1. Field of the Invention

The field of the invention relates to enclosed spaces through which vehicles or pedestrians may pass, the enclosed spaces arranged or configured to reduce polluting gases. Such enclosed spaces may include transportation tunnels or car parks, for example.

2. Technical Background

NOx is a generic term for the mono-nitrogen oxides NO and N02 (nitric oxide and nitrogen dioxide). They are produced from the reaction of nitrogen and oxygen gases in the air during combustion, especially at high temperatures. The two major emission sources are transportation vehicles and stationary combustion sources such as electric utilities and industrial boilers. A smaller amount, typically 5% of the total, is emitted as primary nitrogen dioxide, while the major proportion of atmospheric nitrogen dioxide is a secondary product of atmospheric chemistry (as a reaction with ozone). NOx is a potent greenhouse gas which also contributes to ground-level smog, ozone formation and acid rain. NOx emissions also contribute to the formation of fine particles and ozone smog that cost society increasing amounts of money from illnesses and deaths.

Unfortunately, air emissions targets remain largely unmet for key pollutants, including NOx, particulate matter (PM) and other volatile organic compounds (V OCs) that affect our environment and health. There is a need for investment in more novel and active physical and chemical solutions.

Scientific studies on photocatalysis started about four decades ago, and titanium dioxide has emerged as an excellent photocatalyst material for environmental purification.

TiOz has received a great deal of attention due to its chemical stability, non-toxicity, low cost, and other advantageous properties. TiOz is used in catalytic reactions acting as a promoter, a carrier for metals and metal oxides, an additive, or as a catalyst. Reactions carried out with Ti02 catalysts, which can be powered by light (photocatalysis), include selective degradation of various chemicals such as SOx, NOx and VOCs.

Enclosed spaces through which vehicles or pedestrians may pass, such as tunnels or car parks inside buildings, are places in which polluting gases such as NOx may be produced or may already be present, and such polluting gases may harm human beings present in such spaces. There is a need to reduce the concentration of polluting gases such as NOx in enclosed spaces through which vehicles or pedestrians may pass. It is desirable to reduce in an energy efficient way the concentration of polluting gases such as NOx in enclosed spaces through which vehicles or pedestrians may pass.

3. Discussion of Related Art

JPH11324584A entitled "Tunnel Interior Finish Material made of Inorganic Sheet and Manufacture thereof, has an English Abstract which discloses activation of a photocatalyst by lighting to decompose injurious ingredient in exhaust gas or organic substance stuck to interior finish material and easily cleaning the interior finish material by using an inorganic substance sheet fixed with photocatalyst particles on the surface as the tunnel interior finish material. The JPH11324584A English Abstract further discloses an aggregate and water and added to hydraulic coagulant containing 30-45 pts.wt. of silica containing at least 20 weight % of ultra fine particle silica of diameter under 1 μιη, they are stirred in vacuum, poured in a form to form an inorganic sheet by cold setting, and it is used as tunnel inner facing material. The form is previously spread with pigment containing photocatalyst such as titanium oxide powder, and buried with an inorganic net for reinforce. Hereby, the photocatalyst particle on the surface of the inorganic sheet are activated by lighting in the tunnel or irradiation of the headlight of an automobile, NOx or SOx in exhaust gas is decomposed, and organic substance stuck to the sheet surface can be decomposed to facilitate cleaning.

SUMMARY OF THE INVENTION

According to a first aspect of the invention, there is provided an enclosed space system through which vehicles may pass, the enclosed space system including interior surfaces, a photocatalytic coating on an interior surface of the enclosed space system, and a lighting system in attachment with an interior surface of the enclosed space system, the lighting system including light sources emitting wavelengths in the range between 340 nm and 450 nm, the lighting system arranged to illuminate the photocatalytic coating with the wavelengths in the range between 340 nm and 450 nm, wherein the photocatalytic coating is activatable by the wavelengths in the range between 340 nm and 450 nm. An advantage is that the light with the wavelengths in the range between 340 nm and 450 nm is effective in activating the photocatalytic coating, to reduce the presence of various harmful polluting gases in the enclosed space, and/ or to eliminate bacteria and mould from the surface.

The enclosed space system may be one wherein the lighting system does not emit light with wavelengths below 340 nm. An advantage is that harmful effects to humans of light with wavelengths below 340 nm is avoided.

The enclosed space system may be a tunnel. An advantage is that the light with wavelengths in the range between 340 nm and 450 nm is effective in activating the photocatalytic coating, to reduce the presence of harmful polluting gases in the tunnel, and/ or to eliminate bacteria and mould from the surface.

