Patent Publication Number: US-2009229199-A1

Title: Building structure with having spaces having improved temperature stability

Description:
RELATED APPLICATIONS 
     This application claims the benefit of U.S. Provisional Patent Application Ser. No. 61/068,875, filed 10 Mar. 2008, and entitled “Building Structure With Spaces Having Improved Temperature Stability,” which is incorporated herein by reference in its entirety. 
    
    
     BACKGROUND OF THE INVENTION 
     The present invention relates generally to building structures and more specifically to structures requiring less consumption of energy for maintaining desirable temperatures. 
     Energy conservation is, without question, desirable. In prior structures, such as houses, significant energy was consumed in maintaining living spaces at a comfortable temperature, while the ambient air temperature outside the structure may vary considerably. Prior solutions have been attempted at reducing energy costs, such as the superinsulation of the walls of a structure. Also, separate from superinsulation, other prior structures have been built as a double envelope, or a structure within a structure, to take advantage of a buffer air space between the two walls of construction. The primary purpose of either prior effort was to increase the R-value of the prior structure wall and/or roof members. 
     While an increase in R-value, in effect a greater insulation buffer, may improve the energy efficiency of a building structure, there remains room for improvement in the field for integrated structures having spaces with improved temperature stability. 
     SUMMARY OF THE INVENTION 
     The present invention provides a building structure with spaces having improved temperature stability. A preferred embodiment of the invention provides a superinsulated, at least partial double envelope structure utilizing a thermal mass, preferably of wood, in contact with a fluid flow path, with pipes or other fluid chambers provided under the top of the lowest floor, to complete the path. 
     A building structure according to the present invention includes a basement structure including a basement space, a first floor structure including a first floor space, the first floor structure being at least partially supported by the basement structure, a roof structure at least partially supported by the first floor structure, and a fluid flow path extending beneath and through the basement space, through the first floor space, and below at least a portion of the roof structure. The fluid flow path may be selectively placed in and out of fluid communication with the first floor space. 
     The basement structure may comprise at least one insulated concrete foundation (ICF) wall that extends around at least a majority of the basement space. The basement space may further include a basement front end, a basement back end, and a basement height, and the basement structure may further include a basement floor, which may comprise a poured concrete floor, including a basement floor surface extending between a majority of the distance between the basement front end and the basement back end. The basement height extends substantially perpendicular to the basement floor. The basement structure may also include at least one fluid passageway extending beneath the basement floor surface between the basement front end and the basement back end. 
     The basement structure may further include a portion of the fluid flow path including a first fluid flow duct extending through the basement height, where the first fluid flow duct is located closer to the basement back end than to the basement front end. The basement structure may also include a second fluid flow duct extending through the basement height, where the second fluid flow duct is located closer to the basement front end than to the basement back end. The first fluid flow duct and the second fluid flow duct are at least substantially fluidly noncommunicative through the basement space. Also, the first fluid flow duct and the second fluid flow duct are in fluid communication through the at least one fluid passageway. 
     The first floor structure of an embodiment according to the present invention may further comprise at least one structural insulated panel (SIP) wall that extends around a majority of the first floor space. The first floor space includes a first floor front end, a first floor back end and a first floor height. The first floor structure also includes a fenestration at the first floor front end including a plurality of first floor front end windows. The first floor structure may also include a fifth fluid flow duct extending through the first floor height, the fifth fluid flow duct being located closer to the first floor back end than to the first floor front end. A sixth fluid flow duct may extend through the first floor height, the sixth fluid flow duct being located adjacent the first floor front end windows. At least a portion of the sixth fluid flow duct is at least partially lined with a thermal mass material which may comprise wood, such as southern yellow pine wood glue laminated logs. Each of said logs may have a cross-sectional area of about thirty-six square inches. The fifth fluid flow duct and the sixth fluid flow duct are at least substantially fluidly noncommunicative through the first floor space. Also, the fifth fluid flow duct and the first fluid flow duct are in fluid communication, and the sixth fluid flow duct and the second fluid flow duct are in fluid communication. The fifth fluid flow duct may be selectively placed in and out of the fluid communication with the first floor space, and an electric fan may be positioned inline with the fluid communication between the fifth fluid flow duct and the first floor space, adapted to draw air from the fifth fluid flow duct and blow the air into the first floor space. 
