In a nature reserve overlooking the Berounka river valley and the ancient Karlštejn Castle, Studio Circle Growth has designed Casa de Mi Luna: a family home that rethinks what sustainable living can be in a traditional context. Due to its location on the edge of the protected limestone landscape of Česky Kras, the project was required to meet traditional building requirements: symmetrical gable-roof, rounded eaves, traditional rounded clay tiles—bobrovka—and a mix of lime render and larch cladding for the facade.

Ecological strategy
Behind its vernacular exterior is an ecological strategy based in material intelligence and passive environmental performance. The building is constructed from prefabricated Ecococon straw and timber panels, a bio‑based wall system that combines structural capacity with insulation. These panels are factory‑made with tightly compressed straw inserted into a timber frame, which allows for rapid, dry assembly on site with minimal waste and high thermal efficiency—a significant ecological advantage over conventional timber‑frame plus synthetic insulation builds.

Inside, these panels were plastered with three centimetres of clay plaster, a material that regulates moisture and thermal accumulation, helping to stabilise indoor humidity and temperature without the use of energy-intensive mechanical systems. The final layer is a delicate white kaolin clay plaster on the inside and lime render on the outside. The partitions between rooms and the upper level’s walls have been completed with sheets of pine plywood. These complete a tactile, breathable interior that naturally mediates temperatures and acoustics.

Local material palette

The material palette for finishes is limited and local: dominated by wood and earth, with soft touches of traditional blue, green and terracotta půdovky tiles. “The main idea for the choice of materials was to use as many local and natural materials as possible,” explain the architects. Straw, wood, and clay—renewable and regional resources—form the primary fabric of the house, reducing transport emissions and embedding the build in the cultural landscape. Larch cladding, prized for its natural resistance to decay, and traditionally fired roof tiles further extend the building’s lifespan and minimise maintenance requirements.

Playful, open-plan design 

The interior of the home is playful and open, its ground floor combines a living, dining and kitchen area where the central feature is an emerald green tiled fireplace. From here, a segmented staircase curves up into the double-height space of the second floor landing, delineating the two zones of the ground floor while creating movement between them. Its design integrates function with the form of furniture  On the second floor two symmetrical rooms share a vast arched ceiling. Oriented east and west, these rooms maximise natural daylight and passive solar gain—a thoughtful climatic strategy that reduces reliance on artificial lighting.

Passive heating and cooling
The fireplace is evocative of the traditional stoves from the region, but serves more than an aesthetic purpose. These stoves have been used for centuries in the Czech Republic and surrounding regions, valued for both their ornate craftsmanship and their remarkable efficiency. Unlike conventional fireplaces, the heat from a tiled stove is not lost up the chimney. Instead, hot gases circulate through a network of internal flues within the masonry, gradually transferring warmth to the tiles and surrounding walls. This thermal mass stores heat and radiates it slowly over many hours, providing a consistent, comfortable indoor temperature long after the fire has burned down.

In Casa de Mi Luna, this principle has been adapted for contemporary passive heating. Water heated by the fireplace is stored in a tank and circulated through the walls, where the clay plaster acts as thermal mass, slowly releasing warmth throughout the house. This combination of traditional inspiration and modern engineering reduces reliance on mechanical heating systems to lower energy consumption and create an environmentally responsible, and necessarily cosy, family home.

Sensory experience, sustainable design

The design of Casa de Mi Luna demonstrates how bio‑based prefabrication, passive environmental systems and local materials can create a home that speaks to heritage in a genuinely sustainable way—using low tech design to lower energy demand, improve indoor environmental quality and reduce embodied carbon, all while offering a rich sensory experience of space.