This invention relates to a method for providing a ground source energy system for reducing the build-up of ice on an outdoor traffic-bearing surface, the steps of the method comprising forming at least one borehole adjacent the traffic-bearing surface; installing flow and return ground piping into the at least one borehole, filling the ground piping with a first heat transfer fluid; installing flow and return surface piping in the traffic-bearing surface; filling the surface piping with a second heat transfer fluid; providing an interchange between the first heat transfer fluid and the second heat transfer fluid; and a pumping mechanism to circulate the heat transfer fluids in the piping.

In regions of the world where snow and ice are a characteristic of the climate conditions, there is always potential for disruption and danger to any type of vehicular or foot.

Where wintery conditions are realised, the conditions can and do adversely affect airports. The difficulties with de-icing and snow clearance of aeroplane stands, service roads, taxi-ways and runways at a busy airport cannot be underestimated.

Traditionally, airports that suffer from snow and ice precipitation deal with the problem in a reactive manner with snow clearing machinery and chemical de-icing solutions. There are, however, a number of disadvantages associated with this situation.

Firstly, the unpredictability of weather patterns gives rise to hugely complex snow and ice emergency plans as large quantities of equipment, such as de-icing chemicals and snow ploughs, and large numbers of personnel must be organised. Additionally, there are clear difficulties with de-icing and snow clearance of an aeroplane stand when an aeroplane occupies that stand.

Furthermore, in particularly extreme conditions, for example an abnormally heavy snow fall, lower than average temperatures or prolonged periods of snow and ice, airport maintenance staff struggle to cope. This can lead to disruption severe enough to impact the normal airport operations. This in turn leads to considerable inconvenience for travellers; lost revenue for the airport operators and airlines; and exposes the airport operators to media criticism.

On the other hand, preventive solutions, such as burying heating elements of some sort under the surface, can be difficult to implement, particularly as a retro-fit solution in existing airports. Such solutions involve carrying out significant works on the areas in question, digging up large areas, installing the heating elements, and then replacing the surface. Such installation work amounts to a significant disruption of airport operations as it causes the area in question to be out of commission for a long time. A busy airport, or indeed car park or the like, cannot tolerate sections of hard-standing being out of commission while work is carried out. Furthermore, the expense associated with taking up a surface and relaying it over heating elements is prohibitive, especially if the surface area concerned is not necessarily in need of replacement at that time.

It is therefore an object of the present invention to overcome at least some of the above- mentioned problems.According to the invention there is provided a method providing a ground source energy system for reducing the build-up of ice on an outdoor traffic-bearing surface, the steps of the method comprising: forming at least one borehole adjacent the traffic-bearing surface; installing flow and return ground piping into the at least one borehole, filling the ground piping with a first heat transfer fluid; forming at least one slot in the outdoor traffic-bearing surface; installing flow and return surface piping in the at least one slot such that the surface piping is embedded in the traffic-bearing surface; sealing the surface piping in place; filling the surface piping with a second heat transfer fluid; providing an interchange between the first heat transfer fluid and the second heat transfer fluid; and a pumping mechanism to circulate the heat transfer fluids in the piping.

In this way, a ground source energy system can be installed quickly and conveniently for the traffic-bearing surface, for example an airport stand. By embedding the surface pipework in the surface, rather than burying it underneath, the installation of the surface pipework can be carried out very quickly. Milling slots into the surface, rather than taking up the whole surface, is convenient and expedient. Typically, the work involved can be carried out at night, in the existing downtime of the airport. The significant work involved in forming the boreholes for the ground pipework can be carried out away from the working area the traffic-bearing surface or at an adjacent non-traffic bearing surface.. The invention has the further advantage of limited waste generation. The milling of slots for embedded pipework generates only a small amount of waste, compared to that generated by completely removing and replacing the surface in question so as to bury suitable piping beneath it. Furthermore, the reduction of ice build-up on working outdoor surfaces provides clear safety improvements, ensuring that the surfaces in question are safe for foot and vehicle (including aeroplane) traffic. Additionally, the use a ground source energy system in this way reduces or eliminates the use of chemical de-icers for the surface in question, which saves the cost of these products and is also more environmentally friendly. Finally, a ground source energy pump of this nature is a renewable energy source, only requiring external power for the pumps to circulate the heat transfer fluids. Again this is more cost effective and more environmentally friendly than current solutions. The present invention allows the airport or the like to function at a normal or near normal operational basis with only limited disruption.

