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Buildings with low energy use are a social and economic imperative for India and other tropical regions that will see the largest growth in the next two decades. Energy use largely determines the environmental footprint of a building over its life span. Research, policy and practice are making building energy performance an area of intellectual and professional growth. Increasingly, a new kind of professional is needed in the building design or operations team to help save energy.
Within the M.Tech. program in Building Energy Performance students learn to:
CEPT University is recognized internationally for high quality research and practical experience in energy efficiency and net-zero energy buildings. Our focus on design and management of human habitat provides a supportive eco-system for the building energy performance program. Our faculty consists of industry experts, experienced practitioners and researchers who have a solution oriented approach. We have a world-class research facility that houses the latest equipment for testing and measuring thermal and luminous effects in buildings.
India and other tropical regions are experiencing an unprecedented economic growth and environmental concerns. Regulations, green building rating systems, and owners’ preferences have created a demand for building energy professionals. With a focus on warm climate, the graduates of this program are attractive candidates for job markets in India, South-east Asia and the Middle-east, and for research careers in Europe and North America. They will work in energy consulting firms, building design teams, with building owners and government agencies, taking a leading role for pursuing energy efficiency with a whole-building perspective.
Yashima Jain, Prasad Vaidya, Saket Sarraf
Abstract: The building design community is challenged by continuously increasing energy demands, which are often combined with ambitious goals for indoor environment, environmental impact, and building costs. From an architect’s standpoint, the output results from simulation tools are mainly alpha-numeric charts that are difficult to use and interpret and are generally composed of enormous quantities of results data. These data have a huge potential for design improvement if communicated effectively. Poor data plotting limits the ability to compare, analyse and explore in depth to reveal hidden information, and thus leads to weak decision making. A robust literature review of data representation theory and past work in the development of the representation of thermal and energy simulation results was done. It suggests that there is a need to organize the already available fragmented efforts based on various design stages and design discipline. The methodology includes interviews with practitioners, analysis of current state-of-the-art spatial representations, selection of metrics, and developing the representations for a test case building. Based on the interviews and analysis of the current representations, a theoretical framework was proposed for energy efficiency visualizations. Further, a framework of representations which can be followed to represent energy simulation data to architects has also been proposed. This framework is a combination of representation of various options along x-axis, floors of the building along y-axis and representation of data for various metrics along the z-axis. This provides consistency in the representations, a background map that architects are familiar with so that data can be displayed for easy communication, and options can be compared. The results show not only that such representation can lead to a better understanding of the relationship between the building elements and its performance, but that certain metrics are more useful to stakeholders and combination or overlays of such metrics can lead to better understanding of design performance. This research is an attempt to bridge the communication gap between architects and energy modelers with energy information simulation results represented spatially.
Sahil Verma, Sanyogita Manu
Abstract: India’s energy demand is growing due to transforming economy. Lifestyle and consumption behavior is also changing with economic growth. Because of the accelerated economy, the country is urbanizing rapidly. Recent studies show that by 2030, India’s energy demand in the residential sector will be four-fold as compared to the energy demand in 2010. To reduce the future energy demand in the residential sector, the green building rating systems like IGBC, GRIHA, and LEED came up with design guidelines specifically for residential buildings. IGBC demonstrated savings of 30% to 40% on energy cost. However, research continually demonstrates that green building rating systems do not always ensure targeted energy performance and the way of identifying and addressing the performance gap is through building performance evaluation (BPE). This study was part of a project called Learn-BPE. This is UK- India research project which aims to undertake collaborative research and educational activities to develop the methodology to evaluate the actual performance of buildings from a technical and occupant perspective. This study reports the findings from BPE carried out on an IGBC green home platinum-rated building located in Ahmedabad, India. Monitoring and on-site measurements were carried out from 15th Jan 2019 to 28th Jan 2019. UK-BPE methodology was adopted for evaluation and through the case study, the methodology was evaluated to check its relevance and appropriateness for residential building in India. Annual and monthly energy consumption were analysed. PM2.5, PM10 and CO2 levels were monitored for indoor air quality. Thermal comfort and occupant’s satisfaction survey along with instantaneous measurements of indoor environmental variables were taken. Further, to understand the gap in UK-BPE methodology, a matrix was developed by comparing different rating system applicable to the residential building in India. This matrix helped in identifying the different performance metrics that are used by different rating systems in India. The rating systems considered for developing the matrix were IGBC green- (homes, affordable housing, residential societies), GRIHA- (v2015, existing building, affordable housing, SVA), LEED v4.1 (residential design and construction: multifamily core and shell, adapted for India) and Eco-Niwas Samhita 2018. The matrix helped in finding the gap in performance metric in UK-BPE and Indian rating systems and recommendations were also provided to fill the gap. This study was carried out to evaluate the UK-BPE methodology for residential green building in India. This study helped in understanding the requirements of green building rating system in India and helped in identifying the gap in UK-BPE methods for the Indian context. An extensive study was done for identifying the gaps in methodology and suggestions are given to bridge the gap. To evaluate the performance of the building, UK-BPE methodology was used and the project chooses a prescriptive approach for compliance. The building studied was located in Ahmedabad and its performance was evaluated based on the performance goals as per IGBC green homes and suggested methodology. After analysing all the aspects of case study building, it was found that building was performing and built as per the IGBC criteria requirements, but still there was gap observed in the operation and design due to which occupants were not using them as intended or do not help in energy savings. From the building study, it was concluded that evaluating criteria based upon prescriptive approach alone cannot determine the performance of the building, proper monitoring of that parameter needs to be done to know the actual performance of the building.
