BE1024676B1 - Air-conditioning system and method for controlling a air-conditioning system - Google Patents

Abstract

The present invention relates to a method for controlling a climate control system of a building. The air-conditioning system comprises a plenum, an air outlet with an outlet valve, and an air inlet with a inlet valve for controlling the flow of supplied outside air. The air-conditioning system further comprises an air heat pump with an evaporator, a single fan, and a control device for controlling the at least one discharge valve, the position of the discharge valve being adjusted by means of the control device as a function of a desired discharge rate. Furthermore, the pressure in the plenum is adjusted by means of the control device as a function of the desired discharge flow rate.

Description

(73) Holder (s):

VERO DUCO NV 8630, VEURNE Belgium (72) Inventor (s):

RENSON Luc Louis 8620 NIEUWPOORT Belgium (54) Air-conditioning system and method for controlling an air-conditioning system (57) The present invention relates to a method for controlling an air-conditioning system of a building. The air-conditioning system comprises a plenum, an air exhaust with an exhaust valve, and an air supply with a supply valve for controlling the flow of supplied outside air. The air-conditioning system further comprises an air heat pump with an evaporator, a single fan, and a control device for controlling the at least one discharge valve, wherein the position of the discharge valve is adjusted by means of the control device in function of a desired discharge flow rate. Furthermore, the pressure in the plenum is adjusted with the aid of the control device in function of the desired discharge flow rate.

BELGIAN INVENTION PATENT

FPS Economy, K.M.O., Self-employed & Energy

Publication number: 1024676 Filing number: BE2017 / 5353

Intellectual Property Office

International classification: F24F 5/00 F24F 11/00 F24F 13/14 Date of issue: 24/05/2018

The Minister of Economy,

Having regard to the Paris Convention of 20 March 1883 for the Protection of Industrial Property;

Having regard to the Law of March 28, 1984 on inventive patents, Article 22, for patent applications filed before September 22, 2014;

Having regard to Title 1 Invention Patents of Book XI of the Economic Law Code, Article XI.24, for patent applications filed from September 22, 2014;

Having regard to the Royal Decree of 2 December 1986 on the filing, granting and maintenance of inventive patents, Article 28;

Having regard to the application for an invention patent received by the Intellectual Property Office on 12/05/2017.

Whereas for patent applications that fall within the scope of Title 1, Book XI, of the Code of Economic Law (hereinafter WER), in accordance with Article XI.19, § 4, second paragraph, of the WER, the granted patent will be limited. to the patent claims for which the novelty search report was prepared, when the patent application is the subject of a novelty search report indicating a lack of unity of invention as referred to in paragraph 1, and when the applicant does not limit his filing and does not file a divisional application in accordance with the search report.

Decision:

Article 1

VERO DUCO NV, Handelsstraat 19, 8630 VEURNE Belgium;

represented by

NLO BVBA, Technologiepark 19, 9052, ZWIJNAARDEGENT;

a Belgian invention patent with a term of 20 years, subject to payment of the annual fees as referred to in Article XI.48, § 1 of the Economic Law Code, for: Air-conditioning system and method for controlling an air-conditioning system.

INVENTOR (S):

RENSON Luc Louis, E. Verhaerenlaan 40, 8620, NIEUWPOORT;

PRIORITY:

30/06/2016 NL 2017079;

10/04/2017 NL 2018676;

BREAKDOWN:

Split from basic application: Filing date of the basic application:

Article 2. - This patent is granted without prior investigation into the patentability of the invention, without warranty of the Merit of the invention, nor of the accuracy of its description and at the risk of the applicant (s).

Brussels, 24/05/2018,

With special authorization:

BE2017 / 5353

Air-conditioning system and method for controlling an air-conditioning system

The present invention relates to a method for controlling a building air-conditioning system. The air-conditioning system comprises a plenum, an air exhaust for extracting indoor air from at least one space of a building at the plenum, and an exhaust valve for controlling the flow of air extracted from the at least one space of the building, and an air supply for supplying outside air to the plenum, and a supply valve for controlling the flow of supplied outside air.

The air-conditioning system further comprises an air heat pump with an evaporator for exchanging heat between air supplied over the evaporator and the evaporator, a single fan for drawing in the plenum of the indoor and outdoor air through the at least one air exhaust and the at least one air supply, respectively. and for driving the extracted indoor and outdoor air over the evaporator, and a control device for controlling the at least one discharge valve, wherein the position of the discharge valve is adjusted by means of the control device in function of a desired discharge flow rate. The present invention further relates to a climate control system.

