GB2105458A

GB2105458A - Ventilating buildings

Info

Publication number: GB2105458A
Application number: GB08221310A
Authority: GB
Inventors: Marco Zambolin
Original assignee: Individual
Current assignee: Individual
Priority date: 1981-07-31
Filing date: 1982-07-23
Publication date: 1983-03-23
Also published as: CH651914A5; FR2510728A1; BE893893A; ES514552A0; DK341782A; CA1178841A; FR2510728B1; IT8123283A0; ES8307356A1; DE3228401A1; JPS5852926A; SE8204508D0; GB2105458B; SE8204508L; NL8203061A

Abstract

In a building, particularly an industrial building, air is admitted, at outdoor temperature, into a zone below the roofing, in order to decrease the thermal gradient between the upper and the lower part of the building, and thus diminish the dissipation of heat through the roof. A false ceiling (1) made of porous, preferably translucent material permits uniform distribution of the air flow from the upper zone (2) to the lower area. The air is supplied at super-atmospheric pressure through a duct (3) and distributor (4). <IMAGE>

Description

SPECIFICATION Air conditioning The present invention relates to an airconditioning method and plant, particularly but not exclusively for industrial buildings, to diminish the dissipation of heat occuring in buildings, especially near the roof.

As it is well-known, the heating of premises is very expensive and the problem of reducing the relevant costs by means of suitable measures is becoming a more and more urgent matter.

Despite the fact that modern technology allows the use of materials having an ever-increasing degree of insulation, thermal dissipation continues to be excessively high. In particular, very high buildings are those especially affected by heat dissipation phenomena, due to a concurrence of unfavourable causes.

in almost all cases it is the lower part of the building that is to be heated; on the other hand, in order to keept this part at a proper temperature, it is necessary to heat the whole of the building, and since heat, due to a known physical effect, tends to go upwards, the air temperature in the upper zones of the buildings is higher than that of the working ones.

Furthermore, the roofing is the least thermally insulated area in industrial buildings (both for technical and economic reasons), and it is in correspondence of this zone that the greatest difference between outdoor and indoor temperatures occurs.

It ensures that the maximum dissipation occurs in that part of a building where heating is not a major exigency.

Moreover, the difference in the temperature of the upper and lower part of the building causes hot air to escape through any fissures and holes existing in the upper part of the building, due to the so-called "draught effect".

This produces by reaction the entry of a corresponding amount of cold air in the lower part of the building, wherein heating is most important.

In order to avoid the inconveniences mentioned above, the present invention provides for a method of air-conditioning buildings (industrial sheds in particular), according to which a certain amount of air is let in from outside in the upper part of the building, so as to produce a laminar flow acting as a barrier against the dissipation of heat due to conduction and radiation through the building roof and walls.

The method consists substantially in allowing a certain amount of pressurized air to enter the upper part of the building, and then to evenly spread close to the roof and walls, so that the inner hot air does not come into contact with the roof and walls and no loss of heat occurs.

The admission of air such as the one described above reduces the filtration of air from outside in the lower part of the building, permitting recovery of the heat hovering in strata in the upper part, and to utilize the same to heat the incoming air that is descending.

Basically, the method consists in letting in a certain amount of air from outside through the roof, so as to make a barrier preventing the inner hot air from touching the roof itself and causing dissipation of heat.

The air introduced into the room makes its way downwards, absorbing heat from the higher hot air layers, until it reaches the lower zone at the desired temperature.

To prevent the air introduced in the room from heading downwards following localized lines of flux, preferably there is provided a porous barrier allowing an even distribution of the air flux all over the surface of the building.

Embodiments of the invention, by way of example, are diagrammaticaily shown in the four figures of the accompanying drawings.

Fig. 1 schematically shows the section of a building divided in two by a ceiling 1 consisting of a porous, preferably translucent barrier, which defines, below the roof, a zone 2 where, through a duct 3 and a distributing passage 4, there is admitted from outside an amount of air enough to keep said zone at a higher pressure than the lower zone beneath it; by "porous" there is meant a barrier apt to cause loss of head.

Such a pressure spreads the air uniformly all over the surface of barrier 1 and, as a consequence thereof, the flux of air passed through the double ceiling and heads downwards.

The descending air absorbs the heat hovering in the room, and reaches the lower zone at the desired temperature.

By this system, therefore, a thermal insulation of the roofing is achieved, in that the higher pressure of zone 2 prevents the heated air present in the room from going up and touching the roof itself.

Thanks to the pressurized air present in the room it is then possible to avoid filtrations of cold air into the lower part of the building, wherein -intake openings are usually provided.

The double ceiling 1 is advantageously made of translucent material, with a view to allowing light to pass through, in the case of sheds with overhead lighting.

