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Air & comfort·designed

Hybrid & Natural Ventilation

Why it matters

Buildings breathed for millennia without a single fan: warm air rises, cool air follows. A well-shaped building turns that physics into a permanent, silent, electricity-free air supply. Mechanical ventilation then added the guarantee stack effect lacks: rates guaranteed in all weather. The price is fans running around the clock. The hybrid approach refuses the either/or: nature ventilates whenever it can, machines take over only when the physics falls short, and sensors make the call. The prize is air quality without the energy bill, and resilience that keeps a building breathable through any blackout. There is also something subtler that fully sealed buildings lose: the felt connection between indoors and the weather.

Role in 001's holistic picture

Hybrid ventilation sits between its siblings: HRV owns the deep-winter regime (when opening a window means pouring heat away), and night flushing is natural ventilation moonlighting as a cooling system. Its passive paths are shaped by the same solar geometry that orients the building. The switching logic itself belongs to the building's brain, and the payoff is measured in Indoor Environmental Quality.

In the world

Natural ventilation runs on two engines: stack effect (warm air rising through a vertical path between a low intake and a high exhaust) and wind pressure across facades. Hybrid design adds intake that pre-tempers the air, openings that automation can actuate, and honest sensing (CO₂ as the true occupancy signal, temperature and humidity as the comfort bounds). Minute by minute it decides whether nature or the machine is on duty. This sensor-driven pattern is thoroughly commonplace. The Danish firm WindowMaster documents 75 such projects across 11 countries: motorized windows opened and closed by CO₂, temperature, wind and humidity. They are deployed on ordinary campuses and colleges, far from icon buildings. And the pattern now reaches household scale: VELUX ACTIVE with NETATMO is a consumer kit that opens VELUX roof windows on indoor CO₂, humidity and temperature plus the weather forecast. The same logic, sold in a box.

How 001 engages with it

The Hlibivka design made ventilation architecturally visible: each module's form carries a passive path with over three metres of vertical rise, intake low on the cool northern face and exhaust high on the warm southern one. The stack effect is worked into the building's cross-section from the start, with mechanical support specified as the hybrid partner for demand peaks.

At Unity Hub the hybrid split is drawn in numbers. Mechanical ventilation is sized for the honest average — roughly 1,500–1,800 m³/h. That carries a typical day on its own. Warm-season peaks reach a designed ~2,800 m³/h: a full event and a full yoga session falling on the same afternoon. Opening windows handle them. So the design does without a fan bank oversized for a load that arrives a few times a year. In the published cooling concept natural ventilation works hardest of all the Unity Hub regimes: VELUX roof windows on chain actuators open automatically after dark. They flush the day's heat out through the same glass it entered and pre-cool the CLT mass for morning. The same windows work the day shift: when CO₂ climbs past its setpoint the upper glazing of the 277 m³ dome opens. The yoga hall drives its own stack effect while the lecture hall cross-ventilates. A rain sensor closes everything when the weather turns. Machines carry the base, physics carries the peaks, and the sensors decide minute by minute which is on duty.

Maturity: designed. Architecturally integrated at Hlibivka; the mechanical-plus-windows split and automated night ventilation are design values from the accepted, published Unity Hub concept.

Further reading