How to optimize the lighting in hospitals and achieve energy efficiency?

 

Energy efficiency in hospitals - Lighting (part 5)

 

How to optimize the lighting in hospitals and achieve energy efficiency?

Lighting is one of the major energy consumers in hospitals, as in many other types of utility buildings. Various studies have shown that the lighting installation represents about 20% of the total energy consumption of a hospital.

As for energy-saving, this can be done on lighting, these can be divided into two main categories, each of which is discussed below.

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Smart switching

The fastest savings can be achieved with “smart switching” of lighting. The lighting is often turned on unnecessarily when, for example, there is sufficient daylight or there is no one in the room. With manually operated systems, in particular, the lights tend to be left on unnecessarily.

The advice is therefore to make the best possible use of automatic light control equipment.

Examples include: </ p>

• Daylight sensors
• Presence sensors
• Connection to the building management system (BMS)
• Timers

Efficient lighting

Fluorescent tube (TL) lighting is used for treatment in hospitals. Fluorescent tubes are not only efficient but also provide good quality light. Solid-state light sources or LEDs are expected to be even more efficient than fluorescent tubes in the future, but for now, fluorescent tubes still take priority in terms of color, retention, and color efficiency.

Besides the light source itself, two important factors influence the energy consumption of a lighting installation. The first is the ballast or ballast used for fluorescent tubes. There are two types of ballast: magnetic and electronic. Magnetic ballasts have the disadvantage that a large amount of energy is lost in the ballast itself, up to 20% of the energy consumption of the light source. For a 58 W fluorescent tube, this means that approximately 13 W is lost in the ballast. In contrast, electronic ballasts suffered only losses of 1 or 2%.

Magnetic ballasts still tend to be widely used in hospitals over 5 or 10 years old.

The second factor which influences the energy consumption is the luminaire, in particular the optics, the degree of reflectivity of the optics playing an important role. The higher the reflectivity of the fitting, the higher the light emission and the greater the efficiency.

Examples of these are given in the following case study.

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Case 1: Replacement of conventional magnetic ballasts

Introduction

The hospital in this case is a medium-sized institution with most of the lighting consisting of fluorescent tubes. However, there is no overview of the total energy consumption of lighting. This makes an accurate calculation difficult, but the potential savings can nonetheless be estimated from benchmark data.

Current situation

It is estimated that around 70% of lighting is currently fitted with obsolete conventional magnetic ballasts. As already explained, such magnetic ballasts are responsible for considerable energy losses (around 20%).

Proposal

By using energy-efficient lighting fixtures with electronic ballasts, ballast losses can be reduced and energy saved on lighting.

Estimate of savings and investments

There is no overview of the number of lights in the installations or the energy consumption of the lighting installation. However, based on data from previous studies and the literature, it is estimated that in an average hospital, lighting accounts for around 20% of total energy consumption. In the case study, this means for the hospital that the annual electricity consumption represents approximately 2,400 MWh. This value was first verified on the basis of the total floor area, determining the installed power per m² per 100 lux, which confirmed the estimate.

The savings potential was then calculated as follows:

The percentage of conventional fluorescent Lighting fixtures with conventional ballasts accounts for about 70%. It was also assumed that 90% of total lighting was fluorescent tubes. The majority of fittings have white enamel reflectors.

Total energy consumption of lighting:	2,400 MWh / year
Power consumed by fluorescent tube lighting (90%):	2 160 MWh / year
Losses in conventional ballasts:	20%
Percentage of light sources with conventional ballasts:	70%
Estimated number of conventional ballast fluorescent light sources, based on 58 W per tube:	4000
Total energy consumption of conventional fluorescent lamps	1,780 MWh / year
Potential savings by installing electronic ballasts and efficient optics	26%
Total savings potential	462 MWh / year

The annual energy savings amount to 462 MWh / year, i.e. a financial saving of € 37,000 per year.

 It can be deduced that considerable savings can be made on lighting, even if the investment costs are very high.

If the investments are to be repaid only on the basis of the lower energy consumption, then we arrive at a payback period of between 6 and 9 years, assuming that the existing luminaires are replaced with new ones.

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