Tesco has developed a new modular format for its Express stores that will improve efficiency and cost of construction with the buildings arriving on site almost fully assembled.

The formats will be used for 20 new-build Express stores or forecourts during the next year, with the only exceptions being stores that must be traditionally built to suit local environments, said a spokeswoman for Yorkon, the construction company behind the design. The first is due to open mid-July in Leeds, with two more in the pipeline for Sunderland and Kent, following a year of research.

The initiative is a key part of Tesco's plan to open about 130 Express stores in the year ahead. The modules are placed by crane onto the store site before being bolted together.

Freezers, chillers, checkouts, flooring, walls, windows and toilets are already in place when the units leave the factory.

Once on site, the building is fully constructed within a day, with the store ready for handover in two weeks - about 30% quicker than

traditional methods. Tesco previously had a number of bespoke designs from which it would pick for each location. It will now pick standard modules to fit just three sizes of store - 2,000 sq ft, 2,500 sq ft and 3,000 sq ft, creating cost savings through economies of scale.

Depending on the configuration, it will also need fewer modules per store than previously.

The back of store areas will also be smaller than traditional Expresses due to improved efficiencies in stock holding, while shelves are narrower and taller to offer more retail space in the same floor area.

"This has taken 12 months of planning, looking at every aspect of the store design, inside and out," said the Yorkon spokeswoman.

David Johnson, director and general manager of Yorkon, said that he was committed to working with Tesco on the development of the store design to achieve the best value, improved efficiency, reduced programme times and guaranteed quality.

"The re-engineering initiative is the result of a true partnership and shows what can be achieved with a fresh and intelligent approach to design and construction," he said.