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The University of Washington’s newly opened Molecular Engineering and Sciences Building in Seattle has an interesting molecular makeup all its own: parts of the structure can cool and heat themselves without power.

In the walls and ceilings of the faculty offices, tiny packets of vegetable oil called bio-phase change materials, or bio-PCMs, are embedded to control the temperature. The waxen material inside the packets has a room-temperature melting point of about 73 degrees, so as the building warms during the day, the packets begin to melt and absorb heat energy from the sun. At night as the temperature outside cools, the packets release that heat and warm the interior. The packets then refreeze and become set to absorb the next day’s sunny rays.

The five-story, 90,374-square-foot, $78.5 million building opened in July, and the Seattle office of , the project’s architect, is tracking the performance of the bio-PCMs via sensors in the walls.

鈥淚t’s definitely working,鈥� said Chris Flint Chatto, an associate partner at ZGF Architects in Portland who worked with the Seattle office. 鈥淵ou can see in places where we have PCMs the temperature stays more constant than places that don’t.鈥�

A similar heat recovery chiller system uses PCMs to control the temperature of closed-loop water lines that run through the building and cool the microscope laboratories.

Chatto said bio-PCMs typically cost between $2 and $5 per square foot and that one square foot of the material is needed for every square foot of occupied space. So for a 20,000-square-foot office building, bio-PCMs would cost a premium of $100,000.

But the return on investment, Chatto said, comes from the fact that bio-PCMs make it possible to design a building without a cooling system. The faculty offices in the UW engineering building don’t have one, and that could cut down on energy consumption by as much as one third.

That design required some careful rethinking about how the building is ventilated. It uses elevator-like ventilation stacks that run the length of the building to draw air through the spaces. The naturally ventilated system is expected to cut down on energy consumption related to cooling in the office spaces by 98 percent annually.

That could prove to be a desirable trait to other building owners, considering that commercial buildings consume nearly 20 percent of the nation’s total energy supply 鈥� an increase of approximately 6 percent in the past 32 years, according to data from the U.S. Department of Energy. Today, that energy is worth $200 billion a year.

The UW building is one of the first in the nation to employ the bio-PCM system.