oBIX (for Open Building Information Exchange) is a standard for RESTful Web Services-based interfaces to building control systems. oBIX is about reading and writing data over a network of devices using XML and URIs, within a framework specifically designed for building automation.

Building control systems include those electrical and mechanical systems that operate inside a building, including Heating and Cooling (HVAC), Security, Power Management, and Life/Safety Alarms that are in nearly all buildings as well as the myriad of special purpose systems that may be tied to particular buildings such as A/V Event Management, Theatre Lighting, Medical Gas Distribution, Fume Hoods, and many others.

oBIX is a web services interface because it does not necessarily allow deep interactions with the underlying control systems. This interface can enable communications between enterprise applications and embedded building systems as well as between two embedded building systems. Facilities and their operations to be managed as full participants in knowledge-based businesses.

oBIX is being developed within OASIS[1], the Organization for the Advancement of Structured Information Standards. Version 1.0 was completed as a committee standard in December 2006.

Presently most mechanical and electrical systems are provided with embedded digital controls (DDC). Most of these devices are low cost and not enabled for TCP/IP. They are installed with dedicated communications wiring. Larger DDC controllers provide network communications for these dedicated controllers. There are many well established binary protocols (BACnet, LonTalk, Modbus, DALI) that are used on these dedicated networks in addition to numerous proprietary protocols. While these binary protocols can be used over TCP/IP networks - they have challenges with routers, firewalls, security, and compatibility with other network applications. There is an added challenge in that the industry is split between several largely incompatible protocols.

Because oBIX integrates with the enterprise, it enables mechanical and electrical control systems to provide continuous visibility of operational status and performance. By exposing these operations using web services, it enables owners and tenants to use the full array of standard databases and OLAP tools to analyse their performance. oBIX enables facilities operators, owners and tenants to make decisions based on a fully integrated consideration of all life-cycle, environmental, cost, and performance factors.^{[citation needed]}

oBIX provides a publicly available web services interface specification that can be used to obtain data in a simple and secure manner from HVAC, access control, utilities, and other building automation systems, and to provide data exchange between facility systems and enterprise applications. Release 1 provides a normalized representation for three of elements common to control systems:

oBIX 1.0 provides a low level object model which can be extended during implementation. While points are directly addressable (and thereby settable), direct interaction with the points requires too much knowledge of the underlying control system for the enterprise developer. The underlying points can be aggregated, the results named, alarm levels set, and histories begun using the oBIX contract. If oBIX exposes a low level object model for control systems, oBIX contracts create the higher level type libraries that most programmers actually want to work with.