Early on an autumn afternoon, an untitled 1990 abstraction by Esteban Vicente in the new Parrish Art Museum presented a smudged block of azure hovering over brushy patches of red-orange and umber. Two hours later, the angle of the sunlight coming into the gallery had shifted, and the new light made the warm colors catch fire and the blue sour and recede.

The change was unusual. While many museums allow daylight to enter their galleries, they typically filter it to a neutral glow. The Parrish lets the coastal light of New York's East End of Long Island color the experience of the work on view. Shifting and tonal, light enters the gallery as it might have entered Vicente's Bridgehampton barn-turned-studio in the mid'20th century. 'You find many artists who work here because of the landscape and the light in this place,' says Ascan Mergenthaler, Herzog & de Meuron's partner in charge of the project. 'We took the classic Long Island artist's studio, with a house shape and skylights, as a model for the museum building.'

As you drive east on the Montauk Highway, the Parrish emerges between rural hamlets with an incongruously industrial scale. A long, low rectangular volume, it could be a big-box store or the giant cousin of one of the agricultural buildings that dot the area. At 614 feet long but less than 100 feet wide, its narrow end elevations peak in twinned gables like two fused-together barns. A long metal roof overshoots the structure to create sheltered porches on all sides. Throughout the 34,400-square-foot building, a limited selection of materials'concrete, wood, metal, glass'and luminous open spaces give the museum stunning simplicity, made all the more remarkable because it was born of necessity.

Long before the Hamptons signified celebrities and billionaires summering in secluded vacation compounds, artists and their less ostentatious patrons fled the clamor of New York for the East End. The Parrish counts work by those with a connection to the region as the core of its collection, which now numbers 2,600 objects in a variety of media and spans artists from William Merritt Chase, Fairfield Porter, and Willem de Kooning to Chuck Close and April Gornik. But the Italianate 1897 building by Grosvenor Atterbury in Southampton that served as the museum's previous home lacked space for both its growing holdings and its program of temporary exhibitions. After an aborted attempt to expand, museum officials decided to build. In 2005 they acquired a site a few miles down the road, just outside the hamlet of Water Mill, and selected Herzog & de Meuron to design a new facility.

Mergenthaler and his team envisioned the new Parrish as a cluster of peaked structures, abstracted versions of the barns, sheds, and small residential buildings typically converted by artists into studios. (They also recalled the Monopoly house shapes of earlier Herzog & de Meuron work.) But the museum slashed the original budget of $80 million by nearly two thirds when the recession hit. Despite the dramatic cut, Herzog & de Meuron stayed on board. Mergenthaler reconfigured the constellation of buildings into a single long volume but kept the pointed form. 'It was clear that we would have to work with repetition, and it was a really simple idea to repeat one module in a long way,' he says. The project opened in November at a cost of $26.2 million; with 7,600 square feet of galleries, it nearly triples the museum's exhibition space.

To keep costs down, Mergenthaler used the pocked and craggy concrete that covers the museum's long exterior sides after seeing similarly rough walls in a local basement. The scruffy character of the mottled concrete keeps the vast expanses from looking monotonous. 'The thing that you really engage with first has to have a presence, a solidity, and a character,' says Mergenthaler. 'It's not just cladding.'

Visitors arrive at the museum along paths through a meadow of unmanicured local grasses that lead from a rear parking lot to the entry. Inside, the firm placed the galleries in a grid at the center of the building and bookended them with administrative space on one side and, on the other, a black-box theater and a caf' with a broad outdoor terrace. A cathedral-like axis runs through the center of the conjoined gables and connects all the interior spaces before dead-ending at the offices and theater. Konstantin Grcic designed much of the furniture, including a caf' chair that will have its commercial debut at the Salone del Mobile in Milan this spring. He also created the spindly, Calderesque lamps that hang from a modestly finished plywood ceiling in the entry and office areas.

The galleries, on the other hand, rely on East End daylight supplemented by side-mounted compact fluorescents for illumination. The gabled roofs face true north and south, and while most museums prefer the uninflected character of northern light, each set of three north-facing skylights at the Parrish comes with one wild card to the south. The southern skylights spike the galleries with a more varied and colorful light that gets a volatile glow from coastal water vapor. 'Straight up, the sky looks much like it does everywhere else,' says Andrew Sedgwick of Arup's lighting division, who consulted on the project. 'But down near the horizon, it changes color and brightness more than you would see in other places.' The angle of the roof allows the openings to capture a wide field of daylight without harming the artwork. In fact, the designers applied only UV coating and a nearly invisible hex-cell filter to the glass'look up, and you can see clouds passing'just to block the harshest summer light. According to Sedgwick, the amount of sun exposure that works receive balances out over the course of a year to stay within the threshold recommended by conservators. For shows that include photography or works on paper, scrims stretched on wooden frames manually mount into the skylights'a far cry from the complex and expensive motorized shading systems in many museums today.

The varied light presents a challenge for curators used to constant conditions, but it also captures the character of its place. By adapting its artist's-studio concept to a severely cut budget, rather than starting from scratch, Herzog & de Meuron created one-of-a-kind exhibition spaces. At the Parrish, work created on the East End appears in a way that approximates its origins, while other work takes on the character of the museum's context. And in every gallery, the light is spectacular.

Completion Date: November 2012

Size: 34,400 square feet

Cost: $26.2 million

Herzog & de Meuron