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Directed Research Projects

Strategic framework for Net Zero Energy Campus in India: A case of CEPT University Campus (2016)

Amiya Behera, Yash Shukla, Rajan Rawal
Abstract: To achieve indoor environmental comfort conditions and to facilitate economic activities, building occupants use electric energy. In conventional scenario electric grid provides electricity to buildings. This study attempts to evaluate feasibility of CEPT University campus – an academic, research and development facility located in hot and dry climate zone in India, to become net zero energy campus. A pilot case has been taken as a preliminary study of the research work. Study starts with detailed monitoring of indoor environmental comfort parameters such as temperature, humidity, energy used for various functions such as HVAC, lighting and plug loads, of a newly established net zero energy building located at Anand, Gujrat. While studying this, concurrent energy generation from roof top solar PV was also studied. In second stage campus was divided into number of electrical zones and individual or group of buildings according to electrical loads and locations, were monitored for its energy use. This exercise provides energy consumption profile. CEPT University campus being an academic, research and development, it has varied operation schedule across the year. Campus also hosts indoor spaces with high diversity of use, such as design studios, seminar rooms, library, administration, workshops and ancillary activities. Hence it is important to conduct year round monitoring to capture yearly electricity usage profile, Solar roof top PV generation and indoor environmental conditions. Synthesis of collected data was analysed. Considering availability of areas for solar roof top PV installation, final observations were made to suggest feasibility of net zero energy campus of CEPT university. Study was taken further to develop framework of renewable energy generation installations, economic analysis and technical potential.

Thermal performance of vegetation on urban microclimate (2011)

Jalpa Gandhi, Rajan Rawal
Abstract: Urbanization has direct impact on the spatial structure of the city, which in turn results in the dramatic change of the overall immediate environment. High-rise, high density built areas provides multiple surfaces for the reflection of direct and indirect solar radiation as well as absorption & storage of the anthropogenic heat. It is often seen that this heat gets re-radiated & trapped due to neighborhood buildings causing changes in surface & ambient air temperature. To mitigate such effect various approaches were studied and experimented in the past. Out of which impact of vegetation is considered to be one of the most potent measure to mitigate negative impact of urban form on high surface and air temperature. This is proved through number of research studies and on-site measurements. This study is an approach to understand the role of urban environment on urban area micro-climate with reference to vegetation in the city of Gandhinagar, India. An urban area of Central Business District is configured according to the rules of ground coverage, floor space index (FSI) and site setback as mentioned and laid out in building byelaws of city. For the purpose of this study a three dimensional numerical computer model ENVI-met V3.4, that analyzes micro scale thermal interaction with urban environment is used. Input of environmental data is extracted from Ahmedabad IWEC weather file. Simulations are done for typical summer day. Parametric variations are made to get prediction of surface and air temperature in different built and un-built conditions. Different scenarios are designed besides the model condition where studies are done on basis of different surface materials, changing density of vegetation & changing the type of vegetation. The results are evaluated on the basis of ambient air temperature & Surface temperature. Findings show that on an average 2°C drop in ambient air temperature is achieved in urban area of Gandhinagar’s microclimate with the addition of trees. Vegetation is seen more valuable during harsh afternoon hours, due to its shading and evapo-transpiration properties. This suggests that shading streets with trees is advisable, which results in achieving reduction of minimum 0.5°C & maximum 1.5°C average air temperature across the year. The cooling effect of trees is also seen in the surrounding areas. Strategic plantation of trees and selection of surface material is found as very important aspects to lower adverse effect of urbanization.

Study to Evaluate Window Energy Performance in Indian Building Sector (2011)

Purvi Panchal, Rajan Rawal and Bipin Shah
Abstract: This paper explores conventional window assemblies used in current practice and design parameters which influence heat transfer through the different window components in a window assembly, using THERM 5.2 –two dimensional conduction heat transfers modeling based on the finite element method. A comprehensive set of correlations, based on THERM parametric, is then developed. A comparative analysis for the results of these correlations will be placed to evaluate the energy performance and will be incorporated into the WINDOW 5.2 (from Lawrence Berkley National Labs) programs to calculate the thermal and optical performance indices of the total fenestration product. The aim of the study is to determine the thermal performance of different window components for India considering ECBC (Energy Conservation Building Code ) whether data for the same . The study will analyses the heat transfer with the change in frame material, frame geometry & glazing type and, their impact on the total window heat transfer rates. The result would be collected to develop a comparison chart which will help designer in decision making regarding window assembly performance.

Integration of solar photovoltaics: to suffice interior lighting energy consumption of office buildings in ahmedabad – An approach towards zero lighting energy consumption (2011)

Ashima Charnalia, Jyotirmay Mathur and Rajan Rawal
Abstract: The study focuses on ways to minimize interior lighting energy consumption (ILEC) in daytime use office buildings and proposes use of solar photovoltaic’s (SPVs) to suffice the remaining lighting energy requirement. The objective of the study is to attain interior lighting energy autonomy through Solar Photovoltaic’s. The study in whole focuses on low interior lighting energy consuming building designs whose interior lighting electricity loads are almost entirely met by grid connected roof top SPV systems. Energy Conservation Building Code (ECBC-2007-India) compliant hypothetical building models representative of office buildings in the hot-dry climate of Ahmedabad were modeled in Design Builder on Energy Plus platform. Fifty-four scenarios in all were examined for three-floor plate areas (500, 750 & 1000 m2). The scenarios were derived by keeping the carpet area constant of all the floor plates and varying building aspect ratios, orientation (1:1, 1:2 & 2:1), window wall ratio (40% & 60%) and applying external daylighting devices such as louvers and light shelves. From these scenarios, one building case for all the three different floor plates with the least ILEC was proceeded to integrate rooftop-grid SPV system (24KW SPV system for 500 m2, 36KW SPV system for 750 m2 and 48KW SPV system for 1000 m2 ) to arrive at potential energy generation figures. The study analyzed the two aspects – Energy and Economics, of the attempt. For first Energy analysis, the study analyzed annually to hourly interaction between the building’s ILEC and SPV energy generation. On annual basis, the study was able to illustrate a potential scenario to serve ILEC of 3.8 floors for 500 m2 floor plate, 3.4 floors for 750 m2 floor plate and 3.2 floors for 1000 m2 floor plate of the same building by the same roof top SPV system designed as per floor plate areas. These results were also due to interaction of energy imports and export with the utility grid but the system annually made no net demands on the utility grid to serve ILEC. This meant that ILEC of more than three floors of a building for all three-floor plate areas were demonstrated to be net zero by integration of SPV roof top systems.

The results of three floor plates also demonstrated that with every increase of 250 m2 floor plate area, there is a percentage increase of 56.8% in annual ILEC, with percentage increase of 50% in annual roof top energy generation, with percentage increase of 62.5% in annual energy imports from the grid, with percentage increase of 46.5% in annual energy exports to the grid. This implies that with increasing the floor plate area as the core area increases, there is a percentage decrease of 32.8% in annual net surplus energy on site.The second analysis Economics part, the study projected the life period energy summary to obtain life period cost summary of the installed SPV systems, which demonstrated that rooftop SPV system is still very high capital incentive investment with payback period of 22-24 years, without considering any government subsidiaries.

