More than 50 safety rest areas and travel information centers managed by MnDOT require ongoing maintenance and upgrades to provide adequate service. Cost-effective building improvements offer opportunities to reduce energy consumption, lower maintenance and operating costs, extend building life cycles and decrease greenhouse gas emissions. This project evaluated 15 energy-saving measures (ESMs) and developed a decision support tool to help MnDOT select appropriate measures for individual facilities.
What Was the Need?
MnDOT manages and operates safety rest areas and travel information centers throughout the state that require significant energy and operating expenditures. Effectively allocating limited capital funds among these facilities can help MnDOT maximize sustainability investments while improving operations, controlling costs and reducing environmental impacts.
This project developed a cost-benefit decision support tool to evaluate 15 specific ESMs, individually and in bundles, based on energy savings, capital costs, greenhouse gas reductions, operational impacts and financial performance. The results will help MnDOT prioritize investments based on lifecycle performance, cost-effectiveness, deployment risk and site-specific conditions.
What Did We Do?
Investigators integrated field data collection, utility data analysis and building energy modeling to evaluate 45 rest areas and travel information centers across Minnesota. Site visits, surveys and interviews with maintenance staff provided additional insight into operational practices, equipment conditions and maintenance challenges.
Investigators evaluated 15 ESMs, individually and in bundles, including lighting upgrades, heating, ventilation and air conditioning improvements, insulation enhancements, renewable energy systems and advanced controls. The analysis also examined multiple photovoltaic (PV) deployment scenarios and the operational and maintenance effects of utilizing building automation systems (BAS).
The results were incorporated into a cost-benefit decision support tool that integrates energy, cost, maintenance and financial performance data for all facilities and ESM scenarios.
“The decision-making tool will provide valuable insight for both short- and long-term capital investment planning to improve sustainability and aid in making cost-effective operational decisions,” said Anthony Chevalier, a rest area design and construction manager at MnDOT’s Office of Environmental Stewardship.
What Did We Learn?
Low- to moderate-cost options, including LED lighting and controls, heat and energy recovery ventilators, furnace and boiler upgrades and BAS, provided the most reliable short- to moderate-term cost savings because of their lower capital costs and shorter payback periods.
BAS implementation reduced energy waste and maintenance costs by improving equipment monitoring, fault detection and diagnostics. When estimated maintenance savings were included, the BAS payback period decreased from approximately 79 years to 39 years, demonstrating the importance of considering operational and maintenance impacts in lifecycle evaluations rather than energy savings alone.
In contrast, electricity-dependent measures such as heat pumps required larger initial investments and were more vulnerable to volatile electricity rates, which can result in longer payback periods under unfavorable conditions.
PV systems required the largest capital investments and had moderate-to-long payback periods, but they provided the greatest long-term energy and emissions reductions. Grid-connected PV systems without battery storage were the most feasible deployment strategy under current utility rate structures. Roof-mounted systems generally outperformed ground-mounted systems because of lower installation costs. MnDOT could also consider alternative PV deployment strategies, such as power purchase agreements and community solar gardens, to improve financial outcomes.
Bundling ESMs could increase energy savings by approximately 40% to 45%, depending on the measures combined and applicable utility rate structures. Bundles were most effective when they paired low-cost operational upgrades with targeted system improvements.
Expected service life varied substantially among ESMs. Insulation upgrades and vestibule additions, for example, often last 40 to 50 years or more. Mechanical upgrades, including furnaces, boilers and heat pumps, generally last 15 to 35 years, while BAS and lighting controls typically have service lives of 15 years or less. PV systems generally last 25 to 35 years, although their battery systems often require replacement within 10 to 15 years.
Overall, no single measure was optimal for every facility. Performance depended on capital costs, utility conditions, building site conditions, operational priorities and long-term maintenance needs.
What’s Next?
MnDOT has finalized the decision support tool, which is now available for staff use. By integrating engineering analysis, lifecycle evaluations and operational characteristics, the tool provides staff with information to identify cost-effective sustainability upgrades that align with budget constraints, operational needs and environmental goals.
Because no single ESM is optimal for every facility, the tool can also help MnDOT develop a tiered investment strategy that balances short-term savings with long-term sustainability goals.
