Initially conceived and developed as modular a/c unit for refitting non-air conditioned city buses, today the Citysphere is an inherent part of series production with almost all major vehicle manufacturers. With an eye to the environment and operating costs, more and more transport undertakings are opting for the modular a/c unit with its patented air circulation system. With over 16,000 units produced, this year the Citysphere is celebrating its 10-year anniversary.
What began in 2008 with the first order for Autobus Oberbayern GmbH has developed into a rooftop air conditioning unit that has revolutionised the city bus market in the
moderate climate zones of Western Europe. Alone in the DACH Region, to date approx. 13,000 buses carry a Citysphere on their roof.
Small unit – big impact
Other requirements apply for comfort in the city bus than in the touring coach. Not only the additional fuel costs should be kept as low as possible, but also the service and maintenance costs. In this respect the Citysphere with its low lifecycle costs is simply unparalleled. It cools the interior not as usual by a radical reduction in temperature, but through a combination of cooling and air circulation. A radial fan generously distributes the cooled air directly into the passenger compartment and ensures pleasant temperatures without annoying draughts. This so-called wind-chill effect is completely adequate as an air conditioning in moderate climate zones and it is a far more effective way of creating a comfortable interior climate in the city bus. Additional consumption of fuel in comparison to non-air conditioned buses is hardly noticeable. Due to the hermetic sealing concept the Citysphere is additionally virtually maintenance-free and has ensured to date unrivalled low life-cycle costs.
From a retrofit solution to series production
In its initial phase, the modular a/c unit was offered to transport undertakings that had previously foregone air conditioning for cost reasons, as an option for retrofitting their buses. Gradually, however, vehicle manufacturers also became alert, as efficiency and life-cycle costs are no longer topics that concern only the cost-conscious transport operator. Today, the Citysphere is being installed in series at MAN, Evobus, Iveco, Scania, Volvo, Solaris and many smaller manufacturers. On account of its small coolant requirements (only a fraction of full air conditioning) it is also an attractive solution in view of the escalating cost of coolant R134a. In order to ensure that the Citysphere remains an eco-friendly and reliable city bus solution in future, Valeo is currently working on a solution with alternative coolants such as CO2 and 1234yf.
Major order for Rheinbahn AG: 74 Solaris New Urbino articulated buses, each with three Citysphere units.
Unique on the market
To date there are no comparable products on the market, even though other manufacturers attempt to copy the Citysphere. However, the latter are no match in terms of performance and technical standard. The critical differences lie in the PWM controlled, semi-hermetic scroll compressor with integral motor and infinitely variable power control, and the system’s air manifold with integral radial fan. Other products currently on the market have only a (separate) motor that is adjustable in steps and a compressor. With the aid of integral radial fans in the air manifold, the Citysphere distributes the cooled air throughout the bus, whereby benchmark products introduce air into the vehicle only at certain points. Where the Citysphere guarantees a combination of cooling and patented direct air intake along an optimum comfort curve, other products on the market are less flexible and can often be controlled only in three fixed stages. These characteristics are supplemented by further standalone features: the Citysphere’s fans are PWM-controlled; they consist of a fresh air portion of 15%, and the system is virtually maintenance-free. Furthermore, it fulfils the requirements of VDV Directive 236/1.
Nevertheless, the Citysphere will not be resting on its laurels. In the next few years a second generation of modular a/c units is planned. The latter will be oriented to the
future requirements and technologies of the city bus market.
Here’s to 10 more successful years for Citysphere!