     The roof structure may comprise at least one structural insulated panel (SIP), which at least partially defines an attic space, wherein the fifth fluid flow duct and the sixth fluid flow duct are in fluid communication through the attic space. At least one fire damper may be disposed between the fifth fluid flow duct and the sixth fluid flow duct. 
     A building structure according to the present invention may further comprise a sunshade extending from an external wall of the first floor structure, above the windows. The sunshade may be adapted to obstruct a majority of sunlight that strikes said sunshade during a first portion of a calendar year, such as summer, and may be further adapted to obstruct a minority of sunlight that strikes said sunshade during a second portion of a calendar year, such as winter. 
     The windows included in the building structure may comprise glazings having a U factor of less than or about 0.290. At least one of the South facing windows may include a U factor of less than or about 0.266, a solar heat gain coefficient of greater than or about 0.634, a solar transmittance of greater than or about 0.621, and a low-emissivity of less than or about 0.083. East/West facing windows may include a glazing comprising a solar heat gain coefficient of less than or about 0.330. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1A  is a top plan view of a first embodiment of a basement structure according to the present invention. 
         FIG. 1B  is a top plan view of an embodiment of a form to be used to construct passageways under the basement floor of  FIG. 1A . 
         FIG. 1C  is a cutaway cross-sectional view taken along line  1 C- 1 C in  FIG. 7 . 
         FIG. 2  is a top plan view of a first embodiment of a first floor structure according to the present invention. 
         FIG. 3  is a top plan view of a second embodiment of a basement structure according to the present invention. 
         FIG. 4  is a top plan view of a second embodiment of a first floor structure according to the present invention. 
         FIG. 5  is a top plan view of an embodiment of a second floor structure according to the present invention. 
         FIG. 6  is a front elevation view of an embodiment of a structure according to the present invention, including the basement structure of  FIG. 1A , the first floor structure of  FIG. 2 , and the second floor structure of  FIG. 5 . 
         FIG. 7  is a cross-section elevation view of the structure of  FIG. 6 , taken along line  7 - 7  in  FIG. 2 . 
         FIG. 8  is a cross-section elevation view of the structure of  FIG. 6 , taken along line  8 - 8  in  FIG. 2 . 
     
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Although the disclosure hereof is detailed and exact to enable those skilled in the art to practice the invention, the physical embodiments herein disclosed merely exemplify the invention which may be embodied in other specific structures. While the preferred embodiment has been described, the details may be changed without departing from the invention, which is defined by the claims. 
     Generally, a structure according to the present invention provides spaces having improved temperature stability. Around those spaces is provided a gas circulation path. In contact with at least a portion of the gas circulation path is a thermal mass. While the structure will be described as the front elevation preferably facing south and the back elevation preferably facing north, it is to be understood that variations in building placement are contemplated. 
       FIG. 1  provides a floor plan of a basement  100  that may be used in a structure according to the present invention. The basement  100  includes exterior walls  102  and a basement floor surface  104 , which in combination define a basement space  106 . The basement space  106  extends between a front end  108  and a back end  110 , generally bounded by lateral basement sides  112 . Along at least a portion of the back end  110 , a first fluid flow duct  114  is provided. The first fluid flow duct  114  extends through the entire height of the basement space  106 , as can be more fully seen in  FIG. 5 . Along at least a portion of the front end  108 , a second fluid flow duct  116  is provided. The second fluid flow duct  116 , like the first  114 , extends through the entire height of the basement space  106 . While various positions of the fluid flow ducts  114 , 116  may be established, the ducts  114 , 116  are preferably provided at and including their respective ends  110 , 108  of the basement space  106 . The first duct  114  is not generally communicative with the second duct  116  through the basement space  106 . The first duct  114  is preferably formed by a two-hour fire rated wall  118 , which extends the height of the basement space  106 , and the basement walls  102 . The basement walls  102  preferably comprise a fourteen-inch thick insulated concrete foundation (ICF) wall, covered with a one-half inch thick gypsum board on the interior of the wall. The second duct  116  is preferably formed the same way as the first  114 . 
