Incorporating green principles contributed to cost efficiencies at Cape Town Hospital

A range of green technologies made the Netcare Christiaan Barnard Memorial Hospital a model facility for sustainable hospital operations management. A special double-skin façade and electricity-generating elevators are but some of the solutions implemented that not only make for best environmentally sensitive practice but will also contribute to cost efficiencies.

The glass façade at the hospital offers outstanding insulation

According to Dr Richard Friedland, chief executive officer of Netcare, the 16-floor hospital incorporates an array of design principles and green technology elements which are aligned with global standards, setting a new standard for environmentally friendly hospital facilities in South Africa.

One such innovation is the building’s ‘intelligent’ exterior façade, comprising an external glass skin, with a void separating it from the building’s internal glass windows. This means that together, the internal glass windows and the exterior of the building act as a double skin, offering outstanding insulation to the interior hospital environment.

The void within the two walls can be ventilated when the building needs to be cooled down, or closed to warm it up by means of louvres positioned between the two skins on roof level, which can either be opened or closed.

“The façade is also connected to wind driven extractors and motorised dampers which, in turn, are connected to the building management system. An intelligent and automatically controlled insulation layer enhances the energy efficient heating, cooling and ventilation technology installed in the building,” says Dr Friedland.

“It works like a giant Thermos flask; with the façade forming an insulation barrier which ensures significantly less dependence on the air conditioning units in the hospital for maintaining ideal internal environmental conditions.

“At the same time, the glass façade has an attractive visual effect and patients and visitors are able to enjoy the magnificent views of the harbour, mountain or city scape, depending on where they are in the hospital,” he explains.

Netcare’s environmental sustainability manager, Johan Durand, says that in addition to the double skin, a great deal of attention has also been paid to other insulation aspects of the building. Special double solar glazing, for example, has been used for the windows and façade, and the concrete roofs have been carefully insulated to international specifications. In addition, single solar glazing was fitted for the skylights.

Energy savings

According to Durand the intelligent façade is expected to save Netcare Christiaan Barnard Memorial Hospital some 105 000 kilowatt hours annually in energy.

The heating ventilation and air conditioning system that serves the new hospital is based on a rational design that exceeds South African national building regulations, and is based on an advanced standard as recommended and applied by the American Society of Heating, Refrigeration and Air Conditioning Engineers (ASHRAE).

This allows for better filtration of air to further improve infection prevention and control, while offering greater energy efficiency. Further efficiencies will be achieved through using two water-cooled chillers housed on the roof.

“Cape Town summers can be hot, reaching as high as 37 degrees, requiring large volumes of fresh air to be cooled. The ASHRAE-based system design at Netcare Christiaan Barnard Memorial Hospital achieves high levels of filtration by effectively ‘scrubbing’ the re-circulated air. This makes it possible to reduce the level of fresh air intake per cycle, which is required to meet building regulation levels and reduce the amount of energy required to cool down the air. The ASHRAE-based system is therefore able to achieve meaningful reductions in electricity usage,” says Durand.

“Further, the conditioned air that is expelled to the atmosphere to enable new fresh air intake is used through a heat exchanger to pre-treat and condition the new fresh air. This means that less energy is needed to fully condition the make-up fresh air to inside environmental conditions.”

Green technologies leads to cost efficiencies in hospital design

Integrated building management system

A building management system (BMS) works to reduce the building’s cooling and heating requirements by means of a centralised control of all services within the hospital. “The system focuses on integrating all systems within the building into one environment to ensure that they all operate cohesively and to optimum efficiency,” he adds.

The BMS system also measures the air temperature along sections of the intelligent façade and controls the motorised dampers to either extract or trap warm air depending on climatic conditions outside. The facility’s heating, ventilation and air conditioning system services the internal environment through variable air volume systems. These can be ramped up or down depending on the specific requirements of each individual ward.

“These air-handling units are equipped with economy cycle dampers to monitor outside air temperature. When the outside conditions are favourable, the utilisation of chillers to treat the air and fulfil internal demands is reduced. This system supplements the advantages inherent in the design of the ‘intelligent’ façade. The air conditioning system generates waste heat, which is harnessed to pre-heat the domestic hot water for the facility. The hot water is generated mainly by efficient heat pumps that use three times less energy than conventional electrical heating elements. The hot water storage vessels are fitted with electrical heating elements as a back-up measure,” explains Durand.

The piping system has been designed in such a way that domestic hot water can be circulated throughout the entire building, thereby reducing wastage due to hot water being available close to the points of use. The domestic hot water integration with the air conditioning is expected to save 34 300 kilowatt hours annually.

“We are effectively harvesting every little bit of heat energy and re-using it as an additional form of energy. Previously, this precious resource would have gone to waste, but now we are able to harness it to good effect,” says Durand.

Grey water harvesting and re-use

The hospital is also equipped with a sophisticated grey water harvesting system, which channels waste water from the renal dialysis filtration plant and the autoclaves used to steam sterilise medical equipment, to the ablution facilities. “Grey water harvesting and re-use is expected to save about 3 204 kilolitres of water a year, ” explains Durand.

“In addition, we have fitted low flow showerheads, which use half of the water of a conventional shower, and aerator equipped taps on all hand washbasins to reduce water usage. “Where these fittings have been used in other Netcare hospitals, they have achieved significant water savings.”

Lighting efficiencies

“The hospital’s lighting was not only selected for its aesthetic appeal, but also its efficiency and low cost of maintenance. There is a mix of florescent and LED lighting, resulting in a 40% reduction in energy consumption on lighting,” notes Durand.

Supplying the electricity to the facility are two high efficiency dry type transformers, which are situated on the roof of the building, and will contribute to electrical cost saving.

“Also helping to reduce future energy costs is the mechanism underpinning the facility’s regenerative power lifts, whereby the force of gravity is allowed to do the work when the lift is descending, and the motors act as generators, supplying the energy into a power bank for utilisation when the lifts go up.”

Dr Friedland observes that these features contribute to the environmental sustainability of the hospital and, by extension, help protect the country’s energy resources.

“Although hospitals are classified as low impact concerns in terms of carbon emissions, Netcare nevertheless takes its environmental responsibilities extremely seriously.”

“Efforts to conserve water and electricity should be high on the agenda of each and every South African, and we are committed to limiting our impact on the environment and to the judicious and sustainable management of our natural resource consumption. Netcare’s sustainability strategy aims not only to enhance the robust financial performance of the group into the future, but also to help ensure the future of the South African environment. The group’s impact in the environmental arena has shown that these two objectives are not mutually exclusive,” concludes Dr Friedland.

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