Journal Papers

Journal Papers

Impact of Vegetation and Building Height on Urban Ambient temperature in Hot and Dry climate (2011)

Journal of Habitat Engineering, Vol3-2, pp 209-218
Jalpa Gandhi, Rajan Rawal

Field studies of thermal comfort across multiple climate zones for the subcontinent: India Model for Adaptive Comfort (IMAC) (2016)

Building and Environment, Volume 106, September 2016, Pages 422-426
Sanyogita Manu, Yash Shukla, Rajan Rawal, Leena E.Thomas, Richard de Dear
Abstract: India is witnessing unprecedented growth trends in building construction, particularly office spaces. Indian offices are designed to operate at 22.5 ± 1 °C all year round to meet the stringent “Class A” specifications outlined by international standards in the absence of an India-specific comfort standard. This paper proposes an India Model for Adaptive Comfort – IMAC – based on the field surveys administered in 16 buildings in three seasons and five cities, representative of five Indian climate zones. A total of 6330 responses were gathered from naturally ventilated, mixed mode and air-conditioned office buildings using instantaneous thermal comfort surveys.

Occupants in naturally ventilated Indian offices were found to be more adaptive than the prevailing ASHRAE and EN models would suggest. According to the IMAC model, neutral temperature in naturally ventilated buildings varies from 19.6 to 28.5 °C for 30-day outdoor running mean air temperatures ranging from 12.5 to 31 °C. This is the first instance where a study proposes a single adaptive model for mixed mode buildings asserting its validity for both naturally ventilated and air-conditioned modes of operation in the building, with neutral temperature varying from 21.5 to 28.7 °C for 13–38.5 °C range of outdoor temperatures. For air-conditioned buildings, Fanger's static PMV model was found to consistently over-predict the sensation on the warmer side of the 7-point sensation scale.

Keywords: Indian office buildings, Fanger PMV, Adaptive thermal comfort, Adaptive model, Neutral temperature, Comfort standards
Download Paper

Transient three-dimensional CFD modelling of ceiling fans (2017)

Building and Environment, Volume 123, October 2017, Pages 37–49 Francesco Babich, Malcolm Cook, Dennis Loveday, Rajan Rawal, Yash Shukla
Abstract: Ceiling fans have been used for decades as a means of providing thermal comfort in tropical countries such as India. However, recent years have witnessed a significant increase in the use of air conditioning as a means to achieve comfort, and therefore in the total energy consumption and related CO2 emissions. Ceiling fans are still viable options to limit use of air conditioners or in combination with air conditioners without compromising on thermal comfort and still achieving energy savings. Ceiling fans generate non-uniform velocity profiles, and therefore relatively non-uniform thermal environments, whose characteristics may be tough to analyse with simple modelling methods. This issue can be investigated using CFD. However, to date, there are few works on ceiling fans, CFD and thermal comfort. More accurate models are therefore required to predict their performance. The research presented in this paper aimed to develop and validate a three-dimensional transient implicit CFD model of a typical ceiling fan available in India by comparing simulation results obtained using different URANS turbulence models with measured data collected in controlled environment. The results highlight that this ceiling fan model is able to replicate the predominant characteristics of the air flow generated by the fan such as the meandering plume and the local fine free shear layers. The best results are achieved when the SST k-ω turbulence model is used, with 83% of the simulated values being within the error bars of the respective measured value.

Keywords: Ceiling fan, Thermal comfort, CFD validation, Turbulence modelling, India, Environmental chamber
Download Paper

Packaged scalable energy information systems for hotels (2018)

Journal of Facilities Management
Reshma Singh, Paul Mathew, Jessica Granderson, Yash Shukla, Amiya Ranjan Behera
Abstract: Purpose: Building Energy Information Systems (EIS) are performance monitoring software, data acquisition hardware, and communication systems used to store, analyze, and display building energy data. Some $60 billion is spent annually on wasted energy in U.S. buildings, and actions taken based on EIS data can enable operational energy savings of ~10 percent in the U.S. commercial sector (~2 quads of primary energy). However, EIS adoption is low due to various technical and market challenges. This paper provides technical specifications for standardized EIS packages that can help overcome barriers and accelerate scale.

Design/methodology/approach: A five-step approach was followed: 1. Identifying business drivers as key determinants for hotel sector-specific packages 2. Addressing heterogeneity to develop standardized, tiered packages 3. Determining performance metrics for key stakeholders 4. Recommending streamlined data architecture 5. Developing visualization enabling insights and actions

Findings: Technical specifications for two tiers (entry and advanced) of EIS packages for hotels have been developed. EIS vendor, integrator, and client organization’s facilities and IT staff have been considered as key stakeholders. Findings from six field demonstrations show benefits of (i) cost-effectiveness, through reduced transactional, first, and operational costs, (ii) scalability, by accommodating heterogeneity across the building sub-sector, (iii) simplicity, by integrating meters, gateways, and software in the package, and (iv) actionability in organizations, across various decision making levels.

Building owners and operators can use these specifications to ease procurement and installation of EIS in their facilities. EIS software vendors can use them to develop new product offerings for underserved sectors.
Download Paper

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