DECARBONISATION The transition to all-
electric hospitals is not only feasible but also essential for achieving decarbonisation goals.
and chilled water. While these systems do eliminate the need for mechanical cooling, they treat the warm air from the building as waste, discarding it despite its potential value – even as boilers burn fossil fuels to create more heat.
Jim Crabb
Jim Crabb, PE, LEED AP, is a principal at Mazzetti. For over 30 years, he has been planning and designing high performance mechanical systems for healthcare clients across the country. Jim has been a prominent leader in sustainable healthcare design. He led the design for the first two hospitals in the state of Georgia to use waste energy for all building heating and hot water production. One of those was the first in the state to receive Gold certification under LEED for Healthcare. He has also contributed to two editions of the Guidelines for Design and Construction of Healthcare Facilities and is co-author of the two premier Decarb Healthcare Guidebooks in the USA. Additionally, Jim led Mazzetti’s response to designing COVID hospitals in underserved countries in coordination with the International Federation of Healthcare Engineers (IFHE) and the World Health Organization (WHO).
A more sustainable approach involves transitioning from a single use to a circular heat economy. Most hospitals have more heat than needed and reject the excess to the outside, even in cold weather. Heat pumps and heat recovery chillers recycle and reuse building heat, reducing overall energy consumption, potentially reducing operating cost, and reducing or eliminating on-site GHG emissions.
In most climates, building systems can also benefit from
the integration of thermal energy storage (TES) systems. TES systems store thermal energy during periods of excess and withdraw it when heat recovery is not sufficient. This can help balance energy loads, reduce peak demand, and improve the overall efficiency of heating systems. TES systems can be particularly effective in hospitals, where thermal storage can supplement heat recovery and potentially eliminate the need for combustion.
n Domestic hot water Traditional hot water systems in hospitals typically rely on natural gas or other fossil fuels for heating water. These systems are not only carbon-intensive but also require significant maintenance and operational costs. Transitioning to electric hot water systems can reduce emissions and improve energy efficiency. Electric heat pump water heaters (HPWHs) are a viable alternative to traditional fossil-fuel-based hot water systems. HPWHs use a refrigeration cycle to extract heat from the surrounding air and transfer it to the water, making them highly efficient. They can provide reliable hot water with significantly lower energy consumption and emissions compared to traditional systems. Heating hot water can also be a source for domestic
hot water, so that heat recovery chillers and heat pumps can provide both building heat and domestic hot water, without the need for dedicated HPWHs.
n Ventilation Ventilation systems in hospitals are another source of heat that can be optimised for energy efficiency. Traditional systems often involve constant airflow rates to meet code requirements, resulting in excessive energy use for reheating air. Direct exhaust air heat recovery systems capture heat
28 Health Estate Journal November 2025
from exhaust air and use it to preheat incoming fresh air. This reduces the need to heat ventilation air and lowers energy consumption and emissions. These systems can be particularly effective in hospitals, where ventilation requirements are high and continuous.
n Laundry services Most hospitals outsource laundry services to off-site facilities, which often rely on fossil fuels for heating and hot water. Transitioning to on-site electric laundry facilities can reduce carbon emissions for both transportation of laundry and for process heat. Heat pumps transfer wastewater heat, normally disposed of in sewer systems, to heat incoming wash and rinse water.
In addition to reducing emissions, on-site electric
laundry facilities can provide greater control and flexibility in managing laundry services. Hospitals can optimise their laundry processes, reduce costs, and improve service quality by building and operating these facilities in cooperation with other hospital systems.
The role of solar energy Solar energy offers a free and carbon-free source of energy that can be harnessed for various applications in hospitals. There are two primary means of harvesting solar energy: photovoltaic (PV) production of electricity and solar thermal systems that produce heat. Solar thermal collectors are more efficient at converting solar radiation to useful energy than PV systems, making better use of limited roof or site area. However, solar thermal systems may be more costly to install, more complex, and require more maintenance than PV systems. Hospitals must weigh these factors to determine the right mix for their facilities. Solar thermal collectors can be used to provide space
heat and domestic hot water, with storage options such as insulated water tanks offering a cost-effective alternative to lithium batteries. Although these systems require more engineering and construction labour, they offer significant advantages in terms of efficiency and sustainability. PV systems, on the other hand, generate electricity
that can power various hospital systems, including lighting, HVAC, and medical equipment. Advances in PV technology have improved the efficiency and affordability of these systems, making them a viable option for hospitals looking to reduce their carbon footprint and operating cost. PV systems can be installed on rooftops, parking structures, and other available spaces, providing a renewable source of electricity with minimal environmental impact.
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