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22
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22 (117) 2015
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Real Estate & Construction

How hotels can save money with LED lighting

by Kinga Raczak, biuroKR architectural practice, and Mateusz Szubel, Estera Przenzak and Wojciech Goryl, AGH University of Science and Technology, Faculty of Energy and Fuels
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Poland has over 2,250 hotels, of which over 350 are premium class, four- and five-star hotels1. These facilities are built with the intention to satisfy the customer by offering comfortable, functional space and also excellent service. 

Many of these hotels demonstrate an original architectural concept. An annual hotel industry award recognises outstanding projects. Winners of the Hotel With A Concept award include Hotel Arłamow (2014), Narvil Conference Spa Serock (2013), Pure Hotel Wroclaw (2012), and Hilton Gdansk, the Andel’s  hotels in Lodz and Krakow in previous years.

In the era of architecture with pro-environmental vision, does the term ‘concept’ also apply to the efficient use of energy? If so, what kinds of solutions are most often applied? Are they the result of the economic balance of an investment, or are they as well a response to an increasing customers’ awareness regarding the environmental protection?

From the investor’s point of view, long-term savings are achieved for example by using heat recovery in air-conditioning units with recuperation, monitoring and fluid temperature adjustment in the rooms and energy-efficient light sources. For the customer, important elements affecting the comfort of the stay in the room include adjustable lighting (adjustment of its colour as well as intensity), de-chlorinated bath water, air purity and noise level.

The interests of service providers and recipients often diverge. However, the lighting aspect seems to be equally important for the investor – in economic point of view – and for the customer who wants to relax after a hard day's work in a room with the adequate quality and intensity of light.

In recent years classic incandescent light bulbs have been replaced with fluorescent lamps, and now increasingly often with light-emitting diodes (LEDs). This is due to the significant difference in the efficiency of these light sources. Efficiency in lighting is called ‘luminous efficacy’ – the  amount of luminous flux that can be radiated from one watt of electric energy supplied to a certain source. This parameter may also be given as a percentage of the ideal source (which emits a maximum of 683 lumens per one watt). Luminous efficacy of a traditional, incandescent bulb is only 1-3%. This means that the remaining 97-99% is lost mainly in the form of heat. For fluorescent lamps this parameter is varied in the range of 6-17%, while LED lights are definitely the favourite here, with the luminous efficacy at a level of up to 44%.

The costs of lighting of a typical hotel room –  lit by two bracket lamps above the bed, a small desk lamp, and armchair lamp, and general room lighting – depend on the bulbs used. With  traditional lighting, this would look as follows: bracket lamps: 2x15W, desk lamp: 75W, armchair lamp: 75W, general lighting: 75W. In total, the power needed to illuminate a room with incandescent light bulbs is 255W. But use instead LEDs, and the power requirement is as follows: bracket lamps: 2x2W, desk lamp: 9W, armchair lamp: 9W and general lighting 9W. The total power needed now falls to a mere 31W. Such a set of LED lamps was used in the project of a relatively small (25-room) 5-star hotel in Krakow.

The authors of this analysis have modelled the following average consumption of lighting: in the six summer months, one hour in the morning and three hours in the evening. For the six winter months, two hours in the morning and six hours in the evening. The analysis assumes 100% occupancy of hotel rooms and the use of installed light sources. The total time of lighting used during the winter amounts to 2,920 hours, whereas during the summer – 730 hours. The total energy consumption of incandescent light bulbs is 744.6 kWh over the winter and 186.2 kWh over the summer. In total, for incandescent light bulbs, annual energy consumption in one hotel room is around 930 kWh. Using LEDs, energy consumption drops to 90.5 kWh (winter) and 22.6 kWh (summer), which averages out at 113 kWh per year (more than eight times less energy than with conventional lighting). Assuming the average price of electricity in Poland is 0.56/kWh zlotys, this works per room at out at 521 zlotys for incandescent light bulbs, and 63 złotys for LEDs. Over all 25 rooms in the space of one year, LED lighting saves around 11,500 zlotys compared to the use of traditional light bulbs.

Now, if we look at larger hotel facilities, the savings resulting from the use of LEDs compared to incandescent light bulbs are as follows:

  • Nosalowy Dwór Resort (263 rooms): 120,000 zlotys
  • Hotel Arłamów (250 rooms): 115,000 zlotys
  • Hotel Hilton Wroclaw (189 rooms) 86,000 zlotys,
  • Hotel Dr Irena Eris (85 rooms): 39,000 zlotys.

However, given that the average annual occupancy rates of hotels are less than 100% (72% in Warsaw, 75% in Krakow, 65% in the Tri-City and 64.3% in Wroclaw), actual energy consumption and the potential benefits of LED lighting are correspondingly smaller. But this study does shows huge potential savings for the owners of hotel facilities willing to replace traditional bulbs with LEDs.

The decision to use LED light sources in a hotel results from the investor’s economic interests but should also take the customers’ requirements for comfort into consideration. Lighting needs to be integrated into the intelligent building automation system (Building Management System). The adjustment of LED light sources should depend on the natural flow of light through the windows, without sacrificing efficiency, resulting in additional savings ranging from a few to a dozen percent. Effective collaboration of LED lamps with programmable power supplies facilitates the creation of so-called ‘scenes’, popular with guests because of the possibility to adjust the atmosphere in the room depending on the situation.

So far, we’ve looked at the energy- and cost savings of using LEDs. But what about the comfort of staying in the hotel room – how does the quality of light emitted by LEDs affect the guests? You don’t need sophisticated measuring equipment to determine that the colour of light emitted by traditional light bulbs is different to the colour of fluorescent lamps or some LED lamps. This is because different light sources are characterised by a different colour temperature. A classic light bulb gives a warm light, creating a pleasant, relaxing atmosphere. The colour temperature of this source is relatively low. Wherever the light should stimulate, it is reasonable to use lighting with high colour temperature, which gives the effect of a cold light, characteristic of fluorescent lamps. Manufacturers of fluorescent and LED lamps today offer sources of different colour temperature, depending on the customer’s requirements.

Why, then, an investor considering various alternatives for light bulbs should decide to choose LED lamps, and not for example fluorescent lamps? The quality of light is not due solely to its colour temperature. A very important parameter is the CRI - Colour Rendering Index. It ranges from 0-100, where the highest value means that the colour of illuminated surfaces is rendered the same way as by solar radiation (sunlight). Due to the principle of operation of an incandescent light bulb, it is characterised by a CRI of 100. Nowadays, you can get the same result using LEDs with the colour of the light corresponding to individual components of white light (red, green, blue). Good colour rendition is, however, difficult to obtain from fluorescent sources. In the case of hotel interiors, this parameter may be of particular importance: the light with poor CRI characteristics may cause rapid eye fatigue. In addition, it is necessary to provide colour rendering close to 100% for lighting works of art.

Good quality LED lamps are one of the best light sources available on the market. The quality of light emitted from the LED is comparable to the light coming from the incandescent bulbs and much better than from the fluorescent lamps. And compared to conventional sources, LED consumes much less energy to emit the same amount of light. The price of these modern energy-efficient light sources is continuing to decrease, which causes a significant increase of interest in their use.

[1] ”Hotelarz” magazine  - August 2015 ”2014 – 1.5 mln more guests in hotels”, table ”Hotel market in 2005-2014”
[2] ”Hotelarz” magazine  - August 2015 ”2014 – 1.5 mln more guests in hotels”, table ”Hotels according to star rating”

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