The new 218,000 SF flagship building of the National Renewable Energy Lab in Colorado called RSF will house some of the most advanced research in renewable energy technology. So it’s not surprising that the building itself will also be the most energy efficient in the United States, using two-thirds less energy than a typical building.

 

But what is a little surprising is that one of the main strategies employed to reduce the building’s energy load is not all that high tech. In fact it has been around for centuries -- thermal storage.

 

By creating a basement labyrinth out of staggered concrete walls, the building will act as a giant "thermal battery," efficiently storing passive heating and cooling.

 

The building pulls in cold air at night. As the air winds its way through the concrete labyrinth it maximizes contact with the masonry walls which soak up the cold. During the day hot, fresh air is pulled across the cold walls dropping the intake air temperature and reducing (or eliminating) the work that the AC system performs. With a downsized AC system, this means both significant savings in operational costs and construction costs.

 

Conversely, in the winter the heat is pulled into the labyrinth and again stored for use the next day, where it preheats the cold winter air reducing the amount of natural gas needed to heat the building.

 

It sounds simple but a great deal of computer modeling was required to optimize the size and location of the masonry walls so that they would release the stored energy at the right time of day.

 

Phil Macey of NREL described how factoring in the energy cycles of nature changed the way the building was design from the ground up:

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