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Preg:COPsorpt ¼ Pcool;sorptPreg• Pel,vent defines the electricity demand of the ventila-tors. This electricity demand depends on the overallpressure drop of the air handling units which is quitedifferent for the different designs due to the imple-mented components.• Pel,chiller is the electricity demand of the chiller whichis defined by the fraction between the conventionalcooling and the chiller COP:Pel;chiller ¼ PconvCOPchiller• The total electricity demand, Pel,tot, is the sum of theelectric consumption of the chiller and the ventilators:Pel;tot ¼ Pel;chiller þ Pel;ventResults of the comparison of all the performance fig-ures defined above for the studied systems are sum-marized in Table 2. All given values refer to anominal air flow of 1000 m3/h at return air conditions(26 C). The following conclusions can be drawnfrom this comparison:• The standard cycle with additional cooling coilbehind the heat recovery wheel (scheme of Fig. 3)requires the lowest amount of conventional cooling.However, this cooling is needed at a low temperaturelevel, since the final humidity control of the supply airis realized with this cooling coil.• Both, the 2-wheels cycle (Fig. 5) as well as the 2-cool-ing-coils cycle (Fig. 7) need chilled water at a farhigher temperature. This means that eventually otherenvironmental heat sinks such as well water might beused if available.• The 2-wheels cycle requires a far higher amount ofregeneration heat than both other sorptive cyclesand the highest electricity demand for the ventilators.• The lowest overall electricity demand is shown by the2-cooling coils cycle and a reduction of electric con-sumption of about 34% in comparison to a conven-tional system (Fig. 9) is achieved.Finally, for the installation at the client building ofthe gas utility of the municipality of Palermo (AMG)the 2-cooling-coils configuration was selected, althoughthis configuration shows a higher regeneration heatdemand compared to the standard configuration.However, since the amount of waste heat from the co-generation system is far higher than the heat neededby the desiccant system, this is no limiting condition.4. Design of the complete systemAfter the design of the desiccant air handling unit thedesign of the complete system consisting of the co-gener-ation unit, the air handling unit, the compression chillerand the building related components has been made,Based on a detailed cooling load calculation it becameobvious that not all cooling loads can be covered by the air handing unit. Therefore a fan coil system is oper-ated in addition which is supplied with chilled waterfrom the compression chiller as well. A scheme of theoverall system is show in Fig. 11. Fig. 12 presents a pho-tograph of the system showing the air handling unitmounted outdoors and the hydraulic pipe network.During summer the co-generation system provideselectricity for the compression heat pump (indicatedEHP in Fig. 11) and for the other appliances (e.g. com-puters, artificial lighting, printers etc.) of the office rooms.The waste heat of the co-generation unit is used to heatthe regeneration air of the desiccant system. Excess heatcan be used for domestic hot water preparation (DHS)or is rejected to the environment by the excess water-to-air heat exchanger (EHX). An energy balance of thewhole system for the design case is shown in Table 3.It becomes clear that only a small part of the wasteheat of the co-generation unit can be used for air-condi- tioning purposes. However, it has to be noted that thisbalance is valid for the design case with a very high cool-ing demand. At most time the cooling demand is farlower and consequently the fraction of useful exploita-tion of waste heat is higher.During winter waste heat is directly used for heatingusing the fan-coils as well as the air handling unit.5. System simulationIn order to be able to calculate an energy balance ofthe entire system for a whole year a simulation model ofthe complete system has been set up. Goal of the simu-lation tool is also to investigate different control strate-gies and to develop a tool for design of similar systemsin the future.