US20050011964A1

US20050011964A1 - System and method for controlling the temperature of an open-air area

Info

Publication number: US20050011964A1
Application number: US10/891,791
Authority: US
Inventors: Garrett Greenlee
Original assignee: SUNSET INTERNATIONAL LLC
Current assignee: SUNSET INTERNATIONAL LLC
Priority date: 2003-07-16
Filing date: 2004-07-15
Publication date: 2005-01-20

Abstract

A system for controlling the temperature of an open-air area. The system comprises a boundary wall defining at least a portion of the perimeter of the open-air area to be temperature-controlled, and a floor having a heating or cooling element, wherein the system is effective to control the temperature of the area. The heating or cooling element may include a network of interconnected pipes in the floor, a quantity of fluid disposed within the pipes, a heat exchanger for heating or cooling the fluid, and a pump for circulating the fluid through the pipes. The system may further include a network of interconnected ductwork in the boundary wall, a heating or cooling element for heating and cooling air, a blower for circulating the heated or cooled air through the ductwork, and a plurality of diffusers in the boundary wall to communicate the air to the open-air area.

Description

This application claims priority to U.S. provisional application 60/487,779, filed Jul. 16, 2003, the contents of which are hereby incorporated by reference.

FIELD

This invention relates to a system and method for controlling the temperature of an external area. In particular, this invention relates to a system and method for controlling the temperature of an open-air venue, such as a patio.

BACKGROUND

Open-air venues, such as restaurant and coffee shop patios, are popular with customers who enjoy relaxing outside in the fresh air. In addition, customers seated in an open-air venue are often able to better take in the atmosphere of the locale, such as people-watching and viewing local scenery and architecture. Open-air seating may also be desirable to complement an establishment's decor and/or theme.
In many climates open-air venues are comfortably utilized only a small portion of the year because seasonable temperature variations result in an outside temperature that is often either too hot or too cold. Prior attempts at extending the utilization of open-air venues include enclosing the space with a roof and/or side walls, using heating units such as propane or infrared heaters during the winter, and using spot coolers and/or misters in the summer. Such enclosures and heating/cooling units impede upon the venue's usable space and detract from the outdoor experience by their appearance, noise and the noticeable temperature differential in comparison to the outside air temperature.
There is a need for an open-air venue that can be heated and cooled as needed to extend the number of days during which the venue may be comfortably utilized. There is a further need for a climate-controlled outdoor venue wherein the climate control devices do not detract from the atmosphere of the venue.

SUMMARY

A system and method are disclosed for controlling the climate of an outdoor venue, such as a patio. A foundation serving as a low support wall encloses and disguises air-moving ductwork and diffusers connected to heating and/or cooling equipment. A transparent barrier is located atop the foundation that provides the venue with an open environment while establishing a climate-control area with a wind break. A floor of the venue may also include embedded heating and/or cooling capability. Additional climate-control devices may include movable sun screens to reduce the heat load on the venue during warm weather.
By controlling the environment of the venue in a non-obtrusive way the outdoor experience is much richer, creating an illusory effect of an open, yet temperature-controlled area. This is accomplished by conditioning the living space of an area from the floor up, as opposed to ceiling-down, as is generally practiced in the art. As such, the present invention focuses on the living space from the floor of the venue to about six feet in height. This is a key issue when attempting to condition an outdoor space that has no roof, such that the total spacial volume is nearly infinite.
An embodiment of the present invention is a system for controlling the temperature of an open-air area. The system comprises a boundary wall defining at least a portion of the perimeter of the open-air area to be temperature-controlled, a floor, and a heating or cooling element in the floor, wherein the system is effective to control the temperature of the open-air area.
Another embodiment of the present invention is a system for controlling the temperature of an open-air area. The system comprises a boundary wall defining at least a portion of the perimeter of the open-air area to be temperature-controlled, a network of interconnected ductwork in the boundary wall, a heating or cooling element to heat or cool air, a blower for circulating the heated or cooled air through the ductwork, and a plurality of diffusers in the boundary wall to communicate the heated or cooled air to the open-air area. The system is effective to control the temperature of the area.
Still another embodiment of the present invention is a system for controlling the temperature of an open-air area. The system comprises a boundary wall defining at least a portion of the perimeter of the open-air area to be temperature-controlled, a floor including a network of interconnected pipes in the floor and a quantity of fluid disposed within the pipes, a heat exchanger for heating or cooling the fluid, a pump for circulating the fluid through the pipes, a network of interconnected ductwork in the boundary wall, a heating or cooling element to heat or cool air, a blower for circulating the heated or cooled air through the ductwork, and a plurality of diffusers in the boundary wall to communicate the air to the open-air area. The system is effective to control the temperature of the open-air area.

