Breathing Greenboxes

The Breathing Green-Box project proposes a passive design approach to renovate a kindergarten at 30 Tomino, reimagining educational spaces for young children through a low-carbon lens. The intervention introduces two transparent glazed structures—“green-boxes”—to bring nature, light, and ventilation into the heart of the building, while enhancing thermal insulation during winter. These green-boxes serve as multifunctional buffer zones that connect classrooms with gardens and improve spatial fluidity. The design strengthens environmental performance through greenhouse-inspired passive strategies, natural lighting, cross-ventilation, and envelope upgrades, contributing to more comfortable and energy-efficient learning spaces.

The Breathing Green-Box project explores passive design strategies in the renovation of a kindergarten located at 30 Tomino, rethinking educational spaces for children aged 0 to 6 through a low-carbon lens. The core intervention focuses on two transparent glazed structures—“green-boxes”—designed to take advantage of the greenhouse effect to enhance spatial and environmental performance.

The existing building, constructed in the 1970s, is situated within a dense cluster of high-rise blocks. Classrooms suffer from poor daylight conditions (Daylight Factor ~0.4–1.4%), weak thermal performance (H’t ~1.3 W/m²K), and inadequate ventilation (meeting only 50% of ventilation standards). Moreover, although adjacent to a large rear garden, the building offers limited visual and physical connection to nature.

The renovation strategy removes approximately 5.5% of the total building volume to create a sequence of alternating solid and void forms. Two garden courtyards are inserted between three classroom blocks, allowing daylight and vegetation to penetrate deep into the plan. Two transparent green-boxes are then introduced within the voids (5.5% total volume), forming multifunctional buffer zones that blend interior and exterior conditions.

These green-boxes serve as naturally lit, vegetation-filled interstitial spaces that foster fluid connections between classrooms and the garden. In addition, front-of-house areas are reprogrammed for community functions, enhancing the school’s integration with its urban surroundings.

From a performance perspective, the green-boxes passively reduce the heat transfer coefficient by approximately 30%. In winter, the greenhouse effect raises their internal temperature, limiting thermal losses from adjacent classrooms. In summer, they operate with openable panels to promote natural cross-ventilation and reduce overheating. As a result, daylight levels improve, and ventilation shifts from single-sided to cross-flow.

To further optimize energy performance, the roof structure is reoriented to face south, maximizing photovoltaic (PV) potential. The PV system, combined with heat pump technology, is designed to meet 100% of the heating and lighting energy demand. Simultaneously, the entire building envelope is retrofitted with fiber cement cladding and insulation, reducing the heat transfer coefficient by an additional 70%.

In conclusion, the Breathing Green-Box strategy offers a model for low-carbon school renovation, improving both learning spaces and energy efficiency.