The enclosed space system may be a road tunnel. An advantage is that the light with wavelengths in the range between 340 nm and 450 nm is effective in activating the photocatalytic coating, to reduce the presence of harmful polluting gases from vehicle emissions in the tunnel, and/ or to eliminate bacteria and mould from the surface.

The enclosed space system may be a rail tunnel. An advantage is that the light with wavelengths in the range between 340 nm and 450 nm is effective in activating the photocatalytic coating, to reduce the presence of harmful polluting gases from vehicle emissions, or from electric discharges, in the tunnel, and/or to eliminate bacteria and mould from the surface.

The enclosed space system may be a pedestrian tunnel. An advantage is that the light with wavelengths in the range between 340 nm and 450 nm is effective in activating the photocatalytic coating, to reduce the presence of harmful polluting gases in the tunnel, and/ or to eliminate bacteria and mould from the surface.

The enclosed space system may be a car park in a building, in a ferry, or in a car train. An advantage is that the light with wavelengths in the range between 340 nm and 450 nm is effective in activating the photocatalytic coating, to reduce the presence of harmful polluting gases in the car park, and/ or to eliminate bacteria and mould from the surface.

The enclosed space system may be one wherein the light sources emit wavelengths in the range between 340 nm and 389 nm.

The enclosed space system may be one wherein the light sources emit only light in the wavelength range from 340 nm to 450 nm. An advantage is improved energy efficiency of activating the photocatalytic coating, which may be a cement-based hydraulic binding photocatalytic coating. A further advantage is very little or no health risk to humans in the enclosed space.

The enclosed space system may be one wherein the light sources emit only light in the wavelength range from 340 nm to 389 nm. An advantage is improved efficiency of activating the photocatalytic coating. A further advantage is very little or no health risk to humans in the enclosed space.

The enclosed space system may be one wherein the light sources emit light in the wavelength range 340 nm to 389 nm and in the wavelength range 390 nm to 450 nm.

The enclosed space system may be one wherein the light emitted by the light sources in the wavelength range 340 nm to 450 nm is within a relatively narrow spectral distribution of radiation wavelengths. Examples of light sources with a relatively narrow spectral distribution of radiation wavelengths are light emitting diodes and lasers. An advantage is very little or no health risk to humans in the enclosed space.

The enclosed space system may be one wherein a surface coated with the photocatalytic coating is illuminated with the light in the wavelength range 340 nm to 450 nm at an intensity of light in the wavelength range 340 nm to 450 nm greater than 1.0 W/m2.

The enclosed space system may be one wherein a surface coated with the photocatalytic coating is illuminated with the wavelengths in the range between 340 nm and 450 nm at an intensity in the range of 1.0 W/m2 to 50 W/m2.

The enclosed space system may be one wherein a surface coated with the photocatalytic coating is illuminated with the wavelengths in the range between 340 nm and 450 nm at an intensity in the range of 1.0 W/m2 to 20 W/m2.

The enclosed space system may be one wherein a surface coated with the photocatalytic coating is illuminated with the wavelengths in the range between 340 nm and 450 nm at an intensity in the range of 1.0 W/m2 to 10 W/m2.

The enclosed space system may be one wherein the light sources are one or more of fluorescent lamps, short wave lamps, gas discharge lamps, metal halide lamps and lasers.

The enclosed space system may be one wherein the light sources are light emitting diodes (LEDs). Advantages of LEDs include high power conversion efficiency and compact size.

The enclosed space system may be one wherein the light emitting diodes are arranged on a bar, or on a plurality of bars. An advantage is facilitation of maintenance.

The enclosed space system may be one wherein the light emitting diodes are arranged in the form of a frame including a plurality of LED spotlights, or in the form of a plurality of frames including a plurality of LED spotlights.

The enclosed space system may be one wherein use of the light emitting diodes emitting wavelengths in the range of 340 nm to 450 nm as light sources is scalable over a wide range of enclosed space sizes. An advantage is reusability or scalability of designs for different systems.

The enclosed space system may be one including a side wall coated with the photocatalytic coating, wherein the light sources emitting wavelengths in the range of 340 nm to 450 nm are directed towards the side wall.

The enclosed space system may be one including a ceiling coated with the photocatalytic coating, wherein the light sources emitting wavelengths in the range of 340 nm to 450 nm are directed towards the ceiling.

The enclosed space system may be one including a floor coated with the photocatalytic coating, wherein the light sources emitting wavelengths in the range of 340 nm to 450 nm are directed towards the floor.

The enclosed space system may be one wherein the system is arranged to reduce an amount of NOx gases in the enclosed space.

The enclosed space system may be one wherein the system is arranged to reduce an amount of SOx gases in the enclosed space.