BRIEF DESCRIPTION OF THE DRAWINGS

Further features of the inventive embodiments will become apparent to those skilled in the art to which the embodiments relate from reading the specification and claims with reference to the accompanying drawings, in which:
FIG. 1 is a top plan schematic view of the general arrangement of an outdoor venue according to an embodiment of the present invention;
FIG. 2 is a side elevational view of the general arrangement of a boundary wall according to an embodiment of the present invention;
FIG. 3 is a top plan view of a portion of a network of pipes used with an embedded floor heating/cooling system according to an embodiment of the present invention;
FIG. 4 is a schematic diagram of a temperature control system for a heating/cooling system embedded in a floor according to an embodiment of the present invention;
FIG. 5 is a schematic diagram of a temperature control system for a heating/cooling system embedded in a foundation of a boundary wall according to an embodiment of the present invention;
FIG. 6 is a schematic of a supplemental screen according to an embodiment of the present invention;
FIG. 7A is a view in cross section of the pipes of FIG. 3;
FIG. 7B is a simplified view of the pipes of FIG. 7A; and
FIG. 7C is a view in cross section of pipes installed in a boundary wall according to an embodiment of the present invention.

DETAILED DESCRIPTION

A top plan schematic view of the general layout of a system for controlling the temperature of an external environment is depicted in FIG. 1. An area to be temperature-controlled, such as a patio 10, comprises a boundary wall 12, a floor 14 and a movable screen 16. Boundary wall 12 defines the perimeter of the area to be temperature-controlled. Boundary wall 12 also serves as a wind break to help confine conditioned air temporarily. A floor 14 covers the ground in the area enclosed by boundary wall 12. A movable screen 16 may optionally be located proximate the boundary wall 12. Movable screen 16 may be adapted to move upon a track 18, or may be adapted to move freely, such as on wheels (not shown). The perimeter of patio 10 may be at least partially bounded by a partition 20, such as a wall of a building. Patio 10 may include at least one access 23 in partition 20 and/or boundary wall 12. Access 23 may be, without limitation, an open entry way, a conventional “air door” of vertically-directed air, a screen door, a solid entry door, and conventional plastic strip doors.
A side elevational view of an example boundary wall 12 is depicted in FIG. 2. In a preferred embodiment boundary wall 12 has a foundation 22 and an optically transmissive portion 24. Foundation 22 may be constructed from any conventional materials, such as stone, brick and concrete. Foundation 22 is preferably about 18 inches thick and about 3 feet high, constructed around the perimeter of patio 10. The thickness of foundation 22 will be dictated by the materials selected and the structural requirements for the materials. The thickness of the foundation 22 will also be influenced by the design of conventional heating/cooling ductwork and diffusers 26 to be installed within the foundation, as will be discussed in more detail below. Optically transmissive portion 24 is mounted atop foundation 22 and provides patio 10 with the sensation of an open atmosphere while providing a wind break. Optically transmissive portion 24 may be supported in any conventional manner, such as vertical and/or horizontal frames, structures and braces attached to foundation 22. Optically transmissive portion 24 may be constructed from any conventional materials, such as tempered glass, structural glass, acrylics, and polycarbonates such as LEXAN.
A plan view of a schematic of a portion of floor 14 is shown in FIG. 3. Floor 14 may be constructed of poured concrete having a network of interconnected pipes 30 in the floor. In a preferred embodiment the concrete is poured to a depth of about 6 inches with pipes 30 located about 2 inches below the top surface. In other alternate embodiments of the present invention other materials may be used for floor 14 such as brick, stone and/or wood constructed so as to cover, embed or otherwise encase pipes 30.
A quantity of fluid 39 is disposed within pipes 30. Fluid 39 may be water alone, or water mixed with substances such as ethylene glycol and propylene glycol to promote thermal transfer and prevent freezing of the fluid.
With reference to FIGS. 1, 3 and 4 in combination, a system 40 functioning as a heating or cooling element for controlling the temperature of an open-air environment is shown. System 40 includes a temperature control component 42 for controlling the temperature of fluid 39. Temperature control 42 includes a temperature-setting device 42 a, such as a conventional bimetal thermostat or electronic temperature control, to establish a control setpoint for a temperature to be maintained in relation to patio 10. A conventional heat exchanger 42 b adds heat to fluid 39 when heating of patio 10 is desired, and removes heat from the fluid when cooling of the patio is desired. A pump 44 for circulating fluid 39 through pipes 30 may include, without limitation, reciprocating, centrifugal and rotary pumps.
