Climate Composition Research Articles

Multi-Horizon Predictive Soil Mapping of Historical Soil Properties Using Remote Sensing Imagery

There is increasing demand for more detailed soil maps to support fine-scale land use planning, soil carbon management, and precision agriculture in Saskatchewan. Predictive soil mapping that incorporates a combination of environmental covariates provides a cost-effective tool for generating finer resolution soil maps. This study focused on mapping soil properties for multiple soil horizons in Saskatchewan using historical legacy soil data in combination with remote sensing band indices, bare soil composite imagery, climate data, and terrain attributes. Mapped soil properties included soil organic carbon content (SOC), total nitrogen, cation exchange capacity (CEC), electrical conductivity (EC), inorganic carbon (IOC), sand and clay content, and total profile soil organic carbon stocks. For each of these soil properties, a recursive feature elimination was undertaken to reduce the number of features in the overall model. This process involved iteratively removing features such that random forest out-of-bag error was minimized. Final random forest models were built for each property and evaluated using an independent test dataset. Overall, predictive models were successful for SOC (R2 = 0.71), total nitrogen (R2 = 0.65), CEC (R2 = 0.46), sand content (R2 = 0.44) and clay content (R2 = 0.55). The methods used in this study enable mapping of a greater geographic region of Saskatchewan compared to those previously established that relied solely on bare soil composite imagery.

Global sensitivity analysis and optimisation of design parameters for low GHG emission lifecycle of multifamily buildings in India

In India, nearly 25% of citizens live in slums, unfit for a decent living. Replacing the existing residential building stock and the rapid development of the economy will significantly increase energy consumption and related greenhouse gases (GHG) emissions in the coming decades. Consequently, there is a high need of developing low lifecycle GHG emission, affordable and comfortable multifamily building designs, which can be widely implemented in the Indian construction market.The objective of this article is first to explore the most influential design parameters of the multifamily building located in the in: warm and humid (Bhubaneswar), hot and dry (Jodhpur), and composite (New-Delhi) climate zones of India on life cycle GHG emissions and indoor thermal comfort, and secondly, to perform a multi-objective optimisation considering the life cycle GHG emissions, life cycle cost and initial material investment cost based on the set of the most sensitive design parameters. The study combines a two-step global sensitivity analysis based on the Morris and Fast method with a multi-objective genetic algorithm integrated into one framework based on the parametric multifamily building model with extensive building performance simulations.The global sensitivity analysis results indicated that for all investigated locations: the apartment’s floor area, equipment load, windows-to floor ratio, mechanical ventilation airflow, and cooling temperature setpoint were the most influential design parameters in relation to the lifecycle GHG emissions. Finally, based on the multi-objective optimization, significant reductions in the range of 62–75% in terms of life cycle GHG emissions and 40–54% in terms of life cycle cost were achieved compared to the baseline 7-storey multifamily design scenario based on the minimum requirements of the Indian energy conservation code. At the same time, the initial material investment cost was 25–34% higher. The optimal set of the design strategies, resulting in the lowest life cycle GHG emissions and life cycle cost was found to be minimisation of the apartment’s floor area and windows to floor ratio, maximisation of the on-site renewable energy use, and design of a mechanical ventilation system combined with ceiling fans thus enabling the energy-efficient and thermally comfortable operation of the multifamily building with a high cooling temperature setpoint.

Integrating ZooMS and zooarchaeology: New data from the Uluzzian levels of Uluzzo C Rock Shelter, Roccia San Sebastiano cave and Riparo del Broion.

