I would like to know the design specifications for the temperature control on the new route master buses. Does the current design meet the specification or did it prove to be too hot? I would like all the information regarding the installation of opening windows and the relationship with the air conditioning. What analysis has been done of the temperature on the buses in Summer? What consideration, if any, has been given to replacing the new route masters given the excessive temperature? Does TfL accept that the temperatures are excessive and what is TfL doing about it?

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TfL Ref: 1163-1819

Thank you for your request received by Transport for London (TfL) on 26 July 2018 asking for information about bus temperatures.

Your request has been considered in accordance with the requirements of the Freedom of Information Act and our information access policy. I can confirm that we hold the information you require.  You asked: I would like to know the design specifications for the temperature control on the new route master buses.  Does the current design meet the specification or did it prove to be too hot?  I would like all the information regarding the installation of opening windows and the relationship with the air conditioning.  What analysis has been done of the temperature on the buses in Summer?  What consideration, if any, has been given to replacing the new route masters given the excessive temperature?  Does TfL accept that the temperatures are excessive and what is TfL doing about it?

I would like to know the design specifications for the temperature control on the new route master buses.

We do not hold technical or design specifications for air cooling units fitted to buses in the fleet as private bus operators are contracted to manage vehicles on our behalf. We require all double deck buses to provide cooled air into the upper deck of double deck buses to help lower temperature and make passengers feel more comfortable. These are air-cooling, not more powerful thermostatically-controlled air conditioning units, that lower temperature rather than reduce it to a target level.

Does the current design meet the specification or did it prove to be too hot?

Yes, as the cooling units provide cooler air into the upper deck saloon area and this helps to reduce temperature and make passengers feel more comfortable.

I would like all the information regarding the installation of opening windows and the relationship with the air conditioning. 

The air cooling system on New Routemasters was designed to work with the windows shut so the vehicles were originally designed with windows that did not open. During exceptionally hot summer temperatures, we received many comments from customers that the buses should also have opening windows to enhance wellbeing. We conducted checks of NRMs and non-NRM double deck buses and found temperatures were similar in both, in some cases slightly lower on the NRMs. As passengers also commented about stuffiness, lack of air flow and comfort, we opted to retrofit NRMs already in service and modify the design of NRMs under production to have opening windows built into them.

Please find attached copies of the daily cooling and comfort audits along with a summary spreadsheet which were carried out in July and August 2014. Over the period of monitoring the surveys were undertaken by our own inspectors, bus station controllers and an external organisation we use for engineering quality monitoring (Freight Transport Association vehicle inspectors). Initially we only requested feedback on whether the cooling system was functioning and providing cool air, and for an opinion as to the cooling effect from the passengers perspective. However, later checks included measuring the temperature with a thermometer. This is very subjective in that it is dependent on passenger numbers, the doors opening and closing and where on the vehicle the check was done, and was influenced by the external ambient temperature. For example, the report for 18 July shows the ambient temperature – the temperature outside the bus, was 33c.

A total of 300 New Routemasters were checked on days when outdoor temperatures were high in July and August 2014. Of those, 292 (97.33%) were working at capacity or adequately in the upper saloon in relation to passenger loads, and providing cooled air as designed. 8 vehicles were found to have a faulty cooling system. These vehicles were reported to the operator immediately who instigated investigations and repairs. Additionally there were vehicles that were reported as warm although the system was functioning as designed. There may have been a number of reasons for this, for example, the bus has been on its stand in direct sunlight and the cooler has not been running long enough to bring down the temperature at the point when the check was conducted.

All new double deck buses now have similar air cooling systems and opening windows. We have no plans to replace New Routemasters for the reasons above and continue to endeavour to strike a balance between reducing emissions with a programme of vehicle upgrades and replacement. We continue to study advancements in vehicle design and ancillary systems to see if there are opportunities to enhance passenger comfort further without increasing exhaust emissions. On top of air cooling and opening windows, existing buses have white roofs and insulation to reflect heat, tinted windows to reduce heat gain from sunshine and ventilation.

If this is not the information you are looking for, or if you are unable to access it for any reason, please do not hesitate to contact me.

Please see the attached information sheet for details of your right to appeal as well as information on copyright and what to do if you would like to re-use any of the information we have disclosed.

Yours sincerely

Sara Thomas

FOI Case Management Team

General Counsel

Transport for London

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