Sanchi Pathella, Prasad Vaidya
Abstract: Earlier studies have used Thermal Autonomy (TA) and Residual Cooling Degree Days (RCDD) to estimate the cooling potential of passive cooling techniques. But the cooling energy reduction due to passive strategies was not quantified. The BQEET tool uses the TM41 CIBSE method based on Cooling Degree Days (CDD) to calculate the CDD values using the appropriate Balance Point Temperature (BPT). The tool then estimates the reduction in cooling energy consumption due to passive strategies. This tool is targeted to help architects and designers to select suitable passive strategies in the early design stages. It is also targeted to help planners and policy makers to estimate energy use and cost savings at a large scale, to formulate and implement new policies. Limited testing of BQEET was done by Desai, using the ASHRAE Guideline 14 and IPMVP, since a robust procedure was not within the scope of the study. The Guideline 14 and IPMVP methodology are intended for calibrating the results of a simulation with an existing building and not for testing a simulation software. Hence, there is a need to test the BQEET tool in a robust way. The comparative testing in this study has been carried out for two types of buildings, air-conditioned and mixed mode building operating with passive cooling strategies. The testing procedures start by using the HERS BESTEST models of typical US buildings and modifying them using reference building models for the Indian context. There are no procedures for mixed mode buildings in HERS BESTEST, and no reference models for mixed mode buildings have been developed for India. Therefore, this study defines the mixed mode operation cases and tests them for the number of discomfort hours. The air-conditioned cases are compared for their energy end-uses. The lighting and equipment energy in BQEET are similar to the EnergyPlus results. But the cooling energy in BQEET is 400% higher than that of EnergyPlus. In order to analyse the variation in the cooling energy results, a critical analysis of the components contributing to the cooling energy is carried out. A building physics investigation of the cooling energy calculations of fabric gain, solar gain, fan gain and latent gain due to infiltration and occupancy has been carried out in the TM41 CIBSE method based on Cooling Degree Days, EnergyPlus and BQEET. The errors in the cooling energy calculations of the BQEET tool are identified, quantified and analysed. Modifications in the algorithm of the tool or in the BQEET tool itself are proposed.
Nidhi Rai Jain, Rajan Rawal
Abstract: In India, the energy end-use is anticipated to increase by 56% from 2014 to 2050. It shares 12% of total carbon emissions in the world by Room Air Conditioners (RACs). As increase in energy production using fossil fuels has an adverse effect on climate, there is an immediate need to focus on mitigation scenario. This scenario counts on the change of refrigerant, improvements in system design efficiency and operational approach. Growth in urbanization and rising income is persuading the use of RACs. Seasonal Energy Efficiency Ratio (SEER) is the most used method to quantify efficiency of RAC. Environmental impact of the system is still unexplored. This study is conducted to develop a correlation between indoor comfort temperature, the energy efficiency of RAC and total carbon emissions (direct & indirect) considering its life span. Even with constant improvements in the energy efficiency of RAC using low GWP refrigerants, there is gap observed between the actual performance of the system and total emissions leading to climate change. The purpose of this study is to correlate annual cooling energy demand (w.r.t. comfort set-point temperatures) to energy efficiency and total emissions by a RAC for any city in India. The study was conducted in four stages - literature study, data collection, calculation methods and results. Initially, relevant metrics were identified from past work to quantify the parameters. In the next step, 12 Indian cities were selected based on GDP growth followed by Cooling Degree Days (CDD). Four RAC units were selected based on findings from market survey of 282 RAC systems available in the country. In the third stage, Indian Seasonal Energy Efficiency Ratio (ISEER) and Cooling Seasonal Energy Consumption (CSEC) were calculated for 12 cities using ISO 16358-1 and outdoor temperature bin hours. Carbon emissions were calculated using Total Equivalent Warming Impact (TEWI) score which comprises of direct (refrigerants) and indirect (energy consumption) emissions considering its life span. A method was proposed to calculate ISEER and CSEC using adaptive setpoints with few research gaps identified. The adaptive setpoints were calculated based on Indian Method of Adaptive Comfort (IMAC). Lastly, the results obtained shows that indirect emissions dominate in TEWI score which is calculated using CSEC (kWh). A more significant variations were observed in CSEC in different cities and different comfort models as compared to RACs with different ISEER. This study develops a methodology to calculate ISEER beyond BEE standard method and propose CSEC as a metric for different cities and different comfort models using indoor setpoints. The direct emissions were observed constant in all cities, the variations observed was because of indirect emissions (kWh). Thus, there is need to focus more on CSEC (kWh) than low GWP refrigerant to reduce total carbon emissions which causes climate change.
Garima Kamra, Sanyogita Manu
Abstract: ‘Housing for all – 2022’, a large-scale housing initiative was launched in 2015 by the Indian government for providing quality affordable housing to the lower economic segment by the year 2022. Occupant thermal comfort is one of the significant aspects of liveability and applies to affordable housing as well. These houses have low energy consumption as of now, however, as incomes and comfort expectations increase, energy use and related costs in this segment are expected to surge. Comfort field studies in affordable houses in India remains a subject largely neglected. This report discusses the findings of the thermal comfort conditions and energy use of 20 houses in three affordable housing developments located in Ahmedabad, India. The results discussed are from data collected using three methods. These involved long-term monitoring of household energy use and indoor environment parameters (air temperature and relative humidity (RH)), instantaneous measurements of thermal comfort conditions (air temperature, RH, air velocity, globe temperature) and right-here-right-now thermal comfort surveys. It was observed that average daily energy use ranged from 0.5 - 6.75 kWh and was dependent on appliance ownership and occupant behavior. Energy use was base load driven in these houses. 65% of the occupants reported being comfortable in their thermal environment during the survey period. The conclusions from this study give an insight into the seasonal and daily usage patterns of energy use in the affordable housing segment and potential for savings. It also discusses the prevalent thermal comfort conditions and adaptive measures adopted by the occupants.