In one embodiment, heating fluid 39 to a temperature of about 120° F. results in a temperature of about 105° F. at the surface of floor 14. Heat from the surface of floor 14 will rise, creating a comfortable environment within the area established by boundary wall 12 and (optionally) partition 20. Conversely, cooling fluid 39 with heat exchanger 40 b to a temperature less than that of floor 14 will draw heat away from the floor, helping to prevent the build-up of heat on patio 10 during warm weather.
System 40 may include pipes 30 installed within foundation 22 of boundary wall 12, in the same manner as described above for floor 14. In such embodiments boundary wall 12 preferably supplements the heating and cooling effect of floor 14.
In an alternate embodiment of system 40, other devices may be embedded in the concrete in addition to or instead of pipes 30, such as electric heating elements (not shown), which may be likewise controlled by temperature control 42, specifically temperature-setting device 42 a.
Referring now to FIGS. 2 and 5 in combination, to replace or supplement system 40 during lower outside ambient temperatures an air delivery system 50 provides warm air distributed through a network of interconnected ductwork 52 in foundation 22. A temperature-setting device 54, such as a conventional bimetal thermostat or temperature control, may be used to establish a temperature setpoint for a temperature to be maintained in relation to patio 10. A heating or cooling element such as a conventional electric or gas-operated HVAC unit 56 heats or cools air drawn from an intake 58. Intake 58 may be a fresh-air intake drawing air from outside patio 10, or may recirculate air within patio 10. The temperature-controlled air may optionally be dehumidified by a conventional dehumidifier 60. Movement of air through air delivery system 50 is accomplished using a conventional air-moving fan or blower 62, the temperature-controlled and dehumidified air preferably being emitted from diffusers 26 located low in foundation 22 proximate floor 14. The warm air will combine with the heat from floor 14, resulting in an effective convection heating process. By combining systems 40, 50, patio 10 may be made available for use when the outside ambient temperature is as low as about 20° F.
With continued reference to FIG. 5, air delivery system 50 may also be adapted to operate without HVAC unit 56 and/or dehumidifier 60. In this embodiment system 50 is adapted such that air intake 58 receives heat generated by floor 14 and recirculates the heat by circulating it with ductwork 52 and communicating the air to the temperature-controlled area through a plurality of diffusers 26, providing a convective heating effect to patio 10. Fan or blower 62 may or may not be utilized, as desired.
During warm weather the air delivery system 50 may be used to deliver cool air to patio 10. In such conditions the air temperature leaving the diffusers 26 is preferably about 65° F., with a relative humidity of about 68%. It is preferable not to deliver colder temperatures, which may be perceived by occupants of patio 10 as uncomfortable on bare legs. Colder air temperatures may also cause undesirable condensation in the temperature-controlled area of patio 10. During high-humidity weather, condensation may be reduced by dehumidifying the cooling air with dehumidifier 60. Dehumidifier 60 may receive air from HVAC unit 56 and drive the temperature of the air down to about 54° F. Then, using a conventional re-heat process, dehumidifier 60 may raise the temperature of the air to about 65° F. Mixing in outside air at intake 58 is not preferred during these conditions, due to the high moisture content of the untreated air stream. Re-heating of air within de-humidifier 60 may be accomplished with a conventional “heat pipe” system or “hot-gas reheat.” Both methods are highly effective and efficient way to raise the air temperature while maintaining a de-humidified state.
