UrbanEden’s heating, cooling, and ventilation systems are designed to maximize comfort with minimal energy usage. We started by focusing on the benefits of passive strategies that use no energy, augmenting them with innovation such as a movable PV array that doubles as a shading device. Next, we developed and implemented hybrid strategies that are active (use energy) to create comfort, but do so in support of a passive mechanism. Pumping liquid to roof mounted heat exchangers to allow passive radiant heat transfer to the night sky is an example. Finally, we met our small remaining heating, cooling, and ventilation loads with the highest efficiency active systems available.