Half a mile northwest of their future site, the designs of Yale’s 13th and 14th residential colleges are taking their final shape.

Last month, a two-story mock-up created to test potential design features for Yale’s new residential colleges was constructed in a field next to Science Park’s building 25, said School of Architecture Dean Robert A. M. Stern, the head architect on the project. Stern’s firm designed the structure to contain multiple versions of elements like windows and stonework, so that administrators and architects could analyze the benefits and costs of various alternatives, Stern said.

“I think people understand that when we build something, it’s not for the next five or ten years, it’s for many generations,” University spokesman Michael Morand said. “To make the best decisions, you have give it the time, have lots of eyes and sweat the details.”

After New Haven’s City Plan Commission approved the location for the new residential colleges at Prospect and Sachem streets in November, University officials, trustees and the project’s architects are working to finalize its specific, technical details, Morand said. Since its construction, the mock-up has given administrators, architects and members of the Office of Facilities the chance to weigh in on the particulars of the colleges’ technical design. On Thursday, the Buildings and Grounds Committee of the Yale Corporation — the University’s highest governing body — went to examine the mock-up, the final group heavily involved with the construction of the new colleges to do so.

By late March, the colleges’ architects will determine the final details of the building’s technical design.

The mock-up structure consists of two walls at a 90-degree angle adorned with various types of windows, stones and mortars to present a sample of the colleges’ potential features, Stern said. Its cost is included in the project’s construction contract, Levin said, since creating mock-ups is standard procedure for projects of this scale.

“It’s like a life-size tableau of what many of the architectural features of the college will look like in real life,” University President Richard Levin said, adding that the mock-up looks much more “busy” than the actual colleges will, as it compresses many design elements onto such a small building.

Yet not every component on the mock-up will make its way onto the actual colleges. For example, in examining the structure in this phase, visitors consider the way in which the mortar should be handled: The architects have tinkered with options for the width and thickness of the mortar between rows of bricks and the depth of the grooves along the mortar’s surface, Stern said.

Morand added that attention at this level of detail contributes to the uniqueness of Yale’s architectural landscape, creating an “environment of delight.”

Windows are subject to similar examination, with the mock-up presenting three different options for the final design, Stern said. Each choice comes from a different supplier that can work within the new colleges’ price and contracting constraints to provide a product close to what the architects are seeking.

“We want to see which one comes the closest to what we want,” Stern said.

In figuring out which of several options to select, Stern said that physical appearance is only one factor. Price and performance play a key role in which options will be selected for the new colleges. He added that the mock-up enables his team to test the features in New Haven’s environment and to see how the colors appear under New Haven’s light. With its proximity to Yale’s central campus, the Science Park location effectively approximates the environmental conditions of the actual site.

The mock-up was assembled by Turner Construction, Yale’s contractor for the residential colleges, Stern said.