Located in Sofia's Lozenets neighborhood—one of the city's most desirable areas—Z40 emerges in a complex and diverse context. The environment is composed of different periods, scales, and architectural languages. The project responds to this heterogeneity with clarity, restraint, and quiet elegance, using a disciplined composition to bring order and balance.
Z40 is based on the idea that character can be expressed through moderation. The concept avoids unnecessary embellishments, which lends it a sense of purity and enduring presence. The building seeks a balance between urban clarity and residential intimacy—a calm, well-organized environment for everyday life.
This logic is realized through a process of "carving" and layering. The volume is divided into two bodies, placed one on top of the other, with a slight inward offset. In combination with the green roof, this reduces the visual mass and softens the silhouette. The openings are emphasized with thin protruding frames that add fine detail and depth. The material palette—pale tactile cladding and dark window profiles—emphasizes the clarity of form and allows light to be the primary tool. The details show that complexity is not added from the outside but is extracted from a consistent whole.
Z40 demonstrates how contemporary design can be expressive without excess. Up close, the façade reveals depth and precision, while from a distance it remains calm and legible. The project shows how proportions, materials, and attention to detail can enhance the quality of the living environment—and establish elegance and durability as the norm rather than the exception.

Client: Shalev Investment Group Ltd.
Program: Residential building
Location: Sofia, Bulgaria
Build up area: 3 413 sq.m
Design year: 2018
Redesign year: 2026