High Performing Buildings - Summer 2011 - (Page 53)

G R E a t R i v E R E n E R G y H E a d q u a R t E R S Efficiency increasing the demand for more heating energy from the heat pumps. However, this increased occupancy load brings its own heat load into the conference center and the system balances CO2 levels with dynamic temperature demands. A variable frequency drive responds by increasing the amount of fluids being pumped via the lake loop geoexchange. If this scenario occurs in early November when the lake temperature is cooling from its warm peak in August, less fluid will need to be pumped than if it occurs in late January when the fluid is cooler. The building makes these continuous adjustments while using 40% less energy than a similar building (as determined by ENERGY STAR’s Target Finder), earning an ENERGY STAR rating of 90 and meeting the annual energy performance goals for LEED Platinum certification and the 2030 Challenge. Geothermal energy is transferred from man-made Arbor Lake via a closed loop exchange system using approximately 36 miles of polyethylene tubing. The 6 acre lake behind the building was previously a gravel pit. This energy provides condenser water for both water-to-air and water-to-water heat pumps and chilled water to free cooling coils. Air is delivered to the interior spaces through fan-coil units discharging into a pressurized floor with displacement ventilation diffusers located in each space. Perimeter zones are heated and cooled with heat pumps delivering air through floor grilles along perimeter glazing. Outside air is preconditioned with total energy recovery wheels to minimize mechanical heating and cooling. Opposite Great River Energy Headquarters’ narrow floor plan and east-west orientation maximizes daylighting. The ends of the building are capped with mostly solid walls to control east and west solar glare and heat gain. B u i L d i n G at a G L a n c E name great river energy Headquarters location maple grove, minn. (15 miles nW of minneapolis) owner great river energy Principal use office includes conference center, cafeteria and data center employees/occupants 250 occupancy 60% gross Square footage 177, 385 Conditioned Space 167,071 distinctions/Awards leed nC 2.2 Platinum (first leed Platinum certified project in minnesota) AiA national Committee on the environment Top green Building 2009 American Council of engineering Companies (ACeC) grand Award 2009 Society of American registered Architects national Award 2010 good green design Award 2010, Chicago Athenaeum and european Centre for Architecture Art design and urban Studies Total Cost $65 million all inclusive (land, hard costs + soft costs) Cost Per Square foot $275 Substantial Completion/occupancy April 2008 Lake Geothermal System The Great River Energy office building and conference center delivers on energy performance due to an integrated design approach the team took to the architectural, mechanical and electrical systems. The building team sought to conserve energy with a geothermal heating and cooling system. Reducing Loads, Producing Energy The building team further reduced building loads with an energyefficient lighting design. Dimming ballasts, daylight sensors and motion sensors help reduce artificial lighting needs. The building harvests daylight via perimeter glazing, narrow office floor plates and multiple atriums with light scoops. Summer 2011 H i g H P e r f o r m i n g B u i l d i n g S 53

Table of Contents for the Digital Edition of High Performing Buildings - Summer 2011

Commentary
Contents
Stanford University's Y2E2
The Christman Building
The Gettysburg National Military Park Museum and Visitor Center
Cannon Design Regional Offices, Power House
Great River Energy Headquarters
Letters
Products
Advertisers Index

High Performing Buildings - Summer 2011