High Performing Buildings - Summer 2011 - (Page 54)

A long east-west orientation of the building maximizes daylight harvesting, while windows on the east and west walls are kept to a minimum to reduce unwanted solar heat gain. With reduced lighting requirements, less heat is generated from lighting, reducing the need for air conditioning E n E r g y at a g l a n C E Annual energy use intensity (site) 61 kBtu/ft2 natural gas 5 kBtu/ft2 electricity 56 kBtu/ft2 (includes 6.5 kBtu/ft2 of renewable energy produced from on-site photovoltaic array and wind turbine) Annual source energy 204 kBtu/ft2 to cool the building. High-efficiency fluorescent fixtures are used where artificial lighting is needed. The 200 kW, 166 ft tall wind turbine produces approximately 5% to 10% of the building’s annual energy needs. A 72 kW photovoltaic array generates approximately 2% to 6% of the building’s energy needs. Above Great River Energy Headquarters’ location across the street from a major mass transit hub allowed it to reduce the number of parking spaces by about half of what is required by zoning. Soil left over from excavation was used to sculpt the prairie mounds that anchor the building in space originally dedicated to parking. Below Great River Energy obtained a 15-year-old wind turbine that was previously used in Denmark. It was converted to a single-speed machine to fit the lower wind speed of the Great River Energy site, trading off better performance at lower wind speeds for reduced higher wind speed potential. The turbine has multiple safety features including three methods for braking and dual ice sensors that automatically shut down the turbine if any measureable ice accumulates on the blades. Design and Commissioning The design process (see Living Design Process) used at Great River Energy started with setting performance goals, establishing stakeholder buy-in and running simple energy, daylighting and computational fluid dynamics (CFD) models. This was followed by additional rounds of modeling that were used Annual energy Cost index (eCi) $1.45/ft2 Annual net energy use intensity 54.6 kBtu/ft2 energY sTAr rating 90 Heating degree days 7,565 (base 65) Cooling degree days 751 (base 65) to evolve the design and eventually to optimize the real-world operations and overall system performance. Post-occupancy daylight modeling was used to make minor W at E r at a g l a n C E Annual Water use nov. 2009 – sept. 2010 Potable Water (including cafeteria) 1,945,000 gallons rainwater used for Toilets 250,000 gallons (no Potable Water) site irrigation leed Annual Baseline 8,834,000 gallons Actual irrigation Potable Water use 982,000 gallons or ~90% reduction © lucie marusin 54 HigH Performing Buildings summer 2011 © Paul Crosby

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