including shape, orientation, the angle of the roof, and width of the span have been studied for the conceptual design of conventional greenhouses for Canadian Prairies using a heating simulation model. Five different shapes of greenhouses including even‐span, uneven‐span, modified arch, vinery, and quonset shape have been selected for the study. The simulation results proved that the uneven‐span gable roof shape receives the highest solar radiation, whereas the quonset shape receives the lowest solar radiation. However, the quonset shape greenhouse requires about 7.6% less annual heating as compared to the gable roof greenhouse, but the quonset would not be adopted as multispan greenhouses. Therefore, the gable roof greenhouse is considered as energy efficient for the multispan gutter connected greenhouses whereas quonset shape as a free‐standing single‐span greenhouses. In high northern latitudes, the greenhouse with east‐west orientation is more energy efficient from heating and cooling point of view when the length‐width ratio of the greenhouse is more than 1. The heating energy saving potential of the large span width in single‐span greenhouses is relatively higher as compared to the multispan greenhouses. [ABSTRACT FROM AUTHOR]

Summary: Greenhouses in northern climates require a large amount of supplemental heating for growing crops in winter seasons, so energy‐efficient design of greenhouses based on local climate is important to minimize the heating demand. In this study, greenhouse design parameters including shape, orientation, the angle of the roof, and width of the span have been studied for the conceptual design of conventional greenhouses for Canadian Prairies using a heating simulation model. Five different shapes of greenhouses including even‐span, uneven‐span, modified arch, vinery, and quonset shape have been selected for the study. The simulation results proved that the uneven‐span gable roof shape receives the highest solar radiation, whereas the quonset shape receives the lowest solar radiation. However, the quonset shape greenhouse requires about 7.6% less annual heating as compared to the gable roof greenhouse, but the quonset would not be adopted as multispan greenhouses. Therefore, the gable roof greenhouse is considered as energy efficient for the multispan gutter connected greenhouses whereas quonset shape as a free‐standing single‐span greenhouses. In high northern latitudes, the greenhouse with east‐west orientation is more energy efficient from heating and cooling point of view when the length‐width ratio of the greenhouse is more than 1. The heating energy saving potential of the large span width in single‐span greenhouses is relatively higher as compared to the multispan greenhouses. [ABSTRACT FROM AUTHOR]

Most greenhouses in the Canadian Prairies shut down during the coldest months (November to February) because of the hefty heating cost. Chinese mono-slope solar greenhouses do not primarily rely on supplemental heating; instead, they mostly rely on solar energy to maintain the required indoor temperature in winter. This study focuses on improving an existing thermal model, entitled RGWSRHJ, for Chinese-style solar greenhouses (CSGs) to increase the robustness of the model for simulating the thermal environment of the CSGs located outside of China. The modified model, entitled SOGREEN, was validated using the field data collected from a CSG in Manitoba, Canada. The results indicate that the average prediction error for indoor and relative humidity is 1.9 °C and 7.0%, and the rRMSE value is 3.3% and 11.5%, respectively. The average error for predicting the north wall and ground surface temperature is 4.2 °C and 2.3 °C, respectively. The study also conducted a case study to analyze the thermal performance of a conceptual CSG in Saskatoon, Canada. The energy analysis indicates the heating requirement of the greenhouse highly depends on the availability of solar radiation. Besides winter, the heating requirement is relatively low in March to maintain 18 °C indoor temperature when the average outdoor temperature was below –4 °C, and negligible during May–August. The results indicate that vegetable production in CSGs could save about 55% on annual heating than traditional greenhouses. Hence, CSGs could be an energy-efficient solution for ensuring food security for northern communities in Canada and other cold regions. [ABSTRACT FROM AUTHOR]

Agriculture and agro-based industries consume more energy, mainly derived from fossil fuels. The postharvest storage of agricultural products is crucial for the minimization of postharvest losses, which, throughout the supply chain, are controlled through the provision of optimum temperature and relative humidity conditions. A technoeconomic assessment of nonconventional energy resources (solar, wind and hybrid) in Sudan revealed that solar PV was more suitable in most studied sites for irrigation water pumping, as compared to wind and wind-solar hybrid energy systems [[4]]. [Extracted from the article]

