Case Studies in Thermal Engineering 15 (2019) 100538 Available online 26 September 2019 2214-157X/© 2019 The Authors. Published by Elsevier Ltd. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/). A study on optimum insulation thickness of cold storage walls in all climate zones of Jordan Mohammad A. Batiha a, * , Abdullah A. Marachli b , Saleh E. Rawadieh a , Ibrahem S. Altarawneh c , Leema A. Al-Makhadmeh d , Marwan M. Batiha a a Chemical Engineering Department, Al-Hussein Bin Talal University, 71111, Ma’an, Jordan b Mechanical Engineering Department, Al-Hussein Bin Talal University, 71111, Ma’an, Jordan c Pharmaceutical and Chemical Engineering Department, German Jordanian University, Amman, 11180, Jordan d Environmental Engineering Department, Al-Hussein Bin Talal University, 71111, Ma’an, Jordan A R T I C L E INFO Keywords: Cold storage Energy saving Insulation characteristic curve LCC analysis Optimum insulation thickness Payback period ABSTRACT Cooling of cold storage space in hot climates consumes signifcant amounts of energy, which can be conserved with the help of thermal insulators. The main goal of this study is to conduct a life- cycle cost (LCC) analysis over a period of 10 years in order to determine the optimum insulation thickness (OIT), energy saving, and pay-back period for minimizing installation and operational costs of cold storages in any given climate zone of Jordan. These climate zones were represented by four Jordanian cities, i.e., Amman, Mafraq, Ma’an, and Aqaba. In this analysis, three commercially available insulation materials were selected, namely Rockwool (RW), expended polystyrene (EPS) and polyurethane (PUR), for a wide range of cold storage temperatures (0, 5, 10, 15, 20, 25, and 30 � C). Electricity was considered as a source of energy. It was found that EPS has the best energy savings and shortest payback period compared to other insulation materials. Therefore, its use in cold storage exterior walls insulation, with OIT suggested in any climate zone of Jordan, is economically feasible. An insulation characteristic curve for EPS was prepared, which includes the OIT and cost saving over a wide range of cooling degree-day and coeffcient of performance (COP) values. 1. Introduction Jordan is a relatively small, semi-arid, country located in the Middle East. Jordan has limited conventional energy resources and imports most of its energy needs. Jordan enjoys a climate that is characterized by its long dry summers, cool winters, and is divided into three distinct zones: (i) the Jordan valley, (ii) eastern highlands, and (iii) desert areas. Jordan’s population and energy statistics for 5- year time interval (2013–2017) are listed in Table 1 [1,2]. During this period, the estimated population and primary energy con- sumption have increased by 23.31 and 22.7%, respectively. This increase in the energy consumption levels has added extra pressure on the Jordanian’s economic, social and political sectors. Due to lack of indigenous energy sources, Jordan mainly relies on importing most of its energy needs to satisfy its energy demands. In 2017, Jordan imported 10.207 million toe of crude oil, oil products, natural gas, and coal. This is equivalent to USD 3.42 billion and accounts for 8.6% of its GDP. The total amount of electricity consumed in 2017 was 17574 GWh. Of this total amount, residential and industrial sectors have consumed 46 and 22%, respectively [1]. This elevated * Corresponding author. E-mail addresses: mbatiha@ahu.edu.jo, mabatiha@yahoo.com (M.A. Batiha). Contents lists available at ScienceDirect Case Studies in Thermal Engineering journal homepage: http://www.elsevier.com/locate/csite https://doi.org/10.1016/j.csite.2019.100538 Received 19 June 2019; Received in revised form 22 September 2019; Accepted 25 September 2019