Shoumik Desai, Rajan Rawal
Abstract: The commercial and residential sector demands high cooling requirement, which is mostly achieved by using conventional cooling systems like split ACs, chillers or VRF. These systems currently produce 100 MT of CO2 per annum and hence contribute significantly to carbon emissions. To mitigate such environmental impacts, using low energy cooling systems like an indirect-direct evaporative cooling system (IDEC) is an energy efficient alternative as it uses energy only for pumping water and blowing air. The evaporative cooling technology works on the principles of heat and mass transfer between air and cooling water. Direct evaporative coolers (DEC) works based on mechanical and thermal contact between air and water, while IDEC works based on heat and mass transfer between two streams of air, separated by a heat transfer surface with a dry side where only air is cooling and a wet side where both air and water are cooling (Porumb, Ungure, Fechete, Alexandru, & Mugur, 2016). As the capacity of air to absorb vapor is directly related to its humidity, evaporative coolers are most suitable for regions where high temperature coincides with low air humidity. It can cool air using much lesser energy than vapor compression techniques. This study evaluates the cooling performance of IDECs. The study was conducted in the industrial food processing unit where 61,800 CFM IDEC system is serving 465 m^2 of area. Internal loads are very high owing to the usage of gas furnace and fryers for cooking activity. The wet bulb effectiveness (WBE %) was calculated from the hourly measured values of air temperature (Ta °C) and relative humidity (RH %). These parameters were measured at inlet and supply air. Energy consumption of the IDEC system, air blower fan, and water pump were monitored every hour. Thermal comfort surveys were conducted in the space being served by IDEC. This was done to establish a relation between the system effectiveness, the cooling energy consumption and degree of occupants’ comfort. It was found that IDEC was able to achieve ΔTa of 5- 6 °C, saturation deficit of 30-35%, water consumption of 62.0 lit/hour with an average COP of 5. During August-October WBE varied from 55-83% with an energy consumption range of 29-30 kWh. Whereas, for November-December, WBE varied from 41-67% with energy consumption range of 23-28 kWh. However, despite this high WBE, 71% of the subjects voted the thermal environment to be either “slightly warm (+1)”, “warm (+2)” or “hot (+3)” on 7-point thermal sensation scale and 78% of the subjects wanted to be cooler. On further investigation, it was found that the IDEC was only able to produce 44,743 CFM whereas it was designed for 61,800 CFM. This could be because the system maintenance hasn’t been done for a long time. However, if the IDEC achieved designed airflow then the possibilities are that the WBE might not vary much, but an additional 27% airflow might help counter the heat generated by the cooking process. Also, the system might be able to satisfy the occupant thermal comfort expectations
Vijay Chawan, Rashmin Damle
Abstract: Natural Ventilation is one of the passive strategy for maintaining the occupant’s thermal comfort through fresh outdoor air. It also helps to reduce building energy required for space conditioning. The ventilation of occupied building spaces has two main purposes: one is to provide acceptable indoor air quality which is primarily based on the supply of fresh air and the removal or dilution of indoor pollutant concentration; the other is to provide thermal comfort to the occupants. In today’s scenario, people spend most of their time in indoor environments such as home or offices. Indoor contaminants like volatile organic compounds and stale air cause health problems and results in the so-called sick building syndrome. Naturally ventilated buildings provide adequate ventilation rates consistent with acceptable indoor air quality. Evaluating ventilation performance of a building is challenging due to the difficulty in prediction of indoor air movement under varying outdoor climatic conditions. In this context, water-table acts as effective tool for predicting the ventilation performance of buildings. A water-table is an inexpensive apparatus which may be used to predict airflow patterns for wind-induced unidirectional air flows. It is observed in literature that most of the water-table studies are based on qualitative analysis. Recently, a methodology for quantification of flow patterns generated in the water-table apparatus has been reported. This study involved water-table study with three basic configurations along with complex multizone apartment. Different ventilation metrics were developed for analysing the flow patterns. However, the effect of model scale on the derived ventilation metrics was not considered in this work. This is also observed with other studies in the literature. In view of above, this work focusses on estimating the limiting size of a scaled building model with respect to the water-table apparatus. Different configurations with openings on single side (SS), adjacent side (AS) and opposite side (OS) are studied using model scales ranging from 1:20 to 1:80. It is observed that model scales from 1:20 to 1:60 followed the same trend in terms of the evaluated ventilation metrics. Significant variation in results in terms of ventilation metrics are observed for model scales 1:70 and 1:80. Additional experiments are also carried out to study the effect of speed and aspect ratio. The findings of this research could be useful in selection of appropriate scale for conducting water-table experiments.
Ankit Debnath, Rashmin Damle
Abstract: With a growing awareness of energy efficiency in the hotel industry by the Indian government and hoteliers, energy performance is becoming an increasingly important aspect with India’s emergence as a global tourism hub. Energy audit studies conducted by local agencies and the Energy Department of India shows that hotels have a potential of reducing 20-30% of energy use without compromising the quality of hospitality services. For a correctly sized HVAC system complemented with an airtight envelope can help in substantial energy savings by reducing cooling demands.
In this work, air leakage characteristics of 30 air-conditioned double occupancy hotel rooms in Ahmedabad are studied. The studied dataset compiled consists of 18 rooms with split ACs, 9 rooms with central ACs and 3 rooms with window AC unit. These hotel rooms were tested using blower door method (pressurization/depressurization at 50 Pa) to find out their leakage characteristics. To check the airtightness of a hotel room blower door method is a quick and economical method. Relatively quick and accurate results are obtained by blower door. This research work adopts blower door method to measure leakage characteristics. The test results obtained at 50Pa are automatically converted in the form of effective leakage area (ELA) normalized at 4Pa just after the test is completed. The ACH due to infiltration is then modelled using simulation software for the respective geometry to find energy impact and potential financial savings.
The work was able to identify the correlation between ACH due to infiltration and multiple varying envelope characteristics like WWR, floor area, HVAC systems, window frame and tariff. The measured ACH due to infiltration for the rooms compared with the international standards for airtightness. Majority of the rooms were found to be airtight as compared with the most stringent standard. Factors such as window perimeter area and type of window i.e., fixed and operable for leaky hotel rooms helped in minimizing the infiltration. However, making the room airtight by compromising the outdoor view. Low tariffed rooms with split systems are airtight due to low WWR of typical 22%. Higher tariffed hotel rooms with centralized system were observed to be airtight. These rooms were newly built with bigger floor areas. For the hotel rooms studied, simulations show that the impact of air leakage on energy consumption is not substantial
Vertika Srivastav, Swati Puchalapalli, Sanyogita Manu
Abstract: Retrofit of naturally ventilated educational building is an effective solution to the thermal and visual discomfort problems of the occupants. The Aga Khan Academy is a residential school, located in outskirts of Hyderabad, India. The school functions in an International Baccalaureate (IB) Curriculum. The building is IGBC platinum rated. The project deals with the retrofit procedure of the Senior Academic Block, which is naturally ventilated. The procedure contains steps: First, assessment of the existing conditions through climate analysis, thermal images, measurements & occupant surveys. Second, presenting retrofit design proposal and further optimizing and prioritizing scenarios based on thermal and daylighting simulations. The tools used for the analysis are: EDSL TAS and LightStanza.