In one variant there is provided a method in which the first heat transfer fluid and the second heat transfer fluid are the same and the step of providing an interchange comprises providing a manifold for putting the surface piping and the ground piping in fluid communication. In this way, there is direct fluid communication between the ground piping and the surface piping by way of the manifold. This is a simple and efficient manner of providing heat transfer between the ground and the traffic-bearing surface.

In another variant there is provided a method in which the step of providing the manifold comprises installing the manifold in a chamber beneath the traffic-bearing surface. In this way, the manifold will not form an obstacle on the traffic bearing surface. The chamber may alternatively be located adjacent the traffic-bearing surface.

In a further variant there is provided a method in which the first heat transfer fluid and the second heat transfer fluid are the same and the step of providing an interchange comprises providing a heat pump.

The first and second heat transfer fluids may be the same, but optionally in isolated conduit pathways for mutual heat interchange when juxtaposed in a heat exchanger.

The step of forming at least one slot in the outdoor traffic-bearing surface may comprise forming a perimeter slot surrounding the traffic-bearing surface. In this way, the area of the traffic-bearing surface to be the subject of the method of invention can be defined by the perimeter slot, separating the working area of the surface, that require protection from ice build-up, from surface areas that do not require ice-reduction treatment. A branch slot can project from a perimeter slot. Thus, branch slots can provide surface piping to areas enclosed by the perimeter slot, increasing the surface area protected by the ground source energy system.

One or more slots can be of a different width to the perimeter slot. In this way, surface piping of different widths may be used, allowing low pressure flow to be implemented therein, reducing the specifications for the pumping mechanism.

A plurality of spaced-apart branch slots may be formed, so the surface area protected by the surface piping is increased.

A plurality of parallel spaced-apart branch slots may be formed to allow regular and even coverage of the traffic-bearing surface.

Adjacent branch slots can be spaced apart by a distance of 500mm. This provides for an efficient spacing of surface piping.

The surface piping can be substantially horizontally in the at least one slot. In this way, the surface piping corresponds with the traffic bearing surface.

Synthetic resin can be used to seal the piping in place with a fill material. This is a particularly effective way of securing the surface pipework in place and also strengthening the surface of the slots. Alternatively, the surface piping may be sealed in place using fill material comprising a cementitious material, or a combination of synthetic resin and cementitious fill material.

A dark coloured fill material can be used in the seal. In this way, the synthetic resin will absorb more energy from the sun, thus heating the second heat transfer fluid more effectively, and allowing for improved energy transfer and increased energy storage. Preferably, the synthetic resin is black for maximum energy absorption. Alternatively, the resin may be adapted to be similar in colour to the existing surface.

A borehole cam be drilled to a depth of greater than 55 metres below ground level. This is a particularly effective depth for storage of heat energy in the ground.

A substantially vertical borehole is a particularly convenient way to reach the required depth.

A borehole can be drilled between 100 mm and 650 mm in diameter. This provides for a wide range of borehole diameters for placing one or more flow and return sets of ground piping.

Preferably, the borehole may be 450 mm in diameter.

The first heat transfer fluid and the second heat transfer fluid can be the same but isolated for mutual heat interchange between the vertical piping and the surface piping. In this way, there is a direct transfer of heat from the ground to the surface or vice versa.

Slot formation in the outdoor traffic-bearing surface can be effected using a planing machine with a milling attachment. A milling attachment on a planing machine is an effective and convenient way of forming the slots in the outdoor traffic-bearing surface. Preferably, the milling attachment comprises a drum having at least one cutting tool thereon. A method of claim 19 in which the milling attachment comprises a drum having at least one cutting tool thereon. The width of the at least one cutting tool is adjustable. In a preferred embodiment the drum comprises a plurality of cutting tools, where the spacing between the plurality of cutting tools may be adjustable. In this way, the milling attachment may be used to form more than one slot at a time; may be used to form slots of different thicknesses; and may be used to form slots at variable spacings. The cutting tool may be adapted to forms slots of variable depth.

Another aspect of the invention provides an outdoor traffic-bearing surface comprising a ground source energy system, the ground source energy system comprising ground piping located in at least one borehole, the ground piping containing a first heat transfer fluid; surface piping embedded in at least one slot formed in the traffic-bearing surface and sealed therein, the surface piping being sealed in place and containing a second heat transfer fluid; an interchange that facilitates heat transfer between the first heat transfer fluid and the second heat transfer fluid; and a pumping mechanism for circulating the heat transfer fluids in the piping. In this way, the outdoor traffic-bearing surface is provided with a ground source energy system with minimal disturbance to the surface. The use of slots and embedded surface piping allow for the heating of the traffic- bearing surface without having to bury the surface-interacting parts, involving significant disturbance of the surface.

