As sustainable initiatives and energy efficiency become more the norm than the exception – often design drivers even in budget-constrained public projects – sustainable solutions must respond to the need for simplicity and cost-effectiveness. Portland Community College’s and THA’s commitment to affordable sustainability is demonstrated in the new 45,000 square foot three-story academic building at the Cascade Campus in North Portland. Recently completed modeling projects the new facility, which includes classrooms, faculty workspace, informal student learning spaces, a child development center and space for programs whose mission is promoting educational opportunities, will be 73% more energy efficient than the national average for this type of building.
The measurement is based on the 2030 Challenge which THA adopted in 2009 and whose mission is to achieve a dramatic reduction in the global-warming-causing greenhouse gas emissions of the building sector by committing that all new buildings and major renovations reduce their fossil-fuel consumption by 50% by 2010, increasing the reduction by 10% in 5 year increments to carbon neutrality by 2030.
The metric for the 2030 challenge is site Energy Use Intensity (EUI) in kBtu/sq. ft. per year based on the national average/median energy consumption of existing U.S. commercial buildings as reported by the 2003 Commercial Building Energy Consumption Survey (CBECS). The national average energy consumption of this project type is 104 kBtu/sq. ft.-yr. With an EUI of 28.5 kBtu/sf-yr the academic building exceeds the current 2030 target of 60% and represents THA’s best EUI to date.
This savings is achieved primarily by: an east-west building orientation for optimal solar control; maintaining a low (30%) window to solid wall ratio; continuous exterior R-20 insulation for the walls and R-50 for the roofs; naturally ventilating spaces such as hallways and other transitional areas; and by decoupling required ventilation from supplemental heating and cooling. With this combination of affordable and sustainable design strategies we are able to maximize the public’s investment by minimizing first costs while at the same time reducing long-term operational costs.