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   Coach insulation  evaluated  
Thermal insulation of coaches contributes to overall energy efficiency of passenger stock. Many measures can be carried out not only in new stock but also as a retrofit.
Technology field: Optimisation of comfort functions
close main section General information
  close sub-section Description
   

Principle

If there is a difference between outside and inside temperature in passenger coaches, heat is transmitted through the walls which has to be compensated by air-conditioning and therefore consumes energy. The situation can be improved by the insulation of walls and windows. On the one hand this is a continuous improvement task for the design of new vehicles. On the other hand existing retrofit cycles can be used to improve the heat transition properties of existing stock.

UIC recommendations

The thermal characteristics of railway vehicles (and other confined spaces) are described by the heat transition coefficient (k-value). It measures the heat flow through a certain component (e.g. a wall) in Watts per square meter for an inside/outside temperature difference of one Kelvin (W / m2 K).

UIC leaflet 567 gives maximum k-values for passenger coaches at stand-still:

  • for the primary passenger area: 1,6 W/m2K
  • for the corridors: 2,6 W/m2K

In running trains these values may be exceeded by 0,4 W/m2K

Individual measures

Individual measures to improve the thermal insulation of passenger coaches range from the insulation of walls to the installation of windows with favourable thermal properties. Retrofit experience from SBB show feasibility and profitability of such measures for old stock.

close main section General criteria
  close sub-section Status of development: in use
    (no details available)
  Time horizon for broad application: now
    (no details available)
  Expected technological development: dynamic
    (no details available)
    Motivation:
   
  • Energy saving
  • Passenger comfort
  Benefits (other than environmental): small
   

Passenger comfort

In some cases an improved insulation of coaches (especially windows) eliminates heat bridges and thus negative impacts on passenger comfort.

  Barriers: low
   

Weight reduction efforts

There is often a target conflict between weight reduction and coach insulation efforts. The effort to make the coach body lighter usually leads to deteriorated thermal properties, e.g. aluminium coaches tend to have less favourable thermal properties than steel coaches.

    Success factors:
    In order to reduce the downtime of passenger coaches, existing retrofit cycles should be used to carry out individual measures for improving coach insulation.
  Applicability for railway segments: high
    Type of traction:  electric - DC, electric - AC, diesel
    Type of transportation:  passenger - main lines, passenger - high speed, passenger - regional lines, passenger - suburban lines
    (no details available)
    Grade of diffusion into railway markets:
  Diffusion into relevant segment of fleet: not applicable
  Share of newly purchased stock: not applicable
    Grade of diffusion is not an applicable criterion because coach insulation is a continuous improvement process rather than a specific technology.
  Market potential (railways): high
    (no details available)
    Example:
   

Refitting of B 20-73 at SBB

SBB refitted the B 20-73 coach with a bundle of energy saving measures (CO2 -ventilation, coach insulation etc.). Measures for improving the k-value of the coach included a thermal insulation of the outer shell (6 cm Fiberform 40 kg/m3) and ventilation ducts as well as an installation of new glass for windows with argon fill. These measures improved the k-value from the prior 2,06 W/m2 kg to 1,60 W/m2 kg.

The retrofit programme reduced total energy consumption (incl. traction) by 14 % and showed a good cost-benefit ratio.

close main section Environmental criteria
  close sub-section Impacts on energy efficiency:
  Energy efficiency potential for single vehicle: 2 - 5%
  Energy efficiency potential throughout fleet: 1 - 2%
    General figures on efficiency potential of coach insulation measures are not available. However, given that 20 % of the total energy consumption of a passenger train is needed for comfort functions (mainly heating and cooling) and roughly one third of this value is accounted for by transmission losses, the energy transmitted through the outer shell of the coach will be about 5-10% of the total energy demand. Given the fact that k-values can be improved by some 20 - 40%, it therefore seems reasonable to assume a saving potential of 1 - 4 %.
  Other environmental impacts: neutral
    The materials used need to be assessed from an LCA point of view.
close main section Economic criteria
  close sub-section Vehicle - fix costs: medium
    Obviously the costs strongly depend on the individual measures realised. In the case of the retrofit of B 20-73 at SBB, the additional costs for insulation of walls and installation of new glass for windows amounted to 12.800 Swiss Francs (8700 EURO). An additional 800 Francs (550 EURO) was spent for the insulation of ventilation ducts. These costs would be considerably less for a bigger vehicles series.
  Vehicle - running costs: significant reduction
    (no details available)
  Infrastructure - fix costs: none
    (no details available)
  Infrastructure - running costs: unchanged
    (no details available)
  Scale effects: low
    Certain scale effects are to be expected for the retrofit of large vehicle series.
  Amortisation: not applicable
    The payback time strongly depends on the individual measures realised but will typically be short to medium.
no data available Application outside railway sector (this technology is railway specific)
close main section Overall rating
  close sub-section Overall potential: promising
  Time horizon: short-term
    Coach insulation efforts both in design of new stock and in retrofitting can be an effective means for improving energy efficiency. Although many measures require a taylored solution, the cost-benefit ratio is often satisfactory.
References / Links:  Brunner et al. 2000;  Opel 1999
Attachments:
Related projects:  Savings on Coaches, Type Bpm
Contact persons:
 date created: 2002-10-09
 
 
© UIC - International Union of Railways 2003
 
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