The enclosed space system may be one wherein the system is arranged to reduce an occurrence of bacteria and molds on the surface.

The enclosed space system may be one wherein the system is arranged to reduce an amount of volatile organic compounds gases in the enclosed space.

The enclosed space system may be one wherein the photocatalytic coating is a cement-based hydraulic binding photocatalytic coating. An advantage is that the light with the wavelengths in the range between 340 nm and 450 nm is effective in activating the cement-based hydraulic binding photocatalytic coating, to reduce the presence of harmful polluting gases in the enclosed space, and/ or to eliminate bacteria and mould from the surface.

The enclosed space system may be one wherein the photocatalytic coating is derived from a cement-based photocatalytic composition, which comprises:

(a) at least one cement binder;

(b) at least one photocatalyst;

(c) at least one cellulose ether;

(d) at least one fluidizing agent;

(e) at least one first calcareous filler in the form of particles of which at least 95% by weight has a dimension not greater than 100 μιη;

(f) at least one second calcareous filler in the form of particles of which at least 95% by weight has a dimension not greater than 30 μιη;

(g) at least one silane supported on an inorganic support in the form of powder.

The enclosed space system may be one wherein the photocatalytic composition comprises:

(a) from 15 to 60% by weight, preferably from 20 to 50% by weight, of at least one cement binder;

(b) from 0.5 to 12% by weight, preferably from 1 to 8% by weight, of at least one photocatalyst;

(c) from 0.02 to 3% by weight, preferably from 0.05 to 1.5% by weight, of at least one cellulose ether;

(d) from 0.05 to 5% by weight, preferably from 0.1 to 2% by weight, of at least one fluidizing agent;

(e) from 10 to 50% by weight, preferably from 15 to 35% by weight, of at least one first calcareous filler in the form of particles of which at least 95% by weight has a dimension not greater than 100 μιη;

(f) from 10 to 50% by weight, preferably from 15 to 35% by weight, of at least one second calcareous filler in the form of particles of which at least 95% by weight has a dimension not greater than 30 μιη;

(g) from 0.05 to 5% by weight, preferably from 0.01 to 3% by weight, of at least one silane supported on an inorganic support in the form of powder.

The enclosed space system may be one wherein the cement binder (a) is a Portland cement.

The enclosed space system may be one wherein the photocatalyst (eg. (b)) is photocatalytic titanium dioxide, mainly in anatase crystalline form.

The enclosed space system may be one wherein the photocatalytic titanium dioxide has a granulometry such as at least 95% by weight has a dimension not higher than 50 nm, preferably not higher than 20 nm.

The enclosed space system may be one wherein the photocatalytic titanium dioxide is in admixture with a non-photocatalytic titanium dioxide.

The enclosed space system may be one wherein the cellulose ether (c) has a Brookfield viscosity RVT at 20°C from 100 to 70,000 mPa.s, preferably from 100 to 30,000 mPa.s, more preferably from 200 to 10,000 mPa.s.

The enclosed space system may be one wherein the first calcareous filler (e) is in the form of particles of which at least 95% by weight has a dimension not greater than 70 μιη, while the second calcareous filler (f) is in the form of particles of which at least 95% by weight has a dimension not greater than 20 μιη.

The enclosed space system may be one wherein the first calcareous filler (e) is in the form of particles of which not more than 5% by weight has a dimension not greater than 30 μιη, preferably not greater than 20 μιη.

The enclosed space system may be one wherein the calcareous fillers (e) and (f) are present in a weight ratio (e)/ (f) from 0.2 to 2.0, preferably from 0.5 to 1.5.

The enclosed space system may be one wherein the supported silane (g) is in the form of particles of which at least 95% by weight has a dimension not greater than 100 μ, preferably not greater than 80 μ.

The enclosed space system may be one further comprising: (h) at least one hydrophobized vinyl polymer, preferably a terpolymer of vinylchloride, ethylene and a vinyl ester CH2=CH-0-C(=0)-R, wherein R is an alkyl, linear or branched, C4-C24.

The enclosed space system may be one further comprising: (i) at least one salt of a long chain carboxylic acid.

The enclosed space system may be one wherein water is added to the photocatalytic composition in a predetermined proportion, by mixing until a homogeneous and fluid product is obtained, and that product is applied to the interior surface of the enclosed space as the photocatalytic coating.

The enclosed space system may be one wherein the weight ratio between water and cement binder (a) is from 0.2 to 0.8.

The enclosed space system may be one wherein, after application and drying, the photocatalytic composition forms a coating layer having a thickness from 0.05 mm to 1 mm, preferably from 0.1 to 0.5 mm.

