The expansion plan will see its budget hotel room stock increased by 13,000 over the next four years to 55,000.

With average construction costs per room coming in between £35,000-£45,000, the new build investment programme amounts to around £500m, excluding land.

The investment programme promises a big boost to its preferred contractors: Broadoak Construction, Carter Lauren, R G Carter,  Ogilvie, Patton, Speymill and Thomas Vale.

Costa coffee stores has even more ambitious targets for 2015 with plans to almost double the network of stores to 3,000.

Unveiling strong group annual results with sales up 8% to £1.4bn last year, Alan Parker, chief executive of Whitbread, said: “Whitbread has performed strongly in the most challenging hotel and restaurant trading conditions for a generation.

“We have achieved a significant reduction in net debt while, at the same time, increasing the number of new sites acquired for our future development.”

Next year alone Premier Inn will open 29 hotels to create an extra 2,500 rooms.

The budget hotel market accounts for about 16% of all hotel rooms but has plenty of potential for further growth said Whitbread. In France and the US budget hotels now account for a quarter of all hotel rooms.

In the UK, Whitbread will open around 130 Costa stores during 2010/11. This growth includes opening new high street locations, adding stores in established retail outlets like Tesco and expanding Costa into hospitals and universities.

It will also build in China, India, Russia, the Middle East and Central Europe.

Premier Inn will open its first purpose-built green hotel and Beefeater Grill restaurant in the Autumn.

The 60 bedroom Premier Inn at Burgess Hill, West Sussex will use best performing sustainable construction materials to deliver 70% carbon and 60% water savings.

This includes sustainably sourced timber-frame construction, water recycling and harvesting to provide 100% of the hotel’s toilet water, and ground-source heat pumps for heating.

This template will eventually be rolled out across its entire estate of 580 hotels to help it meet a target of reducing carbon emissions 26% by 2020.