The methodology is divided into four phases. The procedure involves: Assessing the existing conditions through climate analysis, measurement of surface temperature, indoor dry bulb temperature, humidity, daylight levels & occupant surveys; Developing retrofit options and testing them out using simulation tools: EDSL TAS & LightStanza, to quantify their impact on occupant thermal and visual comfort.
The measure taken include passive strategies related to the existing building envelop and addition of a low energy cooling system. Another aspect of this project is to enhance the daylight levels inside the classroom to provide occupants with a blind and glare free environment. The strategies that are recommended for enhancement of thermal and visual comfort are:
- Insulation of Aluminium Panel using 10 mm PU board insulation which achieved 40% comfort hours
- Adding horizontal louvers with slits in between on the windows facing west direction with achieved 50% comfort hours.
- Replacing Pinhead security glass with clear glass which helped to achieve 53% comfort hours along with sDA300/50 is achieved for at least 55% of the space & ASE1000/250 of no more than 10%.
- Converting fixed windows to operable windows which operate to 100% of the opening area in the main windows for ground floor and the clerestory windows combined with top and mid pane has 100% operable area on the first floor. This strategy helped to achieve 65% comfort hours.
- Adding a low energy cooling system – BreezeAir Evaporative Cooler to all the classrooms in a centralized manner helping to achieve 77% comfort hours.
Vasudha Sunger, Prasad Vaidya
Abstract: India is experiencing urbanization at a faster rate, majority of building energy is consumed by cooling, ventilation through fans and artificial lighting. Daylighting can be a key driver in conserving energy with saving potential up to 45%. It has the potential to cut energy use, reduce peak demand, reduce the cooling energy costs and create a comfortable indoor environment. As per ECBC 2017, the lighting power density (LPD) for a workshop facility is 14 W/sq. m, which is second highest out of all the LPD requirements and can have high lighting energy use. This study evaluated the daylight performance by calculating the potential lighting savings and assessing the visual comfort of the newly built workshop building at CEPT University, Ahmedabad, India. This study included measurement of illuminance and surface material characteristics, lighting usage patterns, a calibrated daylight model, and annual simulations using LightStanza (A cloud based daylighting simulation software powered by Radiance). The daylight model was also used to quantify the impact of important design decisions in the building. The calibrated model of the building has a RMSE (root mean square error) of less than 4%. The workshop building is LEED v4 and ECBC 2017 daylight compliant. In terms of glare related visual comfort, it faces no shading or harsh sun issues for most of the year but the spaces are likely to experience glare issues between 5-6 PM during the summer months. If the workshop building is operated as per the existing lighting pattern and usage, it will achieve cost savings of Rs. 86424 annually in lighting energy consumption when compared to the building that has lights on for all occupied hours. However, the building is likely to achieve more lighting energy savings with automated controls.
Sandhiya Jayakumar, Michael Apte
Abstract: Prolonged exposure to indoor air pollution may affect the health, comfort and performance of the occupants. Failing to address Indoor Air Quality (IAQ) problems may lead to short-term health problems like-irritation of the eyes, nose and throat, headaches, dizziness, and fatigue and long-term health issues like-respiratory disease, heart problems and cancer. The health effects may vary for different individuals depending on factors like age and medical conditions, children being young and sensitive to the environment, are more susceptible to the same. Hence, suggested ventilation rates have to be maintained in Schools. The primary focus of this research is to estimate the ventilation rates in schools in Ahmedabad by using the carbon dioxide exhaled by the occupants, using steady state mass balance method and estimating the ventilation rates. The estimated air flow in the naturally ventilated and air conditioned classrooms in Ahmedabad had vastly different results. The air flow in the naturally ventilated classrooms was between 61.5 l/s per person to 15.6 l/s per person. The air flow in air conditioned classrooms was 0.9 l/s per person and 1.0 l/s per person. The air flow in naturally ventilated classrooms are excessively high, more than meeting prescribed rates, while air flow in air conditioned classrooms is far below the prescribed outdoor air rate per person as provided in ASHRAE (2016) and Bureau of Indian Standards (2016). The sampling for this research is convenient sampling due to the time constraint, hence this study will not be a representative sample of either Ahmedabad or India. It is also noted that increasing the ventilation rates with highly contaminated outdoor air is also risky to the health. In such a case, the outdoor air has to be cleaned using energy efficient air purifiers before introducing it into the indoor environment. Optimum ventilation rates may lead to high building operation cost, but this can be avoided by reducing pollution load in the indoor air.
Sahil priyadarshi, Rashmin Damle
Abstract: Evaporative coolers have many applications in the fields of refrigeration, air-conditioning and power-plants. These systems typically work best under hot and dry climatic conditions. Studies have shown direct implications of operating parameters on cooling capacity, and cooling energy consumption. The purpose of this study was to evaluate the cooling performance of terracotta tubes (pots) based direct evaporative cooling system (DECS). The cooling performance is evaluated in terms of wet-bulb efficiency under different operating conditions (air-temperature, relative humidity, and air flow rate) for an indoor application. Further, the cooling capacity (in Watt) and Coefficient of Performance (COP) of the system is calculated and the comparison with other evaporative cooling technologies is done to better understand the system performance. The research methodology consists of four major parts. These are experimental set-up, conducting experiments, results & data analysis, and future recommendations. The experiments were conducted under real ambient conditions in four modes. In first mode, fully saturated (100% wet) pots without water flow at different air flow rates were tested. In second mode, dry pots with water flow at different air flow rates were used. In third mode, dry pots at variable water flow rates at constant air flow rate were used to conduct experiments. In fourth mode, the impact of geometry on the cooling performance was investigated by using two types of pots (type-A and type-B). The performance governing parameters like air temperature, relative humidity, air flow rate, water consumption; voltage and current supplied to the fan and water pump were measured. The results show that on using type-A pots, the system achieves a maximum wet-bulb efficiency of 85%. The inlet (hot) air temperature and RH are in the range of 28.1 – 37.6 °C and 30.9% – 70.5% respectively under 600 cfm of air flow rate and at 950 L/h of water flow rate. The temperature drop achieved by the system on using type-A pots varies from 1.8 – 9.8 °C. The water consumed under this test condition for an operational period of 9-hours is 78 L. However, on using type-B pots, maximum wet bulb effectiveness of 80 % is attained under similar inlet air conditions (temperature & RH) and same air and water flow rate as of type-A pots. The temperature drop achieved by the system on using type-B pots varies from 1.9 – 8.0 °C. The water consumed under the same test condition for an operational period of 9-hours is 94 L. The power consumed by the system varies from 308.6–317.7 W depending on different experimentation modes and test conditions. The COP of the system vary from 1.12-27.11 depending upon the test conditions. On comparing with other evaporative cooling technologies found in literature, terracotta tubes based DECS exhibits high wet-bulb efficiency.