According to a second aspect of the invention, there is provided use in a tunnel of light emitting diodes emitting wavelengths in the range between 340 nm and 450 nm to illuminate an interior surface of the tunnel coated with a photocatalytic coating, wherein the photocatalytic coating is activatable by wavelengths in the range between 340 nm and 450 nm, and wherein the light emitting diodes do not emit light with wavelengths below 340 nm. Advantages include compact sources, which are energetically efficient, and which provide activation of the photocatalytic coating. An advantage is that harmful effects to humans of light with wavelengths below 340 nm is avoided.

The use may be one wherein the light emitting diodes emit wavelengths in the range between 340 nm and 389 nm.

The use may be one wherein the light emitting diodes emit only wavelengths in the range between 340 nm and 389 nm. An advantage is even more energetically efficient activation of the photocatalytic coating. An advantage is little or no health risks to humans.

The use may be one wherein the light emitting diodes emit wavelengths in the range between 340 nm and 389 nm and wavelengths in the range between 390 nm and 450 nm.

The use may be one wherein the surface coated with a photocatalytic coating is

illuminated with the light emitting diodes at wavelengths in the range between 340 nm and 450 nm at an intensity greater than 1.0 W/m2. An advantage is a high rate of reduction of harmful gases.

The use may be one wherein the surface coated with a photocatalytic coating is illuminated with the light emitting diodes at wavelengths in the range between 340 nm and 450 nm at an intensity in the range of 1.0 W/ m2 to 50 W/ m2.

The use may be one wherein the surface coated with a photocatalytic coating is illuminated with the light emitting diodes at wavelengths in the range between 340 nm and 450 nm at an intensity in the range of 1.0 W/ m2 to 20 W/ m2.

The use may be one wherein the surface coated with a photocatalytic coating is illuminated with the light emitting diodes at wavelengths in the range between 340 nm and 450 nm at an intensity in the range of 1.0 W/ m2 to 10 W/ m2.

There is provided use of light emitting diodes emitting wavelengths in the range between 340 nm and 450 nm to illuminate a surface coated with a photocatalytic coating, wherein the photocatalytic coating is activatable by the wavelengths in the range between 340 nm and 450 nm.

BRIEF DESCRIPTION OF THE FIGURES

Aspects of the invention will now be described, by way of example(s), with reference to the following Figures, in which:

Figure 1 shows a cross section of a tunnel including an illumination unit which emits light in a wavelength range between 340 nm and 450 nm. The dimensions of the tunnel are indicated, in cm.

Figure 2 shows a cross section of a tunnel including an illumination unit which emits light in a wavelength range between 340 nm and 450 nm. The dimensions of the tunnel are not indicated.

DETAILED DESCRIPTION

Enclosed spaces through which vehicles or pedestrians may pass, such as tunnels, car parks inside buildings, or car ferry interiors, are places in which polluting gases such as NOx may be produced or may already be present such as by traveling in to the enclosed space from outside, and such polluting gases may harm human beings present in such enclosed spaces. Tunnels may be road vehicle tunnels, such as the Blackwall Tunnel in London, United Kingdom, under the river Thames. In road vehicle tunnels, polluting gases such as NOx may be produced by internal combustion engines. Tunnels may be rail tunnels, such as the Waterloo & City line tunnels in London, under the river Thames, or the Belsize tunnels in London on the Midland main line north of St Pancras station. In rail tunnels, polluting gases such as NOx may be produced by internal combustion engines, or by electric discharge. In car parks inside buildings, or in car ferry interiors, polluting gases such as NOx may be produced by internal combustion engines.

Examples of vehicles include automobiles, trucks, buses, trains, motorbikes, and bicycles.

Light emitting sources may be arranged to illuminate a photocatalytic coating in an enclosed space eg. in a tunnel. Light sources may emit light in the wavelength range 340 nm to 450 nm. Light sources may emit essentially only wavelengths in the range 340 nm to 389 nm, or light sources may emit light in the wavelength range 340 nm to 389 nm and in the wavelength range 390 nm to 450 nm. Known light sources which may emit light in the wavelength range 340 nm to 450 nm include fluorescent lamps, short wave lamps, gas discharge lamps, metal halide lamps, light emitting diodes and lasers. The known light sources which may emit light in the wavelength range 340 nm to 450 nm which include fluorescent lamps, short wave lamps, gas discharge lamps, metal halide lamps, light emitting diodes and lasers, may be powered by mains electricity. The photocatalytic coating may include TiOz. The photocatalytic coating may provide selective degradation of various chemicals such as SOx, NOx and VOCs.

