WO2009157847A1

WO2009157847A1 - Ventilation system

Info

Publication number: WO2009157847A1
Application number: PCT/SE2009/050598
Authority: WO
Inventors: Anders HEDSTRÖM
Original assignee: Camfil Ab
Priority date: 2008-06-24
Filing date: 2009-05-26
Publication date: 2009-12-30
Also published as: EP2310752A4; EP2310752B1; ES2788705T3; EP2310752A1

Abstract

The invention relates to a ventilation system for supplying conditioned air to rooms to be ventilated in a building (B) having several rooms, said system includes a central air-treatment unit (1) connected to an inlet (2) for outside air, ventilation ducts (3), which are connected to an outlet of the central air-treatment unit and which have outlets leading into each room to be ventilated in the building, and outlets from said rooms leading into air ducts (4) for passing air to the outside of the building. According to the invention at least one of the rooms (I-III) to be ventilated is connected to a chamber (V) in which air from said at least one room (I-III) is mixed with fresh air, passed through a filter (18) together with said fresh air, the mixture of air from said at least one room (I-III) and fresh air then being introduced into said at least one room. The invention also relates to a method of ventilating a building.

Description

Ventilation system.

TECHNICAL FIELD

The present invention relates to a ventilation system for supplying conditioned air to rooms to be ventilated in a building having several rooms, said system includes a central air-treatment unit connected to an inlet for outside air, ventilation ducts, which are connected to an outlet of the central air-treatment unit and which have outlets leading into each room to be ventilated in the building, and outlets from said rooms leading into air ducts for passing air to the outside of the building. The invention also relates to a method of ventilating a building having several rooms.

BACKGROUND OF THE INVENTION

When designing ventilation systems of the above mentioned type, the use of all the rooms to be ventilated in a building has to be taken into account when deciding the performance and dimensions of the components of the system. An important factor in this respect is the number of persons that will use each room and the duration of such use since these factors are decisive for the amount of fresh air to be supplied to the room per unit of time. For certain rooms, such as meeting rooms, the use of the rooms vary significantly. Sometimes a lot of persons use the room (maximum use) but most of the time only a few, if any, persons use the room. The ventilation systems must then be dimensioned for allowing such maximum use, at least for a certain period of time. This means that ventilating fans and ventilation ducts in such ventilation systems are oversized for the daily use of the rooms in order to cope with such maximum use.

Another problem is if the ventilation requirements change for an existing ventilation system due to change in standards or regulations or if the number of persons using the rooms is changed. If, for example, the building is a school and the number of pupils in the classes is increased, the amount of fresh air supplied to each classroom per unit of time must be correspondingly increased. This means that more powerful and larger ventilating fans must be used. Furthermore, the ventilation ducts should preferably be given larger dimensions since otherwise the velocity of the air in these ducts must be increased which will lead to larger pressure drops which will increase the energy costs. There is also a risk that the ventilation will be overly noisy. However, in some cases there is no available space in the building for accommodating larger ventilating fans and/or ventilation ducts so in order to meet higher ventilation requirements, a reconstruction of the building must be done to enable a fulfilment of the higher ventilation requirement.

There is thus a need for a ventilation system that is more flexible than ventilation systems of the above mentioned kind and which incorporate such a known ventilation system as an integer part so that such systems can be upgraded without major reconstruction of the building in which this known ventilation system is installed.

The objective of the present invention is to fulfil such a need. SUMMARY OF THE INVENTION

This objective is accomplished by a ventilation system for supplying conditioned air to rooms to be ventilated in a building having several rooms , said system includes a central air-treatment unit connected to an inlet for outside air, ventilation ducts, which are connected to an outlet of the central air-treatment unit and which have outlets leading into each room to be ventilated in the building, and outlets from said rooms leading into air ducts for passing air to the outside of the building, characterised in that at least one of the rooms to be ventilated is connected to a chamber in which air from said at least one room is mixed with fresh air, passed through a filter together with said fresh air, the mixture of air from said at least one room and fresh air then being introduced into said at least one room. By such a ventilation system, the central air-treatment unit can be providing a constant base ventilation to all rooms in the building and one or more of said chambers can provide additional conditioned air to one or more of the rooms in the building, continuously or when need arise. The chambers can also be controlled to vary their performance in time depending on the actual use of a room.

Thus, by such a ventilation system the ventilation and air cleaning can be controlled according to the actual need in the different rooms in the building. An optimised air ventilation and air cleaning can thus be obtained.

In a first preferred embodiment, said fresh air is taken from outside of the building and passes a filter before entering said chamber. In a second preferred embodiment, said fresh air is taken from another room than said at least one room in the building or said fresh air is delivered to said chamber by the central air treatment unit.

