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General information
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Description
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Without air-conditioning the inside temperature of passenger coaches would in many cases exceed outside temperature due to the following heat sources: human beings, lights and other electrical equipment, sunshine through the windows.
For an outside temperature of 12° C and a coach with 80 persons (~ 7 kW) and sun shining through the windows (~ 2 kW), 20° C inside temperature are reached without any additional heating.
If these heat sources cause overheating (> 20° C) of coach and outside temperature is still < 20° C, the coach may be cooled by outside air. For this purpose the air intake may even be increased to values beyond the necessary intake for ventilation. Such an excessive operation of ventilation may save energy air-conditioning. For comfort reasons there is however an upper limit for interior air flow and thus for maximum ventilation (UIC 553, EN 13129).
Excessive ventilation is usually an option for outside temperatures between 10 and 22° C depending on sunshine and occupancy. |
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General criteria
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Status of development: in use |
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Excessive ventilation is currently being used in some trains at German DB AG and at Swiss SBB (double-decked IC2000). |
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Time horizon for broad application: 2 - 5 years |
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(no details available) |
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Expected technological development: basically exploited |
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There may be some improvement potential in the control algorithms of excessive ventilation. |
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Motivation:
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Energy saving |
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Benefits (other than environmental): none |
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(no details available) |
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Barriers: medium |
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Technological A control algorithm for excessive ventilation is required. Ventilation equipment must allow for variable and excessive operation. Passenger comfort According to Swiss SBB there were initial problems with the system due to excessive air flow within the coach. This problem has been resolved in the meantime. |
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Success factors:
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Combining this measure with other improvements of climatisation requiring an intelligent tool, e.g. a smoothened operation of coach climatisation (cf. IC 2000). |
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Applicability for railway segments: high |
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Type of traction: electric - DC, electric - AC, diesel
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Type of transportation: passenger - main lines, passenger - high speed, passenger - regional lines, passenger - suburban lines
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In principle, all passenger coaches may be equipped provided that technological conditions such as variable and excess operation of ventilation equipment are given. |
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Grade of diffusion into railway markets:
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Diffusion into relevant segment of fleet: < 5% |
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Share of newly purchased stock: < 20% |
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German DB AG: Excessive ventilation is a standard in all newly purchased
passenger stock.
Swiss SBB: IC 2000. |
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Market potential (railways): high |
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Excessive ventilation is expected to become a standard in new stock in mid-term perspective. |
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Example:
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Swiss IC 2000. |
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Environmental criteria
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Impacts on energy efficiency:
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Energy efficiency potential for single vehicle: < 2% |
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Energy efficiency potential throughout fleet: < 1% |
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Energy savings result from the net effects of saved climatisation energy and
higher energy demand of ventilation motors.
No quantitative data on energy savings realised is available.
The following calculation gives a rough estimate of the saving potential:
- 20% of the total energy demand of a passenger train is due to comfort
functions (mainly air-conditioning).
- According to a rough estimate by a DB expert, cooling to make up for
interior heat sources amounts to about one third of energy for
air-conditioning.
- Conditions for excessive ventilation (occupancy, sunlight, outside
temperature) are only given in a certain time portion (presumably < 50%) of
operation.
- Excessive ventilation alone will in many cases not be sufficient to reach
target temperature.
Taking these limitations into account, excessive ventilation will save <
2% of overall energy. |
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Other environmental impacts: neutral |
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(no details available) |
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Economic criteria
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Vehicle - fix costs: low |
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(no details available) |
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Vehicle - running costs: minor reduction |
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(no details available) |
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Infrastructure - fix costs: none |
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(no details available) |
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Infrastructure - running costs: unchanged |
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(no details available) |
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Scale effects: not applicable |
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The programming of additional algorithms and implementation into air-conditioning will yield certain scale effects in large vehicle series. |
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Amortisation: (no data) |
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(no details available) |
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Application outside railway sector (this technology is railway specific)
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Overall rating
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Overall potential: promising |
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Time horizon: short-term |
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Cooling by excessive operation of coach ventilation is an effective means to reduce energy demand for air-conditioning. Barriers are medium for a retrofit and low for a dedicated solution in new stock. Energy efficiency is moderate. Economic details are not available, but profitability is expected to be promising. |
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date created: 2002-10-09
