sentences:  Class 172s have fewer seats than the s they replace, but greater overall capacity due to the increased room for standing passengers as well as wider aisles intended to speed boarding and alighting and reduce waiting time in stations.The trains are air-conditioned and have no opening windows, unlike the Class 150s.The Class 172 is designed to a body length, as opposed to the length used on previous Class 150 Sprinter DMUs - increasing capacity.