The word"construction"as used herein includes but is not limited to a building, bridge, tunnel or road.

In recent years an effective and unobtrusive heating system has become available as a post-construction option. This is in the form of underfloor heating. Here, a continuous length of piping, which may be polybutylene or polyethylene tubing or some other material, is laid in an appropriate pattern (dependent upon room shape and function etc.) prior to the final floor being laid. The pipework runs from a heating system via a manifold that then feeds to the relevant areas of the construction. The thermal fluid used in such systems is water which is economical and readily available.

With heating systems such as the one described above, the pipework, once laid, is covered with concrete to form the final floor surface. Thus, the piping becomes completely integral to the floor itself with only the manifolds visible at suitable position elsewhere in the construction.

Many constructions are now constructed from pre-cast concrete. The walls, floors etc. are prefabricated at a remote plant and delivered on-site to be erected or laid, and secured in place according to the construction plans. This obviates the need for the construction of large scale shuttering and does not require the preparation or delivery of on-site concrete. Generally, when the pre-cast construction is complete then the indoor services such as heating, lighting, ventilation etc. are installed.

Since the flooring and walls of pre-cast concrete constructions are laid and erected as finished, there is no opportunity to install under-floor (or in-wall for that matter) heating without the need of an additional screed/plasterwork or joisted floor structure to provide the necessary space for the pipework.

The present invention seeks to provide an environmental control system which is concealed in the floor, ceiling or walls of a pre-cast concrete construction.

According to an aspect of the present invention there is provided an environmental control system for controlling the temperature of a construction, comprising a pre-cast structure for use as a support structure in a construction and a continuous length of piping at least partly embedded within the pre-cast structure for conveying temperature control fluid inside said structure.

The use of a continuous length of piping with only two"ends" (flow and return sections) per block has the advantage that leaks are minimised. However, if the structure is particularly large, it may be advantageous to incorporate a plurality of lengths of piping, each of which is continuous.

Preferably, the system has a source of temperature control fluid which includes means for chilling the environmental control system fluid and/or means for heating the environmental control system fluid.

The structure preferably has an emitting surface which can also act as an absorbing surface when the system is in cooling mode.

The pipes may be located at least 25mm from the emitting/absorbing surface.

Preferably, the pipes are embedded 43mm deep from the emitting surface. There is no maximum distance from the piping to the emitting surface, although clearly the further the distance, the longer it would take for the temperature of the emitting surface to alter.

The loops of piping within the structure are preferably as close as possible in order to maximise the length of embedded pipe, and therefore the efficiency of the system. A practical constraint on the number of loops is the diameter of the piping, however. The pipe centres are advantageously separated by a distance of from 100 to 300mm, and preferably about 150mm In a preferred embodiment, the piping is at least 5mm in diameter, and preferably about 20mm The pre-cast structure of the present invention is suitable for use as a support structure in any construction, such as a building, tunnel, bridge or the like. By support structure is meant a structure which is employed as an integral means of support in the construction, and not just as a"finish"on a supporting member.

The support structure can be used as part of a wall, a floor or a ceiling. An advantage of the present invention is that it enables the whole of the floor (or wall or ceiling) of a construction to be heated and/or cooled, because the floor/wall/ceiling can be formed wholly from pre-cast structures of the invention. The same pre-cast structures can also be used as the floor of one storey and the ceiling of the storey below, or as a common wall between two rooms. Thus the heating/cooling effect of the structures can be utilised to a high efficiency.

A particular advantage of the present invention is that the pre-cast structures act as a thermal storage device. Thus heat can be stored in the fluid (for example water) and in the material of the structure and be emitted the next day. Alternatively, in cooling mode, the fluid and the structure material remains cold until the next day when it continues to absorb ambient heat.