In such an an outdoor traffic-bearing surface at least one borehole can be substantially vertical. Similarly, at least one borehole can be approximately 450 mm in diameter.

At least one borehole can have a depth greater than 55 metres below ground level.

In another embodiment of the invention there is provided an outdoor traffic-bearing surface in which the at least one borehole has a depth greater than 55 metres below ground level.

In a further embodiment of the invention there is provided an outdoor traffic-bearing surface further comprising a perimeter slot surrounding the at least one slot, the perimeter slot further comprising surface piping.

In an alternative embodiment of the invention there is provided an outdoor traffic-bearing surface in which the surface piping is sealed in place with a synthetic or cementitious resin.

An outdoor traffic-bearing surface can feature a synthetic resin in dark in colour.

An outdoor traffic-bearing surface can incorporate adjoining slot sections of different dimensions.

An outdoor traffic-bearing surface can have surface piping arranged substantially horizontally.

An outdoor traffic-bearing surface can use the same the first and second heat transfer fluids and with a direct fluid communication interchange between ground piping and surface piping.

Alternatively, the interchange can feature a heat exchanger.

In interchange can be located within a chamber beneath the surface.

Embodiments of the invention are described by way of example with reference to the accompanying diagrammatic and schematic drawings, in which:

Fig. 1 is a diagrammatic representation of an airport stand modified of the invention;

Fig. 2 is diagrammatic representation of an airport stand including underlying soil strata;

Fig. 3 is a cross-section view of a slot of the invention comprising a portion of surface piping;

Fig. 4 is a flow chart for the design and installation of a ground source energy system of the invention; and Figs. 5(a), (b), and (c) are a plan, isometric and close-up isometric views respectively of an example milling attachment for use in the method of the invention.

Referring to the drawings, Figs. 1 and 2 in which there is shown an outdoor traffic-bearing surface 100 in the form of an airport stand, having a terminal building 102 adjoining it, and an aeroplane 104 in place thereon. A ground source energy system has been implemented in the airport stand. The ground source energy system comprises a set of flow and return ground piping 106, extending vertically into the ground 108 in one or more boreholes (not shown) located at the edge of the airport stand. The ground piping 106 contains heat transfer fluid (not shown). The ground source energy system further comprises a set of flow and return surface piping 110 embedded in a set of slots (not shown) milled into the outdoor traffic-bearing surface 100. The surface piping 110 also contain heat transfer fluid (not shown). The surface piping 110 is sealed in place using a fill material (not shown). The ground source energy system further comprises an interchange (not shown), in this case a manifold that facilitates fluid transfer between the ground piping and the surface piping; and a pumping mechanism (not shown) for circulating the heat transfer fluid in the piping 106, 110. The manifold (not shown) is located in an underground chamber 112.

The heat transfer fluid will typically comprise an ethylene glycol based fluid, which is non-toxic. The pumping mechanism will comprise standard low head pressure circulation pumps.

The airport stand is surrounded by a perimeter slot that runs around the edge of the stand, a set of branch slots branch off the perimeter slot and extend across the airport stand. The branch slots are parallel to each other and are spaced approximately 500mm apart.

The ground pipes are fitted in boreholes drilled in a non-traffic or low-traffic area. The boreholes may be drilled in the outdoor traffic-bearing surface or in a suitable adjacent location. The boreholes are approximately 450mm diameter and drilled to a depth of 60m. Each borehole is equipped with a number of flow and return ground pipes, for example three flow and return pipes per borehole. The design and implementation of the boreholes and ground pipes may vary as required for a particular installation according to the invention. Once the ground pipes are in place in the boreholes, the boreholes may be filled with a suitable grout to maximize heat transfer. Drilling boreholes is a more obtrusive operation than milling slots in a surface, therefore it is preferable to carry out the borehole work away from busy or high-traffic areas.

Fig. 3 shows a cross-section view of a portion of surface pipe 110 in its slot 200 formed in the outdoor traffic-bearing surface 100. The surface pipe 110 has been surrounded by a fill material 202 in the slot. The piping may be sealed in place with a fill material comprising synthetic resin, cementitious fill material or a combination of synthetic resin and cementitious fill. The fill material will be chosen to provide the required strength and may be stronger than the original material of the traffic-bearing surface.

