The present invention relates to a method for in accordance with the preamble of claim 1 for air-conditioning a building with outside air which is heated or cooled as necessary.

The invention also concerns an air-conditioned building in accordance with the preamble of claim 10. The wall and/or roof structures in said building are comprised of an at least partially separate outer shell and an inner shell spaced apart from said outer shell, whereby said shell structures have at least one window or similar structure adapted at each conditioned room space.

Dwelled buildings and constructions reguire light, heat and fresh air, combined with maximally effective removal of con¬ taminated air. These matters are conventionally handled only through compromising due to lacking skills of matching the above reguirements economically and technically.

The greatest weaknesses in existing buildings in terms of air-conditioning and heating are the following:

- Inferior heat insulation at windows. The k-values, or thermal conductivity coefficients at the windows are typically up to four-fold higher than those of the surrounding wall structures.

- Inlet air is conventionally supplied from above and typically also removed from above at the same wall in the room. The person occupying the room usually stays at the opposite wall close to a cold window. Under said window there is generally placed a heated radiator element, resulting in a situation where air passes the occupant, heat is directly removed through the ceiling perimeter and the occupant is blessed only by the noise of the air-

conditioning. This is because the capacity of the air- conditioning eguipment must be high to supply any fresh air to the opposite end of the room. By the same token, the heater element placed under the cold window must be overdimensioned to avoid sensation of draught. Thus, effective air-conditioning in itself presents an effective short circuit to the pneumatic flow, yet failing ever to achieve complete mixing of ambient air in the room.

In the prior-art systems it has also been impossible to discharge air via that section of room perimeter remaining at the window side due to the fact that airflow and cold environment about the window combine into a substantial draught factor and large uncontrolled convection flows in the room.

- In the summertime and spring there is generally an in¬ conveniently high heat load from solar radiation, yet in most of Europe during such a short period the investments in expensive and energy-consuming cooling systems are rare.

In conclusion it can be stated that a conventionally constructed and conditioned building uses excessively high volumes of air and heat in conditioning that yet fail to benefit the occupants in the building.

More advanced air-conditioning systems are also known in the art; these systems are based on the concept of discharging fresh air from the room's lower perimeter at the rear wall, while contaminated air is extracted at the room's upper perimeter. These systems are vastly better in terms of air mixing. Their disadvantage lies therein that they disperse dust and microbes along with the upwardly airflow rising from the floor level.

Several investigations have proven the inlet ducts of a building to be sources of different microbial contaminations

up to a level justifying a generally used expression "sick building" for places where working personnel easily catch infectious diseases.

It is an object of the present invention to overcome the disadvantages associated with the conventional technology and to provide a novel system for air-conditioning a room space.

The invention is based on the idea of. bringing fresh air in a building with a dual-shell construction from an intermedi¬ ate space formed between the shells directly via the windows into the occupied spaces in a conventional way and extract¬ ing the exhaust air from the opposite wall so that all extracted air can be collected into a single duct or a uniform ducting system.

Public buildings and offices are constructed at an increas¬ ing rate with glass outer panels, which can mainly be attributed to the easy cleaning of glass structures and their capability of reflecting excess solar radiation load. The intermediate space referred*to in this invention is designed as a part of the building's dual-shell structure, and as described above, said space formed between the shell structures is utilized as the building's ducting system.

Dual-shell structures in buildings are known from, e.g., DE Patent Specification No. 36 12 731 in which said structure is used, however, only for simplifying the construction work of the building inner shell. According to the GB Patent No. 1,592,783, the dual-shell structure has been employed in the circulating-air heating system by utilizing the inner shell functions as the heat reservoir and allowing the airflow to sweep the inner shell from both sides to attain a higher area for heat transfer.

Utilization of a dual-shell for air-conditioning or heat recovery is not discussed in patent literature or other pub-

lished sources. Conventionally known are, however, several constructions in which the outer walls of buildings are eguipped with channels employed for ducting and heating inlet air from outside the building prior to its routing to the interior spaces. References to the state of prior-art technology are to be found in SE Patent Applications Laid Open Nos. 412,613 and 355,660 and DE Published Patent Application No. 36 09 452. These systems do not, either, disclose the idea of routing the outside air flowing through dual-shell to pass between the window panes prior to its discharge into the conditioned room as is done in the present invention.

More specifically, the method according to the invention is mainly characterized by what is stated in the characterizing part of claim 1.