State of the art

Such a climate control system is known from FR29411521. A drawback of this system is that, in heat exchange mode, continuous control of the fan is required. Because the fan is continuously controlled by a control device, the fan will require more maintenance, be replaced more quickly and produce more noise by adjusting the fan speed. The climate control system will also consume more energy.

Object of the invention

An object of the invention is to provide an improved method for controlling an air-conditioning system. A further object of the invention is to provide a method and air-conditioning system which are more energetically advantageous.

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Description of the invention

This object is achieved with the method according to the invention, as described in claim 1. By controlling the pressure dP in the plenum with the aid of the control device, the desired discharge flows Qa, Qb, Qc can be achieved. If the control of the discharge valves proves insufficient to achieve the flow rate through the discharge, the control device will control the pressure dP in the plenum in order to achieve the desired discharge flow rate Qa, Qb, Qc. In a preferred embodiment of the invention, the control device will control the position of the supply valve to control the pressure dP in the plenum.

It is advantageous that the flow rate of air Q which is driven over the evaporator can be maximally set for a specific desired discharge flow rate Qa, Qb, Qc. In use, one control valve can always be set in an open position. Preferably, the supply valve will be set in a maximum open position.

This will allow more energy to be drawn from the air driven over the evaporator compared to methods where a fixed flow is driven over the evaporator.

In a preferred embodiment of the invention, the speed of the fan will be kept constant.

This object is further achieved with the method according to the invention as described in claims 2-10.

The invention further relates to a climate control system as described in claims 11-20.

Brief description of the figures

The invention will be explained in more detail below with reference to an illustrative embodiment shown in the drawing.

Figure 1 shows a schematic cross section through a building with a climate control system according to the invention;

Figure 2 shows a schematic cross section through a first embodiment of a climate control device;

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Figure 3 shows an exploded view of a second embodiment of a climate control device.

Detailed description of the figures

Figure 1 shows a schematic cross-section through a building 1 with several dimensions and an air-conditioning system 10 comprising an air-conditioning device 100 and an air heat pump 110 with an evaporator 111 in the air-conditioning device 100.

The air-conditioning system 10 further comprises a multi-air exhaust duct 20 for extracting indoor air from multiple walls of the building 1, an air supply duct 30 for supplying outdoor air to the air-conditioning device 100, and an air outlet channel 40 for extracting air from the air-conditioning device 100.

Each exhaust air duct 20 is connected upstream to a space of the building and is connected downstream to the air-conditioning device 100. The air supply channel 30 is connected upstream to supply opening in the building and is connected downstream to the air-conditioning device 100. The air outlet channel 40 is upstream. connected to the air-conditioning device 100 and connected downstream to a discharge opening in the building.

In use, indoor air from the building 1 is supplied to the air-conditioning device 100 via the air exhaust ducts 20. In the air-conditioning device 100, the indoor air is forced over the evaporator 111 and exhausted from the air-conditioning device 100. The indoor air is further exhausted from the building 1 via the air outlet channel 40.

In heat pump operation of the air-conditioning device 100, outside air is furthermore supplied to the air-conditioning device 100 via the air supply channel 30. In the air-conditioning device 100, the outside air is mixed with the inside air and driven together over the evaporator 111 and discharged from the air-conditioning device 100. The mixed air is further exhausted from the building 1 via the air outlet channel 40.

Figures 2 shows a schematic cross-section of an air-conditioning device 100 according to the invention. The air conditioner 100 includes a plurality of air exhaust connections 120a, 120b, 120c for receiving exhaust air

BE2017 / 5353 indoor air, an air supply connection 130 for receiving outdoor air and an air outlet connection 140 for extracting air.

In each air exhaust connection 120a; 120b; 120c is a discharge valve 121a; 121b; 121c provided with a resistance value K * _a ; K * i ,; K * _c . In the air supply connection 130, a supply valve 131 is provided with a resistance value K * o.

Each exhaust air connection 120a, 120b, 120c is connectable to an exhaust air duct 20a; 20b; 20c of a climate control system 10, each air exhaust duct 20a; 20b; 20c a resistance value Ka; Kt ,; Kc has. The air supply connection 130 is connectable to an air supply channel 30 of the air-conditioning system 10, the air supply channel 30 having a resistance value Ko. The air outlet connection 140 is connectable to an air outlet channel 40 of the air-conditioning system 10.

