**1. Introduction**

Due to increasing sales numbers and resulting energy demand for air conditioning as well as related CO2 emissions worldwide, energy e fficient and more environmental friendly air conditioning is required [1]. According to the International Energy Agency (IEA), an increase of more than five billion air conditioning systems between the years of 2016 and 2050 is estimated for the commercial and residential stock [2]. That means more than a doubling of the currently installed units. Income growth in the developing and emerging countries, climate change and increased building energy standards cause this development for air conditioning [3,4]. Currently, air conditioning is responsible for around 20% of buildings' electricity demand from a worldwide perspective [2]. Furthermore, heating, ventilation and air conditioning (HVAC) systems require the largest share of energy used in buildings. Thus, enhancing performance of conventional systems o ffers the opportunity to significantly reduce energy demand and related CO2 emissions, respectively [5].

Air conditioning systems are often used to provide comfortable indoor air conditions in general. Removing latent and sensible loads from outside air is usually required during summer to provide the desired indoor air conditions. Especially moisture removal accounts for peak loads of conventional air conditioning systems since it requires cooling process air below dew point temperature. Cooling and dehumidification are coupled necessarily due to the process itself. Required cooling capacities are

often provided by electrical driven vapor compression cycles. In contrast, removal of sensible and latent loads is separated within a desiccant assisted air conditioning process. A desiccant material is used to remove latent loads from the process air stream. Thus, required cooling capacities are reduced, especially at high outside air humidity ratios. Shallow geothermal energy can be utilized to remove sensible loads from the process air stream. Utilizing the soil for cooling, an equalized energy balance of the soil is essential regarding long-term e fficiency of the geothermal system. This can be improved by using a ground-coupled heat pump for heat supply during winter.
