GB2532710A

GB2532710A - Improved method of radon gas control for buildings

Info

Publication number: GB2532710A
Application number: GB1418590.4A
Authority: GB
Inventors: Ian Nichols Paul
Original assignee: Richard Charles Stevens; Prestige Air Technology Ltd
Current assignee: Richard Charles Stevens; Prestige Air Technology Ltd
Priority date: 2014-10-20
Filing date: 2014-10-20
Publication date: 2016-06-01
Also published as: GB201418590D0

Abstract

A building 7 is located over ground 8 which may release radon gas. An impermeable barrier or membrane 1 is positioned below the buildings floor slab. One or more mats 11 containing zeolite lie under the membrane. The mat(s) may have two layers, a gas and water impermeable layer and a gas permeable non woven layer (Fig 1, 15 and 17 respectively). The mat(s) may be shaped to allow projections, and corresponding pockets to be created (Fig 1, 16, 14) in a lattice like structure. The Zeolite (Fig 1, 18) may be located between said projections. Sump voids 2 are located below the mats and the void(s) are connected to pipes 4 to passively ventilate the void to atmosphere via outlets 3. The Zeolite acts to adsorb and entrain the Radon gas. Ambient air movement creates pressure differentials in the pipe to aid in venting the voids and pipes, thereby preventing Radon gas from entering the building.

Description

IMPROVEMENTS IN OR RELATING TO THE PROTECTION

OF BUILDINGS

The present invention relates to the protection of buildings from radon gas ingress, particularly by the adsorption and entrainment of radon gas for the natural half-life of radon gas to occur safely within a controlled area below a structure.

As technology improves and more advanced testing is carried out to properties due to awareness of the health risks from radon gas entering structures, existing accepted methods of ingress control can fail to give a non-mechanical control to the structure Membranes can be damaged in installation rendering them with poor gas control Performance, in such cases repair is not possible and it becomes necessary to mechanically activate the sump void installed below the membrane by the attachment of a fan to draw from the sump void radon gas, then to safely discharge it to atmosphere outside of the structure.

The installed fan which has to run continuously is firstly a cost factor in using electricity and requires maintenance to perform correctly noise can also prove to be a problem to occupants of the structure and close neighbours to it. There is a requirement therefore for a system with a greater passive performance than existing practice to compensate for possible weakness in the membrane performance and yet not have to make active the sump void. The existing sump void has no actual performance until it is made active by the installation of a fan, the proposed invention changes this situation by the use of gas entrainment mats installed at the time of construction over the sump voids, these mats contain a combination of minerals which have adsorption and entrainment properties these absorb migrating radon gas and entrain it, radon gas has a natural half -life of 3.5 days, this decay occurs within the mat zone in the minerals.

The radon gas emanating from the ground substrate below the structure move up towards the structure by variations in atmospheric pressure levels, the atmospheric pressure variations are due to the structure itself, as wind acting on the building creates a pressure differential on one side of the building to the other. The existing sump void design being passive is usually capped off at the perimeter of the building and gives no relief to sub-ambient pressure drops, thereby pressure drop accelerates the rate of radon gas under the structure footprint.

The proposed improvements to the standard sump void design is to connect the sump void to conduit pipes which run from both sides of the structure below the floor slab to the void sump, thereby allowing both super ambient and sub-ambient pressures to act within the void sump, this will accelerate the flow of radon gas to and within the zone of the adsorption mats increasing radon gas take-up, it will also lower radon gas levels by inducing passive ventilation and dilution with clean air through the sump voids. diffusion also migrates radon gas below the structure, under still ambient conditions where pressure gradients are in equilibrium the mats collect and entrain radon gas for the natural decay process to occur.

The present invention thereby improves the performance of an existing and used proven methodology by both improved passive ventilation, and adsorption and entrainment of radon gas, but in cases of high radon gas ingress the improved system can still be upgraded by the installation of a fan or pump means to achieve a similar performance to a standard designed activated system.

