GB2336202A

GB2336202A - Ventilating buildings

Info

Publication number: GB2336202A
Application number: GB9807831A
Authority: GB
Inventors: Stephen Gage; Christopher Leung
Original assignee: University College London
Current assignee: University College London
Priority date: 1998-04-09
Filing date: 1998-04-09
Publication date: 1999-10-13
Also published as: GB9807831D0

Abstract

A ventilating apparatus for a building comprises a plurality of upper ducts (16n,e) each having upper and lower ends, the upper ends in use being open to the outside of the building and facing in different generally horizontal directions. In a bi-directional version of the apparatus, it also includes: a supply duct (26) and an extraction duct (28a,b), each having upper and lower ends, the lower ends in use being open to the inside of the building; a damper arrangement (32) operable to connect the upper ends of each of the supply duct and the extraction duct selectably to the lower end(s) of one or more of the upper ducts; a sensor (46) for sensing, in use, wind direction outside the building; and a controller for controlling the damper arrangement in dependence upon the sensed wind direction. Unidirectional versions of the apparatus are also disclosed. With each version, when the wind blows, the direction of air flow in the supply duct and/or the extraction duct is predictable.

Description

2336202 TITLE Ventilating Buildings

DESCRIPTION

This invention relates to ventilating apparatus for buildings.

It is known to provide ventilators for buildings which comprise a duct which passes through the roof of the building so that the upper end of the duct is open to the outside of the building and the lower end is open to the inside of the building. With a plain upper end, the ventilator will tend to draw air from the building to the outside when the wind blows. In order to provide for the supply of air to the building, the upper end of the duct could be arranged to face into the wind. However, wind direction is, of course, not constant, and therefore such an arrangement would sometimes supply air into the building and sometimes draw air from it. In order to tackle this problem, it is known to provide a bundle of ducts with their upper ends facing in different directions. When the wind blows, one or-more of the ducts will supply air into the building, and one or more other of the ducts will extract air from it, and so the air in the building can be circulated whatever the- wind direction. A problem with such an arrangement, however, is that the duct(s) which supply and the duct(s) which extract change as the wind direction changes and so room ports in the ducting system change between being inlets and outlets as the wind direction changes. It would be preferable if an inlet was always an inlet, and an outlet was always an outlet.

In order to tackle this latter problem, it is also known, at least from the textbooks, to have a rotatable head on the ducting system which is driven by a windmill so that, when the wind is blowing, the head turns so that the inlet faces into the wind and the outlet is on the leeward side. However, there are problems with such an arrangement relating to the bearings for the rotatable head, scaling between the rotatable head and the z:, C1 fixed part of the apparatus, and the speed of response of -the, rotatable head.

The present invention is concerned with tackling the same problems as this latter arrangement, but without producing the additional problems which it produces.

- 2 In accordance with the present invention, there is provided a ventilating apparatus for a building, comprising: a plurality of upper ducts each having upper and lower ends, the upper ends in use being open to the outside the building and facing in different generally horizontal directions; a lower duct having first and second ends, the first end of the lower duct in use being open to the inside of the building; a damper arrangement operable to connect the second end of the lower duct selectably to the lower end(s) of one or more of the upper ducts; a sensor for sensing, in use, wind direction outside the building; and a controller for controlling the damper arrangement in dependence upon the sensed wind direction. Accordingly, in a "supply" form of the invention, the controller can be operable to cause the damper arrangement to connect the second end of the lower duct to the lower end of at least that one of the upper ducts whose upper end is the more, or the most, windward, whereby the lower duct acts as a supply duct tending to supply air to the building, whatever the wind direction. Alternatively, in an "extraction" form, the controller is operable to cause the damper arrangement to connect the second end of the lower duct to the lower end of at least that one of the upper ducts whose upper end is the more, or the most, leeward, whereby the lower duct acts as an extraction duct tending to extract air from the building, whatever the wind direction. The invention therefore provides predictability. In other words, when the wind is blowing, an outlet for air being supplied into the building remains an outlet, and/or an inlet for air to be extracted from the building remains an inlet. The inlets and/or outlets can therefore be sited in the most advantageous positions for their respective functions, without having to take into account that their functions may change.