     As shown, the front end  108  and the back end  110  of the basement space  106  may not be continuous surfaces between the lateral sides  112 . That is, the basement space  106  may be laterally divided into two or more basement space sections  106   a , 106   b  by offset basement exterior walls  102 . In such case, it may be desirable to provide separate fluid flow ducts for each section  106   a , 106   b  of the structure. For example, a third fluid flow duct  120  and a fourth fluid flow duct  122  may be provided towards the back end  110  and the front end  108 , respectively, of the second basement space section  106   b . As with the first  114  and second  116  ducts, the third  120  and fourth  122  ducts are preferably not generally communicative with any of the other ducts through the basement space  106 . That is, the interior space  111  of each of the ducts  114 , 116 , 120 , 122  is at least substantially closed off from and not in fluid communication with the basement space  106 . 
     Under the basement floor surface  104 , there is provided at least one fluid passageway  124 , which places the first fluid flow duct  114  in fluid communication with the second fluid flow duct  116 . Furthermore, there is provided at least one fluid passageway  126 , which places the third fluid flow duct  120  in fluid communication with the fourth fluid flow duct  122 . If a plurality of fluid passageways  124  are provided, they may be in fluid communication with each other. Likewise if a plurality of second passageways  126  are provided, they may be in fluid communication with each other. Furthermore, if desired, the first passageways  124  located under the first section  106   a  of the basement space  106  may be placed in fluid communication with the second passageways  126 , which are located under the second section  106   b  of the basement space  106 . While a plurality of pipes is one alternative for the passageways  124 , 126 , a preferred method of forming the passageways  124 , 126  under the basement floor surface  104  is to utilize the Airfloor form system, which is made by Airfloor, Inc., of Lincolnshire, Ill.  FIG. 1B  is a top plan view of such a form  190 , and  FIG. 1C  is a cross-section view taken along lines  1 C- 1 C of  FIG. 7 , showing a plurality of the forms  190  cascaded and interconnected, which are supported by a subfloor  195 , such as a structural floor. The forms  190  are then covered with, for example, a concrete material  197 . The concrete  197  may provide the basement floor surface  104 , or further flooring material  199 , such as wood, vinyl, or carpet, may be applied over the concrete  195 . By coupling the first duct  114  with the second duct  116  beneath the basement floor surface  104 , one can avoid unsightly and cumbersome ductwork in the basement space  106 . Furthermore, framed partition walls  129  can be placed in the basement space  106  without regard to airflow disturbances. 
     The basement  100  may be constructed from scratch at the final erection site, or may be provided in modular kit form to be constructed at the erection site; and, other common general building conventions may be followed, such as footings placed at desirable load locations, for example, footing placed beneath Lally columns  127  for support. 
       FIG. 2  provides a plan view of a first floor structure  200  to be situated atop a basement level, such as the basement  100  from  FIG. 1 . The first floor  200  includes exterior walls  202  and a floor surface  204 , which in combination define a first living space  206 . The first living space  206  extends between a front end  208  and a back end  210 , generally bounded by lateral sides  212 . Along at least a portion of the back end  210 , a fifth fluid flow duct  214  is provided. The fifth fluid flow duct  214  extends through the entire height of the first living space  206 , as can be more fully seen in  FIG. 5 , and is in fluid communication with the first fluid flow duct  114  in the basement  100 , preferably through a plurality of joist ducts  213 , which extend through the height of the first floor surface  204  and its supporting structure  205 , as seen in  FIG. 5 . The joist ducts  213  are preferably formed as metallic sleeves that extend through the floor system  204 , 205 . 
