|Title of Invention||
METHOD OF COOLING AIR IN THE UNDER ROOF SPACES OF BUILDINGS
|Abstract||Method of cooling air in under-roof spaces of buildings, comprising the following steps: a) mixing water, cement, aluminium powder and a material selected from sand, gravel and the like, into a smooth mixture; b) spreading the smooth mixture over the roof to obtain a uniform layer of porous concrete; c) drying the layer; and d) soaking the layer with water.|
|Full Text||The present invention relates to a method of cooling air in the under-roof spaces of buildings, said roof being flat- and of non-insulating material.
In the hotter areas of our planet, especially the equatorial and tropical regions, there is a need to significantly reduce the temperature of the interior spaces of buildings to allow people to live and work there even during the hottest hours of the day.
There are many types of air conditioners that can be used for this purpose but they require large quantities of energy, usually electrical energy, to keep them running throughout the entire day.
When it is remembered also that in some parts of the world temperatures are very high all year round, it is not difficult to imagine the huge energy costs of providing air conditioning for whole buildings.
It should be emphasized, too, that the use of the abovementioned air conditioners raises ecological problems that should not be underestimated. Using, as they do, large amounts of electrical power, they contribute, however indirectly, to a considerable production of
harmful substances and significantly raise the level of carbon dioxide emissions into the atmosphere.
The problem underlying the present invention is therefore that of providing a new method that is capable of overcoming the above mentioned problems.
Japanese patent JP 51142848 attempts to provide a solution to the above mentioned problem using porous asphalten concrete.
The document GB 244963 discloses a concrete by using a dry mixture of Aluminum and Cement. But the concrete disclosed in this invention is not suitable for cooling the roof as the contents of the Aluminum does not provide sufficient porosity.
The problem is solved, according to the invention A method of cooling air in under-roof spaces of buildings, said roof being flat and of non insulating material, the method being characterized in that it comprises the following steps: (a) mixing water, cement, aluminum powder and a material selected form sand, gravel into a smooth mixture, said cement and said Aluminum powder being mixed together in a variable weight ratio from 10:1 to 20: (b) spreading said smooth mixture over said roof to obtain a uniform layer of porous concrete; (c)drying said layer; and (d) socking said uniform layer of porous concrete with water.
The method according to the present invention utilizes the principle whereby a liquid, in order to pass into the gaseous state, absorbs the necessary energy (enthalpy of evaporation) from the surface it is lying on and so cools it. If, as in this case, the surface in question is the roof of a building, this effect will be sufficient to significantly lower the temperature in the
spaces underneath the roof, rendering them habitable without the need for costly air conditioning equipment.
All of this is achieved without compromising the strength of the cladding of the roof of the building, because the layer of porous concrete obtained with the method of the present invention has sufficient strength and solidity, even at thicknesses of only 3 cm, easily"to carry the weight of any person who may need to climb onto the roof for maintenance purposes or for any other reason. Using the method according to the present inven¬tion it is possible to cover non-insulating roofs (made of concrete, reinforced concrete or the like) with a uniform porous layer capable of absorbing water. In just the same way as a sponge, this porous layer can then release the water at a slow, constant pace so that the roof is cooled for a long period. In practice, the house is built as an abaorption system refrigerator. The cooling is obtained thanks to the solar irradiation, that allows the water to evaporate from the wet concrete layer.
The uniform layer of concrete with which the roof is covered is made porous by an effervescent reaction generated by the presence of metallic aluminium powder in the initial mixture.
The method according to the present invention is
applicable to any type of building with a flat roof of non-insulating material and can be used to cool structures used as dwellings, offices, shops, stores, hospitals, schools, hotels and the like.
The method according to the present invention lends itself particularly well to the cooling of one- or two-storey buildings. Nonetheless, it can also be applied to buildings comprising more than two storeys combining it if necessary with conventional cooling technology.
With the method according to the present inven¬tion it is possible to condition the air in the interior spaces of buildings at a low cost dictated purely by the consumption of water; this is a trifling cost when compared with the cost of employing conventional air conditioning equipment."