Overall, the study demonstrates a sustainable approach towards interior lighting energy use in the building sector by utilizing renewable solar energy source.
Presented at: International Building Performance Simulation Association -An IBPSA-AIRAH conference, November 2011, Sydney.

Study of prevailing lighting power density in commercial office buildings – Understanding occupants visual comfort against available illuminance. (2010)

Chaitali Trivedi, Rajan Rawal
Abstract: The study presents evaluation on illuminance levels received at work-plane against visual comfort condition and user’s perception in office buildings. Evaluation is done three ways:1) Subjective Evaluation by intervening people2) Objective Evaluation based on the questionnaire used during the survey3) Evaluation based Statistical analysis. Thus an overall comfort rating scale is been derived from the analysis.The study is conducted under three different conditions i.e. In presence of Daylight (DL), in presence of Artificial Light (AFL) and in presence of combination of daylight and artificial light (DL+AFL). The study also highlights on the comfort and light source relation. Relation between illuminance levels and distance from the opening has been derived with the rate of satisfaction. The later part of the document deals with understanding of energy consumption with different lux levels and lighting controls. Three types of Controls (linear controls, linear off control and stepped controls) are taken into consideration for the study.

Relationship between kitchen design and Indoor air quality – Study of indoor air quality in high rise residential kitchens in Ahmedabad (2010)

Deepali Agrawal, Munjal Bhatt
Abstract: Quality of indoor air in residential spaces is important as people spend on average 13 hours at home daily which make them susceptible to airborne contaminants. Air quality is of great significance for these spaes. Indoor air quality is affected by external environmental factors and internal processes. The major source of indoor air pollution in household is from the cooking done in the kitchen due to the inherent process of combustion of the fuel. However limited quantitative data is available to understand the relationship between kitchen design and its impact on indoor air quality. The study attempts to establish a relationship through primary data generation and analysis.

Potential Savings in lighting energy due to advancement in Indian Standard time: An Enquiry in context OF Commercial office spaces in India. (2010)

Padmini Rajaram, Rajan Rawal
Abstract: Indian Standard Time (IST) is calculated with reference to 82.5° E longitude and the difference of +0530 hours from Greenwich Mean Time (GMT). The permanent advancement of IST was proposed in the previous study from +0530 to +0600 hours with reference to 90° E longitude and is estimated to 16% of savings in peak load electricity demand by analyzing all the power consuming sectors such as industrial, agricultural and commercial sectors of India(Ahuja.et al,2006). The present study aims at quantifying the savings in lighting energy consumption for office buildings, due to the permanent advancement of Indian standard time from +0530 to +0600 hours (GMT). The study initiates by walk through energy audit to evaluate lighting load details and occupancy details for two cities; Ahmedabad in the west and Kolkata in the east of India, which are 64 minutes distant from each other. The audited data is used as input parameters for reference models that are modeled using design builder with energy plus platform to determine annual energy consumption for lighting in office buildings. The time advancement in this study is analyzed by evaluating shift in occupancy schedules for offices. Hence parametric combinations of occupancy schedules of 1000 -1900 hours versus 0930-1830 hrs, and 0930-1830 versus 0900-1800 hrs are examined for varying floor plate sizes of 100m², 400m², 800m² and 1200m², with varying aspect ratios, window wall ratio and lighting controls. Further one reference model is simulated to evaluate the savings in lighting energy consumption for all the major cities in India. Results from the simulated models show an average of 6.27% savings in the annual lighting energy consumption for office buildings in all major cities, due to the advancement of time or shift in occupancy schedule, given that linear lighting controls are applied for all the above models. It is also observed that office buildings in eastern India benefits 2% more than the west.
Presented at: International Building Performance Simulation Association -An IBPSA-AIRAH conference, November 2011, Sydney

PCM application in walls and its impact on energy consumption, thermal comfort and cost benefit analysis in hot and dry climate (2017)

Shailee Goswami, Rajan Rawal
Abstract: This study will demonstrate the impact of organic phase change materials (PCM) integration in walls towards energy consumption, thermal comfort and cost benefit analysis. The analysis will be done for a hypothetical 3 storey commercial building, which is Energy Conservation Building Code (ECBC) compliant. This building is fully air conditioned and is situated in hot and dry climate, in the city of Ahmedabad. The testing facility of Guarded hot box is utilized to carry out the experimentation of the static heat transmission characteristics of walls with PCM integration. The building simulation tools like design builder, energy plus and THERM are used for the critical analysis of potential benefit of incorporating PCM in the façade fabric and its effect on thermal comfort and overall energy savings. Also, life cycle cost assessment is done as using manual calculations and MS excel. The results will assess the potential impact of the PCM integration with walls towards improving the thermal comfort (as per adaptive thermal comfort model) and reducing the overall energy consumption. The life cycle cost analysis of the PCM will be a compiled inventory of relevant inputs that will demonstrate the effectiveness of its integration with walls.

Evaluating low energy cooling systems in warm-humid climate for Energy consumption and thermal comfort (2017)

Dharini Sridharan, Rajan Rawal
Abstract: Energy consumed by commercial buildings account for over 35% of the total energy consumption in India making the building sector one of the largest energy consumers. Studies found that energy consumption due to space cooling and lighting in commercial buildings account for nearly two-thirds of the overall consumption. Providing cooling has become unavoidable and designing mechanical systems to provide comfort efficiently is a challenging task. Low energy cooling systems are designed to consume less energy while providing adequate comfort levels. These systems are often coupled with passive cooling approaches and less widely studied in isolation.

A report by the Global Buildings Performance Network (GBPN) on the quality and availability of building performance data around the world showed that the data used for modelling in India is frequently inaccessible and that high quality field study data is required for accurate assessment of the potential savings. This paper evaluates three non-refrigerant based low energy cooling systems for thermal comfort and energy consumption using such field study data in hot and dry climatic locations in India. The energy consumption evaluation is done through on-site energy monitoring of each system and further comparison with other systems through simulations in DesignBuilder and EnergyPlus. The thermal comfort evaluation is done through on-site comfort surveys similar to the Building Use Studies (BUS) methodology or the Building Occupants Survey System Australia (BOSSA). On continuing research for various climatic conditions as part of future scope, this research will help identify opportunities for development in these systems for better performance. It will also assist stakeholders to select an appropriate low energy cooling system for their project by anticipating potential energy and cost savings.

