The story behind the
world's first dual thermostat

Around 1922, when the chief custodian of New York City Schools – a longtime Johnson Controls customer – noticed how much energy was being wasted on empty classrooms, he knew something had to be done. James Gallagher faced a challenge that still feels familiar: heating spaces that no one was using. He realized how much fuel was being wasted by heating unoccupied rooms at Public School #138 in Brooklyn. His vision: a dual thermostat that automatically lowered temperatures in empty rooms, cutting costs and increasing efficiency.

Johnson Controls took notice.

After acquiring the patent from Mr. Gallagher and improving upon some of the finer points, the dual thermostat became a game changer. With the Great Depression right around the corner, which encouraged building owners to save fuel by any means possible, it was an idea whose time had come.

The biggest thermostat development since its invention

Why it mattered then – and still does:

• Smart control: two-temperature thermostat with a central switchboard
• Efficient design: single air compressor and diaphragm-operated valve for each unit
• Automatic savings: air pressure adjustments dropped the control point from 70° to 55° Fahrenheit during unoccupied periods

It was a turning point for the HVAC industry, paving the way for future advancements like the heating-cooling thermostat. But for us, it just another highlight in a long history of world-changing progress.

The evolution of dual thermostat innovation

The same spirit that paved the way for the world’s dual thermostat made its presence felt in 1990 when we introduced Metasys – an open building automation system that set a new industry standard for scalability, resiliency and energy intelligence. More than 25 years later, it remains our flagship building management system (BMS) that’s engineered to meet the demands of mission-critical environments – particularly with the launch of Metasys 15.0.

What you need to know about Metasys 15.0

As a powerful leap forward with smarter tools, faster workflows and deeper insights, Metasys 15.0 delivers the advantages that facility managers need:

• Seamless expansion, supporting 1,000 IP devices per server - 60% more than comparable systems - while reducing infrastructure costs up to 60%
• 24/7 data resilience with new multi-server redundancy
• Ready-to-use Energy Management suite with three-click access to insights
• The industry’s fastest configuration time, reducing equipment setup time by nearly 95% and no need for server shutdowns
• True openness, with support for a wide range of third-party protocols

Whether you’re responsible for a single facility or a sprawling campus, we can help you transform your building from a static entity to a strategic asset. With a global portfolio of proven solutions that range from HVAC, security, automation and beyond, we’re ready to help power your mission.