In a bi-directional form of the invention: the extracti-on form of the apparatus further includes a further lower duct having first and second ends, the first end of the further lower duct in use being open to the inside of the building; the damper arrangement is also operable to connect the second end of the further lower duct selectably to the lower end(s) of one of more other of the upper ducts; and the controller is also operable to cause the damper arrangement to connect the second end of the further lower duct to the lower end of at least that one of the upper ducts whose upper end is the more, or the most, windward, whereby the further lower duct acts as a supply duct tending to supply air to the building. Accordingly, the apparatus provides predictable two-way air flow.

Preferably, the damper arrangement includes at least one respective damper for each of the upper ducts. In this case, in the bi-directional form mentioned above, each damper is preferably movable between: a supply position in which it connects the lower end of the respective upper duct to the second end of the lower supply duct; and an extraction position in which it connects the lower end of the respective upper duct to the second end of the lower extraction duct. This two-way function of the dampers reduces the number of dampers required. In this case, the apparatus is preferably arranged so that: the pathways through the damper arrangement between the upper ducts and one of the lower ducts are generally linear; and the pathways through the damper arrangement between the upper ducts and the other of the lower ducts pass through a chamber which, at least partly, surrounds the lower ends of the upper ducts. This facilitates the construction of the damper arrangement and also provides little resistance to the air flow in one direction.

Preferably,- there are at least three, and more preferably at least four, such upper ducts. The more the number of upper ducts, the less the ripple in the air flow versus wind direction characteristic, but of course the more the number of upper ducts, the greater the complexity and cost.

Preferably, the angular resolution of the wind direction sensor is no less than the angular spacing of the upper ends of the upper ducts, and more preferably is at least twice the angular spacing of the upper ends of the upper ducts. In this case, and if there are at least three upper-ducts, the number of the upper ducts which are connected by the damper arrangement to the lower duct, or one of the lower ducts, is preferably selected by the controller from the set of numbers zero, one and more than one, in dependence upon the sensed wind direction, for example in dependence upon whether the wind is blowing directly at one of the upper ends, or in a direction between an adjacent pair of the upper ends of the upper ducts.

Preferably, the wind direction sensor comprises a rotary wind vane, and means for sensing the angular position of the wind vane.

A specific =ibodiment of a ventilating apparatus in accordance with the invention - 4 will now be described, purely by way of example, with reference to the accompanying drawings, in which:

Figure 1 is a side view of the apparatus, sectioned on the staggered section line 1-1 shown in Figures 3 to 5; Figure 2 is another side view of the apparatus, sectioned on the line 2-2 shown in Figures 3 to 5; Figures 3 to 5 are plan views of the apparatus, sectioned on the lines 3- 3, 4-4 and 5-5, respectively, shown in Figure 2; and Figure 6 is a block diagram of the control system of the apparatus.

Referring to the drawings, the apparatus comprises a vertical upper sleeve 10 of square cross-section which passes through the roof 12 of a building. A cruciform partition 14 extends through the sleeve 10 to subdivide it into four vertical ducts 16n,s,e^ which, for the building in question, are disposed to the North, South, East and West, respectively. The partition 14 projects above the sleeve 10 and is fitted with a cap 18, so that the upper ends of the ducts Ari,s,e,w face generally horizontally to the North, South, East and West, respectively. Louvres 20, or other means, may be provided to hinder the entrance of rain, &c. into the ducts 16n,s,e,w.

The apparatus also comprises a vertical lower sleeve 22 of rectangular crosssection having a pair of partitions 24 to subdivide it into a central, rectangular cross- section supply duct 26 between a pair of square cross-section extraction ducts 28a,b. The upper end of at least the supply duct 26 is flared out at 30 to a squ are-cross -section. The supply duct 26 leads downwardly to one or more air outlets in the building, and the extraction ducts '-"8a,b, lead upwardly from one or more air extracts in the building.