Impact of thermal properties of building material on building energy consumption (2017)

Tanushree Charan, Rajan Rawal, Dipsha Shah
Abstract: Building energy modelling and simulation or building performance simulation (BPS) is a powerful method for studying energy performance of buildings and it helps choose construction materials and methods to optimize energy consumption. BPS uses input parameters to determine energy performance of building. Correct input parameters help predict accurate building energy performance. Amongst other parameters, following three parameters are influenced by local context and hence needs to be derived through various sources locally. They are
- Weather Data
- Thermal Comfort of building occupants
- Building Material’s thermal and hygrothermal properties

Every material used in an envelope assembly has fundamental physical properties that determine their energy performance like thermal conductivity, thermal resistance, and thermal diffusivity. ASHRAE (American Society of Heating, Refrigerating and Air-Conditioning Engineers) Fundamental carries database of building material properties. This data base is widely used across the globe. CARBSE has characterized building material database of material available in Indian market and conditions. Hence, to improve the accuracy of the simulation, the input data should include locally available materials for India.

The study aims to determine the difference in energy consumption due to material input parameters as per ASHRAE, and other international database vis-a-vis CARBSE database and database for locally available materials in India.

Introduction of Air Velocity to achieve Thermal Comfort and its impact on Energy Consumption (2016)

Pooja Chavan, Rajan Rawal
Abstract: In India, energy demand is believed to increase by a factor of 1.5 to 2.5 by 2030. The energy and environmental consequences of conditioning a building are immense. For regulation of indoor thermal environment, air conditioning is used commonly, both in residential and commercial buildings, which results in large energy consumption. As per India Energy Report 2015 by IEA, the air conditioner consumes almost five times as much electricity as an evaporative cooler- which consumes twice as much as electricity as a fan. But an extensive study, suggests elevated air movements can provide indoor cooling effect using less energy in warm environment. The purpose of this study is to evaluate a range of air velocity, which can be deemed desirable, while being used along with Air Conditioning. A series of experiments shall be conducted in a controlled environment (28˚C-32˚C; 60% and 80% RH) to test different air velocities provided by a selective air motion devices. Also, their energy consumption shall be recorded.

As a result, the study aims to provide means to adopt higher temperature for HVAC systems while achieving thermal comfort and offers an opportunity to control owns own microclimate.

Thermal Comfort and Its Effects on Health and Productivity: Evaluating Office Buildings in Mumbai, India (2016)

Cynthia Alex, Rajan Rawal
Abstract: The building sector is one of the largest emitters of CO2 to the global atmosphere and the construction industry in India is growing rapidly with its main focus on the commercial sector. This along with the changing climate, increasing temperatures and purchasing power in metropolitan cities like Mumbai, Bangalore, Delhi and Chennai has led to an exceptional growth in the use of mechanical systems. The economic affordability and availability of these air- conditioning systems has increased the use of mechanical cooling in buildings and has made it a default practice. Today, India’s building energy use accounts for 33% of the nation’s energy use, and this is growing by 8% annually. But scientific studies determine various comfort and adverse health effects associated with the characteristics of buildings, ventilation and conditioning systems and these poorly designed indoor environments and people today spend about 80-90% of their time indoors. Thus this paper aims to understand, explore and learn the well-being and comfort of Occupant's in their space of work and provide optional innovative approaches to maintain and enhance their health and productivity. This paper would investigate and examine the selected office buildings on the basis of three key aspects;
(1) Building Characteristics
(2) Instantaneous Readings
(3) Occupant Survey
Occupant response would also help in diagnosing prevailing issues in a building. The collected data would then be critically analysed to learn the various factors that affect Occupants Satisfaction levels. This would help in identifying improved energy efficient technologies and systems that would aid to enhance their Health and Comfort at work.

This study would in the future help Architects and building decision makers to move beyond the first cost decision making to support investments in high performance and energy efficient technologies.

Movable shading devices and its impact on total energy consumption and solar heat gain (2016)

Chinmay Patel, Rajan Rawal
Abstract: Climate responsive architectural practice has given a rise to various architectural vocabularies. Use of movable external shading devices has given a distinct character to facades along with providing opportunities to reduce solar heat gain and control daylight. Empirical studies have shown advantages of such systems, this study takes a leap forward by examining effectiveness of movable external shading system by deploying scientific rigour. The study evaluates impact of external movable shading in hot and dry climate of India using three approaches – using energy and daylight simulations, using laboratory apparatus, and using field data under controlled conditions. The study starts with one week long field work for daylight study, then validates daylight results with laboratory apparatus and finally calculates overall savings using simulation models. The movable shading system was studied for its effectiveness in four direction North South East W along with 20% - 40% -60% Window to wall ratio and opening condition, fully closed, fully open and partially open at 30 degree, 45 degree and 60 degree to evaluate thermal and daylight results obtained under environmentally controlled indoor conditions. Based on field study, various shading system configurations have been prepared for daylight study. The study uses artificial sky generation consisting of Single Patch Sky Simulator (SPSS) and Mirror Box to study daylight performance of the models under clear and diffused sky conditions. The overall energy savings for the buildings have been then calculated using energy and daylight simulations using DesignBuilder, EnergyPlus, and Radiance software. The simulation assesses impact of external movable shading devices for various window orientations, window-to-wall ratios, and shade openings in the building. Study reveals that external movable shading devices have potential to reduce 15-30% of energy consumption while providing comfortable lighting level inside building.

Key Words: Daylighting, dynamic shading device, louvers, office building, hot and dry, India

Daylight Performance Evaluation of Laser cut panel in Office buildings – a case of Indian cities (2015)

Hema Mulchandani, Rajan Rawal, Agam Shah, Yash Shukla, Charlie Curcija, Sekhar Nori
Abstract: Daylight in office buildings can significantly contribute in lighting energy savings. In addition, daylight improves the occupant’s working environment, performance, health and well-being. Large floor plates for offices accommodates open plan layout, which help to meet contemporary functions of offices. In such cases dependence on electric light increase, leading to higher lighting energy consumption. Limited technologies are available to increase penetration of daylight into the large floor plates. Laser Cut Panels (LCP) is one of the promising technologies, helping reduce electric lighting consumption by illuminating larger floor plates with daylight. This study investigates performance of LCP in three locations in India. Study starts with to develop Bi-directional scattering distribution function (BSDF) to be used within simulation program that assesses the solar and optical performance of LCP. Study relies on combination simulation program such as EnergyPlus for daylight analysis, Ecotect for LCP geometry, Radiance genBSDF for generating BSDF data and visualizations. A business as usual case of a typical office floor plate was considered as reference model. Three variations in LCP geometry and design, three variations in window to wall ratio, combination of LCP on four orientation of window was investigated. Results generated from simulation run are then analyzed in terms of electric light energy savings and spatial distribution of daylight for different variables.

