Nathan Rothman, CEO of Optimum Energy, says the best way to think about air conditioning is in terms of tons.

An average building might require 1 to 1.4 kilowatts of energy to chill a ton of water for its air conditioning system. A building made to LEED platinum specs might require 0.7 per ton. Rothman says Optimum can reduce it to 0.5 kilowatts per ton.

In practice, that adds up to big money. A customer with a 250,000 square foot office building cut power consumption by 500,000 kilowatt hours a year, he said. The system costs around $500,000 but with a $105,000 utility rebate, the payoff will come in under three years.

One of Optimum's systems, destined for Adobe's headquarters in San Jose, will shed 750,000 kilowatt hours off of the building's annual load. Air conditioner power can be both cut for office space and data centers.

"There are 150,000 buildings that meet our criteria," he said. If the software were implanted in each one, 75 gigawatts could be taken off the grid, he asserted. (Rothman, by the way, has a long and colorful business history. He owned a hippie clothing store in the 1960s, a restaurant in Soho, championed a yacht builder and erected manufacturing facilities before this.)

Building controls and heating/air conditioning systems are destined to gain prominence in the next few years. The focus in the energy debate has shifted from green energy production to efficiency for a  host of reasons: It's cheaper; it doesn't require Nobel-quality breakthroughs; President Obama and Energy Secretary Chu have been big efficiency proponents for years; stimulus money is flowing into it.

Large skyscrapers are also arguably primordial energy hogs. Building operations consume 39 percent of the energy in the U.S. and HVAC takes 40 percent to 60 percent of that totall, according to studies from the Department of Energy. That means HVAC accounts for 16 percent of the energy consumption in the U.S. Commercial buildings themselves account for 18 percent of energy consumption. (There is 75 billion square feet of commercial floor space in the U.S. in case you wondered.)

And, although building management companies such as Johnson Controls and Honeywell have continually advanced the efficiency of their products, the design and operation of buildings, proprietary nature of the industry, the aged install base and other factors leave a lot of room for improvement.

So how does Optimum's system work? The company effectively has devised a software-as-a-service system that monitors and controls the chilling systems, which provide the water for air conditioners in large buildings. Control systems for water chilling have existed for years, but often go for overkill. The systems are geared towards keeping the water at a relatively steady 44 degrees, and they keep the flow rate about the same. That means on moderately warm days, more cool air is produced than is required, leading to super chilly rooms or ejected cold air.

"They still make that 44 degree water and dump that cold air," he said.

The equipment for chilling air is pretty sizeable. A big chiller in the basement of a large building might be powered by a 1,000 horsepower motor "That's equivalent to a locomotive," he said. It will then be supplemented by two 500 horsepower motors for fans and other equipment.

In Optimum's system, the water temperature can rise without impacting the temperature inside the building.  Depending on environmental conditions and occupancy, the software can reduce the number of pieces in operation at any given time and also reduce the power going to the machinery in operation. Trend data is also collected, which can be used to anticipate equipment failure. 

The water temperature is ultimately set by an algorithm that analyzes current data on pressure, flow, ambient termperature, water temperature, occupancy, history and other factors.

Although the company makes a hardware nodule for tapping into an existing building control system and occupancy sensors, Optimum makes it money through software.

Over the next few years, expect to see overlapping competition and collaboration between both established (Johnson, Siemens) and emerging (Cimetrics, Tririga) players. Alliances between building control companies and demand response providers with EnerNoc will also likely emerge, Rothman said.

The software, he added, can also add up to several LEED points to a building, in terms of water and energy reduction.

Join industry leaders and influencers at Greentech Media's Green Building Summit in Menlo Park, Calif., June 11.