Contemporary passive design relies on understanding climate and taking advantage of siting, form, detailing, and construction assemblies to create buildings that achieve design excellence while reducing the need for energy consuming equipment to provide comfort and health. Reducing the need for energy makes it possible to downsize HVAC equipment, shorten operating times and seasons, shorten duct runs and, in some cases, eliminate equipment entirely. Passive design can mean shifting first cost from equipment to improvements to the building enclosure. Passive design requires focusing on the architecture first, before supplementing with active systems.