In this study we explore the potential of combining traditional zooarchaeological determination and proteomic identification of morphologically non-diagnostic bone fragments (ZooMS) collected from the Uluzzian levels of three Italian sites: Uluzzo C Rock Shelter, Roccia San Sebastiano cave, and Riparo del Broion. Moreover, we obtained glutamine deamidation ratios for all the contexts analysed during routine ZooMS screening of faunal samples, giving information on collagen preservation. We designed a selection protocol that maximizes the efficiency of the proteomics analyses by excluding particularly compromised fragments (e.g. from taphonomic processes), and that aims to identify new human fragments by favouring bones showing morphological traits more similar to Homo. ZooMS consistently provided taxonomic information in agreement with the faunal spectra outlined by traditional zooarchaeology. Our approach allows us to delineate and appreciate differences between the analysed contexts, particularly between the northern and southern sites, related to faunal, environmental, and climate composition, although no human remains were identified. We reconstructed the faunal assemblage of the different sites, giving voice to morphologically undiagnostic bone fragments. Thus, the combination of these analyses provides a more complete picture of the faunal assemblage and of the paleoenvironment during the Middle-Upper Palaeolithic transition in Italy.

Aerosols on the Tropical Island of La Réunion (21°S, 55°E): Assessment of Climatology, Origin of Variability and Trend

Aerosols are essential climate variables that need to be observed at a global scale to monitor the evolution of the atmospheric composition and potential climate impacts. We used the measurements performed over the May 2007–December 2019 period by a ground-based sun photometer installed at the island of La Réunion (21°S, 55°E), together with a linear regression fitting model, to assess the climatology and types of aerosols reaching this observation site located in a sparsely documented pristine area, and the forcings responsible for the variability of the observed aerosol optical depth (AOD) and related trend. The climatology of the aerosol optical depth (AOD) at 440 nm (AOD440) and Ångström exponent between 500 and 870 nm (α) revealed that sea salts could be considered as the La Réunion AOD440 and α baselines (0.06 ± 0.03 and 0.61 ± 0.40, respectively, from December to August), which were mainly modulated by biomass burning (BB) plumes passing over La Réunion (causing a doubling of AOD440 and α up to 0.13 ± 0.07 and 1.06 ± 0.34, respectively, in October). This was confirmed by the retrieved aerosol volume size distributions showing that the coarse-mode (fine-mode) dominated the total volume concentration for AOD440 lower (higher) than 0.2 with a mean radius equal to 3 μm (0.15 μm). The main contribution to the AOD440 variability over La Réunion was evaluated to be the BB activity (67.4 ± 28.1%), followed by marine aerosols (16.3 ± 4.2%) and large-scale atmospheric structures (5.5 ± 1.7%). The calculated trend for AOD440 equaled 0.02 ± 0.01 per decade (2.6 ± 1.3% per year). These results provide a scientific reference base for upcoming studies dedicated to the quantification of the impact of wildfire emissions on the southwestern Indian Ocean’s atmospheric composition and radiative balance.

The effects of cheatgrass invasion on US Great Basin carbon storage depend on interactions between plant community composition, precipitation seasonality, and soil climate regime

Abstract Annual‐grass invasions are transforming desert ecosystems in ways that affect ecosystem carbon (C) balance, but previous studies do not agree on the pattern, magnitude and direction of changes. A recent meta‐analysis of 41 articles and 386 sites concludes that invasion by annual grasses such as cheatgrass (Bromus tectorum L) reduces C in biomass across the Great Basin (Nagy et al., 2021). Reanalysis reveals that whether cheatgrass affects biomass C stocks is not generalizable, but rather depends on the considerable variation in climate across the subject sites. Our analysis suggests that accurate Great Basin‐scale estimates of cheatgrass effects on C balance are not yet possible. Addition of climate variables to the meta‐analysis reveals that cheatgrass invasion (a) reduced C in above‐ground biomass in relatively summer‐wet sites but not in summer‐dry sites, (b) increased surface soil C in sites with intermediate resistance and resilience classifications (R&R) but not in low R&R sites—that is, mesic/aridic soil climates and (c) did not affect deep soil C. Considering that cheatgrass has expanded most in relatively summer‐dry sites and mesic/aridic sites, omission of climate factors leads to model overestimates of cheatgrass effects on C when extrapolating to larger areas. Estimates of cheatgrass effects on C would also be improved if the analysis considered that (a) perennial grasslands are a common community state in the Great Basin that have intermediary C relative to annual grasslands and sagebrush stands, that is the omission of perennial grasslands from analysis inflates the baseline C storage of uninvaded Great Basin ecosystems, and( b) cheatgrass does not often exist in stable monocultures and soil carbon can reflect current or recent presence of other species. Synthesis and applications. Invasions often reveal heterogeneity in ecosystem structure and function that is not otherwise evident, and the heterogeneity can influence estimation of the net impacts of the invaders. For cheatgrass and other invaders, we propose that formally accounting for the spatial variability of invasion on ecosystem functions will improve the estimation of their net effect on ecosystem C, and thus improve prospects for adjusting management practices to optimize C sequestration.

