The climate in hotel rooms is an ever-occurring reason for complaints by guests – an unavoidable situation.

Hotel operators invest a lot of money to provide guests with a comfortable stay. Satisfied guests will revisit the hotel when necessary, provide positive feedback on the usual portals and this way become key multiplicators. The common star classification in line with HOTREC provides criteria for rating the comfort. This enables “building up” to a four-star hotel as early as in the planning phase. And yet, fulfilling even five-star standards itself is not a guarantee for satisfied guests, for an extremely important factor for a guest’s comfort is the climate. And air conditioning – although it is common practice as of a certain category – is not even an obligation according to German hotel classifications.

But what use is the air conditioning of the room if, for example, due to an unsatisfactory choice, is not able to provide the necessary cooling capacity? Or able to but only manages to with high speeds and a corresponding background noise? Definitely worthwhile is a controlled ventilation system that saves a considerable amount of energy and also caters for comfort plus. The right choice of system, the control unit and the size under due observation of statutory regulations promises great potential energy savings in the long run as well as guests that don’t, as otherwise so often, complain about room temperatures. Planning and installing a system solution that is satisfying for guests, operators and legislator requires a close look at the rooms. Not only is the room volume decisive but also the number of occupants, the position and size of the bathroom, and even the building materials used. But, first thing first…

Many laws, standards and regulations are to be observed

There is a whole conglomeration of laws, standards and regulations to be observed for the design. The DIN EN 15251, 13779 and 12792 govern the room air quality. The Die VDI Regulation 6022 defines the hygiene requirements of units and systems regarding ventilation and air conditioning. And DIN EN ISO 7730 determines as “comfort standard” the “ergonomics of the thermal environment”. This is joined by DIN 18017, which governs the ventilation of interior rooms, especially bathrooms. From environmental aspects, above all the Energy Saving Regulation and, of course, the ErP Directive (also called the Eco Design Regulation) for energy consumption-relevant products are to be observed. German-European regulating frenzy? Maybe. Yet, in the end, the regulations all serve a good purpose – namely to provably generate a good hotel room climate in an energy-saving and environmentally friendly way. 

As an example, we would like to consider a double room with 22m² floor space. It has an en-suite bathroom, as is common for hotels, of 5m². The aim with the air conditioning are minimum and maximum temperatures of 20 degrees Celsius in the winter and 26 degrees Celsius in the summer conform to DIN EN 15251 as well as a corresponding air quality conforming to the standards. First of all, we can hardly get by without controlled and machine-controlled ventilation in times of ever thicker building shells. Airing by opening windows is hardly sensible for two reasons: a tilted window does not achieve the necessary minimum air exchange. In addition, one’s own thermal standard is influenced, for example in winter, when we let in fresh air but also cold air, which in turn has to be warmed up using a lot of energy. Yet how much fresh air does a room actually need? The relevant standard in this case is DIN EN 15251. According to that, the outside air requirements comprise two additive components: the outside air volume flow for people plus the outside air volume flow for, for example, vapours from the carpet. DIN EN 15251 divides air quality into three categories and contrasts each category with a percentage of the expected unsatisfied guests. In the middle category (still with 20 percent unsatisfied guests), a fresh air flow of 25 m3/h per person is defined – i.e. 50 m3/h for our double room. We now have to add the air flow for compensation the building emissions. In this case, there are also three categories: very low-pollutant, low-pollutant and not pollutant. For a low-pollutant building, an air flow of 2.52 m3/h per square metre is defined. For the double room, which is 17 square metres in size when subtracting the size of the bathroom, we owe the room 92.8 m3/h of fresh air. If the rooms have been designed the rooms correctly, the question is then posed as to the “choice of weapon”: which system fulfils my requirements perfectly? The most efficient and the smartest solution is one that logically is asserting itself on the market more and more: centralised ventilation, decentralised air conditioning.

The most efficient solution: centralised ventilation, decentralised air conditioning

Separating the tasks of air conditioning and ventilation guarantees large energy savings and flexible ways of controlling. If, however, both tasks are combined, the centralised ventilation unit not only supplies fresh air – it conditions, heats or cools it as well. However, it is not seldom the case that the requirements for fresh air are low and it merely needs to be heated or cooled. This is particularly the case in hotel rooms. The rooms are frequently vacant during the day because the guest is sightseeing, participating in conferences or visiting the spa area. If the tasks are separated, the centralised ventilation unit, which is equipped with a heat recovery unit conforming to the ErP, only supplies as much fresh air as is necessary to maintain the quality of air. The decentralised units in the rooms only have to adjust the temperature in line with requirements.

It is quite probable that the rooms are frequently empty during the day. But what is certain is that the rooms, when occupied, are inhabited at night. Most of the time that guests spend is thus when asleep. And when the guests are present (in our double room example) 92.8m³/h of fresh air has to be supplied and heated/cooled. The necessity for absolute quietness thus applies to the main share of air condition activities and thus to its noise emission. The units should thus always be dimensioned on the basis of the sound pressure level. This is the only way that is can be guaranteed that the necessary heating or cooling output is rendered under due observation of the noise thresholds.

The requirements have been determined – which units can actually fulfil the requirements?

After the fresh air requirements have been determined and the air conditioning concept has been found, it is now a matter of finding the right units to implement it. Besides the matching performance data, it is important for the products to meet the ErP Regulation. Not only does the environment benefit from that – due to the high degree of efficiency of the units, high energy savings are also possible. The official regulation called “2009/125/EC Directive” relates to energy consumption relevant products, to which ventilation and air conditioning units belong without a doubt. Accordingly, a two-way ventilation unit, i.e. a ventilation unit with extractor and supply fan must have a heat recovery system as of 01 January 2016. In addition, the ErP Regulation stipulates precisely the performance efficiency of the fans depending on the air capacity and equipment.

The Lingen-based company Kampmann is a competent expert for air conditioning solutions in hotels and offers a large portfolio of hotel-compatible air conditioning and ventilation units as well as the corresponding integration in the building management services. A system with Kampmann technology can be mentioned her as an example.

Placed on the roof or in the engineering room: one or more Airblock AG ventilation units, a flexible centralised ventilation system equipped with a diagonal plate heat exchanger and which recovers up to 90 percent of the heat conforming to the ErP 2018. The Airblock KG as the centralised system supplies the decentralised fan coils in the rooms. A solution to this is the Venkon EC , which is also known as the “hotel Venkon”. It is the quietest on the market, highly efficient with EC technology, VDI 6022 conform and naturally also observes the ErP Regulation. This fan coil is distinguished by its particularly quiet basic operating mode – a property that guests will appreciate at night. And even in the heating season, when the Venkon EC is responsible for heating the room, its quiet as a whisper operation pays off. Via KaContro control unit, the Venkon can be integrated in open building management services systems – guests can adjust their personal comfort climate by way of a room control unit. By the way, Kampmann, with their knowhow, is also represented in the Munich Hotelkompetenzzentrum.

In a nutshell

The concrete determination of fresh air requirements, a suitable system where ventilation and air conditioning tasks are separated, the size of the system based on the sound pressure level and the observation of the ErP Regulation are the corner points for an air conditioning system that satisfies guest, operator and the environment. A complex demand where one should get advice from an expert.