TECOGEN'S CHILLERS DEMONSTRATE ULTRALOW EMISSIONS IN INDEPENDENT TESTING Natural Gas-powered Air-conditioners Show Significant Reduction in Air Pollutants and "Greenhouse" Gases WALTHAM, Mass., July 23, 2001 - Tecogen, a leading manufacturer of commercial and industrial natural gas-powered air-conditioners, today announced the results of an independent emissions-testing study recently performed in California. Ten of the company's TECOCHILL® systems, which provide cooling for a high school in the Sanger Unified School District, were tested. All ten performed well within the air pollution standards of the San Joaquin Valley Unified Air Pollution Control District (SJVAPCD) in which the systems are located. For example, the average NOx (oxides of nitrogen) emissions for the Tecogen units were about 3 ppm, less than 10 percent of the local standard. AIRx Testing, an independent compliance laboratory, performed the tests. Not only were the Tecogen emissions well within SJVAPCD standards, they also fell well within the limits established by the South Coast Air Quality Management District (AQMD) - limits that are widely recognized as the strictest in the country. "In addition to reducing NOx and carbon monoxide emissions, our natural-gas driven chillers can also reduce the amount of so-called 'greenhouse' gases being released into the atmosphere every day," said Bob Panora, president of Tecogen. "In fact, compared with an electric air-conditioner that produces the same amount of cooling from electricity supplied by the utility grid, our systems cut CO2 [carbon dioxide] emissions by as much as 60 percent. Even though these greenhouse gases are not yet regulated, it's critical to try and reduce these emissions in order to slow the global warming trend. And clearly, there are no limits as to where we can site these systems - we've already demonstrated that our engines are clean enough to meet the strictest air quality standards in the nation." The TECOCHILL units, which run on natural gas to provide an energy-efficient alternative to electric-based air-conditioning, operate at a high school in California's Sanger Unified School District. Located in California's Central Valley 20 miles southeast of Fresno, the city of Sanger frequently experiences outside ambient temperatures above 100 degrees Fahrenheit. Tecogen's chillers allow commercial and industrial customers to significantly reduce their energy costs by running on natural gas, which is readily available during the summer months when demand for heating is low, but demand for air conditioning is at its highest. And with the "demand charges" and "time-of-day" rates that are being charged by deregulated electric utilities, TECOCHILL customers can cut their electricity bills by as much as 30 to 60 percent. About Tecogen Tecogen Inc. operates in the distributed generation market and is a leading manufacturer of natural gas-fueled commercial cooling and heat-recovery systems. Tecogen has an installed base of more than 1,000 units, which it supports through an established network of engineering, sales, and service support. Formerly a public subsidiary of Thermo Electron Corporation, the company is now privately held. Tecogen is based in Waltham, Massachusetts, with annual revenues of approximately $15 million.