SIEMENS

Denver International Airport is a majestic facility. The roof of its passenger terminal is adorned with 34 pinnacles made of translucent Teflon as a tribute to the nearby Rocky Mountains. With 51 million passengers in 2008, the airport is one of the world’s busiest. Its passenger traffic is the 11th-highest in the world, and its number of flights is the fifth-highest. Its complex infrastructure also makes it a huge consumer of energy, as it required 216 mill. kWh of electricity in 2007, or more than 4 kWh per passenger.
In early 2008, the airport’s operating company therefore asked Siemens’ Building Technologies (BT) division to draw up concepts designed to cut airport energy use. In mid-2009 BT released a study offering optimization proposals aimed at reducing the airport’s overall natural gas demand by 10 % and electricity consumption by 12 %. For its study, BT examined the terminal, waiting halls, and office and equipment buildings. Along with energy-saving considerations, the study also took into account the impact the proposed measures would have on the environment, operating capacity, and passenger comfort.
The study produced a total of 26 proposals, the most effective of which involve measures that would address heating, cooling, ventilation, lighting, and baggage transport systems, which together account for more than 80 % of total energy consumption. "Naturally, airports are looking to achieve extensive savings in terms of not only costs but also energy consumption and carbon dioxide emissions — and to do so as simply as possible and at a low level of investment," says Uwe Karl, head of Airport Solutions at BT. There are also more expensive measures, such as the use of alternative energy generation systems that would immediately result in a high CO₂ reduction but would pay for themselves only after a long period. To help the airport operator with its decisions, the study lists the cost of each individual measure, as well as the associated energy reduction and its amortization period.
A good example of how to achieve a major effect at relatively low cost is offered by systems that control terminal ventilation in line with utilization. The installation of these systems, which employ CO₂ sensors and intelligent ventilation control units, would cost $215,000 — but would lead to annual energy-cost savings of $425,000. Such an investment would thus pays for itself after only six months. Another relatively simple way to save energy is to install energy-saving lamps and LED lighting systems. Lights in the passenger terminal at Denver International are left on 18 hours a day, seven days a week; those in the parking garages and on the runways and apron burn even longer. Use of energy-efficient lighting systems could reduce electricity consumption by more than 11 mill. kWh per year, which, given the U.S. energy mix, corresponds to around 10,000 t of CO₂.
Another measure involves the provision of heat and hot water using biomass, which can cover all requirements in the summer and serve as a supplementary energy source in the winter. Installation costs for such a system would total approximately $3.5 million, while energy savings would add up to almost $500,000 per year, with an associated CO₂ reduction of around 7,000 t p.a.
After conducting a detailed analysis of the proposals, the Denver International Airport operating company will decide which measures it will implement, and at which times. The fact is that airports need to take steps to increase their energy efficiency, since their complex infrastructures make them major energy consumers. After all, thousands of airports around the world are used by billions of passengers and airport employees every year. In addition, studies conducted by the Airports Council International (ACI), the International Air Transport Association (IATA), and the International Civil Aviation Organization (ICAO) show that passenger volumes are rising at a consistent average rate of between 3.5 and 5.8 % per year.

IT Solution for Energy-Hungry Systems. "Our energy-saving measures are implemented in three areas," says Karl. The first area involves finding out which devices can be turned off or modernized, as old machines are often the biggest energy wasters. It therefore makes sense at any airport to use energy-saving lamps that operate in accordance with ambient light conditions and utilization requirements. "In many cases you’re dealing with just one main switch for all the lights," says Karl. "But if you optimize lighting systems to function in line with ambient light conditions and the utilization of specific areas, you can cut costs substantially."
The second area addresses the use of renewable energy sources such as wind, biomass/biogas, geothermal sources, and fuel cells. "Here, decisions have to be made based on individual circumstances," says Karl. Denver’s airport covers almost 140 square kilometers, for example, making it by far the largest in the U.S. in terms of area; so it makes sense to consider the use of biomass/biogas and wind energy." The Siemens study thus proposes such measures as well.
The third area focuses on solutions in the fields of power generation, alternative energy, baggage and freight logistics, IT services, and building technologies. The goal here is to manage the many energy-hungry systems in use with the help of intelligent IT solutions aligned with airport processes, and to regularly monitor and compare energy consumption over time. "Many airports have distributed and independent systems, however, which makes it difficult to gain a good overview," Karl explains. Here as well, the key is to implement intelligent controls that eliminate the problem of constant energy consumption.

Investments that Pay for Themselves. The comprehensive analysis of energy consumption patterns at an airport forms the basis for the generation and implementation of energy- saving measures by specialists. This is the approach being taken at Detroit Airport, where Siemens has been serving as an "energy manager" since 2001 within the framework of a multi-stage project. "Our objective here is to increase the comfort and safety of existing systems and reduce energy and maintenance costs — and to do so with as little expenditure as possible," says Karl. The airport operator therefore sought out a company that had the comprehensive expertise that was necessary and could also offer energy performance contracting. With this form of financing, the vendor contractually guarantees the savings, decides which measures will be implemented, and finances them. In return, the saved energy costs are paid to the vendor until its expenses for financing, planning, and monitoring are paid in full.
With energy performance contracting, the customer doesn’t have to spend any of its own money, but benefits from the savings once the investment has been paid off. The operator of Detroit Airport assessed numerous energy service companies, and two remained in the running following the call for bids. Siemens offered the lowest price and guaranteed the greatest energy savings — and was awarded the contract. "Our systems are like a puzzle; each piece is dependent on the others so that the system functions as a whole," says Len Cranston, who runs the Detroit airport’s machinery center. "Siemens had to serve as the general contractor, decide for itself which optimizations were necessary, and then provide the entire scope of services within the defined timeframe and on budget."
BT experts identified the central heating and cooling system with its 30-year-old, 2,000-t compressors as the airport’s biggest electricity consumers. They were replaced with steam turbine-driven centrifugal chillers, which use less energy and are easier to maintain. The boiler was modernized so as to maintain constant high temperature. Pumps, lines, and flow sensors were also replaced. The control equipment, which was so old that it was no longer possible to get parts for it, was completely replaced. A new computer control system is the new nerve center of the system. In addition, the lighting systems were modernized and numerous smaller measures were implemented. The cost of the complete energy- saving project totaled $15 million. The project reduces energy costs by 23 % each year, which corresponds to an impressive $2 million in savings.
Siemens has also been working on an energy-saving project at Seattle Airport since 2003. In addition to modernizing the lighting system, the project focuses primarily on upgrading the airport’s 30-year-old heating, ventilation, and air conditioning systems. Overall electricity consumption in Seattle has been reduced by 4 % and natural gas consumption by 8 %.