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How Epson Reduces Cleanroom Environmental Impacts

Air is not free!

LoveEarth-BFUThat's right. The air in a cleanroom* is far from free. That's because it's not ordinary air. Cleanroom air conditioning systems use a tremendous amount of energy. Outside air that is taken into such systems has to be heated or cooled and humidified or dehumidified so as to keep the temperature and humidity of the cleanroom constant. The air also has to be filtered to remove airborne particles and other contaminants. Given the energy and expense of treating air, Epson has developed and implemented a variety of projects in cleanrooms to use this precious air more effectively and efficiently.

Projects aimed at "reduction"

Epson launched a project to revamp the manufacturing processes used for manufacturing inkjet printer print heads and ink cartridges so as to reduce environmental impacts. Seeking to eliminate waste, the project team has introduced actions that the manufacturing floor can take to cut costs and mitigate environmental impacts.

Reusing air that was once released as waste

The project team decided to concentrate on air. Cleanrooms constantly circulate air to maintain cleanliness, temperature and humidity. Clean air flows from the ceiling and is exhausted from the floor. Exhaust from machinery and equipment is expelled to the outside via ducts, and an equivalent volume of new air is drawn in from outside. Cleanroom air conditioning and handling systems account for about 70% of the total energy consumed at the manufacturing site we visited, and the expulsion of more air than necessary ends up wasting money. This consideration is what prompted the project team to introduce actions to reduce exhaust.

Installation of compact blower filter units

In the past, all exhaust from machinery and equipment was vented to the outside through ducts. The project team, however, came up with the idea of using compact exhaust units called blower filter units (BFUs) instead of ducts to exhaust the air. BFUs have a built-in intake fan and special filter. They can be installed over the exhaust port of machinery and equipment to remove particles from the exhausted air. These BFUs allow machinery and equipment exhaust that formerly was released to the outside as waste to be re-released into the cleanroom, thus sharply reducing the amount of air vented to the outside. Since the air that passes through a BFU is the same temperature and humidity as the air in the rest of the cleanroom, it does not require further conditioning. BFUs therefore save considerable energy because they allow the volume of air exhausted to the outside to be slashed, meaning that less fresh air from outside needs to be taken in and treated.
Also, since the major construction work required to install ducts is not necessary, the BFUs save construction costs and do not generate the level of waste that end-of-life ducts do. Moreover, machinery and equipment are easier to move when equipped with BFUs instead of ductwork, so the layout of a factory floor can be changed without major expense. Because machinery and equipment can easily be moved as needed to accommodate fluctuations in production volume, space can be used more efficiently.

Savings (7 pieces of equipment) Energy: 23,532 kWh/year CO2: 8.9 tons/year


Ventilating diaphragm vacuum pump exhaust through subfloors

In this example, the flow of air in a cleanroom is efficiently used to save energy and money.
Diaphragm vacuum pumps generate a lot of particles, so ducts were connected to exhaust ports and the exhaust from these pumps was being vented to the outside. The strategy taken here was to cover the entire pump with a plastic cover, and place the pump on a perforated grating. Even without an exhaust duct, exhaust from the covered pump efficiently flows down to the subfloor, instead of spreading into the ambient atmosphere.

Savings Energy: 23 kWh/year CO2: 0.1 tons/year

LoveEarth-Diaphragm vacuum pump

Measurements to find the optimum level of exhaust

A fixed amount of air constantly flows within a certain apparatus. There were six identical apparatuses, and the level of exhaust from each was measured. The measurements showed that the exhaust volume varied from 10 m3/h to 69 m3/h, meaning the apparatus with the highest exhaust volume was exhausting seven times more air than the apparatus with the lowest volume. Next, measurements were taken to determine the lowest level of exhaust that could be maintained without adversely affecting quality. Since it was found that the lowest exhaust volume was perfectly adequate, the exhaust volume of each apparatus was set to 10 m3/h. The cumulative effect of these types of commonsense yet solid actions yielded significant benefits.

Savings (6 pieces of equipment) Energy: 2,193 kWh/year CO2: 9.3 tons/year

The types of efforts described have served to sensitize employees to waste and have spawned spontaneous efforts to eliminate it in all facets of operations, such as by shutting down machinery and equipment when they are not in use. Staff noticed that the more routine the operation, the more likely the presence of hidden waste.

*Cleanroom: a temperature- and humidity-controlled room in which the air is maintained in a highly purified state. Cleanrooms are used for fabricating products that are sensitive to contamination, such as semiconductors and LCDs.