A building construction having a curtain wall construction defined by an interior wall surface including one or more framing members (2, 3) and at least one floor spatially disposed from the interior wall surface of the curtain wall construction defining the safing slot extending between the interior wall surface of the curtain wall construction and an outer edge of the floor, comprising a dynamic, thermally insulating and sealing system for effectively thermally insulating and sealing of the safing slot, comprising: i) a first element comprised of a non-combustible material for receiving a thermally resistant material for insulating, ii) a second element comprised of a thermally resistant material for insulating, wherein the second element includes: a) an outer primary end surface positionable in abutment with respect to the inner surface of the first element; b) an inner primary end surface positionable spatially disposed from the outer edge of the floor for sealing thereadjacent; and c) a lower primary and an upper primary surface extending between the opposing edges of the first element, iii) a third element comprised of a thermally resistant material for insulating positioned in the safing slot, wherein the third element includes: a) an inner primary end surface positionable in abutment with respect to the outer edge of the floor for sealing thereadjacent; b) an outer primary end surface positionable in abutment with respect to the inner primary end surface of the second element and spatially disposed from the inner surface of the first element; and c) a lower primary and an upper primary surface extending between the opposing edges of the first element, characterized in that the first element is comprised of a plate having opposing edges and an inner and an outer surface, wherein the plate is recessed at least 5,08 cm (2 inch) from an inner side of the vertical framing member and extending at least 12,7 cm (5 inch) below the vertical framing member; at least one supplemental element for attaching of the first element with respect to at least one side of the horizontal and/or vertical framing member (2, 3) of the curtain wall construction to ensure form closure. i) a first element comprised of a non-combustible material for receiving a thermally resistant material for insulating, ii) a second element comprised of a thermally resistant material for insulating, wherein the second element includes: a) an outer primary end surface positionable in abutment with respect to the inner surface of the first element; b) an inner primary end surface positionable spatially disposed from the outer edge of the floor for sealing thereadjacent; and c) a lower primary and an upper primary surface extending between the opposing edges of the first element, a) an outer primary end surface positionable in abutment with respect to the inner surface of the first element; b) an inner primary end surface positionable spatially disposed from the outer edge of the floor for sealing thereadjacent; and c) a lower primary and an upper primary surface extending between the opposing edges of the first element, iii) a third element comprised of a thermally resistant material for insulating positioned in the safing slot, wherein the third element includes: a) an inner primary end surface positionable in abutment with respect to the outer edge of the floor for sealing thereadjacent; b) an outer primary end surface positionable in abutment with respect to the inner primary end surface of the second element and spatially disposed from the inner surface of the first element; and c) a lower primary and an upper primary surface extending between the opposing edges of the first element, characterized in that the first element is comprised of a plate having opposing edges and an inner and an outer surface, wherein the plate is recessed at least 5,08 cm (2 inch) from an inner side of the vertical framing member and extending at least 12,7 cm (5 inch) below the vertical framing member; a) an inner primary end surface positionable in abutment with respect to the outer edge of the floor for sealing thereadjacent; b) an outer primary end surface positionable in abutment with respect to the inner primary end surface of the second element and spatially disposed from the inner surface of the first element; and c) a lower primary and an upper primary surface extending between the opposing edges of the first element,