The apparatus furthermore comprises a damper arrangement 32 between the upper 215 ducts 16n,s,e,w and the lower ducts 26,28a,b. The damper arrangement is contained in C a square box having: a base 34 which is perforated in alignment with the extraction ducts 28a,b and in alignment with the flared upper end 30 of the supply duct 26; four side walls 36; and a top 38 which is perforated in alignment with the upper ducts 16n,s,e,w. The cruciform partition 14 and an opposed pair of the sides of the sleeve 10 extend downwardly through the depth of the damper box. Thus, absent the dampers to be described below, each of the upper ducts 16n,s,e,w communicates in a generally straight line with the supply duct 26, and each of the upper ducts 16n,s,e,w also communicates with both of the extraction ducts 28a,b by a more circuitous route via an annular chamber 40 inside the damper box and surrounding the lower ends of the upper ducts 16n,s,e^ 0 The damper arrangement 32 also includes four two-way damper flaps 42n,s,e, w at the lower ends of the upper ducts 16n,s,e^ respectively. The damper flaps 42n,s,e,w are hinged to the base 34 of the damper box and driven by respective servo motors 44n,s,e,w for movement between a vertical position (see for example damper flap 42s in Figure 1) and a horizontal position (see for example damper flap 42n in Figure 1). In its horizontal position, each damper flap 42ns,e,w blocks any substantial air flow from its respective upper duct 16n,s,e,w to the supply duct 26, but permits air flow from the annular chamber 40 (and thus from the extraction ducts 28a,b) to its respective upper duct 16n,s, e,w. Conversely, in its vertical position, each damper flap 42n,s,e,w blocks any substantial air flow from from the annular chamber 40 (and thus from the extraction ducts 28a,b) to its respective upper duct 16n,s,e^ but permits air flow from its respective upper duct 16n,s,e,w to the supply duct 26.

The apparatus also comprises a wind direction sensor 46 disposed, for example, on top of the cap 18, or elsewhere. The sensor 46 includes a rotary wind vane 48 to which is attached an encoder disc (not shown). The disc cooperates with a plurality of, for example, Halleffect or optical sensors, and associated circuitry (not shown) to produce a wind direction signal with a resolution of 45'. The wind direction signal is supplied to a logic circuit 50 (which may be implemented in hardware or software), which in turn controls the servo motors 44n,s,e,w to set the damper flaps 42n,s,e, w in 1-5 their horizontal or vertical positions. The wind direction signal may take the form of, for example, a one-bit-in-eighthigh signal, as shown in Figure 6, or a composite three-bit signal.

Figure 3 shows which of the eight bits of the wind direction signal goes high for each of the eight quantised wind directions, and this is also shown in the following table, together with the corresponding state to which the logic circuit 50 sets each of the four damper flaps 42n,s,e,w:- 6 High bit - Direction Flap 42n Flap 42e Flap 42s Flap 42w 0 NNW - NNE Vertical Horizontal Horizontal Horizontal 1 NNE - ENE Vertical Vertical Horizontal Horizontal 2 ENE - ESE Horizontal Vertical Horizontal Horizontal 3 ESE - SSE Horizontal Vertical Vertical Horizontal 4 SSE - SSW Horizontal Horizontal Vertical Horizontal SSW - WSW Horizontal Horizontal Vertical Vertical 6 WSW - Horizontal Horizontal Horizontal Vertical WNW 7 WNW - Vertical Horizontal Horizontal Vertical NNW It will therefore be seen that, if the wind is blowing directly at the inlet to one of the upper ducts 16n,e,s,w, say upper duct 16n, the air entering that duct 16n is directed down into the supply duct 26, and the other three upper ducts 16e,s,w are allowed to draw air from the extraction ducts 28a,b. If, however, the wind is blowing half-way between the inlets to a pair of the upper ducts 16ne,s,w, say upper ducts 16n,e, the air entering both of those ducts 16n,e is directed down into the supply duct 26, and the other two upper ducts--16s,w are allowed to draw air from the extraction ducts 28a,b.

It should be remembered that the embodiment of the invention has been described above purely by way of example and that many modifications and developments may, be 20 made to it. For example:- The extraction ducts 28a,b may be omitted, together with the chamber 40 in the damper box, with the damper flaps 42 acting as one-way dampers, so that the apparatus acts as an;'Intel ligenC air-supply apparatus. Alternatively, the logic may be reconfigured so that such an intelligent air supply apparatus acts instead as an intelligent air extraction 25 apparatus. - The two extraction ducts 28a,b may be combined as one, or may be further subdivided, and the supply duct 26 may be subdivided.