     Along at least a portion of the front end  208 , a sixth fluid flow duct  216  is provided. The sixth fluid flow duct  216 , like the fifth  214 , extends through the entire height of the first living space  206 . While various positions of the fluid flow ducts  214 , 216  may be established, the ducts  214 , 216  are preferably provided at and including their respective ends  210 , 208  of the first living space  206 . The fifth duct  214  is not generally communicative with the sixth duct  216  through the first living space  206 . The fifth duct  214  is preferably formed by a two-hour fire rated wall  218 , which extends the height of the first living space  206 , and the exterior walls  202 . The exterior walls  202  preferably comprise six-inch thick, solid-core structural insulated panels (SIPs), such as those available from Energy Panel Structures Incorporated of Graettinger, Iowa. As is known in the art, SIPs are formed by sandwiching a layer of high performance rigid foam insulation, such as expanded polystyrene foam, or other insulation between a plurality of layers of plywood or oriented strand board (OSB). 
     The sixth duct  216  is preferably formed differently than the fifth duct  214 . That is, the sixth duct  216  is preferably provided as sunspace  217  that has a fenestration including a plurality of windows  232 , in at least one exterior wall  202 , and further including a thermal mass  250 . The thermal mass  250  has a thermal mass area that preferably includes all surfaces exposed to sunlight penetrating the windows  232 . The thermal mass  250  is formed of a thermal mass material, such as southern yellow pine. The southern yellow pine may be glue laminated, or glulam, as is known in the art. A preferred thermal mass material includes southern yellow pine glulam logs  252  having cross-sectional dimensions of about five and one-half inches by about six and one-half inches, providing a cross-sectional area of about thirty-six square inches. The logs  252  may be stacked vertically or horizontally so as to cover the thermal mass area. Indeed, the back wall  219  of the sunspace  217  may be formed entirely from the southern yellow pine logs  232 , thereby providing thermal mass and structural support. A first section  206   a  of the first living space  206  may be separated from the sunspace  217  by a sliding glass door  221 . 
     As shown, the front end  208  and the back end  210  of the first living space  206  may not be continuous surfaces between the lateral sides  212 . That is, the first living space  206  may be laterally divided into two or more sections  206   a , 206   b  by offset exterior walls  202 . In such case, it may be desirable to provide separate fluid flow ducts for each section  206   a , 206   b  of the structure. For example, a seventh fluid flow duct  220  and an eighth fluid flow duct  222  may be provided towards the back end  210  and the front end  208 , respectively, of the second living space section  206   b.  As with the fifth duct  214 , the seventh  220  duct is preferably not generally communicative with any of the other ducts through the living space  206 . That is, the interior space  211  of each of the fifth  214  and seventh  220  ducts is at least substantially closed off from and not in fluid communication with the living space  206 . 
     However, the sixth duct  216  and the eighth duct  220  are preferably in selective fluid communication with the living space  206 . Such selective communication may be provided simply by manual louvers (not shown), but is preferably automatically thermostatically, perhaps hysteretically, controlled. In-wall electric fans  226  are preferably disposed in the back wall  219  of each sunspace  216 , 222 . The control of the fans  226  may be provided by a programmable controller (not shown), which controls one or more electrical relay switches (not shown) to switch electrical power to the fans  226  on and off. As is known in the art, a first temperature transducer, such as a first thermocouple, is operatively placed to measure the air temperature of the living space  206 . A second temperature transducer, such as a second thermocouple, is operatively placed to measure the air temperature of the sunspace  217 . The programmable controller is adapted to compare a first temperature indicated by the first temperature transducer to a first predetermined, or set, value, to determine whether the first temperature is below the set value by a cold-side hysteretic amount. The programmable controller is also adapted to compare a second temperature indicated by the second temperature transducer to the first temperature to determine whether the first temperature is less than the second temperature. If both conditions are true, that is, if the first temperature is below the set value by at least the cold-side hysteretic amount, and if the first temperature is less than the second temperature, the controller then controls the respective fan  226  to draw air from the associated sunspace  217  into the living space  206 . In other words, if the air temperature of the living space  206  is below a predetermined temperature and the air temperature of the sunspace  217  is greater than the air temperature of the living space  206 , then the warmer air from the sunspace  217  is drawn into the living space  206  by the fan  226 . On the contrary, if the first temperature increases to or is above a first predetermined value, or if the second temperature decreases to or is below a second predetermined value, then the fan  226  is shut off or remains off, whichever may be the case. Similar logic may be employed to automatically control other mechanical operations in the structure, such as automated thermal drapery disposed on the inside of the structure  200  and adapted to aid in preventing heat loss through the windows  232 , such as during the time between sunset and sunrise. 