More than one room can be connected to said chamber.

Said filter in the chamber is preferably a filter of HEPA class.

The central air- treatment unit preferably includes a heat-exchanger in which exhaust air heats the incoming outside air before leaving the building.

Said chamber can contain an air cooler or an air heater.

Two or more of said chambers, each connected to one or more rooms to be ventilated, can be included in the system.

The invention also relates to a method of ventilating a building having several rooms to be ventilated, whereby at least one room has different ventilation requirements than other rooms, said building including a central ventilation system for supplying conditioned air to rooms to be ventilated, which system includes a central air-treatment unit connected to an inlet for outside air, ventilation ducts, which are connected to an outlet of the central air-treatment unit and which have outlets leading into each room to be ventilated in the building, and outlets from said rooms leading into air ducts for passing air to the outside of the building, the method is characterised by the steps of; providing by the central ventilation system a base ventilation to each room to be ventilated ; connecting the at least one room having different ventilation requirements than other rooms to a chamber in which air from said at least one room is mixed with fresh air, passed through a filter together with said fresh air, the mixture of air from said at least one room and fresh air then being introduced into said at least one room; and controlling said air mixture entering the at least one room from said chamber so that the ventilation requirements of said at least one room are satisfied.

In a first embodiment of the method, said fresh air is taken from outside of the building.

In a second embodiment of the method, said fresh air is delivered to said chamber by the central air treatment unit or taken from another room than said at least one room in the building.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will now be described with reference to the enclosed figure, of which; fig. 1 schematically shows a plan view from above of a building provided with a ventilation system according to a preferred embodiment of the invention,

fig. 2 schematically shows the building in figure 1 in a side view with some of the ventilation ducts present in the ventilation system schematically illustrated,

fig. 3 shows a flow chart of the ventilations system of the building in claim 1,

fig. 4 shows a variant of chamber V, and

fig. 5 shows a flow chart of the ventilation system according to a second embodiment of the invention.

DESCRIPTION OF EMBODIMENTS

In figures 1 and 2, a building B is schematically shown. The building B can for example be a school. Three rooms I, II and III are also schematically shown, which could be classrooms. The building B is provided with a conventional ventilation system including a service room IV in which a central air-treatment unit is disposed. The central air- treatment unit is connected to an inlet 2 for outside air and ventilation ducts 3, which are connected to an outlet of the central air-treatment unit and which have outlets leading into each room to be ventilated in the building. In figures 1 and 2 only the ventilation ducts leading to the classrooms I-III are shown but ventilation ducts leading to other rooms in the building are present, as is conventional in the state of art. The rooms ventilated by the ventilation system are provided with outlets leading into air ducts for passing air to the outside of the building. In figures 1 and 2, only outlets from rooms I-III leading to a duct 4 which via the central air-treatment unit in the service room IV leads to an air outlet duct 5, are shown.

The central air-treatment unit 1 disposed in room IV includes a first ventilation fan 6 for transporting fresh air from the inlet 2 to the various outlets for fresh air in the different rooms in building B and a second ventilation fan 7 for drawing used air out of the rooms and transport this air to the outside of the building. A heat-exchanger 8 is preferably disposed in the service room IV so that the incoming fresh air can be pre-heated by the outgoing air before this air leaves the building.

Pressure sensors 9 and 10 for measuring the pressure in the ventilation duct 3 and duct 4, respectively are also included. A throttle 11 regulates the amount of fresh air drawn into the inlet 2. Temperature sensors 12 and 13 and a control valve 14 are also included.

A unit, not shown, for controlling the central air-treatment unit 1 is also disposed in room IV.

The components described above are all components usual in conventional ventilation systems for supplying fresh air to the rooms in a building and functions in the same way as in such systems. According to the invention a small room V, a so called climate chamber, is built in a corner of room I. A duct 15 which is connected to air outlets in each of the rooms I-III leads into the climate chamber V and a duct 16 connected to air inlets in each of said rooms lead out from the climate chamber V. The outlet of a ventilating fan 17 is connected to duct 16 and the inlet to said fan 17 is connected to the outlet of an air-cleaning filter 18. Furthermore, an inlet 19 for fresh air from outside the building B is present in the climate chamber and via a throttle 20 connected to the inlet of the filter 18. A control unit for the climate chamber can be disposed inside the chamber or elsewhere.