A preferred embodiment of the invention will be described, by way of example only, with reference to the accompanying drawings, in which : Figure 1 shows a perspective view of a system element block ; Figure 2 shows a section along the line RR of Figure 1 ; Figure 3 shows a section along the line SS of Figure 1 ; Figure 4 shows a sectional view of several system block elements joined in parallel to the flow and return lines of the system ; Figure 5 shows an embodiment of the entire environmental control system ; Figure 6 shows a schematic of the experimental test apparats; Figure 7 shows a perspective view of the termination box ; Figure 8 shows a sectional view of the termination box of Figure 7 within a system block element.

Figures 9 and 10 show plan views of alternative constructions of system element blocks in accordance with the invention.

Figure 1 shows a system block element 10. The block, which may be an entire interior wall, floor section or the like, is cast from concrete 40 using wooden shutters, which is a method that would be known to anyone skilled in the art. The flow section 30 and the return section 20 are shown protruding from one face of the block 10. It should be apparent that these sections may leave the block from any face of the element block and

from different faces relative to one another, in dependence upon the placement of the block within the system or orientation with respect to the flow and return lines.

Figure 2 shows a section view of the element block 10. The pipework 50 which is formed of 20mm diameter polybutylene pipe is coiled within the interior of the element block 10 and is held in place by the surrounding concrete 40. The configuration of the pipework as shown in the figure is a preferred embodiment, although the number of loops in the pipework may vary depending on the particular size of the block element.

Figure 3 shows a different sectional view of the element block 10 (not to scale). A section through the flow portion of the pipework 70 is shown with a section through the return portion 60 shown above it. The pipes are approximately 43mm deep from the emitting surface 45. Between sections 60 and 70 is the prefabricated concrete reinforcement mesh 80. The use of such a mesh is well known in the art.

Figure 9 shows two element blocks 10 supported on support column 15. Flow section 30 and return section 20 emerge from each block 10 and pass into mains pipework 25.

The arrangement shown in Figure 10 has two element blocks 10 spaced apart and supported on support column 15 with service duct 35 therebetween. Flow section 30 and return section 20 pass into mains pipework 25 which is housed in service duct 35.

Since the system uses the maximum surface area to provide environmental control, the temperature of the water can be kept relatively low in the heating mode, and relatively high in the cooling mode. Comfortable ambient room conditions have been achieved with water temperatures as low as 40°C. Water at this temperature can either be derived from construction heat recovery or from boilers that operate at high efficiencies at these water temperatures.

Conversely, water at between 12°C and 13°C can provide the requisite cooling. Since the average temperature of ground, river or lake water in the U. K. is 10°C, there is a ready supply of environmentally acceptable coolant.

Figure 4 shows three element blocks 10 connected in parallel via the return and flow lines 90 and 100.

Figure 5 shows an embodiment of the environmental control system. A source 130 of environmental control system fluid feeds the system via a flow manifold 110 and a return manifold 120. Such manifolds are manufactured from brass or plastic and can be of various sizes with between 2 and 10 lines of distribution. Their construction is well known to someone skilled in the art. In a preferred embodiment, the source 130 also contains either a heating system or a cooling system. It should therefore be apparent that the environmental control system can be utilised to function either as a heating system or as cooling/air conditioning system depending on the type of source 130 employed. In either case the preferred system fluid is water, although other fluids may be used.

Figure 7 shows a perspective view of a termination box 132 that is fitted to each block prior to shipment. Return and flow pipes 20,30 enter the termination box 132 via corrugated sleeves 134. When the block 10 is ready for shipment, a lid 136 is secured over the box cavity 131. This protects the termination of the flow and return pipes from damage during transit or during installation on site.

Figure 8 shows a sectional view through the termination box 132 when in situ within a block 10. The lid 136 is shown secured in place.

Considerable time and cost savings can be made when incorporating this system into any construction project. This is due to the fact that the system is embedded into the pre-cast

concrete blocks at the very earliest stage. It will be understood that additional savings can also be made since there will be no need for any retro-fitting of a conventional system post construction.

There are a number of advantages, both environmental and from a health and safety aspect, that may not be directly apparent from the above. Since the system does not involve the distribution of air, such as in conventional air-conditioning systems, the possibility of the spread of Legionnaires disease or the occurrence of what is commonly known as'Sick Building Syndrome'is greatly reduced. The system is also completely free from the use of CFC or refrigeration gases ; this is advantageous to both environmental and noise pollution considerations.