Furthermore, the method according to the invention is char¬ acterized by what is stated in the characterizing part of claim 10.

According to the invention the building is eguipped with such windows in which the outer pane is designed as a part of the building's outer shell, while the inner pane corre- spondingly forms a part of the building's inner shell. The intermediate space between the glass panes is combined with the intermediate space between the outer and inner shells to provide a continuous ducting space. This kind of design can reduce flow resistance in riser ducts formed by the inter e- diate spaces. Furthermore, in a preferred embodiment of the invention at least a part of the building's outer and inner shells is fabricated from glass or a similar transparent material which offers an easy way of checking the cleanli¬ ness of the shell structures. In this case the cleaning of the intermediate space is arranged by, e.g., designing the inner shell construction to be dismountable. The system according to the invention can thus avoid the "sick building" syndrome.

Further, according to the invention, it is advantageous with respect to the building's thermal economy to employ such windows in which the panes enclosing the intermediate space are characterized by low-emissivity surfaces. Such surfaces can reflect thermal radiation back to the room space. They can be designed directly to enclose the intermediate space. Alternatively, conventional window panes can be placed between said low-emissivity glass panes and the intermediate space.

Thus, the invention provides a building which has no sepa¬ rate inlet duct, but instead, is ventilated by air taken to the interior of the building via a cool structural part formed between the shells of a shell structure acting as the building's wall that is readily cleanable and fully flushable in summertime.

It is obvious that the intermediate space between the shells becomes heated in the summertime, as well as the intermedi- ate space between the inner and outer pane of the window. This thermal energy can simply be flushed away from the intermediate space by opening venting hatches of the intermediate space that are placed on the roof or upper storeys of the building. Such a facility avoids extraneous temperature elevation of the inner shell in summertime. Furthermore, such a design obviates totally or at least partly the construction costs of a large-capacity cooling system. A cooling system of the above-described kind is conventionally known from FR Patent Specification No. 2,500,508 that describes a building constructed from prefabricated elements with a dual-shell roof and one slanted wall facing the sun, whereby a convection flow can be induced in warm weather between the shell structures of the roof without using a fan.

According to a preferred embodiment of the invention the inlet air is allowed to communicate with the exhaust air from the room spaces of the building via a heat exchanger,

whereby heat can be transferred to, or alternatively, extracted from the inlet air. Exhaust air collected into a single ductwork can be entirely routed out from the building via a heat exchanger, whereby the fresh and cleaned inlet air to enter the intermediate spaces from outside the build¬ ing is initially heated by the energy of the warm and con¬ taminated exhaust air in the heat exchanger. Different kinds of heat exchangers, heat pumps and heat pipes can be uti¬ lized according to the invention. By virtue of the initial heating of the inlet air in the above-described manner prior to its discharge to the room space via the windows, substan¬ tial reduction of heat losses at the windows can be attained.

According to another preferred embodiment of the invention the building is eguippe *with heat emitting windows. Air to be discharged into the room space is directed via a horizon¬ tal slot above the window, whereby the air is heated by means of a heater element placed in the inner window.

In the summertime, air humidifiers installed in the exhaust ductwork offer a way of obtaining auxiliary cooling that reduces ambient temperature in the building theoretically by appro . 8 °C, in practice by approx. 4...5 °C.

The shell structure according to the invention can be applied to both walls and roof in a building.

The system according to the invention provides outstanding benefits. Indeed, a dual-shell structure whose intermediate space is used so that the inlet ventilation air is routed via said space during seasons reguiring heating, while said space is mostly bypassed for the inlet air during high-heat- load seasons, at the same time using said space for cooling the building, offers the possibility of designing a superior system in terms of air-conditioning as well as heat recovery and cooling in air-conditioning so that said system is free from cumulative drawbacks of many other constructions.

Additionally, said system provides an extremely safe building in fire situations, because smoke cannot enter occupied areas via the air-conditioning system.

According to the present invention, an advantageous flow pattern analogous to a piston flow is attained in occupied spaces which can extract contaminated air without mixing and which, according to theoretical studies, is approximately three times more effective conditioning method in respect to a pneumatically non-short-circuited ventilation system of a room space filled with mixed fresh and contaminated air (refer to K. Klobut: Model test of Ventilation Effectiveness, ISBN 951-753-536-8, p. 48...61).