Editorial for the Special Issue “Atmospheric Composition and Regional Climate Studies in Bulgaria”

The Special Issue “Atmospheric composition and regional climate studies in Bulgaria” is focused on the following two problems, which are of great societal and scientific importance: [...]

Strategic design of PCM integrated burnt clay bricks: Potential for cost-cutting measures for air conditioning and carbon dioxide extenuation

Globally, the energy demand of the building sector has increased intensely. The use of air conditioning in buildings for thermal comfort consumes a large percentage of this energy. The significant worldwide energy demand stresses the importance of net-zero or green buildings for a sustainable future. The present work investigates the air-conditioning cost-saving potential of the duplex house designed with various phase change materials (PCMs) incorporated burnt clay bricks. Five PCMs were selected, including three organic mixture PCMs (OM18, OM21, and OM29) and two form-stable PCMs (combination of organic and inorganic mixture). Besides, six different PCM arrangements in bricks (i.e. PCM layer on the outer side, on the middle layer, on the inner side, on the outer side and middle, on the middle and inner side, and on the outer side and inner side) are studied. The thermo-physical properties and latent heat of various PCMs (liquid and solid phases) were measured experimentally. The results showed that the duplex house with outer side PCM layer brick with OM29 PCM provides the best annual energy cost saving ($2079 in hot-arid climates and $2095 in composite climates), the highest carbon emission mitigations (87.80 ton-CO2/year in hot-arid climates and 88.42 ton-CO2/year in composite climates), and reasonable payback period (11.29 years in hot-arid climates and 11.21 years in composite climates).

Mid-life degradation evaluation of polycrystalline Si solar photovoltaic modules in a 100 kWp grid-tied system in east-central India

This study presents the mid-life degradation evaluation of a 100 kWp grid-tied solar photovoltaic (PV) power plant which is in the eleventh year of its operation. The field evaluation includes the visual inspections to identify the extent of degradation present in the PV modules, and the measurement of field current-voltage (I–V) data for maximum power deviation of the operational PV modules. Significant visual degradations were observed in many PV modules like encapsulant discoloration, snail tracks and cell cracks, burn marks on the surface of the PV module, shattering of front PV glass due to lightning strike, discoloration on metallization, corroded metal frame and hot spots. The PV module having heavy snail tracks, visible cracks and burn marks on the surface showed the highest power reduction of 95.9 W with respect to the reference module. The power degradation rate of the reference PV modules, which had no apparent visible degradation, over a period of ten years, was found to be varying between 0.16%/year to 1.72%/year. This study would be helpful in better understanding of the various types of degradations affecting the PV modules operating in the composite climate regions of east-central India.