The evaporator 111 of the air heat pump HO is arranged to exchange heat between air fed over the evaporator and a fluid in the evaporator 111. The evaporator 111 divides an internal volume of the air-conditioning device 100 into a plenum 101 and an exhaust volume 102. In the plenum 101, where the indoor air and the outdoor air are mixed, a pressure dP is measured. The pressure is measured using pressure sensor 160.

The air-conditioning device 100 further comprises only a single fan 150 for drawing in and out air, respectively, through the air exhaust connections 120a, 120b, 120c and the air supply connection 130, and for driving the air from the plenum 101 over the evaporator 111 to the discharge volume 102.

In an embodiment of the air-conditioning device 100, a heating unit can further be provided for heating the outside air before mixing the inside air and the outside air in the plenum 101.

In use of the air-conditioning device 100, on the one hand a ventilation company and on the other hand a heat pump operation can be distinguished, whereby in ventilation operation the air heat pump 110 is put out of use.

In ventilation operation of the air-conditioning device 100, indoor air from the building 1 is supplied via air exhaust connections 120a, 120b, 120c to the air-conditioning device 100 with desired exhaust flow rates Q _a , Qb, Qc. In the air-conditioning device 100, the indoor air is forced over the evaporator and out of the air-conditioning device

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100 exhausted through the fan 150 and the air outlet connection 140 with an outlet flow rate

Q.

In heat pump operation of the air-conditioning device 100, furthermore, outside air is supplied via the air supply connection 130 into the air-conditioning device 100 with a supply flow rate Qoda. In the plenum 101 of the air-conditioner 100, the outside air is mixed with the inside air and expelled together over the evaporator and discharged from the air-conditioner 100 via the fan 150 and the air outlet connection 140 with an outlet flow rate Q.

If the air heat pump 110 is an air-to-water heat pump, water can be heated in heat pump mode for use in central heating (central heating) or as domestic hot water (DHW).

The air-conditioning device 100 further comprises a control device 200 for controlling the air-conditioning device 100. The control device 200 is arranged for controlling the exhaust valves 121a-c for controlling the flow of exhaust air. The control device 200 is also arranged to control the supply valve 131 to control the pressure dP in the plenum 101. The control device 200 is furthermore arranged to control the fan 150 to control the pressure dP in the plenum 101 by by means of the speed of the fan 150.

The control of the air-conditioning device 100 comprises, with the aid of the control device 200, the control of the flow rate of exhaust air by controlling the discharge valves 121a-c and the pressure dP in the plenum 101. During the control of the air-conditioning. device 100 will always have at least one discharge valve 121 and / or the supply valve 131 fully open. Preferably this is the supply valve 131. The discharge valve 121 and the supply valve are so-called control valves. A control valve according to the invention is a valve which has at least one position between an open position (maximum position) and a closed position (minimum position).

In ventilation mode of the air-conditioning device 100, when the air heat pump is out of use, the supply valve in the air supply connection 130 is in the closed position. The control device 200 controls the discharge valves to achieve the desired discharge flow Qa, Qb, Qc. The control device 200 controls the discharge valves 121a-c

BE2017 / 5353 function of the measured pressure dP and the resistance value of the channels Ka; K B; Kc to set the required discharge flow rates Q _a , Qb, Qc.

If the desired discharge flow rate Qa, Qb, Qc can be achieved by controlling the discharge valves 121a-c without at least one discharge valve 121a-c in a fully open position, the control device 200 controls the fan to change the speed of the fan 150 Lower so that the pressure in plenum 101 is reduced. The control device 200 reduces the speed of the fan 150 and controls the discharge valves 121a-c until at least one discharge valve 121a-c must be in a fully open position to set the desired discharge flow Qa, Qb, Qc.

If the desired discharge flow Qa, Qb, Qc cannot be achieved by controlling the discharge valves 121a-c with at least one discharge valve 121a; 121b; 121c in a fully open position, the control device 200 controls the fan to increase the speed of the fan 150 such that the pressure in the plenum 101 is increased. The control device 200 increases the speed of the fan 150 until the desired discharge flow Qa, Qb, Qc can be achieved in all discharge valves 121a-c with at least one fully open discharge control valve and then controls the discharge valves 121a-c to the desired discharge flow Qa, Qb , Qc is set in all discharge valves 121a-c.