Air-conditioning system specialists are engaged in an on-going debate about pressure differentials between the upper and lower floors of a building that cause disturbances in the building's air-conditioning. The so-called smoke¬ stack effect with resultant large leakage losses of air- conditioning and, of course, thermal losses of the building occurring via air leakages are matters being debated. In the present dual-shell system the pressure differential between the intermediate space of the shells and outside air can be measured and controlled using extremely simple means by employing dampers and similar control devices. If a similar control system is to be implemented in a single-shell build¬ ing, this would require air locks between floors, air-tight lift stacks and similar arrangements. By virtue of the intermediate space between the shells operating in an isobaric condition and at a constant pressure differential to the space enclosed by the inner shell, the space enclosed by the inner shell also operates in an isobaric condition, thus achieving a well-managed and controlled behaviour of air flow patterns.

In the following, the invention will be examined in more detail with the help of the attached drawings.

Figure 1 is a diagrammatic cross-sectional side view of a building according to the invention.

Figure 2 is a detailed cross-sectional side view of a left- side wall construction of the building.

Fig. 1 is first examined for the outer and inner shells of the building's wall that are designated in the drawing by reference numbers 1 and 2, respectively. These shell struc- tures are mutually spaced at a distance from each other, whereby a intermediate space 3 remains between them extend¬ ing in the vertical direction from the lower part of the building to its upper part. The width of the intermediate space 3 is designed so as to attain an easy cleaning of said intermediate space. Therefore, a typical value for the intermediate space width is approx. 50...500 mm, preferably 100...300 mm.

The shells 1, 2 can be constructed within the scope of the present invention from any kind of construction material conventionally employed in walls. Thus, they can be of rock (concrete), wood or metal (steel). In a preferred embodiment of the present invention they are, however, made of glass, preferably of a low-k glass. Also other corresponding mate- rials offering transparency such as polyacrylate and polycarbonate plastics are suitable. To minimize heat loss¬ es, the glass-material shell structures can be produced as multilayer constructions in which the intermediate spaces are hermetic spaces filled with, e.g., noble gases. Examples of such glass types are represented by low-emissivity

(Low-e) products marketed under the trademarks K, Kappa and Planiterm. These products have a very low thermal conductiv¬ ity. As mentioned above, transparent wall constructions advantageously offer easy checking for cleanliness in the intermediate spaces. Moreover, surfaces made of glass or similar material are readily cleaned when desired.

Horizontal hatching 4 in Fig. 1 indicate the intermediate floors in a building that separate storeys from each other. The intermediate floors 4 as well as the frame construction of the building can be of any conventional construction material such as concrete or steel.

The inner shell 2 has air ducts 5 formed at the upper perim¬ eter of the walls in occupied spaces. Air can be discharged from the intermediate space 3 into the occupied spaces via these ducts.

The heat recovery system in the building is marked in Fig. 1 by a circle and letter combination LTO. As is evident from the directions of arrows in the drawing, contaminated air is collected from the room into an exhaust air system, where its heat content can be recovered and possibly transferred to the fresh air flowing in the intermediate space 3.

The intermediate space 3 can be eguipped with a fan 6 for inducing outside air into the intermediate space. The fan 6 can further be complemented with means for heating, filter¬ ing and cleaning the outside air. The heating means can be made to communicate with the heat recovery system (LTO) .

Valves and hatches 7, 8 placed to the lower and upper parts of the intermediate space 3 can be employed for the control of air flows.

According to the invention, the fresh inlet air is dis- charged into the room spaces by suction from the intermedi¬ ate space remaining between the outer shell 1 and the inner shell 2 for air-conditioning during seasons requiring heat¬ ing, and then routed from the windows of the inner shell 2 into the room. During warm seasons the intermediate space 3 between the outer shell 1 and the inner shell 2 can be simultaneously opened from below and above in order to cool the intermediate space by means of induced or natural convection, whereby the fresh inlet air is brought by

suction to the room spaces via pipes routed directly from outside through the intermediate space.

In the Scandinavian climate it is important to be able to fully isolate the intermediate spaces of the northern and southern facades, respectively, when necessary. This arrangement namely makes it possible to cool the intermedi¬ ate space between the shell by ventilating (that is, by opening both hatches 7, 8), while as the shadow side of the building still remains cold, only the hatch 7 is opened on this side as indicated in the drawing.