Pooja Shriram Mundhe, Rashmin Damle
Abstract: Today, most of the people spend 80-90% of the time indoors either in the office or at home. Indoor air is contaminated by human activities and building materials like paints, furnishings, adhesives which emit volatile organic compounds. Exposure to these compounds has a short and long-term impact on health. Inadequate ventilation also causes Sick Building Syndrome. It is therefore important to provide the healthy indoor environment, as it has an impact on the productivity of people. Acceptable indoor air quality can be maintained by operating a building in natural ventilation. However, predicting the performance of naturally ventilated buildings is challenging, as the parameters governing the airflow, such as temperature and wind, are highly variable over time. Water table is an apparatus that helps to analyze natural ventilation in buildings due to wind effect. It is inexpensive, easily accessible and provides instantaneous two-dimensional results of airflow patterns in and around the building. The current research focuses on quantifying the qualitative data available from the water table experiment and developing ventilation metrics to quantify air movement within a physical building model simulated in the apparatus. The quantitative results of the algorithm will help to make design decisions in terms of opening sizes, orientation, and appropriate positioning of openings in the building. This will be of utility for educational purposes, serving architects, energy consultants and practicing engineers. The ventilation metric and the algorithm quantify the visual data from the water table and will assist in arriving at design solutions optimized for wind-driven natural ventilation.
Nikhilesh Singh Bist, Michael Apte
Abstract: The need to achieve thermal comfort in residences and strong dependence of air conditioning systems has led to huge energy consumption. In order to reduce the energy consumption of residences and properly size the air conditioners, air leakage needs to be reduced by tighten the building envelope. One such approach to quantify the air leakage is the use of blower door, which uses a powerful calibrated fan to depressurize or pressurize the house at an induced pressure to measure air flow (air leakage) from the house. Blower door technique is independent of climatic condition unlike other ventilation measurement techniques such as use of tracer gas decay method, steady state mass balance method.
In this study, 23 residences of Ahmedabad, 12 bungalows and 11 apartments were measured for air leakage. The study is also a first step towards developing methodology to conduct an air tightness test in residential buildings. For comparison, mean normalized leakage (metric for air leakage) of the 23-measured residence was 2.1, which is comparable in average with US homes. When compared to International standards like LEED homes, IECC, Passivhaus, none of the 23 measured residences comply with the standards. Due to dwindling number of observations, there is very less variation in mean effective leakage area of bungalows and apartments, hence it cannot be used to quantify the air leakage of building stock of Ahmedabad. But, due to old age construction, bungalows have more leakages than apartments. High air flow rates can be observed in buildings with intentional openings, inferior quality windows and cracks on walls. Retrofitting those windows, sealing the intentional openings in an air-conditioned space can lead to huge energy savings for air-conditioned spaces.
Mansi Parekh, Prasad Vaidya
Abstract: The revised version of Energy Conservation Building Code (ECBC) was published in June 2017 after ten years. The new version of ECBC goes beyond minimum compliance, and has two additional levels of ECBC ‘plus’ and ‘super’. ECBC includes a prescriptive compliance path and alternative Whole Building Performance (WBP) compliance path with energy use intensity ratios. This thesis assesses the energy savings and payback period for the prescriptive versions of ECBC-2017, minimum compliance, plus and super levels for an office building in Vishakhapatnam. It also demonstrates alternative cost optimized solutions for these three levels of ECBC using the WBP approach.
The office building is a real building in design stage according to the current construction trends that do not comply with even the previous ECBC version of 2007. Energy simulations are done in eQuest DOE 2.2. The availability & cost of equipment and materials to achieve the ECBC 2017 levels is assessed with a market survey.
Using the prescriptive compliance approach the ECBC, ECBC plus and ECBC super version of the office building in Vishakhapatnam, the energy savings achieved are 17%, 25% and 33% respectively as compared to the base case current practice building. The incremental cost (₹/m2) for these are 845, 1229, and 1454 and the payback periods are 4.3, 4.3 and 3.9 years respectively.
Using the Whole Building Performance approach, it was possible to achieve the compliance of ECBC, ECBC plus and ECBC super levels with much lower incremental cost a compared to the prescriptive version. The energy savings achieved for these bundles for ECBC minimum, plus and ECBC super are 17%, 29% and 38 % and the net incremental cost (₹/m2) are 87 ,292 and 429 with payback period of 0.4, 1 and 1.3 years. Based on the results of the individual measures considered in this study and current technologies available in the market, this study demonstrates an opportunity to achieve energy savings higher than the ECBC super level. Incorporating such measures will yield energy savings higher than ECBC super levels, and such measures could be considered in the design of Net Zero Energy buildings.