A different number of the upper ducts 16 may be employed, for example three, five, six, seven or eight, or even two. In this case, the shapes of the damper flaps may be modified. For example, equilaterally-triangular damper flaps 42 might be employed in the case of six of the upper ducts 16. It is expected that the most preferred number of the upper ducts 16 would be four, five or six.

Pairs of one-way damper flaps may be employed instead of each two-way damper flap 42.

The supply and extraction ducts 26,28 could be concentric, with one surrounding the other.

Other modifications and developments within the scope of the invention will also be apparent to a person skilled in the art.

Each feature disclosed in the description, claims, drawings and abstract may be 15 provided independently or in any appropriate combination.

Claims

A ventilating apparatus for a building, comprising:

a plurality of upper ducts each having upper and lower ends, the upper ends in use being open to the outside the building and facing in different generally horizontal directions; a lower duct having first and second ends, the first end of the lower duct in use being open to the inside of the building; a damper arrangement operable to connect the second end of the lower duct selectably to the lower end(s) of one or more of the upper ducts; a sensor for sensing, in use, wind direction outside the building; and a controller for controlling the damper arrangement in dependence upon the sensed wind direction.

2. An apparatus as claimed in claim 1, wherein the controller is operable to cause the damper arrangement to connect the second end of the lower duct to the lower end of at least that one of the upper ducts whose upper end is the more, or the most, windward, whereby the lower duct acts as a supply duct tending to supply air to the building.

3. An apparatus as claimed in claim 1, wherein the controller is operable to cause the damper arrangement to connect the second end of the lower duct to the lower end of at least that one of the upper ducts whose upper end is the more, or the most, leeward, wherebv the lower duct acts as an extraction duct tendina to extract air from the building.

1 C, 4. An apparatus as claimed in claim 3, wherein:

the apparatus further includes a further lower duct having first and second ends, the first end of the further lower duct in use being open to the inside of the building; the damper arrangement is also operable to connect the second end of the further lower duct selectably to the lower end(s) of one of more other of the upper ducts; and the controller is also operable to cause the damper arrangement to connect the second end of the further lower duct to the lower end of at least that one of the upper ducts whose upper end is the more, or the most, windwardwhereby the further lower duct acts as a supply duct tending to supply air to the building.

5. An apparatus as claimed in any preceding claim, wherein the damper arrangment includes at least one respective damper for each of the upper ducts.

6. An apparatus as claimed in claim 5 when dependent on claim 4, wherein each damper is movable between:

a supply position in which it connects the lower end of the respective upper duct to the second end of the lower supply duct; and an extraction position in which it connects the lower end of the respective upper duct to-the second end of the lower extraction duct.

An apparatus as claimed in claim 6, wherein: the pathways through the damper arrangement between the upper ducts and one of the lower ducts are generally linear; and the pathways through the damper arrangement between the upper ducts and the other of the lower ducts pass through a chamber which, at least partly, surrounds the lower ends of tho upper ducts.

8. An apparatus as claimed in any preceding claim, wherein there are at least three, 20 and preferably at least four, such upper ducts.

9. An apparatus as claimed in any preceding claim, wherein the angular resolution of the wind direction sensor is no less than the angular sipacine of the upper ends of the upper ducts.

- 10 10. An apparatus as claimed in any preceding claim, wherein the angular resolution of the wind direction sensor is at least twice the angular spacing of the upper ends of the upper ducts.

An apparatus as claimed in claim 10 -when dependent on claim 8, wherein the number of the upper ducts which are connected by the damper arrangement to the lower duct, or one of the lower ducts, is selected by the controller from the set of numbers zero, one and more than one, in dependence upon the sensed wind direction.

12. An apparatus as claimed in any preceding claim, wherein the wind direction sensor comprises a rotary wind vane, and means for sensing the angular position of the 10 wind vane.

A ventilating apparatus for a building, substantially as described with reference to the drawings.