Increased cooling capacity, reduced carbon footprint

London hospital opts for the natural refrigerant ammonia



Alfa Laval


Ammonia (NH3)

Cooling Capacity:

0,5 MW



Homerton University Hospital is a renowned healthcare provider in the north-east of London. Around 63,000 patients benefit every year from the hospital's excellent general and specialist medical services, and about 6,000 babies are born at Homerton University Hospital each year. The hospital's previous refrigeration plant ran on the refrigerant R22; however, due to the phase-out of refrigerants impacting on the environment, it had to be replaced by a system that operates with an environmentally friendly refrigerant. A new concept was needed to provide not only an eco-friendly refrigerating system but also an efficient alternative for air-conditioning in the vital parts of the hospital, such as the operating theatres, obstetrics wards and intensive care units. One particular challenge consisted in the limited space available: the new plant had to be installed in the same room as the old system, without any interruptions in operation.



To run the refrigeration plant for the central areas, Homerton University Hospital has opted for an innovative approach based on the natural refrigerant ammonia. The key elements of the system are two NH3 liquid chillers with a cooling capacity of 0.5 MW each. For space reasons, each module was combined with a stainless steel heat exchanger, with two panel heat exchangers for condensation and evaporation together with a U-turn liquid separator, all mounted on a specially designed frame. The plant was completed by two dry coolers on the roof of the building with an output of 612 kW. An innovative safety system with a special failsafe shutdown program ensures maximum plant safety in operation. It prevents any droplets of ammonia from getting into the atmosphere even when there is a leak in the refrigeration system. This aspect is of particular significance, especially in a setting such as a hospital with its safety needs. One impressive result of the new concept: instead of the previous need for 300 kg R22, the new system requires only just over 50 kg ammonia. Thanks to its intelligent design, the plant even manages with 33% less ammonia than conventional ammonia refrigeration systems. Changing over to the new system has given the hospital 50 percent more cooling capacity, while significantly reducing its carbon footprint thanks to the climate neutral ammonia.


Technical data:

Type of Facility:

Cooling System


Refrigeration Charge:

Refrigeration Capacity:

Ammonia (NH3)

50 kg

498 kW cooling water from +12°C to +6°C

Evaporation Capacity:

SST +2.34°C, SDT -46.5°C, condensing with glycol and a dry cooler to minimise charge


Alfa Laval Lund AB

Mr. Jesper Olsen
Phone: +46 46 367 390