7/27/2019 Clackamas Case

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Arecently completed municipal office building in Oregonwas designed and built to the U.S. Green BuildingCouncils Leadership in Energy and Environmental

Design (LEED) silver standard and relies on an energy-effi-cient LoadMatch single pipe heating system supplied by TacoInc. The Clackamas County Public Services Building, whichopened in Aug. 2004, is full ofgreen features, specifically select-ed by the architectural firm that handled the project, GroupMacKenzie. Because energy conservation is an important criteriaunder LEED certification, Clackamas County and the buildingsproperty management group,Johnson Controls, selected a singlepipe heating system for the buildings heating, opt-ing to go with wet rotor circulators rather thancontrol valves.

The Clackamas County building islocated in Oregon City in Northwest Ore-

gon. The building housesvarious government depart-ments. Because a previousbond referendum to financeconstruction of the buildingwas turned down by the vot-ers, the county entered into a20-year contract with John-son Controls PerformanceContracting Division, whichthen oversaw the buildings design and con-struction and now leases the building back tothe county. Building maintenance and energy systems are main-

tained by Johnson Controls.Specifying USGBC-recommended building componentsand energy-saving features does add additional up-front coststo a building. Costs savings come afterwards in the form ofenergy savings over the life of the building. In the case of theClackamas County building, energy saving returns shouldbegin to add up in about a decades time, according to countyestimates. Energy savings will account for most of the sav-ingsabout $64,000 in the first year of occupancy alone, incomparison to the costs associated with the buildings thecounty offices were formerly housed in.

The key to approving the single pipe hydronic system was itslower cost to install and its projected energy savings, according to

Johnson Controls. Because the building was designed to be aLEED-certified building, every decision about components and

systems was weighed in terms of environmental impact and ener-gy conservation potential. The single pipe system was estimatedto save up to 30% of building HVAC system life cycle costs due to

reduced installation costs, less materials needed (pipe and valves),reduced operating costs and maintenance needs.

Based on a system design recommended by Taco, the installedsingle pipe system consists of 70 zones, with one circulator andone Twin Tee per zone. In addition, all of the coil piping andthe circulators were prefabricated to allow minimum installationtime. All heating coils in the buildings spaces employ circulatorswith integral flow checks (IFCs), which eliminate the need for

additional check valves ineach unit. The system isalso self-balancing; thereare no balancing valves inany of the individual units

because the circulatorshave been sized to pro-vide the appropriateflow and head.

With the elimina-tion of both balancingand control valves, thehead loss in the systemis lower and theinstalled pump horse-power is also lower. Asa result , the energy

consumption of the pumping system is reduced. The larger

fan coilsused for supplemental heatuse multiple smallcirculators in parallel so they can be staged to match thevariable air volume across the coils.

Design team members Glumac International, mechanicalengineering firm for the project, and Temp Control Mechanical,the installing contractor, were both familiar with the single pipeheating system concept and wanted to employ it in a projectapplication. Although the building manager was initially hesi-tant about using pumps instead of control valves, they becameconvinced that the single pipe system was the best option forthe building.

This article was provided by Taco, Inc., 1160 Cranston St.,Cranston, RI 02920, (401) 942-8000. Visit www.taco-hvac.com for

more information onLoadMatch single pipe heating systems andgreen building design.

54 PMEngineer February 2005

GreenMunicipal Building

Uses Single Pipe Hydronic System

A municipal building in Oregon is full of green features, including an energy-

efficient single pipe heating system.