1. Energy-saving solutions and devices

In many hotels energy consumption is highly inefficient, mainly due to high heat losses through poorly insulated walls, roofs, windows and heating pipes, poor lighting management and systems that require excessive energy consumption for both heating and cooling. Improving energy efficiency in these areas depends on the investment possibilities of the owners of the objects and the type of structure and technical condition of the building, which determine the scope of possible modernization works.

1.1.       Electronic equipment, household appliances and lighting

Energy-saving devices are a wise, long-term investment for owners of hotels. The energy class of a device is a parameter that determines its energy efficiency. It is determined by how much electricity, water or other resources the equipment consumes. In the new energy classes, in force from 2021, the “pluses” (used in energy efficiency class A in the existing labels) have been abandoned. Currently, the highest energy class is A, and the lowest – G class.

According to EU guidelines, light sources should also be equipped with an energy label which includes information on the energy efficiency class, luminous flux in lumens, electricity consumption of lamps in watts and average life expectancy in hours.

By installing LED lighting, one can significantly reduce electricity costs, but can save even more by investing in an intelligent LED lighting system that has automatic sensors to detect the lighting needs of each area of the building.

The Hotel Corinthia in Lisbon is a special place. With 521 guest rooms, it is the largest five-star hotel in Portugal and the best example of providing luxurious hotel services at the highest level. In places where lighting effects play an important role, such as rooms, corridors and the reception area, 6,330 LED lamps have been installed (Fig. 3). Lower electricity bills are not the only benefit that has been achieved. As the new LED lamps can be connected directly to the 230 V mains, the need for transformers has disappeared. Thanks to the new luminaires, the amount of light produced has increased and energy costs have been reduced by 80%. As a result, the investment returned after 9 months [24].

Figure 3. Arrangement of lighting with LED lamps in the interiors of the Corinthia Hotel

A significant cost of energy in many hotels is the consumption of electricity by the so-called “energy vampires”. Also known as standby power, it refers to the way electricity is consumed by electronic and electrical devices when they are turned off (but are designed to take some energy) or in the standby mode. Typical devices, such as: TV, video, DVD, scanner, printer, desktop computer, charger, modem, etc. in stand-by mode use 5 to 20 W [29]. Automatic-shutdown sockets may be the solution.

1.2. Building insulation

In the era of constantly increasing energy costs, it is important to minimize heat losses from external partitions. Architecture causes the occurrence of numerous thermal bridges, through which a lot of heat escapes to the outside during the heating season. It is very well visible in the photos from the research of the object with a thermal imaging camera. On their basis, it is possible to locate the places of the greatest heat losses and take measures to eliminate them.

Thermal modernization is the best way to improve the energy efficiency of existing buildings and insulating the building includes the following activities:

• Insulation of external partitions – laying an insulation layer that will prevent cooling down or overheating of the interior of the building
• Replacement of doors and windows – selection of appropriate models with high insulation properties that will avoid thermal bridges
• Roof insulation – a well-chosen roof allows one to reduce heat losses by up to several dozen percent

An excellent example of such activities is the thermal modernization of one of the buildings of Stirling University [29]. The old building was thermally ineffective and a series of thermal imaging studies was commissioned. They were made before and after construction works increasing the insulation of external partitions. The “Before” thermogram shows higher wall and window temperatures. “After” indicates much lower temperatures, which means that less heat is escaping through the partitions than before (Fig. 4).

Figure 4. Thermogram before and after thermal modernization of the building

1.3. Heating system and hot water system

The second stage of thermal modernization is the assessment of the efficiency of the heat source in the building and its possible replacement, as well as the improvement of the efficiency of devices and fittings cooperating with the source.  The most effective heat sources are gas boilers or heat pumps. It is especially worth considering condensing boilers which, apart from the combustion energy, also use the heat contained in the water vapor from the flue gas. In a traditional boiler, exhaust fumes with a temperature in excess of 300°C are often released. The condensing boiler uses a larger or additional heat exchanger to reduce this heat to just around 50°C. For example, Sea Power Horyzont in Jastrzębia Góra – an implementation in 2022 or Maxymilian *** Unique Hotel in Kołobrzeg – an implementation in 2022.

Replacing old plumbing fixtures and devices that often consume a lot of energy also significantly reduce energy costs. This action was taken at the InterContinental Hotel in Madrid, which reduced energy consumption by 445,000 kWh per year [21]. The applied solution allowed reducing energy consumption by up to 40%. The 475,000 kWh that the object saves annually translates into a USD 37,000 lower electricity bill. It also means a return on investment in less than two years. The hotel’s CO2 emissions also decreased by 253,000 kilograms per year [21].

To ensure maximum energy savings in the building, the operation of the entire heating system should be automated. Many companies offer accommodation owners ecological energy management tools. These types of systems include wireless thermostats that monitor and control the temperature in the room (Fig. 5).

Figure 5. Control panel in the room

Specific control settings where guests can only select temperatures within a certain range is another way to cut costs. As the seasons change, so do guests’ temperature needs. A simpler solution than fully automatic control systems are thermostats with the possibility of time management through the attached timer. The programmer is designed to automatically switch the thermostat from day mode to night mode, which in practice means lowering the set temperature by 4°C. If we have a set temperature of 21°C, then at night we will get 17°C, which is not only healthier for the body, but can also result in significant savings. Lowering the temperature even by 1°C results in energy savings of up to 6% [7].

Figure 6. Touchless faucet [9]

Water heating is one of the main loads of hotels. Specialized overhead showers and taps are the main areas where inexpensive modernization can be made. Faucets and shower heads with low water flow are a good solution. Faucet aerators are a simpler solution. A more expensive solution is the installation of contactless washbasin faucets with infrared sensors (Fig. 6), which turn on only when hand movements are detected.

1.4. Renewable energy sources

The use of renewable energy sources is becoming a basic requirement of modern energy and environmental policy in most countries in the world.

When buildings are equipped with photovoltaic panels, they can maximize natural energy on days with clear skies and even sell excess energy to the grid. Energy costs will continue to rise, making savings in resorts and hotels with solar panels grow year by year. For example, in a 94-room Hampton Inn hotel in Southern California, a 102 kW photovoltaic panel system was installed (Fig. 7). The solar panels at this hotel produce over 13,000 kWh per month, which cuts energy bills by 35-45% depending on the season. They are currently saving between $ 7,400 and $ 8,800 a month and expect to fully recover their investment in just 7.75 years [2].

Figure 7. Hotel Hampton Inn in California with photovoltaic installation

Heat pumps are other devices that can be used to heat a building and prepare hot water. They use renewable energy accumulated in soil, water or air. It is clean energy available without limitations. Thanks to cooperation with recuperation and photovoltaic installation, heat pumps form a compatible heating system with high efficiency.