Fig. 2 schematically shows the section of a building insulated by the system according to the invention, in the case wherein the use of the porous barrier is not opportune or possible.

If this is the case, the outdoor air is fed in, e.g.

by means of a fan or other known systems, through a duct 5 and a passage 6, although suitable deflectors must be there, in order to make the incoming air contact the whole inner surface of the roofing.

In this way the air tends to adhere tangentially to the surface, according to the Coanda principle, and a real cold air cushion is interposed between the inside of the building and the roof.

In this case too the air cushion prevents heat from reaching the roof and escaping through it.

In Fig. 3 there is schemactically shown a building, for instance a glasshouse or the iike, wherein the double ceiling 7 is built by means of a number of inflatable tubular elements 8, preferably made of a transparent material such as, e.g. polyethylene. When there is a considerable loss of heat also through the walls, for instance in the case of glass surfaces of vast sizes, it is possible to apply the porous barrier even to the walls (as illustrated, always schematically, in Fig.

4). Here a hollow space 10 is formed adjacent the walls by a porous translucent barrier 9; the air which had been previously admitted in the upper part always through a duct 11 and distributing passage 12 spreads through the space 10.

As the amount of heat which gets lost through one wall is proportional to the difference between the outdoor and the indoor temperature, the method according to the invention provides for the admission of a certain amount of air in the upper part of an industrial building, so as to form, in correspondence of the inner surface of the roof and walls, an air cushion preventing heat from getting in touch with said roof and walls.

The air is spread so as to properly insulate the dissipative surfaces, and recover the heat hovering in strata in the upper part of the room by exploiting it to heat the air admitted from outside.

In this manner, heat dissipation through the roof is avoided, since the outdoor and the indoor temperature (very close to the wall) will be the same.

Moreover, the state of over-pressure in which the inside of the building is kept prevents cold air from filtering in the lower part thereof; thanks to this, no inconveniences are caused by dust which would otherwise raise.

The process according to the invention may be variously employed, for example in the building of glasshouses, stables, gymnasiums, swimmingpools, meeting-rooms, cinemas, theatres, etc. It can be applied both to roof and walls, or to glass surfaces only; in the latter case, a suitable interspace is made by means of a porous translucent barrier.

The existing experimental plants were found to pay off in a very short time, thanks to improvements in the environmental conditions and a considerable saving in energy.

Claims

1. A method of air-conditioning a building including providing a heat insulating layer of air adjacent at least the roof of the building by admitting air from outside the building.

2. A method according to claim 1, wherein the admitted air is at a temperature below that of the remaining part of the building and is dispersed over the roof surface.

3. A method according to claim 1 or 2, wherein the air pressure within the building is higher than atmospheric.

4. A method according to any of claims 1-3, wherein the admitted air is conveyed into the building through passage in the upper part thereof.

5. A method according to any of claims 1-4, wherein the admitted air is subjected to a pressure higher than that in the remaining part of the building to produce flow from the heat insulating layer into the remaining part of the building.

6. A plant for putting into practice the process according to the previous claims, characterized in that there is provided for a porous barrier in correspondence of the upper part of the building, said barrier delimiting a zone underlying the roof, there being provided means suitable for taking air from outside and forcing it into said zone, which is therefore kept in an over-pressurized state with respect of the underlying zone.

7. A plant according to claim 6, characterized in that said porous barrier is provided in a translucent material.

8. A plant according to the claims 6 and 7, characterized in that said porous barrier is made by means of inflatable tubular elements arranged in the one close to the other.

9. A plant according to claims 6 through 8, characterized in that said barrier also extends close to the side walls, so as to form a hollow space in correspondence of glass walls or windows - if any.

10. A plant for putting into practice the process according to the claims 1 through 5, characterized in that there are provided for means suitable for admitting air in correspondence of the upper part of a building, as well as means suitable for conveying said air along the roofing and the upper part of the walls.

11. A building having air-conditioning apparatus which comprises means for supplying air from outside the building into an upper part thereof to form a layer adjacent the roof of the building.

12. A building according to claim 11 including an air permeable barrier spaced from the roof through which the supplied air can flow into the space within the building below the barrier.

13. A building according to claim 12 wherein the barrier is translucent.

1 4. A building according to claim 1 2 wherein the barrier comprises a plurality of inflatable tubular elements.

1 5. A building according to any of claims 1 14 wherein the barrier is extended to lie adjacent and spaced from the walls of the building.

1 6. A building according to any of claims 11-15 wherein the air supplying means produces a laminarflow of the supplied air parallel to the roof.

1 7. A method of air-conditioning a building substantially as herein before described and shown in any of the accompanying drawings.

1 8. A building having an air-conditioning plant constructed and arranged substantially as herein before described and shown in any of the accompanying drawings.