Keywords: Daylight Performance, Laser cut panel, Bi-directional scattering distribution function

Analytical study on trade-offs between electric light and daylight to achieve energy efficiency (2015)

Saranya S Nair, Rajan Rawal, Agam Shah
Abstract: To provide daylight within a building is an important strategy to improve indoor environmental quality and reduce dependence on electric lighting. Reduction in energy used for electric lighting can be achieved by installing energy efficient lighting system or by increasing presence of daylight. Penetration of daylight can also bring solar radiation and associated heat component inside the building which increase the cooling demand in air-conditioned buildings. Optimum window area, glazing properties and nature of shading devices will help negotiate between availability of daylight and heat ingress due to solar radiation. This study investigates the impact of climate conditions, glazing systems, Window-to-Wall Ratio (WWR), and orientation on energy demand of building. This study is based in context of climates of Ahmedabad, Bengaluru and Chennai. This study was conducted using COMFEN – a tool based on EnergyPlus simulation engine. A case was developed based on business as usual office floor space. Study analyzes spatial pattern of daylight and energy consumption simultaneously.

Keywords: Daylight, Office building, Glazing systems, Window-to-Wall Ratio (WWR), Orientation, Energy Performance Index, Annual Energy Savings, Average Annual Daylight Availability, Spatial Daylight Availability.

Presented at: 7th National Conference on Advances in Energy Conversion Technologies (AECT) at Manipal Institute of Technology, Manipal.

Approach to assess environmental impact of building materials based on Cradle to Cradle® Principles (2014)

Divya Batra
Abstract: New technology is entailed with not only advantages but also hazards. The ever increasing demand of new materials and new products has made us produce more than what we want. Warnings have been sounded around the world since 1960s about the deterioration of the environment. “The material from which products are constructed makes a significant contribution to its overall impact on the environment. Its influence is felt in number of ways; locally, through the effects of activities such as quarrying; globally, as a result of carbon dioxide emission by using energy used to manufacturing the materials; and the internally, in the effects on the health of the occupants of the building.”(Harris,D.J) Building efficiency has been the guiding factor in today’s designing so realizing improvement in building performance is to accurately quantify the environmental performance of building materials. Materials used might be light in weight and efficient but on the other scale have high embodied energy, chemicals and not defined lifecycle. These after their life are disposed to landfills and only 15-20% goes to reuse where its outcome is down-cycled rather than up-cycle. Thus it becomes important to understand how different material can be disassembled and distributed in different cycle (Biological and Technical) to have an efficient materials cycle for better use and reuse. So the study aims to understand impact of different materials used in the interiors of building on environment. So to work towards understanding materials and component involved in product and thus distributing materials into biological and technical cycle, thus making efficient material and energy flow. To create data base for material banking and material passport system to support material pooling and reuse for up-cycling. Thus exploring the benefits of alternative materials, processes and material recapture through reuse, remanufacturing or recycling, or a whole new way to meet a need in Indian context based on Cradle to Cradle principles which can be used as a design aid, and its use is illustrated with a case study of a typical Office in India.

Keywords: Material assessment, Building, Environment, Chemicals, Recycle, Health, Material Cycle, Cradle to Cradle.

Impact of moisture retention properties of wall assemblies on Occupant’s health in naturally ventilated building (2014)

Shaily Mahera
Abstract: The envelope of a building is subjected to heat and moisture conditions. Heat and moisture from the surrounding environment affects the building’s environmental performance and indoor air quality. Hygrothermal behavior of wall assemblies has an important impact on the indoor air quality and thus human health. This study focuses on understanding the moisture migration properties of different wall assemblies and their impact on the indoor air quality. This indoor air quality further affects the health of building occupants, so it would be an attempt to assess the impact of moisture migration properties on occupant’s health. In the process, the functional and hygrothermal properties of different building materials would be depicted from data collected and experimental studies. This data would, further, be used to perform thermal and hygrothermal simulations in naturally ventilated buildings. Simulated thermal and humidity profiles would be assessed. Lastly, the study would confirm the effect of moisture migration properties of wall assemblies on the IAQ of naturally ventilated buildings and their impact on occupant’s health.

Model the change in trend in the use of electrical appliances and evaluate the potential of maximizing India’s residential equipment efficiency and the subsequent energy demand implications along with the mapping of the electricity consumption pattern of residential buildings in Pune (2014)

Ruchi Shah
Abstract: The study aims to map the existing electricity consumption pattern in residential buildings in Pune, India. The study would also aim to understand the change in trend in the use of electrical appliances over the past ten years along with the increase in the gross domestic product (GDP). One area with significant energy and emissions reduction potential is residential end-uses, as urbanization and rising incomes continue to drive household ownership, usage and demand for residential energy services. The growing trends of urbanization, rise in per capita income are pushing up the requirement for housing units and its impact on the overall electricity consumption. In this paper, i will evaluate the potential of maximizing India’s residential equipment efficiency and the subsequent electricity demand implications through 2025. A detailed LBNL bottom-up, end-use energy model will be used to highlight residential end-use energy linkages between urbanization, economic development and India’s growing building sector. The study would be an attempt to understand the reasons and impact on overall energy consumption and peak energy demand, at the same time an attempt, in forecasting future ownership trends for the largest household energy consuming appliance, an econometric model correlating historical ownership rate to income would be made. The study relies on walk through audits to map the energy consumption along with the parameters such as building character, occupancy and the presence of electrical appliances. Household and personal factors will be assessed by a socio economic self administered questionnaire. The study would include data collection of about 300 samples, representing middle and high middle income group. All the samples would be from Pune, which falls under warm and humid climate zone. Study will attempt to include diverse residential buildings. Gathered data would be analysed with an aim to understand how the usage of electricity in residential house result from a complex interaction between built form, location, energy using equipments, air conditioner tonnage, light loads, number of occupants and other economic factors.

A study to understand energy performance of ‘Window’ design in India evolved over the last century (2014)

Madhvi Singh
Abstract: Indian buildings are believed to be built with an energy conscious approach since an early age. The openings in the building envelope play a major role as they allow natural daylight as well as a visual connection to the outside environment. They, on the other hand, also become a medium for heat transfer between outside and inside affecting the thermal comfort. The study analyses different window configurations used over the last hundred years to understand this belief. It also aims at understanding various approaches and strategies used and derived over the time for shading openings on the facades that include shutters and external shading devices. This research would map evolution of fenestration design and run simulations models to evaluate the visual and thermal performances of the same. The study would conclude with an understanding of relation between changes in window design to their energy performance.

Plug Load Consumption in Typical Commercial Offices in India (2013)

Mithi Dave, Rajan Rawal
Abstract: The increasing penetration and diversity of plug loads and their ubiquitous nature in work environments in India means that they are potentially significant consumers of electricity. End-use energy efficiency measures in buildings have largely ignored plug loads which might be attributed to a dearth of India-specific studies which quantify plug-load energy consumption and their usage characteristics through end-use measurements. Field studies in 30 typical offices covering a total floor space of 8000 m2 and 1160 plug loads were carried out to find plug load consumption characteristics. The study shows plug loads as significant consumers of electricity and reveals wide gaps in design and actual on-site provision for these loads that need to be addressed. The study also quantifies the contribution of standby power from major plug loads found in offices.

