DECARBONISATION
practice results in high energy consumption and carbon emissions. In contrast, electric alternatives such as heat pumps offer a more efficient and sustainable solution. Heat pumps use a refrigeration cycle to move heat from one location to another, extracting heat from a low-temperature source and releasing it at a higher temperature. They use electrical power to move heat rather than combusting fossil fuels, which reduces carbon emissions. The efficiency of heat pumps is measured by their coefficient of performance (COP), the ratio of energy output over energy input. Heat recovery chillers may have COP of 3 or more, as they deliver three units of heating energy for every unit of electrical energy input. Compared to combustion equipment that operates with a COP of less than one. Heat pumps come in various types, including air-source heat pumps (ASHPs), water-source heat pumps (WSHPs), and ground-source heat pumps (GSHPs). ASHPs extract heat from the outside air, while GSHPs and WSHPs utilise water as a heat source. GSHPs, in particular, are highly efficient and can provide both heating and cooling, making them ideal for hospital applications. They involve installing a network of pipes underground, through which refrigerant or water circulates to store excess heat in the ground and extract it when needed.
Heat recovery chillers Heat recovery chillers recover energy from a building chilled water system, making both chilled water and hot water simultaneously. In traditional cooling systems, a chiller absorbs heat from returned chilled water and vents it into the atmosphere. However, heat recovery chillers repurpose this heat for other heating needs, maximising efficiency. These chillers can utilise heat from various sources, including IT cooling equipment, refrigerators, freezers, and medical equipment, integrating them into the chilled water loop. Recovered heat can be used for space heating, domestic hot water, or other thermal needs within the hospital. By recovering and repurposing heat that would otherwise be wasted, these systems can significantly reduce energy consumption and emissions. In addition to reducing carbon
emissions, heat recovery chillers can improve the overall efficiency and resilience of hospital energy systems. By using the same type of equipment for both heating and cooling, they can eliminate combustion boilers and reduce maintenance costs.
Cooling systems In cold weather, buildings use cold outside air for ‘free’ cooling, known in the US as ‘economiser’ mode, where dampers
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Hospitals, being centres for health and healing, should lead by example in reducing their environmental impact
modulate the blend of outside air and return air to deliver cool air without using a cooling coil 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.
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.
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.
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 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.
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.
IFHE DIGEST 2025
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