Experimental study of effect of glass cover tilt angle of solar still in winter season of India’s composite climate

• Solar still’s performance in the winter season with nocturnal productivity. • Model-2 (TA 30°) above latitude angle performed good with 1660 ml/m2 yield, 17.25 % efficiency, and 1.1 % exergy efficiency . • Effect of covering condenser surface by insulating material in nocturnal yield. • Low tilt angle causes back drop of condensate into the basin. • Effect of wind velocity on outer surface temperature of condenser in daylight. The present work consists of an experimental investigation to find the effect of the tilt angle of the condenser surface of solar still (SS) on distilled water productivity and efficiency in the winter season in the metrological condition of Varanasi (25.2623°N, 82.9894°E), India. In this experiment, three models were fabricated with different tilt angles having the same basin areas. The first two models were single basin single slope (SBSS) type SS having tilt angles of 25° and 30° in southward facing. The third model was a single basin double slope (SBDS) type SS having a tilt angle of 15° facing toward the east–west direction. Generally, the latitude angle is used as a tilt angle however the present study revealed that the tilt angle varies according to season (sun-earth positioning) and affects productivity. The findings show the temperature difference between basin water and condenser glass cover is limited which is the driving force of the desalination process. The results showed that model-1, 2, and 3 give maximum yield of 760, 925, 320 ml/m 2 of distilled water with maximum thermal and exergy efficiency of 17.15 % and 0.6 %, 17.25 % and 1.1 %, and 7 % and 0.3 % respectively over seven hours span. This investigation also reveals the heat retaining capacity of SS and effect of polystyrene coverage on glass cover that helps to obtain maximum nocturnal yield of 435, 735, 320 ml/m 2 from model-1, 2, and 3 respectively on different days that make total distilled output to 1195, 1660, 560 ml/m 2 on a particular day. In design perspective, the proper selection of tilt angle facilitates the seamless gliding of condensate to collecting troughs that mitigate the loss of condensate that falls into the basin before reaching to trough.

Design and Optimization of Energy Consumption for a Low-Rise Building With Seasonal Variations Under Composite Climate of India

Abstract The need for maintaining thermal comfort conditions inside the building is a significant contributor to the total energy requirements of the buildings. Thus far, limited research has offered some strategies to mitigate the effect of ambient conditions on the thermal comfort and the building energy requirements for composite climatic zone in India. In order to address this problem, this study was conducted to evaluate and analyze the impacts of four different passive design strategies, i.e., insulation, cool roof, phase change material (PCM) thermal storage system, and shading, on thermal comfort and energy demand in the two-storey building situated in the composite climate zone of Delhi, India. The results obtained by numerical simulation for four different cities, i.e., Delhi, Jaipur, Lucknow, and Indore, have been compared to study the effect of local climatic and seasonal variations within the composite climatic zones. The simulations were conducted using the Design Builder software to capture results for one year. The results indicate that no single passive design strategy is sufficient to maintain comfortable conditions inside the building. The cool roof provides significant benefits in combination with other passive technologies in all seasons except for December, January, and February. The combination of insulation and PCM is useful for winter conditions. Energy saving of up to 20.5% is possible using the combination of all four passive strategies, whereas the cool roof alone gives an 18% reduction in energy load. The PCM with a melting point of about 32 °C is suggested for the cities under study.

Assessment of soiling impacts and cleaning frequencies of a rooftop BAPV system in composite climates of India

As one of the pioneers in solar photovoltaic (SPV) installations, India has witnessed several challenges related to performance; dust accumulation is one among them which needs attention. On the other side, most installers and SPV system owners do not have informed knowledge of dust accumulation rates (DAR) and optimum cleaning frequencies (OCF). It is also a well-known fact that DAR varies based on the SPV system (e.g., ground-mount, roof-mount, building applied/attached, building integrated and many other types). Hence, this paper analyses the effect of soiling specific to rooftop building-applied photovoltaics (BAPV) systems, and the main objective is to estimate the OCF driven by DAR. A rooftop BAPV system installed in India's composite climate zone is chosen as a case study, and its daily performance is monitored. Also, the on-site DAR is measured with micro slides help each day. It is observed that the system has different DAR for different seasons, clearly showing the relationship between energy outputs and DAR. The annual average daily deposition rate of dust was measured as 0.122 gm/m2/day. The maximum soiling loss of 0.39%/day was recorded in spring, followed by 0.34%/day in winter. The minimum soiling loss of 0.24%/day was measured in monsoon owing to heavy rainfall. The rooftop BAPV optimum cleaning frequency has been determined based on the energy lost due to soiling and cleaning cost. Overall, this study reveals that the rooftop BAPV system needs cleaning twice a year, first in spring and second in winter.

