The Fern Passivhaus Apartments comprises 11 one-bed apartments and is the first in the Southern Hemisphere built to the rigorous Passivhaus standard. The Fern achieves passive house principles of stringent air tightness, continuous unbroken insulation, high-performance glazing, structural thermal breaks, and heat recovery ventilation. Full-height triple-glazed sliding doors with flush seals lead onto generous balconies and gardens for the best indoor-outdoor living. All apartments benefit from the natural light and view in the common atrium, which greets visitors on entry with two 15m-high green walls, acting as a rainforest valley in the heart of the city.  Heat recovery ventilation (HRV) works continuously to replace stale air in the apartments with fresh outdoor air, which is first filtered and then passed through a heat exchanger to maintain a comfortable indoor temperature in an energy-efficient way.  The Fern is carbon neutral and highly energy efficient, thanks to the passive house design principles employed throughout. The apartments received NatHERS ratings ranging from 9.3 to 10 stars out of 10.  Triple-glazed, argon-filled, thermally broken windows and sliding doors which incorporate custom seals and a lift-and-slide opening mechanism create a perfect air lock. A 21kW solar photovoltaic array on the roof ensures the apartments will enjoy a fossil-fuel and carbon-neutral power supply. The Fern has a smart microgrid that will allow the residents to be self-sufficient in electricity, but also have the flexibility to connect back to the larger grid. Each apartment has individual metering of electricity and hot water used, so that the residents only pay for what they use. Insulation at The Fern is roughly double the insulation level typically used in Sydney apartments, and is installed as a continuous barrier rather than between structural elements. This eliminates thermal bridges and acts as a blanket to cocoon the living spaces. The roof is R7.0, walls are R3.5, and floors are R1.5.  The Fern is a worthy winner of the 2020 Excellence in Energy Efficiency Awards – Medium Density Housing.