Referring now to FIG. 1 in combination with FIG. 6, during warm weather it is desirable to minimize the build-up of heat on patio 10 due to solar radiation 32 from the sun 34. In a preferred embodiment a movable screen 16 may be located proximate patio 10 to act as a shade by blocking solar radiation 32. Screen 16 may be adapted to move about a track 18. If desired, the screen may be shaped to complement the theme of the venue. For example, a “spinnaker sail” in keeping with a tropical theme for a particular establishment may be appropriately positioned to shade patio 10 from direct sunlight. Screen 16 may be manually moved laterally about track 18 by hand, and may optionally be manually raised, lowered and tilted as needed to effectively block solar radiation 32. Screen 16 may also be adapted to be manually moved freely in relation to patio 10 and independently of track 18, if desired, such as with a wheeled cart or trolley sufficiently constructed to support the screen during breezy or windy weather conditions. In an alternate embodiment, lateral and elevational movement of screen 16 may be manually but remotely controlled, such as by conventional wired or wireless control switches, actuators, relays, motors and the like. Details of the configuration of a remote-controlled screen 16 are conventional and are left to the artisan.
In another alternate embodiment of the present invention, screen 16 may be automatically actuated by electronic controls wherein appropriately located sensors detect light and/or temperature at points about patio 10 and engage actuators and motors to move the screen laterally and/or elevationally to block solar radiation 32 in “hot spots” of bright light and/or higher temperatures. In a similar embodiment, screen 16 may be automatically controlled by motors, control switches, relays, actuators and the like synchronized to the sun's position in relation to the patio during various times of the day at any point in the warm-weather season. A predetermined set of instructions, such as a computer program, may be used with a computer, microprocessor, CPU or other conventional computing or control device to accomplish automatic control of screen 16. Implementation of manual, remote, and automatic controls are conventional will be apparent to one skilled in the art. As such, details of the implementation manual, remote and automatic controls are left to the artisan.
Individual shading units, such as umbrellas at each table within patio 10, may optionally be used but are not preferred because such shades are less efficient and impinge upon the visual and physical space available in the patio.
It should be noted that the intent of the heating and cooling systems 40, 50 (see FIGS. 4 and 5) is preferably not to control the temperature of patio 10 to typical interior expectations, but rather to temper ambient conditions to a comfortable level. Thus, only as much heating or air conditioning as is required for a comfortable temperature is desirable to augment the ambient temperature. For example, the optimum temperature for simulating a tropical setting is about 77° F. to 82° F. Thus, if the temperature is, for example, 50° F., supplemental heat may be added to patio 10 to achieve the desired temperature.
It is also considered important that heating and cooling systems 40, 50 be as inconspicuous as possible so as not to detract from the atmosphere of patio 10. To accomplish this the components of systems 40, 50 are preferably located remotely, such as within an adjacent building or suitably disguised in keeping with the decor of patio 10. Diffusers 26 are preferably located at a low height and are inconspicuous, preferably matching or blending in with foundation 22. For example, diffusers 26 may simply be narrow slits or openings in stone or brickwork of foundation 22. Air movement should be kept to a velocity that provides a cooling breeze during warm weather conditions, yet is not distracting. Noises associated with systems 40 and 50 are preferably kept to a minimum.
Design Calculations
The present invention can be more clearly understood by reference to the following example design calculations. These calculations demonstrate one way to estimate the solar heat load on a patio 10 (see FIG. 1) to determine a portion of the operating requirements for heating and cooling systems 40, 50. The terms and units of measure associated with these equations will be familiar to one skilled in the art and thus will not be discussed. It should be understood that the following examples are not intended to restrict the scope of the present invention in any manner.
The total shortwave radiation, I_t, reaching a surface on earth is given by Equation 1:
I _t =I _DN(cos θ)+I _d +I _r Equation 1
where: I_DN=direct normal radiation, θ=angle of incidence between incoming solar rays and a line normal to the surface, I_d=diffuse sky radiation, and I^r=solar radiation reflected from surrounding surfaces.
On earth's surface on a clear day, I_DNis generally represented by Equation 2: $\begin{matrix} I_{DN} = \frac{A}{\exp (\frac{B}{\sin β})} & Equation 2 \end{matrix}$
where: A=direct normal radiation, B=atmospheric extinction coefficient, β=solar altitude above a horizontal surface.
For a horizontal surface, cos θ of Equation 1=sin θ of Equation 2. Calculating I_DNfor example conditions wherein at a particular time of a particular day at a particular latitude, such as at noon on July 21 at 40° N latitude, A=344 BTU/hr-ft², B=0.207, β=70°, sin β=0.939, then $\begin{matrix} I_{DN} = \frac{344}{\exp (\frac{0.207}{0.939})} = 275 BTU / hr - {ft}^{2} & Equation 3 \end{matrix}$
