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Water Wonder

Fins, eaves, curbs, skylights and panels aid this facility's green goals

By Mark Robins, Senior Editor

In the arid southwest, it is critical to reduce and reuse water in every possible manner to protect groundwater supplies. Tucson, Ariz., is located in the Sonoran Desert, a place rich with unique plant and animal species and a high quality of life, but with few natural water resources. It receives 12 inches or less of rainfall per year.

In its new Eastside Water Facility office, the city of Tucson has incorporated water harvesting, and passive heating and cooling features to attain green goals. Metal is a contributing factor in this three-building project's success.

Standing seam aids green

This self-contained satellite facility for 75 employees contains offices and a shop area, fully stocked warehouse and an outdoor storage yard. The center sits on a 25-acre site and the construction design left almost 8 acres of natural, undisturbed open space set aside.

A standing seam metal roof with a single-slope design containing a high amount of recycled content from Star Building Systems, Oklahoma City, and Battenlok HS Snow White roof panels from MBCI, Houston, has proven pivotal to the building's environmental efforts. Steadfast Structures, Tucson, is the authorized Star Builder who brought the project to Star and played a key role in pricing the project, and in clarification so the order could be written for engineering and drafting to design and detail the building.MA_Green Scene_OCT12-1

"The primary structural material is made up of the structural frames produced by the EAF (electric arc furnace) process which has a high rate of recycled material," says Franz Mutis, PE, LEED AP BD+C, manager of engineering services at Star Building Systems. "The engineers at Star used a tapered section for the primary structural design. The tapered section allows for the most economical and structurally adequate design while maintaining the least weight design."

This type of metal roof was chosen for its long durability, which factors into a low lifetime cost. It is also virtually maintenance free, has a superior warranty and a wide array of cool roof colors that are highly reflective for lower cooling costs. The metal can expand and contract with the outside temperature and the roof can support two photovoltaic offerings that may be applied at anytime in the future.

Water harvesting

In addition to these benefits, this standing seam metal roof's single slope allows for a simplified design and efficient rainfall routing into 12 water harvesting cistern tanks from Southern Arizona Water and Rain Harvesting, Tucson. Their total water capacity storage is 40,176 gallons. Based on average historical rainfall data the potential annual rainwater yield from the facility's roof surfaces is 157,648 gallons.

These galvanized steel tanks also double as passive shade for the buildings' south side. They are visible from both major roadways and promote a new community aesthetic. Metal roof panels significantly reduce incidental particulate contamination of the tank water, which can occur over time with other roofing materials.

"Metal panels are ideal system to collect the water," says Mutis. "Certain types of roofing can't do that. For instance, asphalt shingles can't, because the water gets contaminated."MA_Green Scene_OCT12-2

Furthermore, the single-slope roof design aids in water harvesting efficiency since only one side of the building requires the water tanks. The water is collected from the rain running off the roof into the gutters flowing into the harvesting tanks from the downspouts. The rainwater is filtered as it enters the tank. It is kept dark and oxygenated to discourage algal growth. The tanks' calming inlets ensure that any sediment at the bottom of the tank does not get stirred up. This is not drinking water, but can be used for flushing toilets, washing clothes and garden watering.

Rainwater harvesting helps earn points in the water efficiency category for LEED. "Real time" irrigation controllers gather daily weather data and adjust watering schedules, which help rescue demand for the irrigation system. Also, pervious concrete ramps at the warehouse shed water into landscaping, rather than adding to stormwater runoff.

Heating and cooling

The buildings' single-slope high side faces the north to reduce desert sun exposure. To achieve green goals and increase energy savings, standing seam roof panels are compatible with different types of insulation. R38 insulation, from Therm-All Insulation Inc., North Olmsted, Ohio, lowers the energy required to heat and cool the facility. It increases the R-value in the roof and walls, and reduces the heat transfer through them, maintaining the temperature with less fluctuation.

The reduced energy use was determined prior to construction with an energy model. Energy conservation is reflected in the Energy and Atmosphere credits for LEED.

The facility's steel shade fins from Star Building Systems deflect direct sunlight away from windows, allowing for natural lighting, which contributes to the daylighting credits available through LEED. Because the high side of the building faces north, the east-west sun hits the sides of the shade fins.

Below eave canopies from Star supplement the shade fins. "They allow for strategic placement of the building's fenestrations to maximize the natural light provided by the sun, which goes toward earning daylighting credits," says Mutis. "The canopies also deflect the sun's rays, which heat the building, in turn lowering the energy requirement for the building and increasing the energy efficiency of the structure."Warehouse_WaterharvestersandleantoB

Seventy-five percent of the buildings' interior spaces receive daylight from skylights from Daylighting Systems Inc., Glendale, Ariz., and exterior clearstory windows from Geronimo Ltd., Tucson. These increase daylight, which reduces both artificial lighting and the energy demand.

Weathertight curbs from R & S Manufacturing and Sales Co. Inc., Newbury Park, Calif., position these skylights on the roof's low slope where roof penetrations are typically not recommended. The skylights attach to the curb, which is attached to the roof panels with materials provided by the manufacturer.

Tucson Water and its project contractors worked with nearby residents and businesses throughout the various phases of the entire design and construction to achieve as best a fit as possible into the natural surroundings of area. The green/low impact development was such a success three more satellite facilities are being built.

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Eastside Water Facility office, Tucson, Ariz.

Architect: Albanese-Brooks Associates, Tucson

Authorized builder: Steadfast Structures, Tucson

General contractor: Lang Wyatt Construction, Tucson

Landscape architect: ARC Studios, Tucson

LEED consultant: Architectural Fusion, Tucson

Clearstory windows: Geronimo Ltd., Tucson, www.geronimoglass.com, Circle #45

Insulation: Therm-All Insulation Inc., North Olmsted, Ohio, www.therm-all.com, Circle #46

Metal building system, shade fins: Star Building Systems, Oklahoma City, www.starbuildings.com, Circle #47

Metal curbs: R & S Manufacturing and Sales, Newbury Park, Calif., www.rnssales.com, Circle #48

Metal roof panels: MBCI, Houston, www.mbci.com, Circle #49

Skylights: Daylighting Systems Inc., Glendale, Ariz., www.daylighting.com, Circle #50

Water harvesting tanks: Southern Arizona Water and Rain Harvesting, Tucson, www.southernarizonaraingutters.com, Circle #51