Light emitting diode (LED) sources may be arranged to illuminate a photocatalytic coating in an enclosed space, eg. in a tunnel. LED sources may be in the form of a bar of LED sources. LED sources may be in the form of a frame including a plurality of LED spotlights. A bar of LED sources typically has the advantages of reduced assembly cost, and reduced installation cost, when compared to a frame including a plurality of LED spotlights.

LED light sources include LED light sources emitting wavelengths in the range 340 nm to 389 nm. An example is a Nichia U365 LED (supplied by Nichia Corporation, Tokushima 774-8601, Japan) which has a peak wavelength at 365 nm, a spectrum half width of 9 nm and a radiant flux of 780 mW. A further example is a Nichia U385 LED (supplied by Nichia Corporation, Tokushima 774-8601, Japan) with a peak wavelength at 385 nm, a spectrum half width of 10 nm, and a radiant flux of 900 mW. For both the U365 and U385 LEDs, the intensity falls to half its value along the normal axis at about 65 degrees to the normal axis, and the intensity falls to a quarter its value along the normal axis at about 80 degrees to the normal axis. An advantage of LED light sources is precise control of a relatively narrow spectral distribution of radiation wavelengths, in contrast to for example light sources which emit light over a broad range of wavelengths.

The Nichia U365 LED is an example of an LED which essentially emits only light in the wavelength range 340 nm to 389 nm; the Nichia U385 LED is an example of an LED which emits light in the wavelength range 340 nm to 389 nm and light in the wavelength range 390 nm to 450 nm.

An irradiation intensity for light in the wavelength range 340 nm to 450 nm for inducing photo catalytic activity in a photo catalytic coating (eg. a paint) (such as one described herein) suitable for removing NOx at a sufficient rate, or for having anti-bacterial properties, has been found in experiments to be 1.0 W/m2, or more. An irradiation intensity for light in the wavelength range 340 nm to 450 nm for inducing photo catalytic activity in a photo catalytic coating (eg. a paint) (such as one described herein) suitable for removing NOx at a very high rate, or for having anti-bacterial properties, has been found in experiments to be 20 W/m2, or more. An irradiation intensity for light in the wavelength range 340 nm to 450 nm for inducing photo catalytic activity in a photo catalytic coating (eg. a paint) (such as one described herein) suitable for removing NOx at a sufficient rate, or for having anti-bacterial properties, may be in the range of 1.0 W/m2 to 10 W/ m2, or in the range of 1.0 W/m2 to 20 W/m2, or in the range of 1.0 W/m2 to 50 W/m2.

In an example, a lighting unit includes 3 bars for the lighting unit body; each bar provides 4 LEDs. Thus, each lighting unit consists of 12 LEDs. Each lighting unit body is able to meet the lighting requirements on average of about 1 square meter of surface to be illuminated / irradiated. Each lighting unit body radiates Wrad 9.95 (net of losses of lenses and protective glass) and consumes a.c. 25 WPot. Considering, therefore, a useful tunnel surface profile length of 14m to be illuminated, our simulations show that, using Nichia U365 LEDs, 6 lighting unit bodies (3 x 2 tracks) are required per meter of tunnel length, when the lighting unit bodies are arranged near to the ceiling of the tunnel, to provide a high rate of NOx removal. An example tunnel cross section, showing a lighting unit light source disposed near to the tunnel ceiling, is shown in Figure 1. In Figure 1, distances are given in cm, but are provided by way of example only. An example tunnel cross section, showing a lighting unit light source disposed near to the tunnel ceiling, is shown in Figure 2. In Figure 2, distances are not given.

A simple model calculation supports the simulation results. Six lighting units produce about 60 W of net radiated output. This can provide an intensity of 1.0 W/m2 over an area of 60 m2. Modelling the 60 W of net radiated output to fall on a hemisphere of radius r, area 2jir2, a hemispherical area of 60 m2 corresponds to a radius r of about 3.1 m. Hence points on a tunnel wall or ceiling within 3.1 m of a lighting unit will meet the target intensity of 1.0 W/m2 in this simple model. This simple model already guarantees sufficient illumination of a substantial portion of example tunnel surfaces: see e.g. Figure 1, in which a tunnel surface profile length of about 14m is illuminated.

Our calculations show that the use of LEDs is an energy efficient way of inducing photo catalytic activity in a photo catalytic coating (eg. a paint) inside a tunnel. In the above example, only 6*25 W = 150 W of source mains power is required. It is surprising that devices as small as LEDs are suitable for inducing a high level of photo catalytic activity in a photo catalytic coating (eg. a paint) inside a tunnel in an energy efficient way. Typically, lighting in tunnels has used large, bulky light emitting units.