Keywords: plug loads, measurements, end-use, offices, standby power

Presented at:'4th Master’s Conference - PEOPLE and BUILDINGS' at Sir John Cass Faculty of Art, Architecture and Design, London Metropolitan University, UK

Determining Tradeoff Between Thermal Comfort & Cooling Consumption In Office Buildings (2012)

Krutika Ghawghawe, Sanyogita Manu
Abstract: Energy demand for heating or cooling is directly affected by the required level of thermal comfort. The enquiry will be to understand the impact of setpoint temperature and Coefficient of performance (COP) of a system on energy consumption as well as thermal comfort of occupants in office spaces and analyses it in all the climatic regions of India. The investigation of the mutual relationship between thermal comfort and energy demand is of the foremost importance to define the benchmarks for energy service to calibrate the energy usage. The result of variations in setpoint temperature per degree rise (for a range of 22°C- 28°C) and COP (for a range of 2.0 – 5.0) on cooling load in office spaces are studied. The primary intention of this work is to provide a detailed look at the overall effect on energy consumption of these setpoint temperature changes while considering the range of inhabitant’s thermal comfort and their response to the each one degree rise of setpoint. As many studies have shown that discomfort due to improper indoor temperatures affects productivity adversely. Since India is blessed with varied range of temperatures, it would be interesting to note the alterations on energy consumption and thermal comfort range in different climatic regions. The influence on energy demand of the expected level of thermal comfort and of system control strategies has been investigated by means of simulations.

Embodied and Operational Energy Assessment of Alternative Walling Materials for multi-storey Buildings in Ahmedabad – An approach toward low energy buildings in a lifecycle (2011)

Nirav Sonagara, Kashikar Vishwanath
Abstract: Increasing requirement of energy demand and limited availability of resources has led to the need for energy efficiency in manufacturing of building materials as well as energy used in operation of building making it a critical subject to study. Substantial amount of energy is spent in the transportation and manufacturing process of various building materials. Walling materials used in the envelope of the building are those related to high embodied energy consumption due to their transportation energy, production energy and for improving building’s operational energy. The objective of this study is to identify walling materials which may optimize a building’s energy requirement over its entire lifecycle, by estimating and calculating both embodied and operational energy consumption in buildings particularly in Ahmedabad region (Hot and dry climate). A comparison of embodied energy of alternative walling materials has been made with reference to building’s operational energy requirement. It has been observed that embodied energy of 1 cu m masonry can be reduced by 70% when alternative walling materials are used.

Analysis of Daylighting Devices for Office Buildings of New Delhi, India (2009)

Neha Singhal, Tanmay Tathagat
Abstract: Deep plans have become a common practice in multi-storey buildings’ designing and large open plans have become the preferred choice in order to have flexibility of the space and economic benefits. However, the deep core areas of these buildings cannot be naturally illuminated by side windows, and therefore, such areas depend entirely on electricity for illumination. The work done n the present study is an attempt to find out the benefits of using daylight device technologies to enhance natural illumination of deep plan office buildings. The focus of this study is to determine appropriate passive daylight device for office buildings in the city of New Delhi, India, and helps to understand the barriers that prevent harnessing in the daylight to its maximum potential. This study takes into account the prevailing building typologies in the commercial sector. Four hypothetical models have been derived subsequently by analyzing the existing office buildings typologies of the city. After developing the hypothetical models, various windows to wall ratios have been applied to understand the availability of daylight in these models. The study addresses to three daylighting devices which are available in the international market – light shelves, Anidolic light ducts, Light tubes. The integration of selected devices with the hypothetical models has been considered for more than one scenario, which studies and examines its appropriateness for daylight usage. This entire exercise has been carried out using validated simulation program. The formulation of the simulation exercise has been established on the available weather data. Experiments have been carried out under sunny sky conditions and CIE overcast sky. The exercise also evaluates the cost effectiveness of the integration of daylight device within existing buildings to increase daylight availability and thereby reduced energy loads because of artificial lighting systems. Hence it tries to assess the cost effectiveness of application of such devices. The study demonstrates the technical & economic viability of passive daylight devices in the context of New Delhi, India.

This contribution has been published in the conference on International Building Performance Simulation Association (IBPSA) held at Glasgow – 2009. For further details please visit: IBPSA, BS 2009.

Evaluation of One Dimensional Transient Heat Transfer through Composite Wall Assemblies (2011)

Shilpi Saboo, Munjal Bhatt
Abstract: The main objective of the research is to evaluate one dimensional transient Heat Transfer through composite wall assemblies. The composite wall assemblies are categorized in four parts; monolithic, insulated walls, cavity walls and hollow blocks. The example studied under monolithic walls are brick and stone, cavity walls with varying cavity thicknesses and insulated walls with XPS and EPS on outside and inside. There are two cases of monolithic walls, two cases of hollow block, three cases of cavity walls and four cases of insulated walls. In all eleven cases of composite wall assemblies, simulation is carried out. All the cases are simulated for conditioned and naturally ventilated environment for design day and design week of May and December. The effect of location of insulation, the amount of thermal mass required to attain 2°C of temperature variation from outside to inside, transient heat transfer happening with in the assembly, influence of the layer distribution and thickness on the thermal behavior, are the concerns for which the analysis is being done. The investigation is carried out for the climatic conditions of Ahmedabad, during representative days for May & December. The initial temperature distribution across the wall is assumed to be uniform and equal to the daily mean external air temperature. Orientation and inclination of the assemblies is also kept constant for all the cases. The entire exercise is simulation based in WUFI Software. The effect of insulation location on the heat transfer characteristics of building wall elements under initial transient conditions is studied. Thermal performance with an insulation layer placed on the inside of a wall is compared to that when the insulation layer is placed on the outside. The results of model application under the present conditions show that placing the insulation on the outside proves more helpful. The heat flux values are noted over the first 24 hours and compared for various wall assemblies, seasons and insulation locations.

The 2°C temperature variation is kept as the output and accordingly the thicknesses of various assemblies are varied to achieve the result. Total 10 Wall assemblies are experimented to figure out the optimum variation. All the assemblies are simulated for a typical summer day, extreme summer week to understand the transient heat transfer phenomena. Similar is done for winter. The influence of layer distribution and thickness on the thermal behavior is studied.Impact of variables of Time and Temperature becomes an important phenomenon to study transient heat transfer. The data generated from simulation runs is then analyzed and comparison can be made for various wall assemblies. Final comparison of transient phenomenon between the various cases is made to identify the most efficient strategy for composite wall assemblies.