The incident solar radiation falling on the horizontal surface, I_DH, is given by Equation 4:
I _DH =I _DNcos θ=I _DNsin β=275 (0.939)=259 BTU/hr-ft² Equation 4
A simplified general relation for the diffuse solar radiation is given by Equation 5:
I _DS =CI _DN F _SSBTU/hr-ft² Equation 5
where: C=diffuse radiation factor, CI_DN=sky radiation falling on horizontal surface, F_SS=angle factor between surface is sky (1.0 for a horizontal surface).
If C=0.136 and CI_DN=275, then I_DSof Equation 5 equals:
I _DS=(0.136)(275)(1.0)=37.4 BTU/hr-ft² Equation 6
Assuming I_rof Equation 1 is a sufficiently small value that it can be ignored,
I _t =I _DH =I _DS=259+37.4=296.4 BTU/hr-ft² Equation 7
A heat balance at a sunlit surface has a heat flux, $\frac{q}{A},$
given by Equation 8: $\begin{matrix} \frac{q}{A} = α I_{t} + h_{0} (t_{0} - t_{s}) - ɛ Δ R & Equation 8 \end{matrix}$
where: α=absorptance of the surface for solar radiation, I_t=total solar radiation incident on the surface, h₀=heat transfer by longwave radiation and convection at the outer surface, t₀=outdoor air temperature, t_s=surface temperature, ε=hemispherical emittance of surface, and ΔR=difference between longwave radiation incident on the surface from the sky and surroundings, and the radiation emitted by a blackbody at outdoor temperature.
If it is assumed that patio 10 absorbs no heat, then for the net heat flux to be zero, the solar heat load is given by Equation 9:
h ₀(t _s −t ₀)=αI _t −εΔR=solar heat load Equation 9
For concrete the solar reflectance, ρ, is generally a value of 0.22. Since the absorptance, α=1−ρ, then: α=1−0.22=0.78
For horizontal surfaces exposed to longwave solar radiation from the sky, an appropriate value of ΔR is approximately 20 BTU/hr-ft². Since the emissivity, ε, is approximately equal to α for most solids, the solar heat load is as shown in Equation 10:
h ₀(t _s −t ₀)=0.78(296.4 BTU/hr-ft²)−0.78(20 BTU/hr-ft²)=215.6 BTU/hr-ft² Equation 10
With reference to FIGS. 7A-7C, the following equations may be used to aid in the design of a floor 14 having a cement pad and an embedded network of interconnected pipes 30: $\begin{matrix} q^{'} = \frac{4 π k (T_{1} - T_{2})}{\frac{1}{{Bi}_{1}} + \ln {\frac{d}{π} r_{1} D) \sinh [2 π (D + \frac{D}{{Bi}_{2}}]}} & Equation 11 \end{matrix}$
Where: q′=linear heat flux for each pipe, s=distance between pipe centers, d=pipe depth below the surface, k=the thermal conductivity of the solid, r₁=pipe interior diameter, h₁=pipe heat-transfer coefficient, T₁=pipe coolant temperature, h₂=ambient heat-transfer coefficient, $\begin{matrix} {Bi}_{1} = Biot modulus for the pipe, \\ = \frac{h_{1} r_{1}}{k}, \\ {Bi}_{2} = Biot modulus for exterior surface \\ = \frac{h_{2} d}{k}, \\ D = pipe depth to pitch ratio \\ = \frac{d}{s} . \end{matrix}$
FIG. 7A illustrates a floor 14 placed atop a thermal insulating material 72 and a layer of gravel 74. FIG. 7B illustrates the thermal case for floor 14 of FIG. 7A, and FIG. 7C illustrates a row of pipes in a wall such as foundation 22.
By symmetry, the heat flux through the top surface of floor 14 is one half the total heat flux. If the bottom surface of floor 14 is insulated it is expected that the linear heat flux will be between $\frac{q}{2}$
and q. Since both the top and bottom of each pipe 30 can provide heat flow through the top surface of floor 14, Equation 11 can be modified to account for this by dividing it by two and multiplying the r₁term in the denominator by two, giving Equation 12: $\begin{matrix} q^{'} = \frac{2 π k (T_{1} - T_{2})}{\frac{1}{{Bi}_{1}} + \ln {\frac{d}{2 π} r_{1} D) \sinh [2 π (D + \frac{D}{{Bi}_{2}}]}} & Equation 12 \end{matrix}$
To calculate the convective coefficient of pipe 30, assume a surface heat flux of $100 \frac{BTU}{hr - {ft}^{2}}$
and a circuit temperature drop, ΔT, of 30° F. The following equations may then be applied: $\begin{matrix} GPM = \frac{(100 \frac{BTU}{hr - {ft}^{2}}) (3, 000 {ft}^{2})}{(30) (500)} = 20 GPM & Equation 13 \\ Q_{total} = 20 \frac{gal}{\min} (\frac{1 {ft}^{3}}{8 gal}) = 2.50 \frac{{ft}^{3}}{\min} & Equation 14 \\ Q_{loop} = \frac{Q_{total}}{18} = 0.139 \frac{{ft}^{3}}{\min} (\frac{1 \min}{60 s}) = 0.0023 \frac{{ft}^{3}}{s} & Equation 15 \\ Q = VA, V = \frac{Q}{A}, A = \frac{π D^{2}}{4} = \frac{{π (0.052 ft)}^{2}}{4} = 0.00212 {ft}^{2} & Equation 16 \\ V = \frac{0.0023 \frac{{ft}^{3}}{s}}{0.00212 {ft}^{2}} = 1.09 \frac{ft}{s} & Equation 17 \\ R_{e} = \frac{ρ u_{m} D}{μ} = \frac{(62 \frac{lb}{{ft}^{3}}) (1.09 \frac{ft}{s}) (0.052 ft)}{0.000458 \frac{lb m}{ft - s}} = 7, 673 & Equation 18 \\ {Nu}_{D} = 0.023 {Re}_{D}^{0.8} \Pr^{0.3} = \frac{hD}{k} & Equation 19 \\ H_{2} O, \Pr = 4.53, k = 0.364 \frac{BTU}{hr - ft - ° F .} & Equation 20 \\ {Nu}_{D} = 0.023 {(7, 673)}^{0.8} {(4.53)}^{0.3} = 46.4 & Equation 21 \\ {Nu}_{D} = \frac{hD}{k} & Equation 22 \\ h = \frac{{Nu}_{D} k}{D} = \frac{46.4 (0.364)}{0.052} = 325 \frac{BTU}{hr - ft - ° F .} & Equation 23 \end{matrix}$

