No more stuffy class­rooms

Better air in class­rooms and less expense for federal and munic­ipal govern­ments: Versa­tile venti­lation systems from GLT Grohmann Lüftung­stechnik make everyone happy.

Currently, the German federal govern­ment and cash-strapped munic­i­pal­i­ties are looking for ways to save money. Ideally, this should be done without cutting services or failing to comply with direc­tives from Brus­sels. The German Energy Savings Ordi­nance and EU energy effi­ciency direc­tive require energy-effi­cient upgrades of public build­ings such as schools and kinder­garten. These projects could be an example of how the public sector can save money and increase quality of life at the same time. After all, the German federal govern­ment spent some 650 million euro for heat energy in 2007. State-of-the-art, highly versa­tile air-condi­tioning and venti­lation systems provide enor­mous savings here — while simul­ta­ne­ously improving room air quality. Grohmann Lüftung­stechnik GmbH (GLT) of Forcht­en­berg, Germany offers prac­tical fresh-air solu­tions with heat recovery that can be adapted to a wide variety of struc­tural situ­a­tions in a highly versa­tile manner.

The SLG series school venti­lation systems work in a demand-oriented manner, adapting to the require­ments. The venti­lation is matched to the current use of the room, depending on the number of occu­pants and how they are using it. This is ensured by an inte­grated CO₂ sensor. If the system runs at the lowest setting, only the minimum base air exchange required for hygienic purposes is guar­an­teed. If the room air quality decreases, this signals an increasing CO₂ value and the system increases the air volume auto­mat­i­cally. The central unit guar­an­tees excel­lent reuse of the exhaust waste heat, as it works with a heat recovery percentage of up to 90 percent.

If the outside air temper­a­tures are very low, either an air mixture valve or an inte­grated hot-water heat register takes over the neces­sary heating of the fresh air. If the heat exchanger of the venti­lation unit is located within the feed and return of a heating system, even more savings are possible: “The great advan­tage is that depending on the design of the class­rooms, we do not have to use radi­a­tors in some instances,” empha­sises Erwin Grohmann, the company’s owner. More­over, the systems manu­fac­tured in Forcht­en­berg, Germany, guar­antee that the chil­dren learn and play with clear heads, even if the outside air quality is rela­tively poor. Filter systems of various perfor­mance classes ensure healthy room climate even near heavily trav­elled streets.

The SLG school venti­lation device from Grohmann with the two EC centrifugal fans and the heat exchanger

In the school venti­lation systems, two EC centrifugal fans from ebm-papst Mulfingen provide the neces­sary intake and exhaust air flows — in energy-effi­cient oper­a­tion. Even today, the fan motors exceed the require­ments of the minimum effi­ciency classes that are planned to take effect in January 2011. They work with high effi­ciency of up to 90 percent and thus consume much less energy than the previ­ously used AC motors at the same air perfor­mance. However, these poten­tial energy savings are realised not only when oper­ated under full load, but also primarily when oper­ated under partial load. Where venti­lation systems previ­ously hummed so loudly that they made it diffi­cult to concen­trate in class, EC centrifugal fans elim­i­nate this excuse for bad grades. they make no motor noise what­so­ever, thus sparing the nerves of students and teachers alike.

Govern­ment coffers benefit from not only the energy savings, but also other advan­tages of these plug fans. The previ­ously common belt drive between the motor and fan is omitted. The elec­tron­i­cally commu­tated external rotor motor is inte­grated directly in the light­weight aluminium impeller, which dras­ti­cally reduces the instal­la­tion dimen­sions and the weight of the device.
This makes it substan­tially easier to fit the devices, already saving labour hours during instal­la­tion. in addi­tion, the system thus has fewer wear parts. For these reasons, and because of the mate­rials used, the fans attain a service life of over 40,000 oper­ating hours, which corre­sponds to running non-stop at maximum load and heat for four-and-a-half years.

However, school venti­lation systems usually run in partial-load oper­a­tion and at lower ambient temper­a­tures. “Lower service costs means that govern­ment budgets save twice over the long term,” empha­sises Grohmann. However, Grohmann failed to mention a great disad­van­tage of his system: In future, the children’s hope for a day off from school due to bad venti­lation will be in vain.