The article analyzes the light-spatial composition of a number of Greek Catholic churches of the Ukrainian diaspora designed and built by the famous Canadian architect Radoslav Zhuk. A set of rules and principles used by the architect to create a sacred atmosphere in the interior space of church buildings by means of natural light is established. In general, the light-space composition studied of eight churches built by Radoslav Zhuk in the second half of the 20th century. These are Greek Catholic churches in Canada and the United States built between 1964 and 1968: St. Joseph's Church and Holy Family Church in Winnipeg, Canada; Church of the Blessed Eucharist in Toronto; Church of the Holy Cross in Thunder Bay. Later, in the 70s, according to R. Zhuk's designs, the following build: Holy Trinity Church in Kerhonkson, New York, USA; St. Josaphat Church, Rochester, New York, USA; St. Stephen's Church, Calgary, Canada.
The spatial structure of the first churches built by the architect in Canada is a combination of horizontal rectangular volumes with vertical ones, which carry the main semantic and figurative load. The lighting composition in the interior of the churches is similar in terms of brightness distribution to modern Catholic churches, where the space and surfaces of the sanctuary are the most illuminated. It turned out that in the architectonics of these churches, the architect uses large stained-glass windows in the wall above the main entrance, as well as in the domes and towers above the sanctuary. This creates a high level of natural light in these parts of the prayer hall. The nave itself less lit through narrow and high windows in the walls. This nature of natural light creates a mystical atmosphere. From the area of lesser illumination, people's eyes drawn to the sacred space of the sanctuary, where the sacrament of the Eucharist is celebrated.
In the churches built in the 1970s, a different interpretation of natural light appears. The architect emphasizes the play of light and shadow on vertical tectonic roof surfaces in towers of different heights and spaces under domes. A favorite technique of the architect is the use of horizontal strips of low windows between the walls of the church and the roof. The closest to the Ukrainian tradition in Zhuk's work is the light composition of the Church of the Nativity of the Blessed Virgin Mary, built in Lviv in 2002.