Aircon ducts of the future - an observation

Airconditioned buses are now a standard fare in the Singapore's hot and humid climate. SMRT Buses has a wholly airconditioned fleet, while SBS Transit has a mostly airconditioned fleet (save for a small batch of non-airconditioned Volvo Olympian 2 axles running in the west).

The Scania K230UB and the B9TL are the most common airconditioned buses in SBS Transit's fleet after fleet renewal

SBS Transit's continues an eyball outlet design, allowing both the passengers to adjust/close the outlets as needed.

SBS Transit's aircon outlets as seen on an ex-SBST OC500LE demonstrator, also bodied by Gemilang

TIBS had an eyeball-like design aircon outlets, except you can't close them. They are the most common outlet design on buses such as the Hispano O405s and O405Gs.

The old eyeball outlets found on the TIBS-era SMRT buses.

When the Hispano Habit O405G first debuted, there were several feedbacks on the aircon were not adjustable for the passenger on the outer seats. TIBS responded that the interior design by Hispano is designed to be streamlined into the parallel lighting and curves of the panelling to create a modern look and feel.
Thus this removed the ability to adjust the aircon outlets for passenger comfort (though TIBS elected to install double-glazed-windows to lessen the heat penetrating into the interior to enhance passenger comfort.

The Mercedes O405G Habit and the OC500LE Gemilang shares similar design traits. The interior styling and aircon ducts were inherited over to the Gemilang design, carrying the legacy of TIBS's bus specifications.

The Habit's design influenced the Gemilang interior, with SMRT's interior colour specification , an updated yet familiar design and retained the Habit's aircon outlets. It seemed that SMRT Buses are being slowly influenced in the interior design based on the refurbished SMRT C151 trainsets.

Even the more recently refurbished Scania L113CRLs and DAF SB220Ls are following the Habit/OC styled-interior.

The Habit-like aircon duct found on a refurbished DAF SB220L.

A new trend seemed to start when the SMRT Yutong demonstrator debuted in August 2009, it featured no adjustable aircon outlets, instead providing passengers with airconditioning through a series of small holes

The Yutong features airconditioning through these small non-adjustable outlets.

Following the Yutong a year later was the Citaro demonstrator. The European-spec bus has no adjustable aircon outlets either. The aircon is channeled out via two long slits running on both side of the duct panels for the entire length of the bus. 

Two slits running on both sides of one of the duct panels, channeling aircon for the inner and outer seating passengers/standing passengers

Recently, a hybrid of two designs appeared on the recently debuted Sunlong Hybrid (no pun intended). This hybrid design combines the best of both worlds, though the feasibility remains to be seen.

The hybrid design of aircon outlets and small aircon ducts found near the windows.The aircon outlets are unable to reach the inner seating passenger, due to the way the panelling is designed.

SBS Transit is likely sticking to the eyball outlets in the near future for their buses, though it won't be ruled out that the hybrid design of eyeball outlets and non-adjustable outlets, bringing the best of both worlds for SBS Transit passengers.

For SMRT Buses, there seems to be a trend going on where the buses are becoming more "MRT-like", given the introduction of voice announcements that debuted on the OC500LEs. On SMRT trains, the aircon just flows out from the airconditioning systems; the newer fleet of SMB-registered buses/refurbished SMRT Buses seems to be aiming at a common SMRT "experience" on both the buses and trains.

As long as there are cooling aircon flowing in the interior of the bus, there seems to be no need to fret over adjusting the aircon outlet, allowing the passengers to actually enjoy the trip. I prefer SMRT's no-fret airconitioning idea, though i don't mind (and don't usually) adjust the aircon outlets on the SBST fleet unless needed.