Deutsche Bahn

Air Cooling Feasibility Study for Porterbrook Leasing

Detailed Feasibility Study - Class 455 Air Cooling System Improvements


The pressure ventilated cooling system in the saloons of the 4-car Class 455 units needed to be improved. DB ESG was contracted by Porterbrook Leasing to undertake a detailed feasibility study into the potential benefits and impacts of improving the ventilation system on these units.
DB ESG had carried out several projects on this fleet, including minor modifications to lighting and door components, and PRM, remote condition monitoring and driver advisory system projects. DB ESG therefore possess a detailed understanding of the Class 455s and a good working relationship with the operator, South West Trains (now South Western Railways).

Work undertaken:

Cooling Solution Assessment

DB ESG did an initial assessment into the following options: -

  • Improving the components within the existing Pressure Ventilation (PV) system.
  • Upgrading/enlarging the components within the existing PV system.
  • Introducing additional cooling of the incoming air of the existing PV system.

Replacing the PV system with a full air conditioning recirculation system was considered to be technically viable, but was not found to be a cost effective solution and so was not an option for this study.
Each option was reviewed and the assessment considered whether components could be changed, subsystems added and controls improved to maximize cooling capability. The assessment also investigated the different cooling technologies available, the benefits of each option and any installation challenges involved.

Heat Load and Cooling Calculation

  • DB ESG developed a heat cycle model for the Class 455s, this considered the heat generated by the passengers, the solar gain, transmitted heat and other ambient heating. DB ESG undertook a graded comparison of each of the air cooling options.

Supplier Assessment

  • DB ESG completed an appraisal of the air conditioning/cooling market and identified a shortlist of suppliers for more detailed investigations. DB ESG then worked closely with the shortlisted suppliers to understand their products and how they could be integrated into a Class 455 unit, together with any maintenance requirements.

Integration Design

  • DB ESG undertook an assessment into the feasibility of installing the systems shortlisted in the supplier assessment into Class 455 vehicles. DB ESG produced basic 3D CAD block models of the principal system components and assessed where they could be fitted into the units.

Transfer of Design

  • DB ESG conducted a generic, high level assessment investigating the feasibility of transferring the design to other vehicle fleets.

Feasibility Report

  • Finally, DB ESG produced a feasibility report capturing the commercial and technical information gained during the study. The technical section focused on the merits of each option and recommended the best solution for Porterbrook. The commercial section detailed the expected turnkey costs. The indicative prices for the preferred option were then provided and broken down by one off design and engineering, materials, installation, approvals and whole life maintenance costs.