Phenol resins (PRs) are considered as relatively inexpensive adsorbents synthesized from agricultural biomass via employing a variety of synthesized procedures. The performance of PR for heat transformation application is not widely investigated. In this regard, the present study aims to evaluate the four PR derivative/refrigerant pairs, namely (i) KOH6-PR/CO2, (ii) SAC-2/HFC, (iii) KOH4-PR/ethanol, and (iv) KOH6-PR/ethanol, for adsorption cooling and adsorption heating applications. Ideal cycle analyses and/or thermodynamic modelling approaches were utilized comprising governing heat and mass balance equations and adsorption equilibrium models. The performance of the AHP system is explored by means of specific cooling energy (SCE), specific heating energy (SHE), and coefficient of performance (COP), both for cooling and heating applications, respectively. It has been realized that KOH6-PR/ethanol could produce a maximum SCE of 1080 kJ/kg/cycle and SHE of 2141 kJ/kg/cycle at a regeneration temperature (Treg) and condenser temperature (Tcond) of 80 °C, and 10 °C, respectively, followed by KOH4-PR/ethanol, SAC-2/HFC-32, and KOH6-PR/CO2. The maximum COP values were estimated to be 1.78 for heating and 0.80 for cooling applications, respectively, at Treg = 80 °C and Tcond = 10 °C. In addition, the study reveals that, corresponding to increase/decrease in condenser/evaporator pressure, both SCE and SHE decrease/increase, respectively; however, this varies in magnitude due to adsorption equilibrium of the studied PR derivative/refrigerant pairs. [ABSTRACT FROM AUTHOR]

In the context of global water scarcity, adsorption-based atmospheric water harvesting (AWH) is an emerging technology for providing potable water at anytime/anywhere. In this regard, the study evaluates silica-gel, zeolite, ionogel, polymer, membrane, and metal-organic framework based ten kinds of emerging adsorbents for the AWH systems. A thermodynamic modeling framework comprising of adsorption equilibrium models and governing steady-state equations is performed. Performance of AWH systems is always judged on water production potential (WPP), energy consumption (EC) whereas thermodynamic correctness can be measured by first (η I) and second law (η II) efficiencies. Thereby, the adsorbents are evaluated from perspectives of WPP, EC, η I and η II. As per results, ionogel based adsorbent enables maximum WPP ranging up to 1.55 kg/kg/cycle, EC of 4214.96 kJ/kg w /cycle, η I of 0.54, and η II of 0.21. Whereas MIL-101(Cr) observe WPP ranging up to 0.87 kg/kg/cycle, EC of 4499.84 kJ/kg w /cycle, η I of 0.50, and η II of 0.19. Parametric analyses results show that η I of ionogel and MIL-101(Cr) can be increased up to 0.65 and 0.69 while η II up to 0.23 and 0.25, respectively. Furthermore, η I and η II of dual-stage system can improve by 33% as compared to single-stage that can improve by 68-74% as compared to vapor compression system. [Display omitted] • Silica-gel, ionogel, polymer, membrane, and MOF based ten emerging adsorbents are evaluated. • Thermodynamic modeling framework is used for performance evaluation of adsorbents/AWH. • Water production potential, energy consumption, and 1st/2nd law efficiency of AHW are evaluated. • Dual-stage AWH system can improve first and second law efficiency by 33%. [ABSTRACT FROM AUTHOR]

The greenhouse industry is an energy-intensive sector with a heavy reliance on fossil fuels, contributing to substantial greenhouse gas (GHG) emissions. Addressing this issue, the employment of energy-saving strategies along with the replacement of conventional energy sources with renewable energies are among the most feasible solutions. Over the last few years, solar energy has demonstrated great potential for integration with agricultural greenhouses. The present study reviews the progress of solar greenhouses by investigating their integration with solar energy technologies including photovoltaic (PV), photovoltaic-thermal (PVT), and solar thermal collectors. From the literature, PV modules mounted on roofs or walls of greenhouses cause shading which can adversely affect the growing trend of cultivated crops inside. This issue can be addressed by using bifacial PV modules or employing sun trackers to create dynamic shades. PVT modules are more efficient in producing both heat and electricity, and less shading occurs when concentrating modules are employed. In terms of using solar thermal collectors, higher performance values have been reported for greenhouses installed in moderate climate conditions. Further, in this review, the employment of thermal energy storage (TES) units as crucial components for secure energy supply in solar greenhouses is studied. The usage of TES systems can increase the thermal performance of solar greenhouses by 29%. Additionally, the most common mathematical models utilized to describe the thermal behavior of solar greenhouses are presented and discussed. From the literature, machine learning algorithms have shown a better capability to describe the complex environment of greenhouses, but their main drawback is less reliability. Notwithstanding the progress which has been made, further improvements in technology and more reductions in costs are required to make the solar greenhouse technology a solution to achieve sustainable development. [ABSTRACT FROM AUTHOR]