Because our simulation shows that 6 lighting unit bodies, each including 12 LEDs, hence 72 LEDs in total, are suitable to provide a high rate of NOx removal per metre length of tunnel (in which a tunnel surface profile length of 14m is illuminated), the use of LEDs emitting wavelengths in the range of 340 nm to 450 nm is scalable over a wide range of

tunnel sizes, because the number of LEDs used per metre length of tunnel can be scaled up or down with increasing or with decreasing tunnel size, respectively.

In an example, light emitting sources emitting wavelengths in the range of 340 nm to 450 nm may be directed towards a ceiling of a tunnel coated with a photocatalytic coating. In an example, light emitting sources emitting wavelengths in the range of 340 nm to 450 nm may be directed towards side walls of a tunnel coated with a photocatalytic coating. In an example, light emitting sources emitting wavelengths in the range of 340 nm to 450 nm may be directed towards a ceiling and towards side walls of a tunnel coated with a photocatalytic coating. In an example, light emitting sources emitting wavelengths in the range of 340 nm to 450 nm may be directed towards a floor of a tunnel coated with a photocatalytic coating, for example in a rail tunnel.

Exposure of human beings to low wavelength radiation may be considered to provide some health risk. Excessive exposure to one kind of radiation (shorter-wave, germicidal) can damage tissue. It is present increasingly in sunlight with the thinning of the protective ozone layer, and in tanning salons and halogen lamps. Yet light with wavelengths in the range between 340 nm and 450 nm in natural daylight is required for both human physical and mental health, muscle strength, civilized behavior, energy and learning. There is no evidence of health risks for human health for exposure to light with wavelength in the range between 340 nm and 450 nm. Therefore, for spaces in which humans will be present, it is advantageous to illuminate photocatalytic coatings with light with wavelength in the range between 340 nm and 450 nm. In particular, for spaces in which humans will be present, it is advantageous to ensure that wavelengths below 340 nm are not used to illuminate photocatalytic coatings.

Example Photocatalytic Compositions

There are provided cement-based photocatalytic compositions, and use thereof for obtaining water paints, in particular for outdoor applications, or for applications in enclosed spaces.

There are provided cement-based hydraulic binding photocatalytic compositions, and use thereof for obtaining water paints, in particular for outdoor applications, or for

applications in enclosed spaces.

Example cement-based photocatalytic compositions are provided, which comprise: (a) at least one cement binder; (b) at least one photocatalyst; (c) at least one cellulose ether; (d) at least one fiuidizing agent; (e) at least one first calcareous filler in the form of particles of which at least 95% by weight has a size not greater than 100 μιη; (f) at least one second calcareous filler in the form of particles of which at least 95% by weight has a size not greater than 30 μιη; (g) at least one silane supported on an inorganic support in the form of powder. Such compositions can be employed as a water paint for obtaining wall coatings with very low thickness, in particular for outdoor applications, or for applications in enclosed spaces, which ensure a high and stable photocatalytic effect over time even with relatively low quantities of photocatalyst, generally lower than 10% by weight, with optimal results in terms of uniformity of the coating and resistance of the same to weathering agents.

CLAIMS

1. An enclosed space system through which vehicles may pass, the enclosed space system including interior surfaces, a photocatalytic coating on an interior surface of the enclosed space system, and a lighting system in attachment with an interior surface of the enclosed space system, the lighting system including light sources emitting wavelengths in the range between 340 nm and 450 nm, the lighting system arranged to illuminate the photocatalytic coating with the wavelengths in the range between 340 nm and 450 nm, wherein the photocatalytic coating is activatable by the wavelengths in the range between 340 nm and 450 nm.

2. The enclosed space system of Claim 1, wherein the lighting system does not emit light with wavelengths below 340 nm.

3. The enclosed space system of Claims 1 or 2, wherein the enclosed space system is a tunnel.

4. The enclosed space system of Claim 3, wherein the tunnel is a road tunnel.

5. The enclosed space system of Claim 3, wherein the tunnel is a rail tunnel.

6. The enclosed space system of Claim 3, wherein the tunnel is a pedestrian tunnel.

7. The enclosed space system of Claims 1 or 2, wherein the enclosed space system is a car park in a building, a car park in a ferry, or a car park in a car train.

8. The enclosed space system of any previous Claim, wherein the light sources emit wavelengths in the range between 340 nm and 389 nm.

9. The enclosed space system of any previous Claim, wherein the light sources emit only wavelengths in the range between 340 nm and 450 nm.

10. The enclosed space system of Claim 8, wherein the light sources emit only wavelengths in the range between 340 nm and 389 nm.