     Also shown in  FIG. 2  are sunshades  233 , which extend outward from the exterior walls  202  of the first floor structure  200 , over the windows  232  provided therein. The sunshades  233  are preferably fluted sunshades that allow sunlight to pass through the shades during desired times of the year, such as winter, while blocking the sun through other desired times of the year, such as summer. Although shown as relatively rigid, fluted sunshades, the sunshades  233  may also be comprised of retractable awnings (not shown) that are manually or automatically retractable. Such automatic retraction may be dependent upon desired thermostatic control. 
     The first floor structure  200  may be provided as a completed modular structure to be set atop a basement structure, or may be provided as and constructed from a kit directly atop the basement structure, such as the basement structure  100  of  FIG. 1 . Other common general building conventions may be followed, such as standard framing of non-loadbearing walls  229 . 
       FIGS. 3 and 4  provide second embodiments of a basement structure  100 ′ and a first floor structure  200 ′ according to the present invention, respectively. In some locales, it may be desirable to include a basement structure  100 ′ that, like the first embodiment of a first floor structure  200 , includes a basement sunspace  117 , which provides additional solar collection and thermal mass and may provide slightly more efficient temperature control for the completed structure. In such case, the basement sunspace  117  is constructed substantially similar to the first embodiment of the first floor sunspace  217 , including a thermal mass material  150 , preferably comprising a plurality of southern yellow pine glulam logs  152 , which are also stacked to form the back wall  119  of the sunspace  117 . A sliding glass door  121  may provide physical access to the sunspace  117  from the basement space  106 . Although the windows  132  are shown, the fenestration may include sliding glass doors (not shown), to provide the feature of a walk-out basement, if desired. Sunshades  133 , which may be the same as or similar to the sunshades  233  described above, are suspended above the basement windows  132 . 
       FIG. 4  provides the second embodiment of a first floor structure  200 ′. The construction of the second embodiment is substantially the same as the first  200 , but further including a first sunspace duct  223 , which cooperates with one or more floor ducts  115  to provide fluid communication between the sixth fluid flow duct  216  and the second fluid flow duct  116 , allowing convection of warm air from the basement sunspace  117  through to the first floor sunspace  217 . A railing  225  may be provided in the first floor sunspace  217  to provide a balcony overlooking the basement sunspace  117 . The railing  225 , itself, may be constructed of the thermal mass material  250 . 
     While a structure according to the present invention may include only the basement  100  and the first floor  200 ,  FIG. 5  provides a plan view of a second floor structure  300  to be situated atop a first floor structure, such as the first floor structure  200  from  FIG. 2 . The second floor  300  includes exterior walls  302  and a floor surface  304 , which in combination define a second living space  306 . The second living space  306  extends between a front end  308  and a back end  310 , generally bounded by lateral sides  312 . Along at least a portion of the back end  310 , a ninth fluid flow duct  314  is provided. The ninth fluid flow duct  314  extends through the entire height of the second living space  306 , as can be more fully seen in  FIG. 5 , and is in fluid communication with the fifth fluid flow duct  214  in the first living space  206 , preferably through a plurality of joist ducts  313 , which extend through the height of the first floor surface  304  and its supporting structure  305 , as seen in  FIG. 5 . The joist ducts  313  are preferably formed as metallic sleeves that extend through the floor system  304 , 305 . 
     Along at least a portion of the front end  308 , a tenth fluid flow duct  316  is provided. The tenth fluid flow duct  316 , like the ninth  314 , extends through the entire height of the second living space  306 . While various positions of the fluid flow ducts  314 , 316  may be established, the ducts  314 , 316  are preferably provided at and including their respective ends  310 , 308  of the second living space  306 . The ninth duct  314  is not generally communicative with the tenth duct  316  through the second living space  306 . The ninth duct  314  is preferably formed by a two-hour fire rated wall  318 , which extends the height of the second living space  306 , and the exterior walls  302 . The exterior walls  302  preferably comprise six-inch thick, solid-core structural insulated panels (SIPs). As is known in the art, SIPs are formed by sandwiching a layer of high performance rigid foam insulation, such as expanded polystyrene foam, or other insulation between a plurality of layers of plywood or oriented strand board (OSB). 
