•Multi-year comfort field study was conducted in office buildings using evaporative cooling strategy.•Comfort temperature calculated using the Griffiths method was found 28.8 °C ...(SD=±1.9 °C).•Acceptable indoor humidity and airspeed range of 35–85% and 0.75–1.5 m/s.•Adaptive comfort model for evaporatively cooled buildings was presented.
Thermal adaptation can play a significant role in defining thermal comfort levels for evaporatively cooled office buildings commonly found in India. However, there are no dedicated studies to record the occupant perception and indoor thermal comfort in these buildings. The contribution of adaptive thermal comfort theory on occupant perception remains unclear for accurate design and operation of evaporatively cooled office buildings in India. Therefore, a multi-year field study of thermal comfort was conducted in ten office buildings operated under evaporative cooling systems in the composite climate of Jaipur, India. Transverse type questionnaire following Class II measurement protocols was carried out for recording office occupant's sensation and preferences for different indoor variables using ASHRAE 55 seven point and five-point scales, respectively. A total of 1554 datasets were collected spread over a total period of eighteen months, covering the entire summer season which includes very hot and dry days as well as few rainy days. Comfort temperature calculated using the Griffiths method was found 28.8 °C (SD=±1.9 °C). Results from the field study showed acceptable indoor humidity and airspeed range of 35–85% and 0.75–1.5 m/s for office subjects. Furthermore, 80% and 90% acceptability limits based on operative temperature and SET* were determined for present field surveys and results were compared with the existing adaptive models in National Building Code of India for different building types. This work is the first step towards the formation of an adaptive comfort model for evaporatively cooled buildings in the composite climate of India.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Thermal comfort standards such as ASHRAE 55-2013 defines comfort boundaries which are based on the experimental results conducted in climatic chambers and field studies. The current comfort standards ...do not reflect the cultural and climatic diversity of India. A thermal comfort field study was conducted in 32 naturally ventilated buildings, collecting a total of 2610 samples spread over a total period of four years, covering all seasons, wide age groups, clothing types, and building types. In the present study, ASHRAE comfort boundaries at three different air speeds - still air (up to 0.2 m/s), natural air flow (0.2 m/s–0.5 m/s) and forced air flow with ceiling fan assist (0.5 m/s–1.5 m/s) are investigated. The method of calculation suggested by the ASHRAE 55-2013 and ISO-7730 were followed to determine extended acceptable temperature ranges for comfort at elevated air speed. Comfort boundaries are defined based on climate specific adaptations, the role of air speed and thermal preferences. Results from this study indicate that subjects in naturally ventilated buildings of this region are comfortable at temperatures different from those suggested by ASHRAE 55 and ISO-7730 standards. New extended boundaries of comfort zones are proposed considering various adaptations specific to this region, including the role of air speed to offset the temperature. The proposed comfort zones show that subjects are comfortable up to 32 °C at still air condition (0 m/s–0.2 m/s) and up to 35 °C at higher speed (up to 1.5 m/s) in naturally ventilated buildings in the composite climate of India.
•About 82% of the subjects found comfortable at prevailing indoor conditions in present study.•Applicability of ASHRAE 55 comfort zones at elevated air speed is evaluated.•Study reveals that comfort zones are dependent on climatic specific adaption and comfort expectations.•Study proposes new boundaries of comfort zones using adaptive comfort approach.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK, ZRSKP
Thermal adaptation plays crucial role in energy efficient operation of buildings without compromising with human thermal comfort. Elevated air velocity is commonly desired to restore comfort ...requirements at higher temperatures especially in NV and MM buildings located in tropical countries like India. This article is the systematic field study comprising a total of 4872 responses (1874 from NV buildings and 2998 from MM buildings) collected over a period of six years (2011-2017) during summer and moderate seasons under composite climate of Jaipur (India). Subjects' responses and concurrent field measurements were utilized to investigate the impact of elevated air velocity on indoor thermal comfort. This research is a first attempt of its kind that deals with graphical quantification of air velocity required to offset increased temperature and follows similar approach as presented in ISO 7730. A redefined air velocity offset chart for Indian subjects working in office buildings has been proposed using the evidences (i.e. comfort expectations, preferences and local adaptation) collected from actual field observations. Thus, the offset in comfort operative temperature from base value of 28.04 °C and 26.93 °C for NV and MM buildings were obtained to be 4.78 °C and 4.24 °C, respectively for the elevated air velocity of 1.5 m/s.
