Political and economical changes that have been started in Poland since 1989 strongly influenced the building construction market. New owners or managers of institutional buildings have begun the process of retrofitting, focusing on:
- reconstruction of building cover joined with exchange of windows and insulation of external barriers,
- modernization of technical equipment of building - introducing new low energy HVAC systems.
The main goal that has to be reached is to prevent the conditions of climate comfort (proper Indoor Air Quality) and to optimize total energy consumption of building. The paper presents the problems that can appear during realization of retrofitting process of VAC (Ventilation & Air Conditioning) systems in Polish hospitals.