Shown in Fig. 2 is a more detailed cross section of the left-side wall of a building corresponding to that illus- trated in Fig. 1. Reference number 9 in the latter drawing designates a window of the room space that is heat-emitting according to a preferred embodiment of the invention. For that purpose, that transparent part of the window remaining on the inner-shell side has an electrically heated flat surface. The lower part 13 of the wall can also be made of glass, e.g., sand-blasted glass having a similar double- or triple-layer structure as the transparent window 9. The ventilation air duct comprises an elongated slit 5 formed to the upper edge of the window. The front side of the slit has a control means 10, e.g., a downward bent lip formation whose purpose is to deflect the inlet air entering the room space from the intermediate space 3 via the air duct slit 5 so that the ventilation air sweeps across the room-side surface of the window 9 (laminar flow by the Coanda effect), whereby the air becomes heated. Window heating is used particularly during the heating period of the building.

Exhaust air from the room space is routed via an exhaust air system 11 to heat with the help of a heat exchanger and/or heat pump unit the fresh inlet air flowing between the shells prior to routing the air into spaces inside the inner shell occupied by people or animals.

According to a preferred embodiment shown in Fig. 2, the shell structure comprises two dual-layer window construc¬ tions at the window locations. Therein, the outer shell is provided with a window construction in which the outside surface is of a radiation-absorbing sun tint glass. Advanta¬ geously, spaced apart from said outermost glass pane, is adapted a glass pane of high IR absorbance, or preferably, of low emissivity. The intermediate space between said glass panes is filled with a noble gas. The opposite side of the window's intermediate space is provided with a similar dual- layer glass construction in which, however, the glass pane facing the window's intermediate space is of conventional float glass. The innermost glass pane facing the room space is of a low emissivity glass with an electrically heated surface on the side remaining toward the room space.

Energy transfer in the above-described embodiment takes place as follows: In summer the solar short-wavelength radiation (λ approx. 0.3...2 μm) is absorbed by the outermost glass pane, with a resultant temperature rise. Consequently, the outermost glass pane emits IR band radiation (λ approx. 4...20 μm) into the intermediate space between the outer glass panes. The radiation is reflected from said surface of low emissivity. Due to heat conduction, however, a portion of the thermal energy is conveyed to the window's intermediate space 3, with a resultant temperature rise. A portion of the radiation is further conveyed via the float glass pane of the inner glass construction, whereby said radiation is re-reflected into said window's inter- mediate space from the low-emissivity glass pane of the inner glass construction. Air flow passing through the window's intermediate space cools the surfaces of the glass panes. The heated air rises upward and is expelled to the outside.

In the wintertime, solar radiation passes through and heats the window's intermediate space 3 as described above. The situation herein is, however, changed in the sense that the

12

low-emissivity glass pane surface facing the room space is heated with electric energy, thus making it emit IR radiation to the room space. Correspondingly, IR radiation from the room space impinges said glass pane surface and becomes reflected therefrom. Thermal stray radiation losses from the room remain low by virtue of the special glass pane surface. However, a small portion of IR radiation emitted by the room and the electrically heated inside glass pane surface finds its way through the innermost glass pane via the float glass pane into the window's intermediate space 3. The low-emissivity glass pane surface of the outer window construction prevents the stray IR radiation from further escaping to the outside environment by reflecting said radiation back to said intermediate space, thus causing a small temperature rise in said intermediate space. Supply air to the room space is --also in this case routed via said intermediate space 3 and the air duct 5 in the manner described in the text above. When necessary, the supply air can be subjected to additional heating as also described earlier.

Thus, the above-described preferred embodiment of the invention has glass panes of low-emissivity surfaces enclosing the window's intermediate space from both sides, whereby said surfaces entrap thermal radiation into said intermediate space. Depending on the situation, the heat accumulated can then be transferred via the intermediate space in a centralized manner either into the room space, or alternatively, out therefrom.

In a preferred embodiment of the invention the intermediate space 3 is divided into vertical riser spaces. These risers are then mutually connected to each other by horizontal pressure-equalizing ducts 12. Because the inner and outer shells advantageously have essentially transparent constructions at the riser spaces, considerations on a consistent appearance of the structures and easy cleaning of the intermediate space make it advantageous to design the

riser spaces to have an equal width along the building's outer wall to that of the windows. To control air leaks, the vertical riser ducts are provided with pressure control means such as dampers and valves that make it possible to equalize pressure differentials between the outside air pressure and pressure in the intermediate space 3 in order to avoid leak disturbances. Such a system can handle asymmetric wind pressures on the building as well as pressure differentials induced by asymmetric solar radiation heat loads.