Degradation and reliability analysis of photovoltaic modules after operating for 12 years: A case study with comparisons

The long-term performance monitoring and characterization of field-exposed solar photovoltaic (PV) modules are essential for efficient power generation. This paper is an attempt at performance evaluation of the amorphous silicon (a-si), Heterojunction Intrinsic Thin layer (HIT), and Multi-Crystalline (mc-si) technologies after twelve years of outdoor exposure in the composite climate of India. Characterization techniques such as Visual Inspection, Infra-Red (IR) Thermography, Electroluminescence (EL) Imagining, and Electrical characterization have been carried out. I–V measurements, power losses, current degradation, and voltage degradation calculations are carried out. The percentage of electrical decline is 8.61%, 2.73%, and 29.08%, for Isc, Voc, and PMP respectively in a-si solar modules. For HIT modules 1.97%, 0.68%, and 0.48% for Isc, Voc, and VMP respectively. Finally, for the mc-si PV modules, these are 3.76%, 0.5%, and 1.44% for Isc, Voc, and PMP respectively over 12 years. The average degradation rates are found to be 1.24%/year, 0.14%/year, and 1.50%/year for a-si, HIT, and mc-si modules respectively. The EL imagining of the a-si modules shows the localized shunt over the surface of the modules as well as disconnected cell interconnects whereas no such defects are over the m-ci and HIT modules.

Energy Analysis of Semi-transparent Building Integrated Photovoltaic Window in Hyderabad, India Using Automated Parametric Simulations

In recent years, semi-transparent building-integrated photovoltaics (BIPV) technology has attracted attention for its renewable energy utilization. This research aims to develop a methodology for assessing the energy-saving potential of semi-transparent photovoltaic (STPV) window, which has a complex relationship with daylighting and air conditioning (AC) electricity consumption. A case study has been developed for the composite climate of Hyderabad, India. The study examines four commercially available single and double pane STPV windows and similar non-photovoltaic windows. For evaluation, an automated parametric simulation tool was developed to compute the net electricity consumption (NEC) for a representative model building with different window systems, and several window-to-wall ratios (WWR) and orientations. The result shows benefit in adopting the STPV window system across all directions and higher optimal WWR in STPV window as compared to normal window with the same opto-thermal characteristics.

Energy Efficiency Renovation Financing Models for Homeowners and Net Present Value Analysis: Case Study from India

In India, the lack of financing mechanisms has been identified as a major impediment in achieving energy efficiency (EE) and requires focused research to identify barriers and propose innovative financial models. This paper presents details of selected Government of India initiatives that highlight interlinking strategies of energy efficiency renovations, their financing models, and institutional policies needed for their implementation. These initiatives show that residential buildings have tremendous scope for retrofitting as they successfully attract finances through Energy Service Companies (ESCOs) and Renewable ESCO (RESCO) routes. This research highlights understanding of financial and technical barriers in energy efficiency retrofitting for existing residential buildings. Additionally, it discusses financial models and technical interventions being employed in energy efficiency residential retrofitting projects and demonstrates a retrofitting cost model for an actual case study project for composite climate using various physical and technological interventions. The work includes developing retrofitting scenarios through Government initiatives of technical interventions, then performing energy saving calculations, and finally developing cost model explaining the actual savings and payback periods for the potential intervention’s investments. These steps led to the development of a potential cost model which can assist both homeowners and energy professionals in identifying and implementing energy retrofitting measures in the residential building sector.