A comparative study on energy savings and economics for insulating materials used in wall in hot and dry climate (2009)

Dhara Naik, Madhvi Patel
Abstract: An important factor impacting energy efficiency in building is its envelope and also the amount of energy consumed depends on the design of the fabric of the building. A systematic approach to determine the most energy efficient and at the same time most economically viable insulating material when used on the external wall of the building is developed in this paper taking Ahmedabad as an example. Thus the paper explores the potential of these insulation materials to reduce the cooling load in office buildings when used on inside of a wall. The optimization is based in life cycle cost analysis. A hypothetical model through survey of office buildings typical of practice in Ahmedabad is evolved for the study. An excel worksheet is prepared through which the heat gain/loss through the differently oriented walls of the building façade is calculated using finite difference method. The payback period and life cycle cost for each of the insulating material selected is then comparatively analyzed on the cost of insulating material and annual cooling loads. The results show that most energy efficient material in terms of energy consumption is polyurethane foam of 75mm thickness and gives savings of 23% annually as compared to base case. However 50mm polyurethane gives a payback year of 1.5 years. In term of life cycle cost over 50 years, 75mm polyurethane proved to be better material than others.

Passive Design Indices: Quantifying the Potential for Passive Design Strategies in a Climate (2017)

Jaydeep Bhadra, Prasad Vaidya, Saket Saraf
Abstract: The study focuses on developing indices to assess and compare passive design strategies based on their potential for a climate. Cooling accounts for 40%-60% of summer peak load in large metropolitan cities and AC sales in India are growing at 30% per year (Clean Energy Ministerial, 2014). Climate plays crucial role in how our buildings are designed and how they consume energy. Diverse climatic conditions can be found in same broader climatic regions and this change can be seen within few kilometers of distance. The currently available climate analysis tools do not explore the inter-relationships between climatic parameters (Upadhyay, 2016). Earlier work shows 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 (Pawar et al 2015). (Levitt, Ubbelohde, Loisos, & Brown, 2013) proposed Thermal Autonomy as a metric which measures how much of the available ambient energy resources a building can harness. This study takes that approach forward to establish weather data based indices for advanced passive design strategies, such as evaporative cooling, natural ventilation, night-flush cooling etc. Variables in weather data that relate to the source and sinks for each strategy are identified. Threshold limits for variables is based on implementation of the strategy. Weather data (TMY2) of 60 Indian cities is analyzed to develop the indices.

Passive design indices will enable policy makers to develop climate zone maps that highlight the potential for specific low energy solutions in a climate. Since these indices provide a measure of the potential for the use of passive strategies in a climate, they will provide firsthand information to designers to select the correct strategy based on the opportunity available in the climate.

Keywords: Passive design, Indices, Climate, Weather analysis, Potential, Low energy cooling.

Comparative analysis of daylighting systems for a high-rise office building in Mumbai (2016)

Nitika Torvi, Agam Shah
Abstract: In dense urban areas, high rise buildings cause sky obstruction which in turn create dark interior spaces. Daylighting can be a major issue in designing energy efficient building. In recent years, daylighting of deep plans has become very important, not only to reduce total energy consumption of the building but also to provide healthy spaces for the users. Daylighting helps to design a visually comfortable space depending upon the function of the space. Innovative daylight redirection systems can be used to enhance indoor daylighting using available sunlight. This study evaluates the daylight redirection systems like light shelves and anidolic ducts, these systems are reviewed and a comparison is made with respect to efficiency, light output and light redirection. It is only a simulation based study and not an experimental one because of the stipulated time frame. This study specifically shows the case of office building in Mumbai. In this study a high rise office building “Commerze- II” Oberoi garden city, Goregaon(E) is modeled in Rhino and simulated in Diva for Rhino by integrating the daylight redirection systems in the four orientations while taking a hypothetical surroundings into consideration. The hypothetical surroundings is derived based on the survey conducted for 25 buildings to find two most common sky exposure angles found for High rise office buildings in Mumbai. Simulation is done according to the IES LM 83 document guidelines for sDA and ASE. The study suggests the pros and cons of these systems over each other for the modeled High-rise building in Mumbai to optimize the daylight performance of the building based on the analysis of simulation results.

The study of Skylight to Roof Ratio (SRR) in the industrial sheds of Vadodara (2016)

Ridhima Passi, Agam Shah
Abstract: Day lighting is a primary design strategy to reduce energy consumption especially during peak loads of energy demand. It is evident that there is lot of growth in the industrial field and new areas are been dedicated for the industrial set ups outside the city. The industries which are getting build in these areas do not have enough space between the two sheds to have adequate amount of light from the windows. Some industrial sheds have purposely less wall window ratio due to their machinery running on the sides and for safety and security reasons also. Area of some of the sheds is so large that the interior areas does not get appropriate amount of light through windows. Hence the main access to natural light in these buildings can be through roof that is through Skylights.

The skylight roof ratio (SRR) is the ratio of the area of skylight in comparison of the total roof area. One can find out how much amount of day light is entering the volume through skylights which will create a healthy working environment for the workers to work. The paper is about the appropriate proportion of the skylight with respect to the volume of the space. The study is to find out uniform natural light in a particular volume of space through skylights which are fixed. The distribution, number and the size of skylight used in a particular volume are the main factors to achieve the required illumination within that space. The material of the skylight is another important factor for the uniformity of the light in the space. The study will include experiments with different materials and their effects on the day light performance of that space. The research conducted will be based on testing of scaled model.

Evaluation of daylight performance of existing classroom spaces at Ahmedabad (2016)

Kratika Piparsania, Agam Shah
Abstract: The study uses building energy simulation tools to analyze the conceptual models representative of existing classroom spaces in Ahmedabad, in order to study the daylight performance and compare it with the best practice. The existing classroom spaces are studied and examined and the best representative classroom are then simulated to check the annual performance and retested with parametric variations such as floor area, orientations, w/o shading devices, size of openings, reflectance of materials, WWR etc. The illuminance levels in the classroom spaces are also measured and compared with the simulation results, to get awareness about the difference real and virtual outcomes. Different dynamic and climate based daylight metrics are evaluated with reference to IES-LM doc and LEED. The data generated from simulation run are then analyzed. Optimal design aspects are identified and observations are made in terms of daylight and design for different variables. More importantly the approach is to provide the suggestive measures towards meeting the criteria of the daylight metrics and to know how they can be achieved and if they fall under the criteria ,why they have achieved it for the given classroom .The research would benefit architects and designers who will in future design any classroom space to achieve the specific daylight metric or if they need to evaluate any space in order to access the daylight performance within the scope of the research.

Analysis of proposed institutional campuses & potential of Net Zero energy campuses in India (2016)

Ankita Bokhad, Rajan Rawal, Prasad Vaidya
Abstract: The concept of a Net Zero Energy (NZE), one which produces as much energy as it uses over the course of a year, recently has been evolving from research to reality. Currently, there are only a small number of highly efficient buildings that meet the criteria to be called "Net Zero". As a result of advances in construction technologies, renewable energy systems, and academic research, creating Net Zero Energy buildings is becoming more and more feasible. The idea of net-zero energy building has been in the list of trends in architectural advances for quite some time now. A net-zero energy campus on the other hand emerging phenomenon in India. It is basically the similar approaches that one takes to make a building net-zero energy, but on a larger scale. At the campus level, one can make use of the character of the site. What makes the goal of net-zero energy at a campus level more achievable is the fact that one can always enforce policies to limit use of energy use and hence save energy.

