Peace and quiet at a pleasant temper­a­ture

For many hotel owners, air-condi­tioning systems are often a neces­sary evil: while they may ensure optimum room temper­a­ture, they also use a lot of energy and their noise can prevent guests from getting a peaceful night’s sleep. In hotels for example, the average oper­ating time of fan coils is currently around 80 %, compared to around 40 % in office build­ings. The Abasto Hotel in Gern­linden, near Munich, has got to the root of the problem and now uses a new gener­a­tion of fan coils – to the satis­fac­tion of all parties concerned. Thanks to the highly effi­cient Green­Tech EC fans, rooms can be cooled bliss­fully quietly to the guest’s preferred temper­a­ture using 70 % less energy.

The Abasto Hotel opened in mid-september 2012 around 30 km from Munich, in the district of Gern­linden (figure 1). The 31 modern rooms have been fitted out to the latest stan­dards, and that includes the air-condi­tioning. for the hotel’s owner, robert rentzsch, who is himself a trained heating installer, the new system fully realises his vision for perfect air-condi­tioning.

Lower noise and energy consump­tion with increased comfort

Both the guest rooms and the “farmhaus” restau­rant in the base­ment are equipped with the latest air-condi­tioning tech­nology from Kamp­mann GmbH, based in the German town of Lingen (Ems). Fan coils known as “Venkons” are hidden behind the venti­la­tion slits (figure 2, page 6). The hotel guests cannot see them but they can certainly feel their effects. When the guest checks in at recep­tion, the booking soft­ware trans­mits the starting signal to the Venkon.

By the time the guest goes to unlock the door, the room will have been cooled or heated to room temper­a­ture (21 degrees Celsius). If the guest wants the room to be warmer or cooler, they can amend the temper­a­ture up to three degrees in either direc­tion via the Ka-Control control device. The unit does not make any noise. Describing an expe­ri­ence that nearly every hotel guest will be familiar with, Rentzsch recalls “I have been in many hotels where the air-condi­tioning got on my nerves. When you actu­ally have a unit in the room that both heats and cools and is prac­ti­cally inaudible it really makes your stay much more comfort­able.”

In order to make this feeling of comfort the stan­dard in noise-sensi­tive appli­ca­tions, Kamp­mann has devel­oped a system design for its fan coils specially for appli­ca­tions in hotels. In order to fulfil the tough require­ments for low noise, the air-condi­tioning specialist has sought coop­er­a­tion with its chosen high-perfor­mance partner ebm-papst. At the heart of the Venkon is a centrifugal blower, and this is produced by fan manu­fac­turer ebm-papst based in Mulfingen, Germany (Figure 3a).

When Kamp­mann devel­oped the latest gener­a­tion of the Venkon, the key factors it looked at were space require­ments, noise level and power consump­tion. ulrich Budde, sales Manager for Kamp­mann in southern Germany and Austria explains that “The crucial factors for us with the fan coil was that the motors would have a partic­u­larly low noise level and that there would be a high level of control in the lower speed range.” Both factors are inex­tri­cably linked; hotel air-condi­tioning systems employ the lower speed range because it offers the lowest noise levels.

Contin­u­ously adjustable – for greater satis­fac­tion

The lower speed range is also the range with the greatest poten­tial for energy savings. Stan­dard AC motors only offer incre­mental control, whereas modern Green­Tech EC motors are contin­u­ously adjustable across the entire speed range. Even at low speeds, the high level of energy effi­ciency of the EC motors brings bene­fits, as the motors are supplied with an input of 0-10 V.

The Green­Tech EC centrifugal fans are avail­able as single, dual or triple fans with a power of between 40 and 250 W, to suit the room size. In all sizes, they offer energy savings of up to 70 % and noise reduc­tion of up to 5 dB(A). Thanks to the plug-and-play solu­tion, existing units can also be retro­fitted without a great deal of work (figure 4).

ebm-papst’s product range includes EC fans in the power range 400 W – 12 kW for venti­la­tion and air-condi­tioning tech­nology (VACT). The RadiPac range (Figure 3b) with aluminium-welded impellers and inte­grated control elec­tronics enable a design that saves on space compared to models with belt-driven motors.

