What is surprising about Cold Air Distribution is not simply that a heat pump heats and cools a Passive House—it is how much of the conventional HVAC system the right heat pump can make unnecessary. The Ecoforest R290 air-to-water heat pump can produce approximately 2°C chilled water for cold-air cooling, provide space heating, and generate domestic hot water above 65°C. This unusually broad operating range allows ventilation air already required for healthy indoor conditions to become the building’s heating and cooling distribution system. Instead of adding equipment, CAD asks how much can be removed. But the project is also designed to answer a bigger question: how much HVAC capacity do ultra-low-energy buildings actually need? Five Canadian pilot buildings are becoming living laboratories. For two years, heat meters, electrical circuit monitors, indoor and duct sensors, airflow operating data and on-site weather stations will measure what is happening inside the buildings, how the systems respond, and the real outdoor conditions driving those loads. This creates something still lacking in Canada: detailed real-world data connecting weather, occupancy-related internal loads, HVAC operation and actual heating and cooling loads in Passive House buildings. This project therefore combines heat-pump innovation with evidence—not just demonstrating a new system, but generating the knowledge needed to design simpler, smaller and more affordable heat-pump-based mechanical systems at scale.