The research focuses on analysing upcoming net zero energy campuses in India on the basis of their architectural expression, envelopes and systems and integration of renewable sources on the site campus. This would lead to a consolidated piece of work that might inform about the relevant practices to achieve net zero. This may also inform us about some other practices, which might not be as helpful in achieving net zero balance, so they could be considered secondary.

Impact of native evergreen trees on the visual comfort in an office space in Ahmedabad, India (2014)

Ankit Bhalla, Sanyogita Manu
Abstract: This study investigated the impact of native evergreen trees on the daylight availability in office spaces in Ahmedabad, India. An evergreen tree, native to the hot and dry climate of Ahmedabad, was selected and its impact on daylighting in interior spaces is analyzed compared to a no-tree scenario. The distance of the tree from the window was varied to examine parameters such as contrast and brightness at the task plane for the equinox and solstice days. Desktop Radiance 2.0, which is a backward ray tracing daylight simulation software, was used, followed by a calibration study. Uniform and sunny sky conditions based on Ahmedabad climate data were considered. The results indicate that trees can be very effective in achieving visual comfort in conditions of harsh sunshine outdoors. The type of tree is of more importance for visual comfort than the distance between the tree and the window. The evergreen tree performed well to mitigate visual discomfort. Careful selection of the tree type and its positioning on the southern facade reduced illuminance levels but helped improve visual comfort by almost 50%. This study also explains in detail the method used for determination of Leaf Area Index and Leaf Area Density used for calculating the crown density of the tree, which may help future work attempting to study the impact of vegetation on the thermal or visual performance of building envelope.

Presented at: 30th International PLEA Conference, December 2014, Ahmedabad

Study on reasons for occupant control of windows and its impact on energy consumption in residences on India (2014)

Surbhi Pandit
Abstract: Traffic is a significant part of urban environment contributing about 55% to the total urban noise and is an inescapable by-product of ever growing industrial environment in India. As a standard WHO has fixed 45 decibels as the safe noise level for a city, which if exceeded, can cause loss of hearing and irreversible changes in nervous system. On the contrary, the metropolitan cities of India: Mumbai, New Delhi and Chennai have registered an average more than 90 decibels. It is observed that noise forms a major constraint for employing adaptive comfort strategies like use of balconies, opening the window for increased ventilation, etc. due to which a higher discomfort is reported. This study focuses to understand on occupants’ behaviour of opening/closing the windows in residences of India. A Survey will be conducted in Delhi, Mumbai, Ahmedabad and Indore covering minimum 300 residences, to track the reasons responsible for control of windows. In this survey, occupants will be asked to fill up a survey questionnaire on window operation and measurements of temperature, relative humidity and noise levels inside and outside the residence will be taken. Statistical analysis of survey will help bringing out a range of these parameters responsible for window operation under which windows are kept open or closed. The study will also evaluate the energy required in room to achieve comfortable environment inside through mechanical modes of cooling when windows are closed due to unfavourable outside, with the help of a simulation tool in which temperature, humidity and noise levels outside the room will be the input parameters. This study will help tracking the range of temperature, relative humidity and noise levels under which windows can be kept open. Also difference in energy consumption of same space will be identified if kept closed.

Impact of the building envelope on the indoor thermal comfort in institutional buildings: Study in Jaipur Region (2014)

Poonam Shah
Abstract: One of the most important factors that affect human health and performance in a building environment is thermal comfort. Thermal comfort in building results from a complex set of physical conditions, occupant sensations, their behavior as well as the characteristics of the building. The enquiry will be to understand the impact of the building envelope on the indoor thermal environmental conditions. The primary intention of this work is to provide a detailed look at the overall effect of building envelope (building material and construction techniques) on the thermal characteristics of the space. The study includes thermal comfort surveys and simultaneous measurements of indoor environmental variables. The questionnaire for survey is prepared to obtain the subjective responses from the respondents on various thermal comfort parameters such as temperature, humidity and air flow along with a response on overall thermal comfort. Hence, the study would conclude the impact of different construction materials and techniques on the indoor thermal comfort.

Keywords: Building envelope, construction material, construction techniques, indoor environment, thermal conditions, and composite climate.

Study of Thermal Sensation of Occupants in Office Buildings located in Hot and Dry Climatic Zone, Ahmedabad, India (2012)

Chinta Shree Sowmya, Rajan Rawal
Abstract: Thermal comfort as defined by ASHRAE 55 standard defines, “It is the state of that condition of mind which expresses satisfaction with the thermal environment and is assessed by subjective evaluation”. In India, we follow a range of temperature based on ASHRAE 55 standard for air conditioned buildings. Many researchers have claimed that this temperature range is narrow and not appropriate for Indian conditions. There are very few studies in the Indian context which have focused on this issue. The study is a part of larger study conducted at CARBSE (Centre for Advanced Research in Building Science and Energy), CEPT University. The study aims to understand the thermal sensation of people working in office buildings lying in hot and dry climate of Ahmedabad, India. Field studies were conducted for two building types i.e., naturally ventilated and air conditioned where thermal comfort votes along with parameters of air movement, clothing, activity levels etc. from occupants using questionnaires were collected. Simultaneously, the indoor environmental conditions were also measured near every occupant. Peak summer (May) and peak winters (January) were chosen for this purpose. In summer, the study was extended to naturally ventilated buildings. This field study was conducted independently by the author. The other surveys were conducted by CARBSE, with author being one of the survey team members. Three buildings were surveyed to understand thermal comfort conditions along with adaptive thermal comfort strategy in this building type. In naturally ventilated buildings, where the mechanical cooling or heating systems are absent, occupants adapt themselves in order to achieve comfort. The study also aims to find a relation between the thermal sensations of people and its variation with building characteristics. The results are compared to the ASHRAE 55 standard for air conditioned as well as naturally ventilated buildings to ascertain its suitability for hot and dry climate.

Keywords: Thermal comfort, naturally ventilated, air conditioned, thermal comfort votes, air movement, clothing, activity, indoor environmental conditions, adaptive thermal comfort, thermal sensation, building characteristics, ASHRAE 55 standard.

Impact of Presence of Courtyard on Thermal Characteristics of Vernacular Residential Building – An Exploration in Hot-dry Vernacular Context of Ahmedabad (2012)

Mihir Vakharia, Rajan Rawal
Abstract: The practice of having a courtyard in hot-dry and hot-humid climate has been in practice since medieval times. This study focuses on presence of courtyard in residential unit - “Pol-House” house as it is known in vernacular language, in the city of Ahmedabad. This study is an endeavour to understand thermal characteristics of indoor spaces adjacent to courtyard. The study is based on the hypothesis suggesting that the presence of courtyard helps in attaining thermal comfort in naturally ventilated residential buildings. On-site measurements and building energy simulation tools, such as computational fluid dynamic tools have been used to understand thermal characteristics of pol house. The study is divided with on site measurements for indoor environmental variables (Relative humidity, Air temperature, Air velocity, and Surface temperature and Globe temperature) for seven days and Simulation study of Pol house with courtyard vs. without courtyard. Thermal characteristic of courtyard improve the thermal environment of the both adjacent and enclosed spaces.