In heat pump operation of the air-conditioning device 100, when the air heat pump 111 is in use, the supply valve in the air supply connection 130 (initially) is opened to the maximum to drive the highest possible air flow rate over the evaporator. This will allow maximum energy to be extracted from the mixed air. During heat pump operation, the control device 200 will not control the fan 150, and the speed of the fan 150 is kept at a certain value. The control device 200 controls the discharge valves in function of the measured pressure dP and the resistance value of the channels Ka; K B; Kc to set the required discharge flow rates Q _a , Qb, Qc.

If the desired discharge flow rate Qa, Qb, Qc cannot be achieved by controlling the discharge valves 121a-c, the control device 200 controls the supply valve to increase the pressure in the plenum 101. The control device 200 partially closes the supply valve such that the pressure in the plenum 101 increases until the desired discharge flow rate Qa, Qb, Qc can be achieved by controlling the discharge valves 121a-c and controls the

BE2017 / 5353 discharge valves 121a-c until the desired discharge flow Qa, Qb, Qc is set in all discharge valves 121a-c.

If the desired discharge flow Qa, Qb, Qc can be achieved by controlling the discharge valves 121a-c without at least one control valve 121a-c, 131 (discharge valve 121a-c or supply valve 131) in a fully open position, the control device 200 controls the supply valve 131 to decrease pressure in plenum 101. The control device 200 opens the supply valve 131 such that the pressure in the plenum 101 decreases until at least one control valve 120a-c, 130 must be in a fully open position to achieve the desired discharge flow rates Qa, Qb, Qc. Thereafter, the control device 200 controls the discharge valves 121a-c until the desired discharge flow Qa, Qb, Qc is set in all discharge valves 121a-c.

The air-conditioning device 100 according to a second embodiment is further shown in figure 3. A lid (not shown) can close a housing airtightly relative to a peripheral edge thereof. A number of air exhaust connections 120a, 120b, ... are present in the wall of the housing, the passage of which is adjustable with the help of the exhaust valves 121a, 121b, .... On these air exhaust connections, there are just as many air exhaust ducts 20, 20a, 20b, .. to connect. Furthermore, the wall of the housing has an air outlet connection 140 to which an air outlet channel 40 can be connected.

The space in the housing is divided by a baffle 103. On one side of the baffle 103, the air outlet connections 120a, 120b, ... open into a plenum 101 and on the other side of the baffle, the outlet outlet 102 opens into the air outlet connection 140 from. The baffle 103 has a permeable grille 104. The fan 150 is connected to the air outlet connection 140; in operation, the fan draws air through the air exhaust connections 120a, 120b, ... in the housing, through the grille 104 in the baffle 103 and exhausts the air to the air outlet connection 140. Depending on the position of the various valves 121a, 121b, .... a larger or smaller flow rate is obtained in the ducts connected to those air exhaust connections. This means that more or less air can be extracted from the room in question. The position of the valves can be adjusted on demand. In that connection, for example, CO2 sensors 122a, 122b, ..., moisture sensors and the like can be incorporated into the

BE2017 / 5353 concerning rooms, ducts or in the exhaust air connections 120a, 120b, ... are present. The values detected by these sensors are passed on to a control device 200. Based on the software of this control device 200, the valve positions and possibly the performance of the fan 150 can then be set.

The air drawn in by the fan is heated in the rooms and has a certain energy content. For the purpose of utilizing this energy content, a heat pump 110 is provided. The heat pump 110 has an evaporator 111 through which the air drawn in by the fan 150 passes. The heat present in the air is taken up by the evaporator 11, and according to a known cycle, the fluid present in the heat pump 110 is supplied to the condenser 112 by means of pump 113 and circuit 114.

The operation of the heat pump 110 is greatly influenced by the flow rate of the air flow generated by the fan. If the demand in the rooms is low, the flow rate of the airflow along the evaporator can become so low that the operation of the heat pump deteriorates sharply. With the aim nevertheless to be able to guarantee a sufficiently high flow rate, and thereby to optimize the operation of the heat pump, an air supply channel is provided which is connected to the air supply connection 130 which opens into the plenum 101. This air supply connection 130 has a supply valve 131, of which the position can be controlled by the control device 200. The sensor 160 connected to the control device 200 measures the pressure dP in the plenum 101. If this turns out to be too low for an optimum discharge of air from the rooms, the control device 200 closes the supply valve 131 in such a way that the pressure in plenum 101 increases and that sufficient air can be exhausted from the rooms.

