The new library currently being built next to city hall in Sammamish is being constructed to cutting edge standards, and will be the first library of its kind to adopt a number of energy saving design features.
This week The Reporter took a look around the library-in-progress with Construction Manager Bob Carns to learn more about how the building will take advantage of nature’s own energy – light, heat and air – to reduce energy consumption and increase the comfort levels of patrons.
One of the most remarkable features of the building is the use of geothermal heating and cooling.
While the construction site may look just like a heap of dirt and mess, about 6 feet underneath that soil a state of the art energy system has been put in place.
Geothermal heating and cooling systems work by absorbing the heat contained under the surface of the earth, and circulating it through a closed loop.
In the case of the new library, that closed loop includes a system of pipes laid into the radiant concrete floor.
This geothermal loop circulates a carrier fluid, in this case water, through a system of coiled pipes buried in the ground.
“They’re a lot like a big slinky,” Carns said. “They stretch the slinky out, lay it in a long trench, and then fill it up.”
As the fluid circulates underground it absorbs heat from the ground, which in this area is typically at about 55 degrees.
A heat pump uses electricity to extract the heat from the fluid.
Even cold ground contains heat, and due to advances in technology, geothermal heat pumps are more available now to everyday builders than in previous decades.
By utilizing the natural heat from the ground, more heat is generated than if electricity alone had been used directly for heating.
Switching the direction of the heat flow, the geothermal system can be used to circulate cooled water through the building in the summer months.
This alternative energy technology that is becoming more common, particularly in states like Washington where there is a lot of exploration into green design.
While some private houses are currently taking advantage of geothermal loop systems, the new Sammamish building may well be breaking new ground for library facilities.
“It’s just driven by the library’s desire to do the right thing,” Carns said.
The reason geothermal technology is more energy efficient is this: air temperature ranges throughout the various seasons drop as low as 26 degrees and rise as high as 86 degrees. To provide a comfortable working environment air conditioning systems need to convert this to about 70 degrees.
The water in a geothermal loop is already at a fairly constant 60 degrees by the time it circulates out of the ground, meaning that much less energy output is required to reach that 70 degree point.
According to Brian Griffith of mechanical engineering firm Stantec, one of the library design teams, water is four times more efficient at distributing energy than air, and the geothermal loop system meshes very well with the radiant flooring.
This ensures even temperatures throughout the building, and reduces the energy wastage of having particularly cold or warm sections, as is often the case with air conditioning systems.
But Griffith said the way the building was heated or cooled was only part of the idea of energy efficiency.
“What it is also about is reducing the need for energy consumption,” he said. “We do this by creating a good quality “envelope,” the building’s shell.”
Griffith said that a number of other modern design elements had been included to both help the building retain warmth or repel excessive heat, regulating fluctuations in the internal temperature.
Some of these are as simple and traditional as shade trees, and the inclusion of operable windows, so those inside can make use of breezes and fresh air. It might not sound like a particularly new or interesting idea – but when was the last time you were in an institutional building and were able to open a window? Sealed environments are energy intensive, and the use of natural elements such as this is a big part of the library’s construction which designers believe will save between 30 and 50 percent on energy costs. Another is the inclusion of large windows and sky lights, so as often as possible the library will be lit by natural light from outside.
The east-west siting of the building will maximize daylighting and minimize solar heat gains.
But it’s not all low-tech. The large west facing window will feature the use of Warema blinds, a technology from Germany equipped with a solar tracking system which automatically regulates the positioning of the blinds to provide the most, or least, shading, depending on the temperature inside the building.
As the City of Sammamish begins to deal with the imposition of new, stricter Department of Ecology storm water regulations, they will be pleased to know that the library next door is ahead of the game when it comes to filtration and retention.
A portion of the roof will soon be covered will 8 to 10 inches of soil into which will be planted rows of low maintenance Sedums, a hardy leaf succulent native to the area.
The purpose of this green roof is to filter rain water that falls on the roof and regulate the water’s flow into a system of filtration and retention tanks underneath the site. Green roofs such as this are one of a number of design features that the Department of Ecology is encouraging cities like Sammamish to include in their development as a way to simulate the natural functioning of watersheds.
They have also been found to improve insulation values.
Parking for the library will be directly underneath the library building, thus reducing the footprint of impervious surface.
Opening of the new library is targeted for January 2010. The future use of the existing library at the corner of 228th Ave Southeast and Inglewood Hill Road has not yet been decided.
For more information on the new Sammamish library building, go to www.kcls.org/bond/sammamish