The following equations and data may be used to calculate the ambient convective heat transfer coefficient of system 40 (FIG. 4). Assuming heated plates facing upward:



	Laminar Fluid Flow	Turbulent Fluid Flow

	104 < Gr_fPr_f< 109	Gr_fPr_f> 109

	$h = 0.27 {(\frac{ΔT}{L})}^{\frac{1}{4}}$	$h = 0.22 {(ΔT)}^{\frac{1}{3}}$

$\begin{matrix} L = (\frac{Width + Length}{2}) = \frac{(100 + 30)}{2} = 65 ft where L = a vertical or horizontal dimension in ft . & Equation 24 \\ h : \frac{BTU}{hr - {ft}^{2} - ° F} & Equation 25 \\ Δ T = T_{W} - T_{\infty}, ° F & Equation 26 \\ {Gr}_{f} = \frac{g β (T_{W} - T_{\infty}) L^{3}}{υ^{2}}, \Pr_{f} = \frac{υ}{\infty} & Equation 27 \\ {Gr}_{f} \Pr_{f} = {Ra}_{f} = \frac{g β (Δ T) L^{3}}{υ∞} & Equation 28 \\ T_{f} = \frac{(T_{W} - T_{\infty})}{2} & Equation 29 \\ Let : T_{w} = 100 ° F, T_{\infty} = 40 ° F : T_{f} = \frac{(100 ° F + 40^{°} F)}{2} = 70^{°} F & Equation 30 \\ \frac{g β}{υ^{2}} = 2.315 \times 10^{6} \frac{1}{r_{A} {ft}^{3}}, \Pr = 0.7118 & Equation 31 \\ Ra = \frac{g β}{υ^{2}} (\Pr) (L^{3}) (Δ T) = 2.315 \times 10^{6} (0.7118) (65 {ft}^{3}) ({0.60}^{°} F) = 2.715 \times 10^{13} Tubulent : h = 0.22 {(Δ T)}^{\frac{1}{3}} = 0.86 \frac{BTU}{hr - {ft}^{2} -^{°} F} & Equation 32 \end{matrix}$

The surface conductances for air are shown in Table 2, taken from the American Society of Heating, Refrigerating and Air-Conditioning Engineers (“ASHRAE”) “ASHRAE Handbook” (Pub. 2003 by ASHRAE):

	TABLE 2


	Surface Emittance

Position of Surface	Direction of	Non-Reflective	Reflective
Surface	Heat Flow	(ε = 0.9)	(ε = 0.09)


STILL AIR		$h_{1} \frac{BTU}{hr - {ft}^{2} - ° F .}$	$h_{1} \frac{BTU}{hr - {ft}^{2} - ° F .}$

Horizontal	Upward	1.63	0.76
MOVING AIR
Any (15 mph wind)	Any	6.00

For masonry, the average surface emittance=0.9

Note that the prior calculation for still air and zero emissivity is roughly equal to the value given here for emissivity=0.05. Therefore, 1.63 BTU/hr-ft²° F. will be used for h₂for still air in order to include the effect is of surface emittance. For a 15 mph wind the value is 6.0 BTU/hr-ft²-° F.
The thermal conductivity of concrete is approximately 0.54 BTU/hr-ft²-° F., as given by the ASHRAE Handbook.

