Research Paper Novel air conditioning system configuration combining sensible and desiccant enthalpy wheels Wael M. El-Maghlany ⇑ , Aly A. ElHefni, Mohamed ElHelw, Abdelhamid Attia Department of Mechanical Engineering, Faculty of Engineering Alexandria University, Alexandria, Egypt highlights  Two energy wheels are utilized to retrofit existing air conditioning system.  The heating coil function is dispensable via exhaust air energy recovery.  Significant decrease in the cooling coil capacity has been established.  The saving in power consumption is 87.15% in winter and 13.53% in summer. article info Article history: Received 15 March 2017 Revised 1 August 2017 Accepted 4 August 2017 Available online 5 August 2017 Keywords: Desiccant Enthalpy wheel Air conditioning Energy saving abstract There is a great importance of studying various solutions to reduce energy consumption. The energy con- sumption in the air conditioning systems became remarkable in the recent years. This paper addresses a retrofit for improving the thermal performance of air conditioning systems in buildings with large energy consumption. Intensive care units in hospitals are one of the most energy consumption units due to all fresh air utilization. An existing hospital building was used for this study, targeting the retrofit of air con- ditioning system having 100% fresh air for the intensive care unit (ICU). In the proposed new system, an arrangement of two energy wheels is studied for the first time to retrofit existing system through exhaust air energy recovery. Simulation model has been developed on the basis of the building energy simulation program (EnergyPlus). An hourly simulation has been performed for an entire year and the proposed ret- rofit air conditioning system was found to be more energy efficient. The results show a significant decrease in the cooling coil capacity with zero heating load capacity and hence a saving in power con- sumption up to 87.15% in winter (February) and lowest saving of 13.53% in summer (August). Ó 2017 Elsevier Ltd. All rights reserved. 1. Introduction Energy efficiency is an important measure for any country to manage energy resources. According to the International Energy Agency (IEA) in world energy outlook 2016, it is estimated that a 30% rise in global energy demand is expected by 2040 where mil- lions of people will still be without basic energy services. More- over, some countries are now struggling with major energy shortages. In this study, we have an interest in Egypt’s case. In last years; the country has experienced frequent electrical power blackouts. It is now clear that the problem started long before its consequences became obvious. The plans implemented to expand the energy grid for securing energy was not rational. Thus electric- ity consumption is increasing much faster than capacity expansions. Moreover, the country has a considerable percentage of aging infrastructure and experiences serious natural gas supply shortage. In order to provide for its citizens and keep its factories running, Egypt needs significant energy management measures. Sales numbers for fans and air conditioners are rising quickly. Amongst 1996 and 2006 the sale of air-conditioning (AC) units exceeded 54,000 units per year; however between 2006 and 2010 this number has increased to grasp an average 766,000 units per year [1]. The government has started adopting various sets of energy rationalization measures and took steps towards increasing the dependence on renewable energy sources. This takes us to the fact experts’ point that energy efficiency is a key factor to solving power shortage problem. Energy efficiency solutions usually take less time and are more cost-effective, meaning that their returns on investment are of shorter period than with renewable energy projects. The two major consumers of electricity are households and industry, followed by government and public utilities. Retrofit http://dx.doi.org/10.1016/j.applthermaleng.2017.08.020 1359-4311/Ó 2017 Elsevier Ltd. All rights reserved. ⇑ Corresponding author. E-mail addresses: elmaghlany@alexu.edu.eg, elmaghlany@yahoo.com (W.M. El- Maghlany). Applied Thermal Engineering 127 (2017) 1–15 Contents lists available at ScienceDirect Applied Thermal Engineering journal homepage: www.elsevier.com/locate/apthermeng