11. The enclosed space system of Claims 9 or 10, wherein light emitted by the light sources is within a relatively narrow spectral distribution of radiation wavelengths.

12. The enclosed space system of any of Claims 1 to 7, wherein the light sources emit wavelengths in the range between 340 nm and 389 nm and wavelengths in the range between 390 nm and 450 nm.

13. The enclosed space system of any previous Claim, wherein a surface coated with the photocatalytic coating is illuminated with the wavelengths in the range between 340 nm and 450 nm at an intensity greater than 1.0 W/ m2.

14. The enclosed space system of Claim 13, wherein a surface coated with the photocatalytic coating is illuminated with the wavelengths in the range between 340 nm and 450 nm at an intensity in the range of 1.0 W/ m2 to 50 W/ m2.

15. The enclosed space system of Claim 13, wherein a surface coated with the photocatalytic coating is illuminated with the wavelengths in the range between 340 nm and 450 nm at an intensity in the range of 1.0 W/ m2 to 20 W/ m2.

16. The enclosed space system of Claim 13, wherein a surface coated with the photocatalytic coating is illuminated with the wavelengths in the range between 340 nm and 450 nm at an intensity in the range of 1.0 W/m2 to 10 W/m2.

17. The enclosed space system of any previous Claim, wherein the light sources are or include one or more of fluorescent lamps, short wave lamps, gas discharge lamps, metal halide lamps and lasers.

18. The enclosed space system of any previous Claim, wherein the light sources are, or include, light emitting diodes (LEDs).

19. The enclosed space system of Claim 18, wherein the light emitting diodes are arranged on a bar, or on a plurality of bars.

20. The enclosed space system of Claim 18, wherein the light emitting diodes are arranged in the form of a frame including a plurality of LED spotlights, or in the form of a plurality of frames including a plurality of LED spotlights.

21. The enclosed space system of any of Claims 18 to 20, wherein use of the light emitting diodes as light sources is scalable over a wide range of enclosed space sizes.

22. The enclosed space system of any previous Claim, the enclosed space including a side wall coated with the photocatalytic coating, wherein light sources emitting wavelengths in the range between 340 nm and 450 nm are directed towards the side wall.

23. The enclosed space system of any previous Claim, the enclosed space including a ceiling coated with the photocatalytic coating, wherein light sources emitting wavelengths in the range between 340 nm and 450 nm are directed towards the ceiling.

24. The enclosed space system of any previous Claim, the enclosed space including a floor coated with the photocatalytic coating, wherein light sources emitting wavelengths in the range between 340 nm and 450 nm are directed towards the floor.

25. The enclosed space system of any previous Claim, wherein the system is arranged to reduce an amount of NOx gases in the enclosed space.

26. The enclosed space system of any previous Claim, wherein the system is arranged to reduce an amount of SOx gases in the enclosed space.

27. The enclosed space system of any previous Claim, wherein the system is arranged to reduce an occurrence of bacteria and molds on the surface.

28. The enclosed space system of any previous Claim, wherein the system is arranged to reduce an amount of volatile organic compounds gases in the enclosed space.

29. The enclosed space system of any previous Claim, wherein the photocatalytic coating is a cement-based hydraulic binding photocatalytic coating.

30. The enclosed space system of any previous Claim, wherein the photocatalytic coating is derived from a cement-based photocatalytic composition, which comprises:

(a) at least one cement binder;

(b) at least one photocatalyst;

(c) at least one cellulose ether;

(d) at least one fluidizing agent;

(e) at least one first calcareous filler in the form of particles of which at least 95% by weight has a dimension not greater than 100 μιη;

(f) at least one second calcareous filler in the form of particles of which at least 95% by weight has a dimension not greater than 30 μιη;

(g) at least one silane supported on an inorganic support in the form of powder.

31. The enclosed space system of Claim 30, wherein the photocatalytic composition comprises:

(a) from 15 to 60% by weight, preferably from 20 to 50% by weight, of at least one cement binder;

(b) from 0.5 to 12% by weight, preferably from 1 to 8% by weight, of at least one photocatalyst;

(c) from 0.02 to 3% by weight, preferably from 0.05 to 1.5% by weight, of at least one cellulose ether;

(d) from 0.05 to 5% by weight, preferably from 0.1 to 2% by weight, of at least one fluidizing agent;

(e) from 10 to 50% by weight, preferably from 15 to 35% by weight, of at least one first calcareous filler in the form of particles of which at least 95% by weight has a dimension not greater than 100 μιη;

(f) from 10 to 50% by weight, preferably from 15 to 35% by weight, of at least one second calcareous filler in the form of particles of which at least 95% by weight has a dimension not greater than 30 μιη;

(g) from 0.05 to 5% by weight, preferably from 0.01 to 3% by weight, of at least one silane supported on an inorganic support in the form of powder.