     The tenth duct  316  is preferably formed differently than the ninth duct  314 . That is, the tenth duct  316  is preferably provided as sunspace  317  that has a fenestration including a plurality of windows  332 , in at least one exterior wall  302 , and further including a thermal mass  350 . The thermal mass  350  has a thermal mass area that preferably includes all surfaces exposed to sunlight penetrating the windows  332 . The thermal mass  350  is formed of a thermal mass material, such as southern yellow pine. The southern yellow pine may be glue laminated, or glulam, as is known in the art. A preferred thermal mass material includes southern yellow pine glulam logs  352  having cross-sectional dimensions of about five and one-half inches by about six and one-half inches, providing a cross-sectional area of about thirty-six square inches. The logs  352  may be stacked vertically or horizontally so as to cover the thermal mass area. Indeed, the back wall  319  of the sunspace  317  may be formed entirely from the southern yellow pine logs  332 , thereby providing thermal mass and structural support. Preferably, there is a second sunspace duct  323  that is open to the first floor sunspace  217 , allowing convection of warm air from the first floor sunspace  217  to the second floor sunspace  317 . A railing  325  may be provided in the second floor sunspace  317  to provide a balcony overlooking the first floor sunspace  217 . The rest of the second level living space  306  may be separated from the sunspace  317  by a sliding glass door  321 . The second level living space  306  may include a plurality of rooms, such as a plurality of bedrooms  306   a , 306   b , 306   c,  a plurality of bathrooms  306   d , 306   e  and a study or den area  306   f.  The fluid communication between the tenth and sixth fluid flow ducts may be provided through floor ducts (not shown) in addition to the sunspace duct  323 . 
     The tenth duct  316  is preferably in selective fluid communication with the living space  306 . Such selective communication may be provided simply by manual louvers (not shown), but is preferably automatically thermostatically, perhaps hysteretically, controlled. An in-wall electric fan  326  is preferably disposed in the back wall  319  of the sunspace  317 . The control of the fan  326  is the same as or substantially similar to the control of the fans  226  described earlier, of course with temperature references to the third floor sunspace  317  and living space  306 . 
     Also shown in  FIG. 5  are sunshades  333 , which extend outward from the exterior walls  302  of the second floor structure  300 , over the windows  332  provided therein. The sunshades  333  are preferably fluted sunshades that allow sunlight to pass through the shades during desired times of the year, such as winter, while blocking the sun through other desired times of the year, such as summer. Although shown as relatively rigid, fluted sunshades, the sunshades  333  may also be comprised of retractable awnings (not shown) that are manually or automatically retractable. Such automatic retraction may be dependent upon desired thermostatic control. 
     As shown, the second living space  306  may be provided above only a section  206   a  of the first living space  206 , or it may extend to cover the entire first living space  206 . The second floor structure  300  may be provided as a completed modular structure to be set atop a first floor structure, or may be provided as and constructed from a kit directly atop the first floor structure, such as the first floor structure  100  of  FIG. 2 . Other common general building conventions may be followed, such as standard framing of non-loadbearing walls  329 . 
       FIG. 6  shows a front elevation of a structure  1000  according to the present invention, wherein several of the windows  232 , 332  may be seen, thereby allowing light to pass into the respective sunspaces  217 , 317 . The windows  232 , 332  that may be used are preferably selected based on the final erection site of the building  1000 . That is, the specific glazings to be used are chosen at least partially based on the location of the building  1000 . When a structure  1000  according to the present invention is constructed on a plot of land, the front end  108  of the basement  100  is preferably aimed directionally due South, and the structure assembled accordingly. The structure  1000  is particularly suited for location at or greater than thirty-two degrees North geographic latitude on Earth. The glazings used for the windows  232  provide desired solar receptivity. For instance, any windows  232 , 332  that face South preferably include a U factor of about 0.266 or lower, a solar heat gain coefficient of about 0.634 or higher, a solar transmittance of about 0.621 or higher and a low emissivity of about 0.083 or lower. Windows  232 , 332  that face directionally East or West preferably include a U factor of about 0.290 or lower and a solar heat gain coefficient of about 0.330 or lower. The solar transmittance and low emissivity ratings for the East/West windows  232 , 332  are thought to be of less criticality than the other parameters specified. Also in  FIG. 6 , the roof  500  of the structure  1000  can be seen. A preferred roof  500  is preferably formed from structural insulated panels (SIPs)  502 , which are then covered with a desired roofing material  504 , such as asphalt shingles, as seen in  FIG. 8 . Panels  502  are joined to the exterior walls  202 , 302  of the first floor structure  200  and the second floor structure  300 , respectively, as is known in the art. 
