Passive solar heating is taking on labyrinthine proportions in order to save money and energy at NREL’s upcoming Research Support Facilities (RSF) in Colorado. The new, ultra energy efficient office building will consist of two lengthy wings, connected in the center by a lobby and conference area, each resting directly above a dark labyrinth. No it is not designed to confuse bull-headed beasts, nor house Bush-era members of the Department of Interior, but a labyrinth with a much more benign and energetic purpose.

This “solar” labyrinth will collect and store energy to help heat or cool the building above. It is a huge exercise in capitalizing on the thermal properties of concrete, as well as the valuable heat generated by the sun (especially in Colorado where winters are cold but relatively sunny). The labyrinth is comprised of several staggered concrete support walls beneath the massive concrete floor of the RSF itself. You might call it a sort of shallow basement, but one that will trap warm air, which in turn will slowly pass through the concrete floor throughout the night and into the morning to ease heating loads for the offices above.

The Solar Formula

The sun enters the equation by way of a transpired air collector — a metal sheet with tiny, well-placed holes designed to draw air through. The solar heated air will be drawn by fans down into the labyrinth through air vents designed into the buildings’ stairwells. There it will embark on its slow, warming journey back into the building.

In the summertime, cool air at night will be drawn down into the labyrinth where it will slowly journey upwards to help keep the air cool and ease heating loads. The S-curves of the basement will force the air to linger awhile before escaping through vents, maximizing the amount of energy (cooled or heated) retained by the building itself.

Waste Heat Un-Wasted

NREL’s new labyrinth will also trap waste heat from the computer center housed in the facilities above. This air too will be trapped and take the same journey as its solar heated counterpart. Even in mild spring or autumn days, the waste heat from the computers can be used to stem off the morning chill, providing for a comfortable environment for workers as they arrive.

The solar and computer heat that passes through the labyrinth can warm the building about 5 to 10 degrees before it is heated further by the heating system. “That may not sound like much,” said Phil Macey, senior associate at RNL, the design firm for RSF, “but it is meaningful across a whole year.”

The labyrinth beneath the north wing of the facility will be used for heating, while the labyrinth beneath the south wing will be used for both heating and cooling.

NREL’s new building on campus is expected to reach LEED-Platinum status, the highest rating handed out by the U.S. Green Building Council and could end up being one of the most energy efficient office buildings in the world.

Can You Have One?

This solar labyrinth is actually a lot like solar radiant heating, which many single-family homes in America already use. In that case a labyrinthine system of tubing is laid into a concrete slab (before it is poured) and hot, solar heated air (or water) is passed through those tubes during the day. The warmth of that air is transferred to the concrete and then slowly into the house as a whole.

In another (somewhat contrary) way it is reminiscent of a solar chimney or solar cooling tower, in which air in an attached tower is heated by the sun and begins to rise, forming an updraft which draws air out of the house. In the meantime, cool air is pulled into the house from below ground or, perhaps, from a basement.

I can see no structural reason why any normal home could not utilize the technology employed here by NREL. Just think of all those crawl spaces out there that could be circulating useful cool or hot air. Two things though: For one it is questionable how much of a difference a labyrinth would really have in a typical home — many times these designs work most effectively on a large scale.

Secondly, the added expense of ventilation and the time, labor, and materials needed to design and pour all that concrete might outweigh the energy savings for the average home. Still, that doesn’t negate the coolness and possibility behind such an ingenious design for the eco-home of the future. It could also work if we found a way to harness the waste heat from home appliances and HVAC systems.

Via Renewable Energy World

Posted on June 25th in Passive Solar by Dan.