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



General information

	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.

General criteria

	Status of development: in use
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	Time horizon for broad application: now
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	Expected technological development: dynamic
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	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
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	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
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	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.

Environmental criteria

	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.

Economic criteria

	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
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	Infrastructure - fix costs: none
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	Infrastructure - running costs: unchanged
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	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.

Application outside railway sector (this technology is railway specific)

Overall rating

	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