Maaz Dixit, Sanyogita Manu, Rajat Gupta
Abstract: Buildings consume 33% of total energy (24% domestic and 9% commercial) in India and this is growing at 8% per annum. Reliance on unsustainable energy and increasing demand for energy is a major concern in buildings in India. Although there have been green buildings built in India, proper implementation and use of the same is not seen. This leads to higher than predicted energy use. There have been limited studies done in India prevailing how to design and operate an energy efficient building. Building Performance Evaluation is essential to reduce this gap and help buildings perform better. Despite the improvements in whole building systems and services and energy efficient building design and implementation, there is a growing gap observed between the intended and actual performance of buildings, leading to higher or lower than expected energy use. The project will develop and validate post-occupancy BPE methodology for Indian buildings through field studies. The stakeholders benefited from this study are energy experts & designers, building occupant and owners. This will help to close the loop and help feed data for the next design as well as help the existing buildings perform better. The actual performance of a LEED Platinum rated and GRIHA 5-star rated institutional building (Academic block 1-A and 1-B in Manipal University, Jaipur) through on-site measurements, monitored energy data and building use by the occupants. This field study was carried out in the first two weeks of February (6th- 20th February). Energy performance index for this building is 26.5 kWh/m2· year which is 2% better compared to targeted savings according to GRIHA 5-star rating. The environmental parameter of the building was monitored (dry bulb temperature, CO2, and RH). All spaces were thermally comfortable according to NBC 2005. Most spaces had acceptable noise levels except for open office spaces and classrooms on the second & third floor (NBC 2005). 79% of the users from the surveyed population felt the design met their needs. According to the survey of user control interface, all space types had ease of access to the interface. However, certain spaces (classroom, personal cabin, and open office) did not have access to thermostat control. Constant involvement of the facilities management team and proper use of building according to the design helps maintain the building performance. For further evaluation projects of green-rated buildings, field study measurements are a challenge. A proper monitoring plan will help in more robust and accurate measurements on site. Detailed analysis of the submittals for rating systems is crucial to execute a better BPE. Some additions and alternations are required in the customized BPE method which will lead to better performance evaluation in short period of time.
Kurva Dhonde, Rashmin Damle
Abstract: Building energy simulations are used for carrying out detailed calculations for the energy use prediction of the building. A building comprises of several load components like people, equipment, electrical lights, HVAC systems, walls, roofs and fenestrations. Several studies in the past have shown that the fenestrations account for significant heat load increment in the building. The heat gained through fenestrations in the building can be identified through simulations. To accurately predict the heat gains through fenestrations, details of the fenestration like window opening size, the glazing material, window frame material, window frame size, shape and size of the shading devices are given as an input to the simulation engine. Also, the other important inputs for the glazing are the U-value and the solar heat gain coefficient (SHGC) of the glazing material. The SHGC value considered in the simulation is typically that is provided by the manufacturers. This values are derived under standard testing conditions prescribed by associations like the National Fenestration Rating Council (NFRC). And, the shading devices are additionally modelled to identify the impact of solar gain. However, there are different calculation methods that take into account the effects of adding shading devices and provide combined value of SHGC. This is done by taking into account the manufacturer’s SHGC value and the dimensions of shading device used. This gives an effective SHGC value that can be considered as an input to the simulation without modelling the shading devices. Two of such methods are studied in this research and compared with the simulation results. The impact of SHGC value through two different methods are studied in terms of solar gains (kWh) through fenestration and cooling energy. The results are also compared with the results of the simulation model in which the shading devices are modelled and the manufacturer’s SHGC value is considered instead of effective SHGC value. Further, the impact on cooling energy reduction is determined and compared for different latitudes, climates and overhang depth. The results show that the cooling energy reduction obtained from the methods with detailed heat transfer mechanisms are closer to the results obtained from the simulation with the physical shading device. Therefore, the generalization of the SHGC formula in the other method is not appropriate.
Arjun Desai, Prasad Vaidya
Abstract: Past studies have quantified the potential of various passive design strategies to achieve thermal autonomy. Bhadra, Vaidya, & Sarraf (2017) have shown that for 60 cities in India, minimum thermal autonomy calculated by using the thermostat set point as the benchmark, is at 12% for night cooling, 75% for evaporative cooling, 28% for ground cooling and 32% for radiant cooling. This thesis takes that approach further and quantifies the reduction in cooling energy due to three passive strategies, using the CIBSE method with Cooling Degree Days (CDD) for 60 Indian cities.
Three passive strategies: night ventilation, comfort ventilation and evaporative cooling are considered for mixed mode institutional buildings in India. Evaporative cooling is further divided into evaporative precooling and simple evaporative cooling. Using the CIBSE TM41, the Balance Point Temperature (BPT) for two different versions of Indian buildings is established based on different thermal comfort models: 1) buildings complying with the latest energy code i.e. Energy Conservation Building Code (ECBC 2017); 2) business-as-usual buildings in India. Using these BPT values and the latest TMY files, first CCD values are calculated for fully air-conditioned buildings. Then, the residual CDD for the three passive design strategies are calculated. Cooling energy consumption is then calculated for all the cases for the 60 cities.
This study calculates two versions of BPT for Indian buildings, which are more realistic that those published in the past. The results indicate the cooling energy reduction possible due to three common passive design strategies. The results show that the CDD calculated by using ASHRAE 55 comfort model is almost 1.5 times that of the earlier published values. For Ahmedabad, the value of base temperature ranges between 16-25°C for a BAU building as compared to 18.3°C constant base temperature considered by ASHRAE. Cooling energy can be reduced by upto 25% just by using passive strategies in buildings. The energy results of this method for one city are compared with Energy Plus results in terms of the annual Energy Use Intensity (EUI). The Normalised Mean Biased Error value for the CDD method used is 4.6% while the Root Mean Squared Error value is 15% which fall in the acceptable range as per ASHRAE Guideline 14 and IPMVP.
Arihant jain, Michael Apte, Sanyogita Manu
Abstract: There is a rapid increase in the building footprint, and buildings consume 33% of the total energy in India as per a study done in 2010. Building sector has huge potential for saving energy. But before managing energy, we need to measure it. Therefore, studies related to building energy performance and its evaluation are needed in Indian context. Research has shown that intended energy performance is not equal to the actual energy performance. The Learn BPE project aims to identify and understand this energy performance gap of a building. The post occupancy building performance evaluation (BPE) requires continuous sensing and monitoring of various environmental parameters and energy consumption. The most commonly used commercially available system (HOBO data logger) can measure 3 parameters, namely- temperature, RH, and illuminance, and one external channel for other sensor types. Such equipment that are used for BPE studies have more than required accuracy and precision. Hence, sensors with higher accuracy and specifications, which cost higher, are built into them. A methodology in the form of a Do-It-Yourself, for developing an affordable sensing and monitoring solution with optimum accuracy and precision, is tailor made for BPE studies, and is flexible enough to be customized according to ones need.