When the ventilating fan 17 in the climate chamber is put into operation, used air from rooms I-III as well as fresh air from inlet 19 is drawn into the chamber V and passes through the filter 18. Fresh air from inlet 19 is mixed with used air from rooms I-III either before entering the filter 18 or in the filter. In filter 18 the incoming air, i.e. the mixture of used air from rooms I-III and fresh air from the outside, is cleaned so that only clean air leaves chamber V and is supplied to rooms I-III via outlets from duct 16.

By the provision of a climate chamber according to the present invention, the ventilation system described above can operate so that the central air-treatment unit 1 can be controlled only to provide a base ventilation dimensioned to take care of normal ventilation needs, i.e. ventilation needs for most of the rooms in the building, whereas rooms having special ventilation needs are connected to a climate chamber. The rooms having special ventilation needs can for example be rooms for general meetings or seminars where the ventilation need varies during periods of time, or rooms in which the ventilation need is much higher than in the other rooms in the building, such as classrooms in a school building. By having the central air-treatment unit only providing a base ventilation, ventilating fans having a relatively small capacity can be used and ventilation ducts be optimally dimensioned for the air flow required for the base ventilation. In comparison with ventilation systems lacking climate chambers in which the ventilating fans and the ventilation ducts must be dimensioned to cope with a higher air flow in order to be able to supply the required amount of air per time unit to rooms with special ventilation needs, a considerable saving of costs and space required for the air-treatment unit and the ventilation ducts is obtained. Furthermore, since pressure drops in the system increase with increasing flow rate, the energy losses in conventional ventilation systems lacking climate chambers are much higher than in a system according to the present invention. In a system according to the present invention the ventilation ducts can be dimensioned so that the maximal air flow rate required by the base ventilation does not produce a lot of noise which is hard to achieve in conventional ventilation systems.

Another advantage is that the ventilation system according to the present invention is much more flexible than conventional ventilation systems. The climate chambers are rather small, for example about 1.5 m x 2 m, and can therefore often be installed in rooms with special ventilation needs. Thus, if special ventilation need arise in a room in a building it is easy to provide that room with a climate chamber according to the present invention. Moreover, if the use of a room so that special ventilation need not longer is required it is easy to remove the climate chamber and the ducts leading to and from the chamber. In a variant of the shown embodiment, the climate chamber can be constructed as a mobile unit and said ducts could be releasable mounted in the ceiling of the rooms served by said climate chamber. Such a mobile unit can be movable within the building or placed outside a room on the ground floor and be connected via the window or the like. The ducts leading to and from the climate chamber can be textile channels with diffusors fastened to the ceiling. In case of a mobile climate chamber, such channels can be mounted easily removable.

The number of climate chambers provided in the ventilation system according to the present invention will vary depending on the number of rooms with ventilation needs larger than is provided by the base ventilation and by the variation of said ventilation needs. If the ventilation needs are common for several rooms, then one climate chamber can serve all those rooms but if the ventilation needs are different, one chamber for each room is preferred.

The climate chamber also provides clean air to the rooms it is connected to. The quality of the air in these rooms is thereby greatly improved. The filter 18 is of HEPA (High Efficiency Particulate Air) class, for example a HEPA- filter from Camfil AB, Sweden. Other types of air cleaning filters, such as a molecular filter can of course be used. The filter 18 can be a set of filter units and it is possible to use different types of filters in such a set of filters, such as a combination of HEPA-filters and molecular filters. A useful application of the ventilation system according to the present invention is upgrading of existing conventional ventilation systems in buildings. If a conventional ventilation system is to be upgraded more powerful ventilating fans and larger dimensions of the ventilation ducts are usually required. More powerful ventilating fans would require more space which in some cases in turn would require a rebuilding of the room accommodating the air-treatment unit. Such a rebuilding is not always possible. Moreover, a change of ventilation ducts is not always possible and is any way a costly and time-consuming measure to take and would for these reasons usually be avoided. This means that in upgraded conventional systems the original ventilating ducts usually remain which will lead to that the flow rate in the ducts would be higher than the flow rate the ducts originally were designed for. This would in turn lead to increasing pressure drops in the ducts and to high energy costs. If instead one or more climate chambers according to the present invention were installed connected the rooms having the largest ventilation needs, the already installed conventional ventilation system can be retained and controlled to provide the base ventilation according to the present invention. Such base ventilation would usually require a lower flow rate in the ventilation ducts than the flow rate dimensioned for before upgrading. This will lead to decreasing pressure drops and energy savings. These energy savings would be larger than the energy required for operating the climate chambers.

Optionally, the climate chamber can be provided with a heater and/or a cooler 21. If rooms I-III, for example, are classrooms for IT-education provided with a lot of computers, a lot of heat is produced by the computers. In such a case, a cooler would preferably be provided in climate chamber V.