32. The enclosed space system of Claims 30 or 31, wherein the cement binder (a) is a Portland cement.

33. The enclosed space system of any of Claims 30 to 32, wherein the photocatalyst

(b) is photocatalytic titanium dioxide, mainly in anatase crystalline form.

34. The enclosed space system of Claim 33, wherein the photocatalytic titanium dioxide has a granulometry such as at least 95% by weight has a dimension not higher than 50 nm, preferably not higher than 20 nm.

35. The enclosed space system of any of Claims 33 or 34, wherein the photocatalytic titanium dioxide is in admixture with a non-photocatalytic titanium dioxide.

36. The enclosed space system of any of Claims 30 to 35, wherein the cellulose ether

(c) has a Brookfield viscosity RVT at 20°C from 100 to 70,000 mPa.s, preferably from 100 to 30,000 mPa.s, more preferably from 200 to 10,000 mPa.s.

37. The enclosed space system of any of Claims 30 to 36, wherein the first calcareous filler (e) is in the form of particles of which at least 95% by weight has a dimension not greater than 70 μιη, while the second calcareous filler (f) is in the form of particles of which at least 95% by weight has a dimension not greater than 20 μιη.

38. The enclosed space system of any of Claims 30 to 37, wherein the first calcareous filler (e) is in the form of particles of which not more than 5% by weight has a dimension not greater than 30 μιη, preferably not greater than 20 μιη.

39. The enclosed space system of any of Claims 30 to 38, wherein the calcareous fillers (e) and (f) are present in a weight ratio (e)/ (f) from 0.2 to 2.0, preferably from 0.5 to 1.5.

40. The enclosed space system of any of Claims 30 to 39, wherein the supported silane (g) is in the form of particles of which at least 95% by weight has a dimension not greater than 100 μ, preferably not greater than 80 μ.

41. The enclosed space system of any of Claims 30 to 40, further comprising: (h) at least one hydrophobized vinyl polymer, preferably a terpolymer of vinylchloride, ethylene and a vinyl ester CH2=CH-0-C(=0)-R, wherein R is an alkyl, linear or branched, C4-C24.

42. The enclosed space system of any of Claims 30 to 41, further comprising: (i) at least one salt of a long chain carboxylic acid.

43. The enclosed space system of any of Claims 30 to 42, wherein water is added to the photocatalytic composition in a predetermined proportion, by mixing until a homogeneous and fluid product is obtained, and that product is applied to the interior surface of the enclosed space as the photocatalytic coating.

44. The enclosed space system of Claim 43, wherein the weight ratio between water and cement binder (a) is from 0.2 to 0.8.

45. The enclosed space system of any of Claims 30 to 44, wherein, after application and drying, the photocatalytic composition forms a coating layer having a thickness from 0.05 mm to 1 mm, preferably from 0.1 to 0.5 mm.

46. Use in a tunnel of light emitting diodes emitting wavelengths in the range between 340 nm and 450 nm to illuminate an interior surface of the tunnel coated with a photocatalytic coating, wherein the photocatalytic coating is activatable by wavelengths in the range between 340 nm and 450 nm, and wherein the light emitting diodes do not emit light with wavelengths below 340 nm.

47. Use of Claim 46, wherein the light emitting diodes emit wavelengths in the range between 340 nm and 389 nm.

48. Use of Claim 46, wherein the light emitting diodes emit only wavelengths in the range between 340 nm and 389 nm.

49. Use of Claim 46, wherein the light emitting diodes emit wavelengths in the range between 340 nm and 389 nm and wavelengths in the range between 390 nm and 450 nm.

50. Use of any of Claims 46 to 49, wherein the surface coated with a photocatalytic coating is illuminated with the light emitting diodes at wavelengths in the range between 340 nm and 450 nm at an intensity greater than 1.0 W/m2.

51. Use of Claim 50, wherein the surface coated with a photocatalytic coating is illuminated with the light emitting diodes at wavelengths in the range between 340 nm and 450 nm at an intensity in the range of 1.0 W/ m2 to 50 W/ m2.

52. Use of Claim 50, wherein the surface coated with a photocatalytic coating is illuminated with the light emitting diodes at wavelengths in the range between 340 nm and 450 nm at an intensity in the range of 1.0 W/ m2 to 20 W/ m2.

53. Use of Claim 50, wherein the surface coated with a photocatalytic coating is illuminated with the light emitting diodes at wavelengths in the range between 340 nm and 450 nm at an intensity in the range of 1.0 W/m2 to 10 W/m2.