Temporary shelters are extensively used by emergency services (rescue, disaster relief, military response) and other end-users requiring temporary mobile power solutions for differ-ent purposes (event organization, vacation homes, summer camps, etc.). The Covid-19 pan-demics resulted in an increase of motor homes worldwide sales. When temporary shelter connection to power grid is impossible, the off-grid liquid fossil fuel generator can be used for electricity generation. Since the liquid fuel supply is often lim-ited, the stock of fuel requires storage that may pose an explosion risk. Quickly installable and energy-efficient ventilation / cooling system with heat recovery is essential to ensure adequate air hygiene and occupants’ comfort in temporary structure. This paper presents a mobile modular electric energy generating unit with photovoltaic (PV) panels for providing temporary shelters (tents) in Latvian climate conditions with heat-ing, ventilation, and air conditioning (HVAC). All calculations were performed using the com-puter model developed with TRNSYS tool and based on real data from mobile modular energy unit for spring, summer and autumn 2020 and winter 2021. The results show that mobile modular energy unit can be successfully applied for off-grid HVAC system operation of tem-porary shelters in the Latvian climate conditions.