Analysis of Indian Traditional Jali (Stone Latticed Screen) For Daylighting through Simulations (2011)

Dharmesh Gandhi, Vishal Garg
Abstract: This study analyses Jali (stone latticed screen) for its daylight performance. Jali is an Indian term used for lattice work done on windows in ornamental/geometrical patterns. Jalis are used extensively in Islamic architecture. The physical function of the Jali is to reduce the amount of light admitted inside and to cut out its blinding glare; to allow the passage of air but arrest powerful gusts, which essentially makes it a climate control device for various climates in India. The screens of Islamic architecture represent the best examples attesting to this observation. In this study about 256 stone Jalis of 30 Islamic mosques in Ahmedabad city (23° 1? N, 72° 34? E; hot and dry climate) built during 13th to 16th century were studied and documented. Frame size, solid/void ratio, height-of-void / thickness of Jali ratio were recorded. Based on this documented data 27 representative Jalis, (simplified geometry, without ornamentation) of 250mm x 250 mm frame size, were prepared for 3 different thicknesses, 3 different solid/void ratios, and 3 height-of-void / thickness of Jali ratio. These representative Jalis were simulated in Radiance 1.02 for different times of the day in four orientations. Radiance is a suite of tools for performing lighting simulation which works on backward ray-tracing. The simulation results revealed that the thickness and depth of the stone Jali played an important role in blocking direct sun light, providing uniform daylight, and preventing glare, for the location of Ahmedabad.

Evaluating thermal comfort of occupants [in conditioned office spaces] (2010)

Smriti Singla, Shruti Narayan
Abstract: The main aim while designing a space is to provide comfort to its users. In any office buildings, productivity of employees and hence the health is a main cause of concern for the parent company. Sick building syndrome was one of the main reasons for creation of new field in science called “Thermal Comfort”. Hence, thermal comfort models were developed to help the architects and other building engineers in design process. There are different models like Fanger and Adaptive for defined the comfort zone; may it be static or dynamic. Though based on established studies and related research, it has been successfully proved that adaptive model of thermal comfort is better applicable than the static model, most of the offices in the national capital region of India still use static model of thermal comfort (ASHRAE 55 – 1999). It may be explained on the basis of lack of field studies on thermal comfort to benchmark the present perception of the occupants in real conditions or on the basis of fact that the national building code of India still propagates the static model of comfort. Hence the main objective of this research is to evaluate thermal comfort of occupants in air conditioned office spaces in national capital region of India. It is carried out by evaluating the present state of thermal comfort in the office setups of 12 multinational corporations in the region. The evaluation is carried out by directly relating the onsite comfort parameters (air temperature, relative humidity and air velocity) to the comfort votes given by the occupants.

The results show that there is a potential scope of expanding the presently suggested thermal comfort band to higher temperatures even in air conditioned spaces. Further, based on established studies, it can be stated that an increment in set point temperatures of the thermostats’ regulating the temperature of a space does help reduce the energy consumption of the building (every two degree increase in temperature results in a 20% reduction in cooling loads of the building) and hence supports more sustainable and environmentally responsible buildings.

Optimizing WINDOWS for Thermal and Daylighting Performance: A case of Commercial Buildings in Ahmedabad, India (2009)

Sanyogita Manu, Rajan Rawal
Abstract: This study uses building energy simulation tools to analyze hypothetical models representative of commercial buildings in the hot-dry climate of Ahmedabad to understand the daylighting and thermal performance of windows. Impact of variables such as floor area, aspect ratio, glazing/window area, orientation, glazing types and overhang has been observed on the building lighting and cooling loads using parametric simulation. The data generated from simulation run is then analyzed using Multiple Regression Analysis to express loads as a function of floor area, aspect ratio and orientation of windows. A near optimal window is identified and observations are made in terms of trade-offs between lighting and cooling load savings for different variables.

Effect of Courtyard on Thermal Performance of Commercial Buildings In Hot-Dry Climate, Ahmedabad, India (2009)

Rachit kumar, Rajan Rawal
Abstract: Energy efficiency in buildings is becoming an important concern to the building designers. Commercial buildings consume a huge amount of energy in heating, cooling lighting of the building spaces; hence there is a need to find effective design measures to develop energy efficient buildings. Courtyard is a traditional design measure which can be used in reducing energy consumption of the buildings. It has been seen in Indian cities often, the current urban development plan is trying to integrate courtyards in the design of buildings. However what would be the effect of incorporating courtyards in the energy consumption of commercial buildings, also to what extend would courtyards help within the limitations of building by laws and varying site proportions of new master plans in Indian cities. The study focuses on the effect of courtyard form with different proportions, wall to window ration (WWR) and overhangs on the thermal performance of the commercial buildings. The hypothetical model of courtyard building configurations depends on available urban schemes (site proportions) and building by laws (Setbacks, Ground Coverage and Floor Area Ratio). For varying building heights, different hypothetical building configurations have been derived, on which various WWR and overhangs have been applied. The computer energy simulation program DesignBuilder Version 2.04.002 was used in this study as a simulation tool to evaluate the impact of these parameters on the thermal performance of the buildings. The result of the simulation showed that the courtyard building thermal performance differed from various configurations. In general, determining the relative qualities of the configuration versus another specific proportions is difficulty and also introducing a courtyard in a building is not always an acceptable solution unless it’s all parameters are not proficiently used. This study assisted in understanding the difficulties of courtyard building configuration to its maximum potential for new commercial architecture in hot-dry climate of India.

Effect of Colours in Interiors…an attempt to understand the energy of color with light on its spatial quality and efficiency (2009)

Rohini Singh, Rajan Rawal
Abstract: The paper attempts to analyze the relationship between surface color reflectance and lighting power density for a given set of context. Analysis was based on digital modeling using validated energy simulations tool. The study establishes itself on this premise. The exercise elaborates evaluating the impact of vertical and horizontal planar interior elements’ surface reflectance & examines its impact on LPD. This is done through different scenarios derived from the base case. All derived scenarios were then confirmed to the established standard of visual comfort. The result was collated to develop a chart illustrating the finding.

Presented at: International Building Performance Simulation Association -An IBPSA-AIRAH conference, November 2011, Sydney.

Supported by:

Ministry of New and Renewable Energy Govt. of India, Gujarat Energy Development Agency, U.S. Agency for International Development iNDEXTb (Industrial Extension Bureau) Govt. of Gujarat, Shakti Sustainable Energy Foundation, New Delhi