Various embodiments of the invention will now be more particularly described by way of example, with reference to the accompanying drawings in which: Figure 1 is a schematic cut away perspective view of an adsorption mat for use in a system of an arrangement of the invention, Figure 2 is a schematic perspective view of an adsorption mat, Figure 3 is a schematic view of an embodiment of a system according to the invention installed to reduce radon gas ingress from the ground into a building, Figure 4 is a schematic view of another embodiment of the invention.

With reference to Figure 1, a mat for use in a system according to the invention In which the mat is constituted by two layers, a gas and water impermeable sheet and a gas permeable non woven textile membrane 17, 18 is a zeolite mixture which can by example consist of a mixture of clinoptilolite, analcime, chabayite, and is located within the void area 16 of the mat The sheet 15 is made from a flat sheet of polyethylene which is press-moulded such as to have a regular array of spaced projections 14 upstanding from the face thereof. The projections 14 are generally cylindrical but with a slight taper for ease of moulding and with substantially flat, coplanar tops parallel to the face 15. The projections 14 are spaced at a distances slightly greater than their diameters. They are shown arranged in a regular lattice array, that is in mutually perpendicular lines and rows but could be in array, wether regular or irregular provided that there are substantial interconnecting spaces between them which constitute an interspace to contain the zeolite compound mixture18.

With reference to figure 3 of the drawings, this shows a building 7 located over a region of ground 8 producing radon gas. A barrier such as 1 of figure 3 has been laid over the entire ground area covered by the building 7 beneath the floor slab 23 of the building. A plurity of sump voids 2 are connected to pipe means 4 which extend to the exterior of the building 7 to terminate in vent outlets 3. Mats 11 containing the zeolite mixture 18 are located over the sump voids 2 radon gas rising from the ground 8 is restricted from entering the building 7 by the gas resistant barrier 1 and enter the sump voids 2, where ambient air movement creats pressure differentials in the pipe means 4 radon gas will be migrated out to vent outlets 3, Where ambient conditions are still, and no natural ventilation occurs, radon gas Levels will rise below building 7 and in the zone area of the sump voids 2 where the zeolite mixture 18 will adsorb and entraine the radon gas, entrained gas will then over time commence degrading by the natural half-life action of 3.5 days that of radon gas. The combination of enhanced ventilation performance over the standard design systems now used, plus the adsorption and entrainment action of the zeolite mixture 18 to reduce rising radon gas levels in non-ventilation conditions to degrade safely in the sump void zones 2 thereby reduce the potential of radon gas entering the building 7 through any failings in the gas barrier 1 that may occur.

Claims

CLAIMS1. A system for use in protecting buildings from the ingress of radon gas by preventing a flow of gas from a gas-containing area to an adjacent region; the said system comprising: A gas impermeable barrier installed so as to separate the said gas containing region and provide at least one void between the said two regions; Provide at least one sump void including an adsorption entraining mat containing zeolite mixture connected by a plurity of pipe means terminating to atmosphere external to the building to terminate in at least two venting outlets.
2 A system as claimed in Claim 1 wherein at least one sump voids is installed which communicates to atmosphere by pipe means to at least two or more venting outlets designed and best located to use natural pressure gradients acting upon the said building to create pressure differentials within the said sump voids to induce ventilation performance.
3 A system as claimed in claim 1 and 2 where the said sump voids incorporate a mat cover which incorporates a zeolite mixture component which interacts with the said sump voids to enable adsorption and entrainment of radon gas to occur.
4 A system as claimed in 3 where the interaction of the said venting outlets connected to a purity of pipe connections and terminate within the said sump void areas and mat locations to transmit ambient pressure variations due to wind effect acting upon the said building.A system as claimed in 1 where the said sump voids are connected to a plurity of pipe connections to enable migration of radon gas accumulation to move to and through the said mats located above the sump voids to enable maximum adsorption and entrainment levels within the zeolite mixture.