Page 60 - Green Builder March-April 2016 Issue

ENERGY S0LUTIONS

Sustainable Power From This Day Forward

Multifamily Energy Solution:

Watts From Wastewater

“SHARCs” and “Piranhas” eat heat from raw sewage and return it for use in buildings.

BY CATI O’KEEFE

T HEY MAY SOUND scary, but for the environmentally
conscious and owners of multifamily buildings,
International Wastewater Systems’ heat-seeking SHARCs
and Piranhas are harbingers of a new energy source for
buildings. These heat recovery products can conduct
simple and direct heat exchange from untreated wastewater to
provide energy-saving, cost-effective solutions for heating, cooling
and hot water.

When you consider that, according to the Department of Energy,
400 billion kW of hot water goes down the drain annually in the
United States, this represents an important tech innovation that
multifamily builders should consider using.

“After the Paris climate talks mandated carbon reduction, my
personal thought was: ‘Why do we throw it all away?’” says IWS
company founder Lynn Mueller, referring to the estimated 25 to 30
percent of heat that is carried by water into sewers daily around the
world. “We can recover this energy that’s being thrown away. Once
a heated water cycle starts, we can use the water, then we capture
the heat before it goes into the sewer […] and then do it over and
over. It is counted as part of your base load, because the amount of
sewage is constant in the world.”

THE NUTS AND BOLTS IMAGE CREDIT: INTERNATIONAL WASTEWATER SYSTEMS

Here’s how the system works: Wastewater maintains a fairly constant Components. The SHARC system includes the Sewage SHARC filter
temperature as it travels through sewers to the treatment plant— and heat exchanger, along with DDC controls. An in-line sewage
typically about 60°F. In a sewage heat recovery system, a heat pump macerator is optional.
is used to capture the warmth of wastewater and transfer it to the
clean water stream that enters buildings. It operates as a closed-loop completed several installations, which provide the buildings’ heating
system, meaning that the dirty water never touches the clean water. and cooling from either the municipal or the building’s sewage waste
It takes a lot less energy to heat 60°F water than to heat cold water. water. In a recent 172-unit condominium complex installation near
And in the summer, buildings with sewage heat recovery systems the University of British Columbia, the system provides hot water for
can reverse their heat pumps and use the system to dissipate excess
building heat.

The Piranha is designed for smaller buildings, such as multifamily
residences and hospitals, and the SHARC is sized for commercial
buildings.

IWS is presently designing systems that will be installed in the
United States and Canada as well as the UK. The company recently

58 GREEN BUILDER March/April 2016 www.greenbuildermedia.com