The fact that the system is completely integral to the boundary structure of any given indoor space, allows for total freedom with regards to interior room layout and design ; there is no system equipment occupying valuable space.

Example The system will be best understood by way of an example of operation under test conditions.

With reference to Figure 6, a reinforced concrete slab was cast with integral water cooling pipes 145 embedded. The inter pipe spacing was variable by varying the interconnections between the pipes. The objective of these tests was to determine the heat transfer characteristics of a chilled concrete block element.

The test apparatus consisted of a calorimeter box 135 constructed around the suspended test slab 140. The heat absorbed by the slab was balanced by electrical heating of the air in the spaces above and below.

The calorimeter box 170 walls were constructed from acrylic sheet 171, 150mm polystyrene 172 and plain sheet steel 173. Air-tight hatches 180 allowed access into the upper and lower compartments of the box.

The estimated heat transfer from each chamber of the box was not more than 1. 8 W K- relative to the inside/outside air temperature differential.

Each compartment contained a 100W heater 160 and a 12. 6W fan 150. The heaters were independently controlled by digital means with thyristor switching and the fans were used to counteract the cooling effect of the slab. Calibrated thermocouples were embedded into the slab during casting to enable temperature measurements during the testing procedure.

A heat exchanger and chiller (not shown) were used in combination to supply temperature controlled chilled water to the slab. The spacing between pipe centres could be 100mm, 150mm or 200mm The test programme consisted of a series of tests, each with the appropriate water and temperature parameters that would give the approximate required temperature differential. At the end of each test, the temperature of the surface of the slab was measured using an infra-red spot temperature meter, along with the temperature of the calorimeter walls.

The results of the tests are summarised in Table 1. Test Nom air Nom water°CPipeWaterWater in °C Air up °C Air down °C °CConHgOut°C 117/2313/16100nun14.9213.0017.123.1 '217/2313/16100mm15.6413.0017.223.0 '317/2313.75/15.25100mm15.2213.7617.123.0 '417/2315/18100mm18.2215.0119.122.9 '517/2317/20100mm19.3317.0019.823.0 '617/2513/16100mm16.6112.9917.824.9 '717/2513/16150mm16.1012.99T4'249 '817/2517/20150mm19.5117.0220.525.0 '917/2513/16200mm15.8812.9918.725.0 'To17/2517.75/19.25200mm19.3117.7520.8'25'! Tl17/2517/20200mm19.2217.0020.725.0 '1217/2513/14.5100mm14.3312.9917.124.8 13 17/25 11/12.5 100 mm 12.61 11.01 17.0 24.8

Table 1.

Early in the testing programme, it became apparent that cooling effects from the upper surface of the test slab accounted for only 5 to 10% of the total. Consequently, additional tests to examine the effects of surface insulation were not necessary since it was evident that it would not be required in real construction installations.

Due to lower than expected laboratory temperatures, a small correction of 1. 8 W °C~' of inside/outside temperature difference was applied to the cooling estimates.

The temperature of the slab surface was measured at numerous points across the slab, perpendicular to the embedded pipes. The surface temperature varied by less than 0. 5°C across the entire width. Table 2 shows the average temperature across the slab width. Location Temperature °C Slab surface16. 4 Opposite surface23. 0 Wall surface 23.2 Air temperature 24. 8 Mean radiant temp °C (centre) 21. 1 Dry resultant temp 22. 9

Table 2.

Current tests on the longevity of the system have indicated that there is no degradation to the system or concrete structure for up to sixty years. It is therefore anticipated that the system would last the life of the construction without the need for disruptive refurbishment or maintenance.

The overall conclusions that were drawn from the test results can be summarised as follows : There is significant'radiant cooling'by the slab.

In the region of 90 to 95 % of cooling was directed from the lower surface of the slab.

Top surface insulation is not necessary Radiant cooling of the slab significantly reduces the dry resultant temperature.