The resulting space saving also facil­i­tates instal­la­tion and start-up. The intel­li­gent control elec­tronics of the Green­Tech EC centrifugal fans enable a number of different automa­tion and manage­ment tasks to be imple­mented via MODBus. Major savings can be made on the elec­trical oper­ating costs thanks to the ability to control the Green­Tech EC centrifugal fans based on actual require­ments.

Bene­fits of a decen­tralised system

The hotel’s owner, Robert Rentzsch, explains that “for me, the energy-effi­cient EC motors were a crucial deter­mining factor, because i had designed the entire building with a view to keeping the oper­ating costs as low as possible.” The hotel owner has installed 40 Venkons in the Abasto Hotel: 31 in the guest rooms and nine in the restau­rant. Heat is provided via a heat pump with 45 °C flow temper­a­ture, and cooling is provided using ground water. The high­light of the system is that heating and cooling takes place actu­ally inside the room itself; the venti­la­tion unit under the roof merely provides fresh air and recovers 81 % of the heat from the air extracted from the room.

Stan­dard centralised units heat and cool the air centrally and then distribute the air around the building via air ducts. The Air-block C venti­la­tion unit (figure 5) manu­fac­tured by Kamp­mann using Green­Tech EC fans now only supplies the fresh air – the decen­tralised Venkons inside the hotel rooms are oper­ated indi­vid­u­ally. The unit is there­fore very compact and the supply air ducts can also be made smaller. As a result, trans­port losses are also greatly reduced.

For Robert Rentzsch, the factor of whether a system is decen­tralised or not is in itself no insignif­i­cant matter: “For heating installers, space is always a major issue.” This is because entralised systems neces­si­tate ducts with large cross-sectional areas. Rentzsch has managed to install the system with just 30 centime­tres of inter­me­diate ceiling at the Abasto Hotel. With a centralised system he would have required up to 80 centime­tres – dead space that would only have increased costs. “I was convinced straight away that we should be heating and cooling the air where it is actu­ally going to be used”, says Rentzsch.

The oper­ating costs at a glance

“I believe that the concept we have here is the best possible solu­tion for hotel appli­ca­tions”, claims Ulrich Budde with convic­tion. He is also pleased about the increased level of control­la­bility. If the air quality is OK, the system simply provides heat or cooling as required; if the temper­a­ture is OK, the system simply provides venti­la­tion. However, it is not always easy to commu­ni­cate the best solu­tion. Although at Abasto Hotel the investor is also the user, and there­fore close atten­tion was paid to the oper­ating costs. “As a general rule, investors look above all at the invest­ment costs and the minimum legal equire­ments”, says Budde, explaining the market situ­a­tion. A key factor is the life cycle costs over the
entire service life.

The minimum require­ments are also becoming more strin­gent: the Euro­pean union’s Energy-related Prod­ucts Direc­tive demands a much higher level of energy effi­ciency. Air-condi­tioning devices with Green­Tech EC tech­nology help with compli­ance as they already go signif­i­cantly beyond the require­ments. What is more, build­ings equipped with high-quality tech­nology with a long service life fare much better on the real estate market. Finally, guests are much happier when they can stay in a hotel room with bliss­fully quiet air-condi­tioning tech­nology; they will be more likely to come back for another stay and will spread the word.

Conclu­sion

The successful use of Green­Tech EC tech­nology in this hotel appli­ca­tion clearly illus­trates just how much this tech­nology has to offer hotel owners in compar­ison to a stan­dard air-condi­tioning system with AC motor and incre­men­tally controlled winding. Firstly they benefit from the reduc­tion in noise thanks to the EC motor, which is up to five deci­bels quieter – for the human ear this equates to a reduc­tion in the overall noise impres­sion of almost half. Secondly, they can reduce energy consump­tion by up to 70 % thanks to the high-perfor­mance, contin­u­ously adjustable control func­tion­ality across the entire range. Hotel owners save on energy costs, archi­tects and building plan­ners benefit from a future-proof solu­tion and guests can finally have a more peaceful night’s sleep.