       FIG. 7  is an illustrative cross-section showing a gas circulation path  600  beginning in the first floor sunspace  217 , extending up through the second floor sunspace  317 , which serves as the tenth fluid flow duct  316 , and into an attic space  406  through a fire damper  440 . A preferred fire damper  440  is a static fire damper that conforms to established standards, such as UL 555, and providing a preferred minimum air flow area of two square feet. The path  600  then preferably extends through the attic space  406 , above the ceiling  307  of the second floor  300 , and then down through the ninth fluid flow duct  314 , the joist ducts  313 , the fifth fluid flow duct  214 , the joist ducts  213 , and the first fluid flow duct  114 . The path  600  then extends through the fluid passageways  124  under the basement floor surface  104 , up through the second fluid flow duct  116 , through the floor ducts  215  and back into the first floor sunspace  217  serving as the sixth fluid flow duct  216 . A similar path exists beginning in the fourth fluid flow duct  222 , extending up through a fire damper  440  and into an attic space (not shown) above the second living space  206   b . The similar path then down through the seventh fluid flow duct  220 , the joist ducts  213 , and the third fluid flow duct  120 . The similar path then extends through the fluid passageways  126  under the basement floor surface  104 , up through the fourth fluid flow duct  122 , through the floor ducts  215  and back into the eighth fluid flow duct  222 . One or more of the ducts may be separated from the others by way of louvers or dampers. This may be desirable to control the rate of convection or other air flow, or the dampers may be provided to assist in controlling a fire, in case of emergency. 
     Not shown in any figure are some mechanical systems that aid in the temperature stability and efficiency of the structure  1000 . For instance, though energy costs may be reduced, a standard thermostatically controlled furnace and/or an air conditioner may be required to maintain desired temperatures in the spaces  106 , 206 , 306  of the structure  1000 . Where forced air ducts are utilized for heating/cooling, motorized dampers are preferably provided inline with the ductwork, preferably prior to each duct outlet vent. Alternatively, if other forms of heat are used, such as electric baseboard heat, each heater is preferably on a separate switchable circuit, thereby allowing selective control of the individual heaters. The motorized dampers and/or heating circuit switches can be logically controlled by a universal furnace thermostat, which receives indications of air temperature from temperature transducers, such as thermocouples, placed in desirable locations throughout the structure. 
     In addition to the mechanical heating and/or cooling systems, it may be desirable to include an energy recovery ventilator, also not shown in any of the drawings. The preferred ventilator is the Venmar AVS Energy Recovery Ventilator, model Duo 1.2, available from Venmar Ventilation Incorporated of Drummondville, Quebec, Canada. The ventilator acts as an air exchanger which keeps the internal spaces of the structure  1000  fresh, as it exchanges inside air with outside air, capturing energy as needed depending upon the season. The ventilator is ducted into both the interior living spaces of the structure, as well as the fluid flow ducts. The fluid communication of the ventilator air exchange with the ducts aids in controlling humidity in the ducts. The preferred ventilator has an air flow rating of preferably greater than about fifty cubic feet per minute and less than about one hundred and fifty cubic feet per minute, and more preferably about sixty cubic feet per minute to about one hundred and twenty cubic feet per minute. 
     The foregoing is considered as illustrative only of the principles of the invention. Furthermore, since numerous modifications and changes will readily occur to those skilled in the art, it is not desired to limit the invention to the exact construction and operation shown and described. While the preferred embodiment has been described, the details may be changed without departing from the invention, which is defined by the claims.