Using energy efficiently, preventing waste, and utilizing eco-friendly (raw) materials are seemingly small things, but taken together they have a big impact when it comes to sustainable print production. Heidelberger Druckmaschinen AG (Heidelberg) is systematically working on solutions that, in addition to reducing waste - the primary factor in improving sustainability - also boost energy efficiency. One such solution is the new-generation CombiStar, which is now available. This combination unit conditions the dampening solution and ensures constant inking unit temperature control. It is now equipped with more energy-efficient pumps and electronically controlled compressors that cut energy costs by up to 50 percent. Units such as the CombiStar are the third-highest consumer of electricity in a press after the main motor and the air supply system. In the case of presses with dryers, they occupy fourth place. In the new CombiStar, the inking unit pump for temperature control circulation is fitted with an electronically controlled drive and the refrigerating units now have an energy-efficient digital scroll compressor. Stepless adjustment of the refrigerating units to the cooling capacity required by the machine significantly boosts the system's efficiency. 

Annual reduction in CO 2 of up to eight metric tons in field test 
The field test of the new energy-efficient CombiStar generation at Häuser KG went extremely well. Based in Cologne, this company with its own online print portal -Druckdiscount24.de - is currently one of the largest sheetfed offset print shops in the German region of North Rhine-Westphalia. Its workforce has increased from just 20 in 2000 to more than 200 today. Web-based business currently accounts for some 80 percent of sales. The Heidelberg equipment in operation at the full-service print shop includes three Speedmaster XL 105-8-P presses with simultaneous plate changing and Prinect Inpress Control, and two Speedmaster SM 52 four-color Anicolor presses, while the comprehensive postpress equipment includes four Polar 137 XT high-speed cutters and two Stahlfolder KH 78 KTL folding machines. 

It was easy to compare the electricity consumption at Häuser, because all the Speedmaster XL 105-8-P presses at the print shop process roughly the same job spectrum and each press completes around 60 job changes per day. A CombiStar cabinet from the previous generation and a cabinet with the energy-efficient design of the new generation were fitted with electricity meters and the electricity consumption was recorded over a period of ten months. "The energy-efficient CombiStar used 34 percent less power than the older CombiStar unit," says a delighted Heiko Mazur, owner and managing director of Häuser KG. "Calculated over an entire year, this adds up to energy savings of 15,000 kWh. Based on the total electricity consumption of all the presses, which amounted to 250,000 kWh, this represents a saving of no less than six percent," he adds. The Häuser print shop switched over completely to green electricity in January 2013. Had it been using the standard German energy mix, it would therefore have achieved an annual reduction in CO 2 of up to eight metric tons. 

CombiStar Pro also offers free-cooling technology for further energy savings 
The water-cooled presses at Häuser are connected to a central free-cooling system. This means that the low temperature of the outdoor air is used directly for cooling as long as it does not rise above around 20°C. Consequently, the refrigerating unit is only needed for inking unit temperature control in the warmer months. 

The free-cooling function can optionally be integrated directly into the equipment cabinet of the CombiStar Pro from Heidelberg. If outdoor temperatures rise above 15°C, the active refrigerating unit is switched on in stages to assist cooling. From approximately 20°C, it provides 100 percent of the cooling capacity required. If the outdoor temperature drops, the active refrigerating unit is deactivated in stages. The efficiency of this system thus depends on the outdoor temperature, the design of the recooler - the bigger the better - and the temperature specified in the inking unit. 

The CombiStar Pro is also equipped with the Digidos unit for high-precision metering of dampening solution additive and a device to measure the conductivity of the process water. This means the quality of the dampening solution and the fresh water can be evaluated.