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Multi-Source Systems

Project Name:

Social Security Administration, Harold Washington Building

Client: Government Services Administration


The Harold Washington Social Security Administration building in Chicago has a rich history of green practices dating back to its construction in the 1970′s. By the early 2000′s, the building sported more solar panels than any other building in Chicago. The building had already switched out all toilet fixtures to reduce water consumption, but the GSA wanted to conserve additional water by capturing rooftop rainwater for irrigation.

System Type: Multi-Source, Multi-Use

Commissioning Date: 10/08/2010

Challenge: While there was some value in watering the landscaping with rainwater, there is very little landscaping around the building, meaning that the total water savings from a relatively expensive system would be slight. And because the building was existing, the options for supplies and uses were limited.

Solution: Wahaso did an audit on potential supplies and demand and discovered very significant potential savings and uses. In addition to rooftop rainwater as a source, Wahaso also identified cooling condensate and groundwater as good additions to the supply. And cooling tower make-up was the big non-potable use identified, along with boiler make-up in the winter, flushing toilets and irrigating that small amount of landscaping. Four decommissioned 8,000 steel tanks were recommissioned to hold the non-potable water supply.

Results: The system saves over 3 million gallons of municipal water annually - about 100 time more than it would if it had only irrigated landscaping. And the original value of that savings - $9,000 per year - has already increased by almost 100% due to rising water costs.

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