Integration of 100-kWp PV with low-voltage distribution power system in composite climate: performance and energy metrics analysis

ABSTRACT In India, PV integration with the low-voltage distribution system is growing rapidly. PV systems require embodied energy for their construction; additionally, they give energy support to the grid and also have an impact on grid parameters including Power Factor (PF), Maximum Demand (MD) and capacitive reactive-power (Q) requirement. Analysing the impact of PV integration on grid supply parameters, including performance and embodied energy-based-energy metrics is the current need. The study is performed by real-time data monitoring on 100-kWp grid-integrated PV in a composite environment. The annual average final yield:(3.76 kWh/kWp/day), system efficiency:(10.89%), performance ratio:(72.15%), energy pay-back time:(6.19 years), electricity production-factor:(4.04) and life cycle conversion efficiency:(12.50%) suggest that the system is energy efficient. The integration of PV with the grid has reduced the average PF and MD to 0.91 (lagging) and 133.63 kVA, respectively, whereas Q has increased to 28.67 kVAR. With a Levelised-cost-of-electricity:(LCOE) of Rs 6.19, the system has a pay-back of 5.29 years.

An innovative approach for retrieval of gridded urban canopy parameters using very high resolution optical satellite stereo

ABSTRACT Paucity of information on Urban Canopy Parameters (UCPs) is considered as one of the major reason behind limited urban climate research and modelling in developing region of Asia, Africa, and Latin America. UCPs define those characteristics of urban built form which have direct or indirect influence on urban climate. Most of the studies in developed world have utilized 3-Dimension (3D) Geographic Information System (GIS) database either developed from ground survey or Remotely Sensed (RS) data such as Aerial Photographs, Airborne Light Detection and Ranging (LiDAR) and high-resolution Interferometric Synthetic Aperture Radar (InSAR) data for retrieval of UCPs. However, non-existence of 3D GIS database and limited availability of above RS datasets in developing region necessitates to employ widely available low-cost alternative datasets for retrieval of UCPs. Hence, this study focuses on retrieval of UCPs by employing Very High Resolution Satellite (VHRS) optical stereo data, which has repeat availability, low cost and extensive coverage, in a highly dense and complex urban environment with a challenging composite climate like Delhi, India. A novel methodology for extraction of gridded UCPs from VHRS optical stereo data has been developed in this study to overcome the limitation of extraction of individual building footprint in dense and compact urban built-up. The validation of key UCPs such as building height (Mean error, Root Mean Square Error (RMSE) and Mean Absolute Error <1 m in all height groups), Building Surface Area (Accuracy 84.27%) and Sky View Factor (RMSE = 0.046 and correlation = 0.94) with ground measurements has displayed reasonable accuracies. Hence, the study demonstrates successfully the use of VHRS optical satellite stereo data for generation of gridded UCPs in a highly heterogeneous and dense urban built-up environment. The developed approach is globally replicable in any city of any country.

PERFORMANCE EVALUATION OF PARABOLIC CONCENTRATOR WITH THERMAL STORAGE SYSTEM FOR DOMESTIC APPLICATIONS

Solar energy is a free natural resource but its harvesting requires a high capital investment whichprohibits its maximum exploitation. A Parabolic Dish Solar Collector (PDSC) with a thermalstorage system was been constructed and developed to harness solar beam radiation. The thermalstorage system and PDSC were constructed using locally and less cost materials such asgalvanized metal sheet and steel rods curved to obey the equation of a parabola then weldedtogether with circular support rings which was then lined with stainless steel reflector pasted forthe construction of PDSC. The receiver was made of blackened aluminium material incorporatedwith coiled copper tube carrying water as the heat transfer fluid. A parabolic dish which acts of aheat collector is used to track and reflects solar radiation at a single point (focus) on a receiverabsorber. Heat transfer from the solar collector to the storage tank was done by usingthermosyphonic principle to circulate the water (heat transfer fluid) between storage tank andheating system (receiver). The evaluation of thermal storage and analyzing the efficiency oftracking and non-tracking parabolic dish solar collector was carried out during month of June,2020 for the composite climate of Sokoto. According to the finding, the efficiency of trackingPDSC with thermal storage system and non- tracking PDSC with thermal storage tank weredetermined and obtained to be 52.9% and 50% respectively.Keywords: thermal efficiency, parabolic dish collector, solar radiation, storage system andstainless steel reflector.