Table 3 contains a summary providing design points for a patio having the properties and variables discussed above:

TABLE 3


			T1
		h1	Fluid		k		h2
s	r1	(BTU/hr	Temp.	d	(BTU/	D	(BTU/	Bi1
ft	ft	ft²° F.)	(° F.)	(ft)	hr-ft-F)	(d/s)	hr-ft²-F)	(h1 r1/k)

0.750	0.024	332	100	0.167	0.54	0.2223	10000.00	14.70
0.750	0.024	459	106	0.167	0.54	0.2223	10000.00	20.34
0.750	0.024	577	131	0.167	0.54	0.2223	10000.00	25.57
0.750	0.024	799	156	0.167	0.54	0.2223	10000.00	35.40
0.667	0.024	332	120	0.167	0.54	0.2501	0.86	14.70
0.667	0.024	332	120	0.167	0.54	0.2501	1.60	14.70
0.667	0.024	332	120	0.167	0.54	0.2501	6.00	14.70
0.667	0.024	332	130	0.167	0.54	0.2501	0.86	14.70
0.667	0.024	332	130	0.167	0.54	0.2501	1.60	14.70
0.667	0.024	332	130	0.167	0.54	0.2501	6.00	14.70

	T2	Td	T1′
	Ambient	Temp	T1-	q′	q″	Surface	Qt
Bi2	Temp.	Drop	(Td/2.)	(BTU/	(BTU/	Temp	Total BTU
(h2 d/k)	(° F.)	(° F.)	(° F.)	hr-ft)	hr-ft²)	(° F.)	3000 FT²

3087.04	32	30	85	77.64	103.52	32.01	310,549.81
3087.04	32	30	91	87.14	116.18	32.01	348,543.92
3087.04	32	30	116	124.60	166.14	32.02	498,412.39
3087.04	32	30	141	162.46	216.61	32.02	649,832.63
0.27	40	30	105	26.40	39.60	86.05	118,803.20
0.49	40	30	105	39.27	58.90	76.81	176,700.12
1.85	40	30	105	67.32	100.98	56.83	302,943.65
0.27	40	30	115	30.46	45.69	93.13	137,080.62
0.49	40	30	115	45.31	67.96	82.48	203,884.75
1.85	40	30	115	77.68	116.52	59.42	349,550.37

EXAMPLE EMBODIMENT

The present invention can be more clearly understood by reference to the following example embodiment. It should be understood that the following example is not intended to restrict the scope of the present invention in any manner.
Patio 10 (see FIGS. 1-6) may be adapted to simulate an open air, tropical setting. To extend availability with weather conditions in central Ohio weather, patio 10 is environmentally controlled. A boundary having a stone foundation about three feet high encompasses patio 10, establishing a perimeter. Optically transmissive glass or polycarbonate is mounted atop the foundation, raising the overall height of the boundary to about six feet, effectively creating a conditioned space and acting as a wind break.
Ductwork is embedded within the foundation of the boundary wall. Low velocity, long throw diffusers are located along the floor line to disperse conditioned air. The principle works from a “raised floor” HVAC design concept that conditions the space from the floor rather than the ceiling. This puts the emphasis on the “living space,” which is about the first six feet from the floor.
In warm weather the design leaving air temperature from the ductwork is about 65° F. The air travels along the floor without adversely cooling bare legs. The intent is to temper the extreme days, not to condition to interior level expectations. Further, an innovative, architecturally interesting sun shade is employed. A triangle shaped spinnaker sail from a sail boat is mounted via a three point connection. The sail is placed on rails about 20 feet above the patio along a path that matches the contour of a rotunda building structure. It moves along the rail, effectively tracking the sun to keep the rays from building a heat load on the cement below. This allows the patio stay partially shaded and keep an open feel, unencumbered by umbrellas at every table.
Far more prevalent in central Ohio is cold weather which deters outside dining. A heater is employed to heat the patio. A concrete floor is poured with an embedded glycol loop. A dedicated boiler system creates the hot water necessary for the loop. The heat from the cement radiates, warming the patio space from the floor up. As the heat rises it will create a comfortable atmosphere.
When the temperature drops below 40 degrees, warm air will be generated and dispersed from the diffusers along the boundary wall. Alternatively, system 50 may pick up heat from floor 14 and create a convective process.
This design allows for a comfortable outdoor experience through an ambient temperature range of about 20 to 95° F. The typical patio in central Ohio is useful for approximately two months out of the year. Accounting for the extreme inclement weather, such as heavy rain or snow, patio 10 is available for use a cumulative ten months out of the year.
While this invention has been shown and described with respect to detailed embodiments thereof, it will be understood by those skilled in the art that various changes in form and detail thereof may be made without departing from the scope of the claims of the invention.

Claims

1. A system for controlling the temperature of an open-air area, comprising:

a boundary wall defining at least a portion of the perimeter of the open-air area to be temperature-controlled;

a floor; and

a heating or cooling element in the floor, wherein the system is effective to control the temperature of the open-air area.

2. The system of claim 1 wherein the heating or cooling element comprises:

a network of interconnected pipes in the floor;

a quantity of fluid disposed within the pipes;

a heat exchanger for heating or cooling the fluid; and

a pump for circulating the fluid through the pipes.