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BFBNIB, DOBA, GIS, IJS, IZUM, KILJ, KISLJ, NUK, PILJ, PNG, SAZU, UILJ, UKNU, UL, UM, UPUK
The authors have tried to strike a balance between a short book chapter and a very detailed book for subject experts. There are three prime reasons behind for doing so: first, the field is quite ...interdisciplinary and requires simplified presentation for a person from non-parent discipline. The second reason for this short-version of a full book is that both the authors have seen students and technically oriented people, who were searching for this type of book on hydro energy. The third reason and motivation was considering engineers who are starting their career in hydro energy sector. This book is targeted to present a good starting background and basic understanding for such professionals.
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FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NUK, OBVAL, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
Effect of inclination of absorber on the airflow rate has been investigated in a solar induced ventilation system using Roof Solar Chimney (RSC) concept. During summer months, due to the higher ...altitude of sun, absorber at small inclination with the horizontal plane captures more solar radiation, but suffers with reduction in the stack height. Results of the developed solution show that optimum absorber inclination varies from 40° to 60° depending upon the latitude of place. At Jaipur (India) 45° is found to be optimum for obtaining maximum rate of ventilation. At this inclination, the rate of ventilation is about 10% higher as compared to 60° and 30° inclinations. Experimental investigations show good agreement with the theoretical results. Roof Solar chimney of this size can easily be mounted on residential buildings for enhancing natural ventilation.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
Earth–pipe–air heat exchanger (EPAHE) systems can be used to reduce the cooling load of buildings in summer. A transient and implicit model based on computational fluid dynamics was developed to ...predict the thermal performance and cooling capacity of earth–air–pipe heat exchanger systems. The model was developed inside the FLUENT simulation program. The model developed is validated against experimental investigations on an experimental set-up in Ajmer (Western India). Good agreement between simulated results and experimental data is obtained. Effects of the operating parameters (i.e. the pipe material, air velocity) on the thermal performance of earth–air–pipe heat exchanger systems are studied. The 23.42
m long EPAHE system discussed in this paper gives cooling in the range of 8.0–12.7
°C for the flow velocities 2–5
m/s. Investigations on steel and PVC pipes have shown that the performance of the EPAHE system is not significantly affected by the material of the buried pipe (pipe). Velocity of air through the pipe is found to greatly affect the performance of EPAHE system. The COP of the EPAHE system discussed in this paper varies from 1.9 to 2.9 for increase in velocity from 2.0 to 5.0
m/s.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
The efficiency of conventional tube‐ in plate type solar collectors is limited due to higher heat losses for surface based solar energy absorption and indirect transfer of heat from hot absorber ...surface to working fluid having poor heat transfer properties flowing through tubes. In this paper, a prototype direct absorption solar collector having gross area 1.4 m2 working on volumetric absorption principle is developed to investigate the effect of using Al2O3–H2O nanofluid as heat transfer fluid at different flow rates. Experimentation was carried using distilled water and 0.005% volume fractions of 20 nm size Al2O3 nanoparticles at three flow rates of 1.5, 2 and 2.5 lpm. ASHRAE standard 93-86 was followed for calculation of instantaneous efficiency of solar collector. Use of nanofluid improves the optical and thermo physical properties that result into an increase in the efficiency of the collector in all cases of using nanofluids in place of water. Collector efficiency enhancement of 8.1% and 4.2% has been observed for 1.5 and 2 lpm flow rate of nanofluid respectively. Optimum flow rate of 2.5 and 2 lpm towards maximum collector efficiency have also been observed for water and nanofluid respectively.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Understanding the factors that drive the use of residential electricity in India is essential for designing policies that can reduce its expected growth. This study empirically examines the magnitude ...and causes of variation in electricity use in a sample of Indian dwellings with and without air conditioning (AC), using an interview-based survey approach applied in 41 dwellings located across two cities representing the composite climate of India. Statistical analysis was used to unpack the relationship between electricity use and socio-technical factors. Despite the small sample size and having the same climatological realm, there was a wide variation observed in electricity use by income groups and the presence of ACs. The mean annual residential electricity consumption (REC) was observed to be highest in high-income group dwellings (5,618 kWh/year), followed by middle-income group dwellings (3,870 kWh/year) and lowest in low-income group dwellings (2,169 kWh/year). The mean REC of AC dwellings (4,208 kWh/year) was found to be nearly double that of non-AC dwellings (2,260 kWh/year) with significant seasonal variation. Multivariate regression analysis revealed that the presence of ACs, household size (number of occupants), annual non-AC appliance hours, dwelling size (number of rooms) and income group accounted for 80% of the variability in REC across the study sample. Residential energy policy in India should consider these key factors that drive REC. To be effective, such policy programmes need to be customised for different income groups, adopting incentives as well as energy awareness campaigns to influence both purchasing and habitual behaviours.