Even at a low flow rate through the exhaust air connections 120a, 120b, ..., a desired, sufficiently high flow rate along the evaporator 111 can be obtained. It is not necessary to increase the flow rate flowed through the rooms. Thus, both comfort in the rooms can be maintained, while at the same time efficient energy recovery for the central heating and the like remains possible.

BE2017 / 5353

Reference list

1. Building 10. Air-conditioning system 20, 20a-c. Exhaust air duct 30. Air supply channel 40. Air outlet channel 100. Air-conditioning system 101. Plenum 102. Exhaust volume 103 Shot 104 Air-permeable grille 110. Air source heat pump 111. Evaporator 112. Condenser 113. Pump 114. Circuit 120a-c. Exhaust air connection 121a-c, Drain valve 122a-c Air parameter sensor 130. Air supply connection 131, Supply valve 140. Air outlet connection 150. Fan 160. Pressure sensor 200. Control device Qoda Supply flow Qa, Qb, Qc Desired Drain Flow

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Q Outlet flow dP Pressure in the Plenum

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Claims (20)

Conclusions Method for controlling an air-conditioning system (10) of a building (1), the air-conditioning system (10) comprising: a plenum (101); an air exhaust (20a, 120a; 20b, 120b; 20c, 120c) for extracting indoor air from at least one room of a building (1) at the plenum (101), and an exhaust valve (121a; 121b; 121c) for controlling the flow rate of air exhausted from the at least one space of the building (1); an air supply (30, 130) for supplying outside air to the plenum (101), and a supply valve (131) for controlling the flow of supplied outside air; an air heat pump (110) with an evaporator for exchanging heat between air fed over the evaporator and the evaporator (111); a single fan (150) for drawing in and outside air into the plenum (101) through the at least one air outlet (20a, 120a; 20b, 120b; 20c, 120c) and the at least one air inlet (130), respectively, and driving the aspirated indoor and outdoor air over the evaporator (111); and a control device (200) for controlling the at least one discharge valve, wherein the position of the discharge valve is adjusted with the aid of the control device (200) in function of a desired discharge flow Qa, Qb, Qc, wherein with the aid of the control device ( 200) the pressure dP in the plenum (101) is adjusted in function of the desired discharge flow Qa, Qb, Qc. The method according to claim 1, wherein the control device (200) is arranged for controlling the at least one supply valve and wherein in heat pump operation of the air-conditioning device (100), when the air heat pump (110) is in use, using the control device (200) adjusts the position of the supply valve in function of the pressure dP in the plenum (101). BE2017 / 5353 Method according to claim 1 or 2, wherein in heat pump operation of the air-conditioning device (100), when the air heat pump (110) is in use, the speed of the fan (150) is kept constant. Method according to claim 2 or 3, wherein the flow rate of air Q which is driven over the evaporator (14) corresponds to a maximum value in function of the desired discharge flow rate Qa, Qb, Qc. A method according to any one of the preceding claims, wherein the control device (200) is arranged to control the fan (150), and in ventilation operation of the air-conditioning device (100), when the air heat pump (110) is out of use, the speed of the fan (150) is adjusted by means of the control device (200) in function of the pressure dP in the plenum (101). A method according to claim 5, wherein in ventilation operation of the air-conditioning device (100), the position of the at least one supply valve is kept constant. 7. Method according to claim 5 or claim 6, wherein the feed flow Qoda corresponds to a minimum value. A method according to any one of the preceding claims 2-4, wherein the air-conditioning device (100) in the plenum (101) comprises at least one pressure sensor (200) for measuring an air pressure in the plenum (101); and wherein, in heat pump operation, each supply valve is controlled in function of measured values of measurements with the plenum pressure sensor. A method according to any one of the preceding claims 5-7, wherein the air-conditioning device (100) in the plenum (101) comprises at least one pressure sensor (200) for measuring an air pressure in the plenum (101); and wherein, in ventilation mode, the fan (150) is controlled in function of measured values of measurements with the pressure sensor located in the plenum. BE2017 / 5353 A method according to any preceding claim, wherein each exhaust air (20a, 120a; 20b, 120b; 20c, 120c) comprises at least one sensor for measuring an air parameter in the exhaust air at the exhaust air connection (120a; 120b; 120c) ; and wherein a