SANTA BARBARA, Calif. - A Whitestone Research study for a U.S. Department of Energy (DOE) national laboratory assessed the cost effectiveness of achieving government mandated energy savings for an older federal building. While proposed changes affected all building systems, over 75 percent of energy savings came from modifications to HVAC equipment. The study found that mandated reductions in energy consumption of 30 percent by 2015 can be implemented in a cost effective way for older buildings.
This study evaluated the life cycle cost effectiveness of alternative combinations of energy-saving components for a laboratory at DOE’s Pacific Northwest National Laboratory (PNNL). Following an extensive review of energy-saving options, two alternative retrofit projects were specified by partner firm Jacobs Engineering. The first alternative had a lower initial cost, while the second had a higher initial cost but substantially greater energy savings. The second alternative’s energy savings exceeded the 30 percent reduction mandated by recent federal legislation.
Life cycle costs of the alternatives include initial installation, maintenance and repair (M&R), and energy consumption discounted over a 40-year period. M&R costs were estimated using the MARS Facility Cost Forecast System for the existing building and alternative component inventories. Calculations of energy consumption recognized direct energy savings (from energy-consuming equipment) and indirect savings (such as reduced heating and cooling loss from triple-glazed windows). Whitestone noted that over 100 interviews and secondary sources and a variety of models were required to obtain the necessary energy performance and cost data.
The analysis showed that the second alternative was the lower cost alternative - 12 percent less than life cycle costs for the current building configuration and 16 percent than alternative 1 - despite the higher initial cost. Whitestone Research said the rankings were robust even when evaluated using the shorter investment period (25 years) and lower discount rate (2.6 percent) usually used for non-energy projects.
Not all of the changes in alternative 2 were found to be cost effective. Much of the savings came from modifications to mechanical equipment, while changes to roof coverings (green roof with growing medium) and transformers would not recover their installation costs with subsequent operations savings.
Feb. 2, 2009: Study Indicates Older Buildings Can Meet Federal Efficiency Goals
February 2, 2009