The use of the method according to the present invention is furthermore completely environmentally friendly: it produces no toxic substances or pollutants of any kind and cuts emissions of carbon dioxide into the atmosphere to zero.
In a particularly advantageous embodiment of the present invention, the cement and the aluminium powder are mixed together in a variable weight ratio of from 10:1 to 20:1. The roof is preferably covered with a layer of porous concrete between 3 and 6 cm thick.
The layer of porous concrete is soaked with water by periodically spraying it whenever it becomes completely
In another aspect, the present invention relates to a ready-prepared mix consisting of cement and aluminium in a variable weight ratio of from 10:1 to 20:1 and to the use of this ready-prepared mix in carrying out the method described above--.
In yet another aspect, the present invention relates to the use of aluminium powder for the production of porous concrete. This aluminium powder is preferably used in a variable weight ratio of from 1:10 to 1:20 relative to the cement.
In order to explain the invention more clearly a preferred embodiment thereof will now be described by way of non-restrictive example.
800 kg of Portland cement, 54 kg of aluminium powder and 7.2 t of sand were mixed with water and worked until a smooth mixture was obtained having a consistency similar to that of a conventional concrete mixture.
During mixing it was possible to observe a certain effervescence of the mixture.
The mixture was then poured onto the flat reinforced-concrete roof of a house, which consisted of a single 8 x 10 m storey, to form a uniform layer appro¬ximately 3.5 cm thick. Once it was completely dried, the
layer of porous concrete was sprayed on two occasions, with an interval of 3 hours between the two, with 50 1 of water on each occasion.
In this way it was possible, with a temperature measured on the surface of the layer of porous concrete of 60-63°C, to maintain the interior of the house at a constant temperature of 24°-2 6°C.
To achieve this result with conventional cooling systems it would have been necessary to deploy four electrical cooling systems, each consuming 3 kWh; these electrical systems would have had to remain active for six hours a day.
There follows a simple calculation which demon¬strates the remarkable savings achievable with the method according to the invention for cooling the interiors of buildings when compared with ordinary electrical air conditioning systems.
Annual cost of cooling using conventional tech¬nologies :
Annual electricity consumption:
3kW X 6 hours x 4 systems x 365 days = 26 280 kW
Cost of one kW: 0.20 DM
TOTAL 5256.00 DM
Annual cost of cooling using the method of the
Annual water consumption: 0.1 m3 x 365 days = 36.5 m3
Cost of 1 m3 of water: 2.00 DM
TOTAL 73.00 DM
As is clear from the above figures, the costs related to the-use of the method according to the inven¬tion are around one seventieth of the costs related to the use of a conventional air conditioning system and this result is achieved in a totally environmentally friendly way, with no emissions into the atmosphere of toxic substances or pollutants and with zero carbon dioxide emissions.
1. A method of cooling air in under-roof spaces of buildings, said roof being flat
and of non insulating material, the method being characterized in that it
comprises the following steps:
(a) mixing water, cement, aluminum powder and a material selected
form sand, gravel into a smooth mixture, said cement and said
Aluminum powder being mixed together in a variable weight ratio
from 10:1 to 20: 1.
(b) spreading said smooth mixture over said roof to obtain a uniform
layer of porous concrete;
(c) drying said layer; and
(d) socking said uniform layer of porous concrete with water.
2. The method according to claim 1, in which said uniform layer of porous
concrete is between 3 and 6 cm thick.
3. The method according to any one of the preceding claims, in which said
socking takes place at predetermined intervals by spraying.
4. Ready-prepared mix consisting of cement and aluminum in a variable weight
ratio of from 10:1 to 20: 1.
5. A method of cooling air in the under-roof spaces of buildings substantially as
herein described with reference to the accompanying drawings.
|Indian Patent Application Number||72/MAS/1999|
|PG Journal Number||13/2008|
|Date of Filing||19-Jan-1999|
|Name of Patentee||LUIGI RIVA|
|Applicant Address||CASCINA GHIRINGHELLA-20065, INZAGO, MILANO,|
|PCT International Classification Number||C04B 22/04|
|PCT International Application Number||N/A|
|PCT International Filing date|