discharge valve is controlled in function of measured values of measurements with the sensor located in the air discharge (20a, 120a; 20b, 120b; 20c, 120c). Air-conditioning system (10) comprising: a plenum (101), an air exhaust for extracting indoor air from at least one room of a building (1) at the plenum (101), and an exhaust valve for controlling the flow rate from the at least one space of the building (1 ) exhaust air; at least one air supply (130) for supplying outside air to the plenum (101), and a supply valve for controlling the flow of supplied outside air; an air heat pump (110) with an evaporator for exchanging heat between air fed over the evaporator and the evaporator (111); one single fan (150) for drawing in and outside air through the at least one air outlet (120a; 120b; 120c) and at least one air supply (130) in the plenum (101), respectively, and for passing over the evaporator (111 ) floating of the extracted indoor and outdoor air; and a control device (200) for controlling the at least one discharge valve, the control device (200) being arranged for adjusting the position of the discharge valve by means of the control device (200) in function of a desired discharge flow Qa, Qb, Qc, characterized in that the control device is adapted to control the pressure dP in the plenum 101 in function of the discharge flow Qa, Qb, Qc. Air-conditioning system (10) according to claim 11, BE2017 / 5353, wherein the control device (200) is adapted to adjust the position of the supply valve in function of the pressure dP in the plenum (101). Air-conditioning system (10) according to claim 12, wherein the control device (200) is arranged for, in heat pump operation of the air-conditioning device (100), to keep the speed of the fan (150) constant. Air-conditioning system (10) according to claim 12 or claim 13, wherein the control device (200) is arranged for the flow rate of air Q that is driven over the evaporator (14) to correspond to a maximum value in function of the desired discharge flow rate Qa , Qb, Qc. Air-conditioning system (10) according to any of the preceding claims 11-14, wherein the control device (200) is adapted to adjust the speed of the fan (150) in function of the pressure dP in the plenum (101). Air-conditioning system (10) according to claim 15, wherein the control device (200) is arranged for, in ventilation operation, keeping the position of the at least one supply valve constant. The air conditioning system (10) according to claim 15 or claim 16, wherein the control device (200) is adapted to match the supply flow rate Qoda with a minimum value. The air-conditioning system (10) according to any of the preceding claims 12-14, wherein the air-conditioning device (100) in the plenum (101) comprises at least one pressure sensor (200) for measuring an air pressure in the plenum (101); and wherein the control device (200) is arranged for, in heat pump operation, controlling each supply valve in function of measured values of measurements with the pressure sensor located in the plenum. 2017/5353 BE2017 / 5353 15 Air-conditioning system (10) according to any one of the preceding claims 15-17, wherein the air-conditioning device (100) in the plenum (101) comprises at least one pressure sensor (200) for measuring an air pressure in the plenum (101); and wherein the control device (200) is adapted to control, in ventilation mode, the fan (150) in function of measured values of measurements with the pressure sensor located in the plenum. Air conditioning system (10) according to any of the preceding claims 11-19, wherein each air outlet (20a, 120a; 20b, 120b; 20c, 120c) comprises at least one sensor 10 for measuring an air parameter in the exhaust air in the exhaust air connection (120a; 120b; 120c); and wherein the control device (200) is adapted to control a discharge valve as a function of measured values of measurements with the air outlet (20a, 120a; 20b), 120b; 20c, 120c) standing sensor. BE2017 / 5353 σ « BE2017 / 5353 BE2017 / 5353 2017/5353 BE2017 / 5353 Excerpts Air-conditioning system and method for controlling an air-conditioning system The present invention relates to a method for controlling a climate control system of a building. The air-conditioning system comprises a plenum, an air exhaust with an exhaust valve, and an air supply with a supply valve for controlling the flow of supplied outside air. The air-conditioning system further comprises an air heat pump with an evaporator, one 10 single fan, and a control device for controlling the at least one discharge valve, wherein the position of the discharge valve is adjusted with the aid of the control device in function of a flow rate adjusted. Furthermore, the pressure in the plenum is adjusted with the aid of the control device in function of the desired discharge flow rate. Î5