The U.S. Department of Energy estimates that higher education facilities account for 13 million metric tons of carbon emissions each year—a hefty footprint that many colleges and universities have publicly committed to reduce. However, the path to decarbonization is littered with obstacles. The average campus is a diverse facility with complex heating and cooling requirements, and many institutions were built around aging infrastructure that creates unique retrofitting challenges. Combined with the financial constraints faced by many postsecondary schools, net-zero goals can feel increasingly out of reach.
Even with these hurdles, prioritizing sustainability has become a necessity, and it is important to begin carving pathways now toward decarbonization. Partial decarbonization with hydronic heat pumps provides an opportunity for campuses to quickly improve energy efficiency while also reducing operational expenses. Teams that take this approach can leverage cost-savings to pay for continued sustainability efforts as they work toward full decarbonization over time. And for many campuses, this solution lies within the existing heating and cooling infrastructure.
Leveraging simultaneous heating and cooling loads
The average campus requires simultaneous heating and cooling to serve a variety of buildings, from energy-intensive laboratories and medical buildings to student housing and athletic facilities. When a standard chiller and boiler system is used, these functions operate independently. Traditional chillers extract heat from the chilled water loop and then reject it to the atmosphere using cooling towers, where it is largely wasted. At the same time, boilers are burning fossil fuel to generate hot water or steam to satisfy campus heating requirements.
In comparison, a water-to-water heat pump is a single piece of equipment that contains dual functionality to move heat to where it is needed. Just like traditional chillers, heat pumps contribute chilled water to the campus loop, extracting heat removed by air handling and terminal units as they cool campus buildings. That same heat is then raised to a higher temperature by the heat pump and used to generate heating hot water through refrigerant compression instead of combustion. This process of generating chilled and hot water simultaneously with a heat pump can be four to five times as efficient as a conventional chiller and boiler system.
High-performance heat pumps are able to provide flexibility that enables the equipment to be integrated within many existing HVAC infrastructures and scaled over time. Even for campuses using centralized steam heating systems, small-footprint compound centrifugal heat pumps and variable-speed screw heat pumps can enable a decentralized approach with heat pumps installed in parallel with existing steam-to-hot water heat exchangers at each building. In this configuration, the heat pump extracts low grade heat from the return chilled water loop, reducing the cooling tons the main central plant needs to provide. Simultaneously, the heating hot water generated by the heat pump to serve the building reduces the fossil fuel generated steam that the campus boiler plant needs to produce. This increases system efficiency and, in most cases, significantly reduces heating and cooling utility costs.
Carving out funding
Taking advantage of simultaneous heating and cooling with hydronic heat pumps creates an opportunity to achieve partial decarbonization while freeing up a funding source for future sustainability efforts. In fact, moving away from conventional chiller and boiler systems to simultaneous heating and cooling with heat pumps can lead to substantial utility cost savings because the single electricity input to the heat pump is providing two beneficial outputs: chilled water and hot water. These cost-savings result in fast paybacks on the initial heat pump investment and establish a source of funding for full-scale decarbonization.
On average, campuses that have installed water-to-water heat pumps have achieved four to five times the efficiency of a traditional chiller and boiler system. These savings can net a system payback in two to five years. And because cooling tower usage is minimized, both water and sewage utilities and water treatment costs are proportionately reduced. Water saving in the millions of gallons annually are common.
In addition to the cost-savings delivered by heat pumps, their flexible design provides an opportunity to scale strategies as teams navigate their long-term sustainability roadmap. Heat pump installation can be applied to a single building, a defined zone or an entire campus. Combined with central plant optimization software, performance can be measured and reported against benchmarks or modeled by projected student occupancy and external weather conditions. These outcomes can then be used to estimate energy, water and cost savings, providing realistic proof-points that can inform capital investment decisions and long-term strategic plans.
As decarbonization goals continue to shift across higher education, one point remains clear: decarbonization can no longer wait for the future. Partial decarbonization that leverages simultaneous heating and cooling creates an opportunity to begin reducing emissions and deliver significant cost savings that lead to further enable equipment upgrades and emission reductions.