Several open source hardware components were compared against each other in terms of cost, specifications, ease of use, and functionality, and after this comparative analysis, suitable hardware was selected and put together to develop the system. The open source hardware and software platform- Arduino was selected due to its wide community support, low cost hardware, and its ease of use in terms of both hardware and software. The sensors were selected on the basis of their cost, accuracy, resolution, measurement range, and response time. The temperature and RH sensors were calibrated through a calibration lab for accurate results. The illuminance sensor was not calibrated but compared against a calibrated Testo lux meter. The whole system was packaged by developing 3D printed sensor casing, and laser cut MDF board casing.
As a result, an open source data logger (OPENSDL) was developed, which could measure temperature, relative humidity, and illuminance levels. A DIY was also developed, with the help of which, any stakeholder could develop the same or similar system with custom needs and custom hardware. The DIY, hardware required, the code for running the system, all of it was uploaded on Github (https://github.com/arihant93/OPENSDL.git). The OPENSDL is an affordable, extensible and customisable solution which can be further developed and can be made more suitable for performing BPE studies against its commercial counterpart. Currently, the system is an affordable solution for educational and personal needs. The system has some issues like loose connections, loose adhesion, casing with no grip, and battery life but these can be worked upon and improved to make a better version of this system. Most of the improvements can be done just by developing a printed circuit board instead of the customised hand-made board.
Shailee Goswami, Rajan Rawal
Abstract: The aim of this study is to demonstrate the impact of inside surface PCM application on walls of an office building, towards reducing the overall energy consumption, improving the thermal comfort and analysing the cost benefit potential. The office building is a G+2 floor building, which operates at change-over mixed mode on a seasonal basis. It is located at Ahmedabad, which has hot and dry climate. The heat transmission characteristics of the wall with inside surface PCM is analysed, along with added external XPS insulation, by using the testing facility of Guarded hot box. These experiments are carried out as per the ASTM C1363-05 standard test methods. Simulation software: design builder v4.7 and energy plus v8.3 are used for the whole building analysis. Three combinations of wall assemblies are analysed – internal surface PCM, internal PCM + external XPS and external XPS. The simple payback period of the PCM is calculated using the excel tool.
Experimental setup of the guarded hot box validated the PCM operation and effectiveness as envelope component and demonstrated a time lag of almost 9 hours when PCM is used.
In case of PCM with melting point 29, the latent heat stored by the thermal mass of the walls is gradually released, leading to the formation of a more stable indoor environment, while in the outdoor environment extensive temperature fluctuations exist. Software simulation analysis showed decrease in cooling energy consumption by 1.54%, The addition of external insulation in combination with internal PCM is increasing the energy savings to almost 4.02%. There was 4% increase in comfort hours (using adaptive comfort model definition) when compared to the baseline buildings with PCM installed at a hot and dry climate of India. Simple payback period calculation is resulting in high payback period of 28 years for PCMs, which can be reduced to 17.5 years combining it with insulation.
Kartikey Sharma, Saket Saraf
Abstract: The buildings sector in India accounts for a third of the total energy consumption of the country. Given the recent and anticipated economic growth in India, the sector is likely to play a more significant role in the energy sector than it currently does. As the building sector follows the “business as usual” construction practice; energy savings potential largely remains unexplored for the country. The aim of this study is to estimate the energy savings potential for two key commercial building types: Offices and Institutional establishments; across all climate zones for the country. Once the representative prototypes are derived, their energy savings potential is estimated by applying energy conservation measures on buildings typologies selected for the study by means of energy simulation. After estimating the energy savings potential for the selected building types, the savings are projected to the selected commercial building stock for the whole country. The propject savings are considered for different scenarios, and the best scenario shows the savings of 3000 GWh at national level for office and school types considered here.
Jaydeep Bhadra, Prasad Vaidya, Saket Saraf
Abstract: The study aims to develop indices to assess the potential of passive cooling strategies for a climate. Cooling accounts for 40% to 60% of summer energy demand in metropolitan cities with hot climates like Delhi, & air-conditioner (AC) sales in India are growing at 30% per year (CEM, 2014). Recommendations based on current climatic zone may not be appropriate as many microclimatic conditions and variations are found in few kilometres range. The currently available climate analysis tools do not explore the inter-relationships between climatic parameters such as dry-bulb temperature, dew point temperature, wind velocity and cloud cover. Earlier work showed that it is possible to develop a weather-data-based classification to map the potential of some basic passive design strategies, such as building orientation, layout, plan, window-wall ratio etc. This study takes that approach forward to establish weather-data-based indices for strategies such as evaporative cooling, comfort ventilation, radiant cooling, earth cooling, and night ventilation. Weather data variables are identified for each strategy. This study uses adaptive thermal comfort models to represent the expected indoor comfort conditions. Typical Meteorogical Year (TMY) weather data of 59 Indian cities are analysed to develop the indices. Thermal Autonomy and Discomfort Degree Days are the metrics developed to measure the potential of the passive strategies. An Excel processor and a Power BI user interface tool have been developed. These enable the user to compare the potential for strategies within a climate and compare different locations for their climatic potential for a strategy. This work can be extended to develop climate zone maps that highlight the potential for specific low energy solutions in a region.
Dharini S. K., Rajan Rawal
Abstract: Low energy cooling systems are designed to consume less energy while providing adequate comfort levels. A report by the Global Buildings Performance Network (GBPN) states that data used for simulation modelling is quite inaccessible in India. It also states that for accurate assessment of potential savings, good amount of reliable field study data is required. This paper evaluates two non-refrigerant based cooling systems with such field study and experimental data for thermal comfort and energy consumption in hot and dry climatic location in India. As a representative location of this climate, experimentation and simulations are done for the city of Ahmedabad. The systems studied are a direct evaporative cooling system and a 2-stage evaporative cooling system. In-field measurements and readings taken in the month of March were used to determine the experimental performance of the system. Energy consumption data inputs were fed into the thermal model of an office building which was modelled as per draft version of Energy Conservation Building Code (ECBC) India. This was performed in DesignBuilder and EnergyPlus combination for comparative performance over a baseline case. This baseline office case was served with a VRV system. Energy consumption savings and thermal comfort observations were reported over this baseline case of simulation model. A long-term thermal comfort survey based on previous perceptions of comfort from 16 occupants served by each of these systems was also reported for understanding. The EPI as a result of cooling through VRF, DEC and 2SEC is 89, 54 and 55 kWh/m2.yr which comes to 40% energy savings in both evaporative cooling cases. The hours not met were 505, 839 and 848 for VRF, DEC and 2SEC respectively. In terms of comfortable hours, DEC meets setpoints better than 2SEC. However, in the broader context, even with cooler effectiveness of 1, the evaporative cooling system does not have the capacity to meet setpoints. i.e has high unmet hours. If a building owner is interested in providing minimum comfort conditions and is in favorable of adaptive thermal comfort, evaporative cooling system can be installed. DEC can be the first priority as it does not have the complexity of installation like in 2SEC and initial cost is also not as much as 2SEC. However if providing comfort to occupants is the main goal and setpoint requirements are stringent, then evaporative cooling systems –both DEC and 2SEC are not suitable for office buildings where internal loads are very high.