3. The system of claim 1 wherein the heating or cooling element comprises a plurality of electric heating elements in the floor.

4. The system of claim 1, further comprising a heating or cooling element in the boundary wall.

5. The system of claim 1 wherein the boundary wall includes a foundation and an optically transmissive portion.

6. The system of claim 1, further including a movable screen to shade at least a portion of the open-air area.

7. The system of claim 6 wherein the screen moves freely in relation to the open-air area.

8. The system of claim 6 wherein the screen moves upon a track.

9. The system of claim 8 wherein the screen is manually repositioned to maintain shading of the open-air area.

10. The system of claim 9 wherein the screen is manually repositioned with a remote control.

11. The system of claim 8 wherein the screen is automatically repositioned to maintain shading of the open-air area.

12. The system of claim 1, further including a partition defining a portion of the perimeter in conjunction with the boundary wall.

13. The system of claim 1, further comprising:

a network of interconnected ductwork in the boundary wall;

an air intake for receiving air and circulating the air through the ductwork; and

a plurality of diffusers in the boundary wall to communicate the air to the open-air area.

14. A system for controlling the temperature of an open-air area, comprising:

a network of interconnected ductwork in the boundary wall;

a heating or cooling element to heat or cool air;

a blower for circulating the heated or cooled air through the ductwork; and

a plurality of diffusers in the boundary wall to communicate the heated or cooled air to the open-air area, wherein the system is effective to control the temperature of the open-air area.

15. The system of claim 14 wherein the diffusers are inconspicuous.

16. The system of claim 14, further including a dehumidifier.

17. The system of claim 14 wherein the boundary wall includes a foundation and an optically transmissive portion.

18. The system of claim 14, further including a movable screen to shade at least a portion of the open-air area.

19. The system of claim 18 wherein the screen moves freely in relation to the open-air area.

20. The system of claim 18 wherein the screen moves upon a track.

21. The system of claim 20 wherein the screen is manually repositioned to maintain shading of the open-air area.

22. The system of claim 21 wherein the screen is manually repositioned with a remote control.

23. The system of claim 18 wherein the screen is automatically repositioned to maintain shading of the open-air area.

24. A system for controlling the temperature of an open-air area, comprising:

a floor including:

a network of interconnected pipes in the floor, and

a quantity of fluid disposed within the pipes;

a heat exchanger for heating or cooling the fluid;

a pump for circulating the fluid through the pipes;

a network of interconnected ductwork in the boundary wall;

a heating or cooling element to heat or cool air;

a blower for circulating the heated or cooled air through the ductwork; and

a plurality of diffusers in the boundary wall to communicate the air to the open-air area, wherein the system is effective to control the temperature of the open-air area.

25. The system of claim 24 wherein the boundary wall includes a foundation and an optically transmissive portion.

26. The system of claim 24, further including a movable screen to shade at least a portion of the open-air area.

27. The system of claim 26 wherein the screen moves freely in relation to the open-air area.

28. The system of claim 26 wherein the screen moves upon a track.

29. The system of claim 28 wherein the screen is manually repositioned to maintain shading of the open-air area.

30. The system of claim 29 wherein the screen is manually repositioned with a remote control.

31. The system of claim 26 wherein the screen is automatically repositioned to maintain shading of the open-air area.

32. A method for controlling the temperature of an open-air area, comprising the steps of:

defining at least a portion of the perimeter of the open-air area to be temperature-controlled with a boundary wall; and

installing a heating or cooling element in a floor of the open-air area, wherein the method is effective to control the temperature of the open-air area.

33. The method of claim 32, further comprising the steps of:

installing a network of interconnected pipes in the floor;

placing a quantity of fluid within the pipes;

heating or cooling the fluid; and

circulating the fluid through the pipes.

34. A method for controlling the temperature of an open-air area, comprising the steps of:

defining at least a portion of the perimeter of the open-air area to be temperature-controlled with a boundary wall;

installing a network of interconnected ductwork in the boundary wall;

heating or cooling air;

circulating the heated or cooled air through the ductwork; and

communicating the air from the ductwork to the open-air area, wherein the method is effective to control the temperature of the open-air area.

35. A method for controlling the temperature of an open-air area, comprising the steps of:

installing a network of interconnected pipes in a floor of the open-air area;

placing a quantity of fluid within the pipes;

heating or cooling the fluid;

circulating the fluid through the pipes;

installing a network of interconnected ductwork in the boundary wall;

heating or cooling air;

circulating the heated or cooled air through the ductwork; and

communicating the air from the ductwork to the open-air area, wherein the method is effective to control the temperature of the area.