We treat design as impact, not decoration. We believe the best buildings start with a clear idea, tested against real constraints, then carried through without losing the thread. We work closely with clients, consultants, and local partners, and stay hands-on so decisions stay clear.

The aim is simple, make buildings that perform, and that people actually want to be in.

WE ARE KOSY

KOSY is Sydney-based and led, with Nordic roots and international experience. The studio brings concept discipline and practical decision-making to projects across scales, grounded in real constraints, approvals, budget, programme, and climate.

Founded during the 2020 lockdown, KOSY began as a collaboration between former colleagues in Copenhagen and Sydney. KOSY in Australia is led by Sebastian Grøgaard as Principal, working with a small core team, collaboration partners and bringing in trusted specialists when needed. 

Sebastian grew up in Norway and brings a Nordic emphasis on clear organising ideas, design informed by constraints and disciplined project development.

His background includes senior project leadership roles at BIG (Bjarke Ingels Group), 3XN, and Snøhetta across New York and Sydney, and he currently leads the High Performance Technology Master of Architecture graduation studio at the University of New South Wales (UNSW), tackling themes such as urban density, adaptive reuse, climate, and performance in architecture.

APPROACH

KOSY balances blue-sky thinking with pragmatic delivery. The studio starts with a clear idea, then tests it early against approvals, buildability, programme, cost, and climate, so intent survives delivery. The work is collaborative by default, shaped with clients, consultants, and specialist collaborators from day one, and anchored in human comfort, daylight, shade, ventilation, acoustics, and the everyday life of the building. KOSY stays small by default, with Principal-led accountability throughout.

REUSE FIRST

Start with existing fabric and constraints, and treat them as design drivers from day one.

PRACTICAL OPTIMISM

Pressure-test ideas early against approvals, buildability, programme, and cost, so design intent survives delivery.

HUMAN COMFORT

Design for daylight, shade, ventilation, acoustics, and how the building is used day to day.

SELECT COMMISSIONS AND RECOGNITION

Abarca Headquarters, San Juan, Puerto Rico
12-storey workplace, completed.

Marine Business Research and Innovation Center (MBRIC), Ceiba, Puerto Rico
3,200 m² research hub for the Caribbean blue economy. In delivery.

MBRIC has been recognised with the American Institute of Architects (AIA) Puerto Rico Honor Award for Unbuilt Design (2025) and the Colegio de Arquitectos y Arquitectos Paisajistas de Puerto Rico (CAAPR) Biennale Award, Unbuilt Project of the Year (2025).
 

SERVICES

Building design
Interior design
Workplace and commercial fit-out, refurbishment, and upgrade
Concept design through documentation support
Feasibility studies and client guidance

CONTACT

If you'd like to get in touch about a project or just say hello, please reach out via the channels here.