•Calibrated simulation models used for energy saving assessment.•Study implemented building code and advance energy efficiency measures.•Maximum 33% energy saving is possible using building ...code.•Advance energy efficiency measures save 50.29% energy in four star category hotel.•Economic analysis shows lowest payback for lighting fixtures.
Commercial buildings of conventional practices consume significant energy, especially hotel buildings. Therefore, the study aims to estimate energy saving potential in three categories of hotels from Jaipur city, India. Energy Conservation Building Code (ECBC) and advance Energy Efficiency Measures (EEMs) beyond ECBC specifications were implemented such as building envelope, Heating, Ventilation and Air-Conditioning (HVAC) system and lighting system for estimating energy saving potential. Dynamic thermal simulation tool was used for modeling and simulation of existing hotel buildings and simulation models were calibrated against actual energy consumption of study hotels. Implementation of ECBC to hotel Category-1, Category-2 and Category-3 demonstrates energy savings of 37.2%, 18.42% and 25.82%, respectively with payback period of 2.39–6.41 years whereas application of advance EEMs in respective hotels led to increase in energy savings up to 61.75%, 53.92% and 54.61% in respective hotel category with payback period of 4.22–5.11 years. Implementation of ECBC code to existing hotel buildings in Jaipur city can save 27.9GWh/year and with the use of advance EEMs, the city can save 67.04GWh/year of energy. This study concludes that there is significant energy saving potential in hotel buildings in India through implementation of ECBC and other energy efficiency measures.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
•Summer performance of a forced ventilated PV-DSF system is assessed.•PV panel transparency, air cavity and velocity are selected as design parameters.•Mathematical correlations are developed for ...energy characterization.•Correlations are validated experimentally for their robustness.
Performance of Photovoltaic-double skin façade (Photovoltaic-DSF) system in summer has been critical. Owing to high solar ingress, cooling requirement of a building significantly increases. Photovoltaic-DSF system provides a shield and controls the heat gain through fenestration in the interior spaces. In the present article, mathematical correlations are developed for energy characterization of forced-ventilated Photovoltaic-DSF system in India's hot summer zone i.e. Jaipur. The Photovoltaic-DSF system has been installed and monitored for Jaipur's summer months (May to July). L25 Orthogonal array of design parameters (air cavity thickness, air velocity, and PV panel's transparency) and their respective levels have been developed using Taguchi design to perform experiments. Based on experimental results, multiple linear regression has been used to forecast solar heat gain coefficient, PVs electrical power and daylighting illuminance indoors as function of design factors. The statistical significance of mathematical relationships is sorted by variance analysis, which is found to be in good accord with field measurements (R2 > 0.90). The proposed correlations are pragmatic in designing Photovoltaic-DSF systems for hot summer conditions. The Photovoltaic-DSF system with 30% transmittance and air velocity of 5 metres per second in 200 mm air cavity thickness achieved maximum energy performance in hot summers.
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CEKLJ, GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
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