Decision-Making Model for Energy Efficiency with Building Envelope Design

A building envelope, comprising of opaque (walls, roofs, basement walls) and transparent (fenestrations) components, acts as physical barrier in preventing the ingress and impact of harsh outdoor climatic conditions on indoor comfort levels, which are mostly maintained by means of HVAC systems accounting for almost 55% of total energy consumption in a typical office building in India. These buildings show a potential energy reduction from 20% to 50% with efficient designs, which involve decisions related to parameters of envelope form, orientation, windows, shading, and materials. Since high solar radiation remains major concern for 2/3rd part of year in composite climate, therefore envelope design in this climate requires logical values for design parameters, instead of thumb rules. The aim of this paper is to bring out quantified energy efficiency potential of individual and combinations of design parameters, and to present results in the form of hand-held model offering choice of decisions.

Investigation on Subjects’ Seasonal Perception and Adaptive Actions in Naturally Ventilated Hostel Dormitories in the Composite Climate Zone of India

A seasonal adaptive thermal comfort study was done on university students in naturally ventilated dormitories in the composite climate zone of India. A total of 1462 responses were collected from the students during the field study spread over the autumn, winter, spring, and summer seasons of the academic year for 2018 and 2019. A “Right Here Right Now” type of surveying method was adopted, and the indoor thermal parameters were recorded simultaneously using high-grade instruments. The subjects’ mean thermal sensation (TS) was skewed towards a slightly cool feeling for the combined data. Most occupants preferred a cooler thermal environment during the summer season, while hostel residents desired a warmer temperature during autumn, winter, and spring seasons. During the summer season, the PMV−PPD model overestimated the subjects’ actual thermal sensation, while it underestimated the their thermal sensation in the winter season. The mean comfort temperature Tcomf was observed to be close to 27.1 (±4.65 °C) for the pooled data. Mean clo values of about 0.57 (±0.25), 0.98 (±0.12), 0.45 (±0.27), and 0.36 (±0.11) were recorded during the autumn, winter, spring, and summer seasons, respectively. Furthermore, switching on ceiling fans and opening doors and windows improved occupants’ thermal satisfaction during different seasons. The study results show the effective use of environmental controls and the role of thermal adaptation in enhancing the subjects/overall thermal satisfaction in the composite climate of India.

A novel variable refrigerant flow system with solar regeneration-based desiccant-assisted ventilation

Variable refrigerant flow (VRF) based air-conditioning systems provide better thermal comfort with respect to the conventional all-air systems involving either constant air volume (CAV) or variable air volume (VAV) technique. In this study, a novel VRF strategy involving potential of improved indoor air quality has been proposed by integrating solar energy with desiccant-assisted dedicated outdoor air system (DOAS). DOAS is responsible for ventilation and humidity control. An indirect evaporative cooling arrangement is incorporated in the path of supply air from desiccant for reducing the load on the VRF system. Using Energyplus simulations, thermal and electrical energy characteristics of the proposed system have been investigated for three climatic conditions. A comparative assessment of the novel system has been made against the conventional VRF and all-air VAV air-conditioning system. Results show that for warm-humid climate, electrical energy saving potential of the proposed solar energy-assisted VRF system is around 23.9 % and 9.5 % than the conventional all-air VAV and VRF systems, respectively. Under composite climate the saving offered by the proposed system with respect to VAV and VRF is determined as 13.8 % and 9.4 %, respectively. Finally, the energy saving obtained with solar energy based VRF for the hot-dry climate is 17.5 % and 11.6 % against conventional all-air VAV and VRF systems, respectively. Excellent solar fraction is observed for composite and hot-dry climates, whereas for warm-humid climate, it is determined as 0.97. A comparative analysis with conventional cooling coil assisted DOAS-VRF system also shows energy savings by the proposed system.