In order to reduce heat demand, the America Memorial Library (AGB) will be held from 1st to 5th. OG provided the external walls with an internal insulation and the windows energetically refurbished. The energy source for the production of heating heat is switched from gas to district heating, the entire heat distribution is renewed for the purpose of switching from a single-tube system to a two-pipe system. In combination with the conversion of lighting to LED, CO2eq emissions are significantly reduced and thus a contribution to climate protection.