Fig. 4 shows a flow chart of the method for design and installation of the ground source energy system according to the invention. In step 300, the outdoor traffic bearing surface to be protected from ice and snow is surveyed so as to identify the dimensions thereof and further to identify any fixed structures or other obstacles in the area that need to be accommodated. For example, a typical airport stand is measures 80 metres by 80 metres, giving a stand area of 6,400 m ² . If this whole stand area is to be protected from snow and ice build-up, that whole area must be equipped with embedded surface piping. For maximum efficiency, the surface piping should be spaced apart no more than 500 mm. These dimensions indicate that approximately 12,800m of pipe will be required for that stand, based on the following calculation 80m x 80m x 2 pipe runs per meter.

Next in step 302, the ground source energy system of the invention is designed, including specifying the quantity, diameter, depth, spacing and location of the boreholes for the ground pipes and the number of flow and return ground pipes will be fitted in each borehole. Similarly, the quantity, width, depth, spacing and path of the slots of the surface pipes are calculated, as well as the diameter of the surface piping to be fitted at different sections of the slot. In order to effectively distribute and collect heat via the surface piping, the design must take into consideration the flow path and pressure loss calculations associated with circulating the second heat transfer fluid through the surface piping. To achieve optimum performance - that is a turbulent flow with

Reynolds number of circa 2500 - sizing of the surface piping is important. The surface piping will be configured to reflect several circuits and will reduce in diameter (according to the pressure calculations as the piping progresses across the target area) to 75mm and then to 63mm, 50mm, 40mm and 32mm. The differing pipe sizes will determine the slot dimension for each section of the installation.

Next, in step 304 work begins on the installation of the ground source energy system with the milling of a perimeter slot around the full perimeter of the traffic-bearing surface to be protected. Typically, the perimeter slot will be 100mm wide by 100mm deep. At this time, the perimeter slot is used to accommodate a pair of primary feed and return pipes to connect the outdoor traffic- bearing surface in question to the manifold. Such primary feed and return pipes will typically have a diameter of 90 mm, so slots of 100 mm by 100 mm are used for these pipes.

Next in step 306, the branch slots for the remaining surface piping are formed. As discussed in relation to step 302, the slots will be of different dimensions to allow for optimum operation. The slots of are formed using a standard planing machine, as is known in the art for use in road works. The planning machine is fitted with a milling attachment adapted to generate slots of the desired width and depth. Typically, the milling attachment is equipped to form a plurality of spaced apart parallel slots simultaneously. In a preferred arrangement, the milling attachment is four metres wide, allowing for the milling of eight slots simultaneously, with a centreline to centreline distance of 500 mm.

Next, in step 308, the surface piping is installed in the slots. Again, as discussed in relation to the design process in step 302, the surface piping will have different diameters as it travels along the slot in the traffic-bearing surface. The piping may manufactured from polyethylene PE100+ or cross-linked polyethylene (PEX) and may be joined together using a fusion weld technique. The surface piping may be held in place once installed by a temporary fix, such as pins or weights. The heat transfer fluid and suitable circulation pumps to circulate that heat transfer fluid in the surface piping, the ground piping and to and from the manifold and also installed.

In step 310, a fill material Is backfilled into the slots so as to fill the remaining space around the surface piping. The fill material may be black or otherwise dark coloured so as to increase energy absorption from the sun. Preferably, the fill material is reasonably quick-setting with good heat transfer properties. The resin will form a level finish with the surrounding surface. Once the resin has set, any temporary measures used to hold the piping in place may be removed.

In step 312, the surface piping is connected to the manifold via the pair of primary feed and return pipes. The manifold is preferably located in an underground chamber. Preferably, the underground chamber is located away from the airport stand or the like to minimise disturbance from its construction, and is 1500 mm by 1500 mm by 1500 mm, with a suitable access lid.

In steps 314, 316 and 318, which may take place prior to, after, or at the same time as steps 304 to 312, the method of installation of the ground piping is outlined. First in step 314, the boreholes are drilled to the dimensions specified at the design stage in step 312. Next in step 316, the ground piping is installed in the boreholes. The boreholes may then be filled with a heat- conducting grout to aid heat transfer between the ground pipes and the ground. Finally, in step 318, the ground piping is connected to the manifold, either directly or via a suitable set of feed and return pipes. The ground piping is filled with the heat transfer fluid, and suitable circulation pumps are fitted to circulate the heat transfer fluid in the ground piping, to the manifold and in the surface piping.

