Heat Pumps / HR Chillers
Traditionally, hospitals have heated the facility using hot water or steam boilers which rely on the on-site combustion of natural gas. At the same time, many hospitals are also cooling using a chiller plant and cooling tower to reject heat to the outside and exhausting heat through exhaust fans or economizer systems. A more efficient, and less carbon intense approach would be to satisfy the heating load using a heat pump system, which runs solely on electricity, requires zero on-site combustion, and recovery waste heat from inside the building to be repurposed for other heating needs such as space or water heating.
Cost to implement 💰💰💰💰♦
Carbon reduction potential 🌲🌲🌲🌲🌲
Heat pumps can be used to provide all space heating and domestic hot water production for hospitals, effectively eliminating on-site combustion of natural gas for these two large uses. Heat Pumps operate similarly to chillers, by transferring heat between the outside and inside but in a reverse process. Typical gas-fired boilers have a coefficient of performance (COP), or effective efficiency, of less than 1, and most commonly 0.8. This means the resulting heating energy from the combustion process is less than what you put into it, due to efficiency losses. With a heat pump system, the COP can be in the 4-7 range since the electrical energy being put into the system is uses to transfer existing heat from outdoors to indoors. The efficiency will largely depend on outdoor temperature and humidity levels.
How does this decarbonize?
Heat pumps run on electricity and do not use any natural gas. Using heat pumps as the only source of heat and domestic hot water can eliminate the cost of combustion equipment and the cost of the space they require, effectively using a slightly larger footprint for a cooling plant to provide both heating and cooling and eliminating the space required for a heating plant.
Where has it been done before?
Kaiser Westside and Kaiser Anahiem both have effective heat recovery chiller systems.
Mazzetti has designed hospitals in Georgia and Washington with ground-source heat pumps that provide all heating and domestic hot water, as well as smaller-scale applications of heat recovery chillers to provide building heat with recovered energy. In California, the climate supports similar systems, which will be demonstrated through energy modeling. Another heat pump strategy uses variable refrigerant flow (VRF) heat pumps to move heat between building zones. Mazzetti converted the 3rd floor of Sutter Health California Pacific Medical Center’s Stern Building from a conventional CAV system with steam reheat to a VRF heat pump system. That system has been in operation for 14 years, working as designed with no issues, and providing the facility with the anticipated occupant comfort.
What are the barriers to successful implementation?
If the heating load is too high and outdoor weather coniditions are too extreme, heating with a heat pump or heat recovery chiller only may not be sufficient and supplemental heating will be required to meet the demand. Hot water energy storage could be a possible supplemental solution.
Regulations require onsite fuel storage for building heating. When heat pumps are used for that purpose, backup electrical power systems and their fuel storage fulfill the requirement without separate fuel storage.
How to implement
Calculate the carbon reduction using my data