Energy flow management in the production of sheet metal products

An analysis of natural gas consumption identified potential to optimise both the space heating and the generation of process heat.



Drilbox manufactures a wide range of storage and presentation boxes for drilling and other tools at its production site in Giengen. All of the products made in the Giengen factory are of sheet steel.

Heat and process energy at drilbox are generated primarily using natural gas.

In view of rising energy costs and the need to renew or refurbish several production and heating facilities, drilbox decided to carry out an energy flow analysis of the whole site in respect of its main energy source, natural gas.

The following objectives were set for all of the buildings at the Giengen site:

   • Creation of an energy input balance focusing on gas consumers
   • Identification of the potential to optimise both space heating and process heat and the related measures
   • Inclusion of a planned 650m² factory extension into an energy-saving heating concept using existing heating systems and sources

In order to identify the areas with the greatest energy losses, total gas consumption was allocated to the main gas consumers and the site divided into areas with comparable heat-related boundary conditions.

The data used to record the current situation was taken from the year 2004, for which monthly gas consumption data was available.


Around 50% of the gas consumed is used for space heating. The specific actual consumption was calculated and compared with reference values to identify the potential for savings, the result being a theoretical energy savings potential of around 200,000 kWh p.a., or EUR 6,400 p.a., with a significant upwards trend.

An improvement in the thermal insulation was suggested as a starting point for optimisation, but implementing this is highly complex, as it needs to be adapted to the individual building sectors in the factory. Organisational measures were also suggested, such as controlled aeration, or the avoidance of heat losses due to ventilation (open factory doors).

It is difficult to avoid uncontrolled ventilation in the storage and workshop areas due to open or unsealed passages (e.g. louvre blinds). Radiant heating requires 2°C lower room temperatures and can save up to 50% in energy consumption compared to hot air heating.

Considerable energy losses are experienced where the generation of process heat is concerned due to the direct conduction through the roof of hot air and exhaust gases from the baking oven in the powder coating facility and the parts washer.

The installation of air-to-air heat exchangers was suggested as a means of recovering the waste process heat. The theoretic energy potential of heat recovery amounts to around 60,000 kWh p.a. and would be sufficient to heat the planned 650m² new factory building without having to expand the existing central heating system.

In all, the surface engineering facilities (purification/degreasing/powder coating) show an energy optimisation potential in the region of 20% to 30%. The energy savings would thus amount to 130,000 – 190,000 kWh p.a., a financial saving of EUR 4,200 – EUR 6,000 p.a.

More Project Information

Project period: 2004 - 2004

Project region: Germany (Baden-Württemberg)

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Source:  Landesanstalt für Umwelt Baden-Württemberg