Devna Vyas, Michael Apte
Abstract: The potential of cooling with natural ventilation and forced ventilation demands attention and scientific study in order to 1) cater to the need of the larger portion of the population; those who cannot afford to air-condition 2) in order to reduce India’s energy consumption and reduce its greenhouse gas emissions due to space cooling demands. Ventilative cooling refers to the use of natural or mechanical ventilation strategies to cool indoor spaces using outdoor air. The most common ventilative cooling technique is the use of increased ventilation airflow rates during cooler outdoor periods, and night ventilation, but other techniques may also be considered. The effectiveness of Ventilative cooling is dependent on the availability of suitable ambient conditions to provide cooling to space. The objective of this study is to evaluate the benefit of harnessing the cooler ambient air to remove heated indoor air by using ventilation. The aim is to enhance indoor temperatures without resorting to more energy intensive methods such as air conditioning. The thesis attempts to provide a scientific basis to architects and building designers in understanding the benefits and limitations of natural and mechanical ventilative cooling in a typical set of residences located in hot and dry and temperate climate. The knowledge can guide designers towards incorporating ventilative cooling strategy as part of the building design when appropriate. The ventilative cooling benefits are calculated primarily using simulation tools. Further, the study also includes results from field measurements for short-period carried out in an apartment building to compare the results with the simulation models. Benefits in indoor air quality due to natural ventilation is not in the scope of this research. It is concluded from the study that adding ventilating cooling using natural ventilation in a typical residential apartment provides 5-43% increase in comfortable hours for two climate zones of India as compared with free running building. Ventilative cooling with mechanical ventilation provides significant comfort benefits (14-25% as compared to ventilative cooling with natural ventilation) and is beneficial to incorporate in residential apartment buildings in two climate zone of India. When compared to mixed mode buildings with no ventilative cooling, ventilative cooling can reduce thermal load of the apartment by 4-14% and 24-34%. While ventilative cooling is more effective in temperate climate, significant benefits can be achieved even in hot and dry climate of India during night periods. A novel method to continuously measure ventilation rate is developed for affordable yet accurate measurements. the measurements reinforced findings from the simulation results that ventilative cooling can provide significant benefits.
Bipinchandra Patel, Rashmin Damle, Michael Apte
Abstract: The aim of this work is to study the technical potential resulting from the integration of evaporative cooling (direct, indirect and combined) with a mechanical cooling system. This work is limited for the small day-use office space in hot and dry climate of India (refer Annexure - A).
For this purpose, an office space (in Ahmedabad) was identified for which access and architectural & air-conditioning drawings and AC system details are available. Envelope, shading, adjacencies, internal gains, operating schedules, ventilation rates are studied. Base Case model was derived with appropriate changes for year-round mechanical cooling. Annual consumption, peak demand, cooling system size are derived for a cooling set point temperature (CSPT) of 25.5°C using simulation software.
Evaporative cooling strategies like direct evaporative cooling (DEC), indirect evaporative cooling (IEC) and their combinations (IDEC) are simulated with and without mechanical cooling system. Ideal evaporative air flow rates (to meet the cooling loads) for integrated system are found out. Effect of keeping DEC switched off during humid months and during morning hours in winter months are studied. Effect of using IEC for three humid months and using DEC in remaining nine months of the year is also studied. Finally, Simulations for potential of sensible heat recovery device is also explored in this study.
Evaporative cooling systems can be integrated with mechanical cooling system in many combinations. For the similar thermal comfort, hybrid system of mechanical cooling with DEC, IEC and IDEC help reduce VRF cooling system size by 29%, 20% and 38% respectively. HVAC energy is also reduced by 17%, 12% and 26% respectively. Similarly peak HVAC power is also reduced by 21%,12% and 27%.
Use of heat recovery device is justified in case of mechanical cooling only. Heat recovery devidce help reduce mechanical coolical cooling system by 31%, HVAC energy by 7% and peak HVAC power by 15%
Abdul Moeed Chaudhary, Prasad Vaidya
Abstract: The thesis is on lighting retrofit of CEPT University located in India. The research aims to reduce energy consumption and enhance visual comfort of the university. The assessment of the spaces included lighting audits, monitoring of lights, schedule of usage, visual comfort surveys and measurement of illuminance levels. At CEPT University, electricity consumption due to artificial lighting is estimated at 32% of the total due to usage of spaces during the night. Health issues like headache, stressed eyes, glare, and low illuminance levels resulted in more than 50% of the occupants taking breaks for eye recovery. This thesis limits the scope to provide retrofit solutions to meet the requirements of NBC and ECBC for studio, classroom, and private office using the UFC recommendation where appropriate. These three space types contribute to 86% of the lighting energy of the campus. Retrofit solutions were proposed to address the issues identified in the audits and surveys, using technologies from a market survey. The proposed solutions included, lamp sources, fixtures, fixture layouts, interior surface modifications, switching and controls, and task lighting where applicable. These solutions were evaluated for light distribution using Relux lighting simulation software and for cost-effectiveness with a simple payback analysis. The energy savings due to the proposed retrofit are 21%, 44% and 42% for studios, classrooms, and private offices, and the simple payback due to is found 9.5, 3.8, 6.8 years respectively. If all rooms of these 3 space types are retrofitted (67 out of 122 spaces on campus) with the solutions identified, it would amount to an annual energy cost saving of INR 178,670 and annual energy saving of 19,852 kWh for an aggregate payback of 8 years.