In figure 4, a variant of chamber 5 is shown. In this variant a filter 22 is installed in the inlet 19 for outside air.

Figure 5 shows a flow chart of the ventilation system according to a second preferred embodiment of the invention. The only difference between the ventilation system according to figures 1-4 and the ventilations system according to figure 5 is that the fresh air entering the chamber V in the ventilation system shown in figure 5 is delivered by the central air-treatment unit and not taken from the outside of the building. Components of the ventilation system according to figure 5 corresponding to similar components in the ventilation system according to figures 1-4 are given the same reference signs with the addition of a prime sign. In the ventilation system according to figure 5, chamber V is provided by fresh air from the central air-treatment unit via a duct 23 and throttle 24. In all other ways, the ventilation system according to figure 5 functions in the same manner as the ventilation system according to figures 1-4.

Instead of supplying fresh air to chamber V from the central air- treatment unit it is possible to supply fresh air to room V form a room in the building having a high quality of the air within it. The described embodiment can be modified in several respects without leaving the scope of invention. The air-treatment unit can for example include an air-conditioner and the inlets for outside air in the system are preferably provided with low class filter units. The climate chambers could be used in combination with other types of ventilations systems than the conventional type described above. The climate chamber need not be placed or built in a corner but could be disposed elsewhere in the room or elsewhere in the building. The system can include more than one climate chamber. Furthermore, the fresh air from outside and the used air from rooms to be ventilated can be mixed before entering the filter in the climate chamber instead of after entering the filter. The scope of the invention should therefore only be limited by the content of the enclosed patent claims.

Claims

1. A ventilation system for supplying conditioned air to rooms to be ventilated in a building (B) having several rooms, said system includes a central air-treatment unit (1) connected to an inlet (2) for outside air, ventilation ducts (3), which are connected to an outlet of the central air- treatment unit and which have outlets leading into each room to be ventilated in the building, and outlets from said rooms leading into air ducts (4) for passing air to the outside of the building, characterised in that at least one of the rooms (1-111) to be ventilated is connected to a chamber (V) in which air from said at least one room (I-III) is mixed with fresh air, passed through a filter (18) together with said fresh air, the mixture of air from said at least one room (I-III) and fresh air then being introduced into said at least one room.

2. Ventilation system according to claim 1, wherein said fresh air is taken from outside of the building.

3. Ventilation system according to claim 2, wherein said air from the outside of the building passes a filter before entering said chamber (V).

4. Ventilation system according to claim 1, wherein said fresh air is taken from another room than said at least one room (I-III) in the building.

5. Ventilation system according to claim 1, wherein said fresh air is delivered to said chamber (V) by the central air treatment unit (1).

6. Ventilation system according to any one of claims 1-5, wherein more than one room (I-III) is connected to said chamber (V).

7. Ventilation system according to any one of claims 1-6, wherein said filter (18) in the chamber (V) is a filter of HEPA class.

8. Ventilation system according to any one of claims 1-7, wherein the central air-treatment unit (1) includes a heat-exchanger (8) in which exhaust air heats the incoming outside air before leaving the building (B).

9. Ventilation system according to any one of claims 1-8, wherein said chamber (V) contains an air cooler (21) and/or an air heater.

10. Ventilation system according to any one of claims 1-9, wherein two or more of said chambers each connected to one or more rooms to be ventilated, are included in the system.

11. Method of ventilating a building (B) having several rooms to be ventilated, whereby at least one room (I-III) has different ventilation requirements than other rooms, said building including a central ventilation system for supplying conditioned air to rooms to be ventilated, which system includes a central air-treatment unit (1) connected to an inlet (2) for outside air, ventilation ducts (3), which are connected to an outlet of the central air-treatment unit and which have outlets leading into each room to be ventilated in the building (B), and outlets from said rooms leading into air ducts (4) for passing air to the outside of the building, the method is characterised by the steps of; providing by the central ventilation system a base ventilation to each room to be ventilated ; connecting the at least one room (I-III) having different ventilation requirements than other rooms to a chamber (V) in which air from said at least one room is mixed with fresh air, passed through a filter (18) together with said fresh air, the mixture of air from said at least one room (I-III) and fresh air then being introduced into said at least one room; and controlling said air mixture entering the at least one room from said chamber so that the ventilation requirements of said at least one room are satisfied.

12. Method according to claim 11, wherein said fresh air is taken from outside of the building.

13. Method according to claim 11, wherein said fresh air is delivered to said chamber (V) by the central air treatment unit (1).

14. Method according to claim 11, wherein said fresh air is taken from another room than said at least one room (I-III) in the building.