During the summer months, the surface piping embedded in the tarmac or the like of the outdoor traffic-bearing surface act as solar collectors. The heat transfer fluid contained within the surface piping embedded into the airport hard-standing area will warm up as the piping gets hot and a the pumping mechanism directs the warmed fluid to the ground piping in the boreholes. The majority of the heat is retained within the strata of the ground until the winter season demands that it is returned to the surface piping so as to prevent ice from building-up on the traffic-bearing surface and causing disruption to the airport operation.

Figures 5a through 5c show an embodiment of a milling attachment for a planing machine. The milling attachment may be used to form the slots in the traffic-bearing surface according to the method of the invention. The milling attachment, indicated generally by the reference numeral 500, comprises a wide circular drum 502 with a plurality of spaced apart ring-like cutting blades 504 projecting therefrom. The cutting blades 504 may a number of cutting or grinding teeth or other suitable means for cutting typical hard-standing surfaces. The location of the cutting blades 504 on the drum 502 may be varied so as to make slots at different spacings. Similarly, the thickness of the cutting blades may be varied so that the width of the slots can be varied. The drum may be fitted with more or fewer cutting blades as required to form the desired slot pattern.

Some aspects of the invention embrace a heat exchange and recovery system for a building in conjunction with a ground surface slab including an indoor or outdoor traffic bearing surface, with a heat exchange conduit network for a building heating and/or cooling system co-operative coupled to a ground source heat recovery and/or conditioning network including boreholes for deeper underground heat conditioning and under-surface matrix for surface conditioning;

configured to allow long term building waste heat to be stored underground for later surface temperature elevation.

Throughout the specification, the person skilled in the art will understand that, while the invention is suitable for use in areas of an airport, including but not limited to airport stands and taxi-ways, the invention is not limited to use in airports but may also be used in other facilities having areas of hard-standing where a build-up of snow and/or ice would be undesirable, for example, car parks, outdoor plazas and the like. Similarly, the details of the invention will vary according the size, location, purpose, and other factors of the outdoor traffic-bearing surface to be fitted the ground source energy system. The system described herein in relation to the accompanying figures is an example only and should not be considered as limiting the invention. Furthermore, the person skilled in the art will understand references to ice, snow or the like to encompass ice, snow, hail, frost and other such cold-weather substances whose build up on the a traffic bearing surface would render human or vehicle movement on the surface dangerous.

It will be understood that while the borehole for use in the invention is preferably vertical, it is not necessarily so, and may reach the required depth by travelling at an angle through the ground, or by a combination of vertical and angled portions, achievable by directional on demand drilling.

Throughout the description and claims of this specification, the words "comprise" and "contain" and variations of them mean "including but not limited to", and they are not intended to (and do not) exclude other components, integers or steps. Throughout the description and claims of this specification, the singular encompasses the plural unless the context otherwise requires. In particular, where the indefinite article is used, the specification is to be understood as contemplating plurality as well as singularity, unless the context requires otherwise.

The present application relates to a method for installing a ground source energy system for preventing.build-up of ice on an outdoor traffic-bearing surface, and an outdoor traffic-bearing surface equipped with such a ground sour heat pump. The method of the invention allows for installation of the heating elements in the traffic bearing surface in a quick and efficient manner, thus minimising the time that the traffic-bearing surface is out of service. The invention is described in relation to an airport stand but may also be used in other areas of an airport such as service roads, taxi-way and runways; and may be used with other outdoor traffic bearing surfaces such as car-parks, plazas and the like.

Features, integers, characteristics, compounds, chemical moieties or groups described in conjunction with a particular aspect, embodiment or example of the invention are to be understood to be applicable to any other aspect, embodiment or example described herein unless incompatible therewith. All of the features disclosed in this specification (including any accompanying claims, abstract and drawings), and/or all of the steps of any method or process so disclosed, may be combined in any combination, except combinations where at least some of such features and/or steps are mutually exclusive. The invention is not restricted to the details of any foregoing embodiments. The invention extends to any novel one, or any novel combination, of the features disclosed in this specification (including any accompanying claims, abstract and drawings), or to any novel one, or any novel combination, of the steps of any method or process so disclosed.

The reader's attention is directed to all papers and documents which are filed concurrently with or previous to this specification in connection with this application and which are open to public inspection with this specification, and the contents of all such papers and documents are incorporated herein by reference.