Solar Energy Attic Air Heat Reservoir System

Abstract

A solar energy attic air heat reservoir system including methods for selecting, installing and operating air movers coupled with HVAC components, air filters, and thermostatic control devices operating systematically for space heating. Solar insolation conducted through building roof materials heats the large volume of attic airspace sealed from normal ventilation during heating season to preserve heat energy, with heat transfer coefficient of convection contributing to and sustaining heating of attic air. Thermostatic digital temperature control devices communicate in series between the building attic and interior for optimum used of heated air supply for environmental control. Methods include computer program applications for feasibility, apparatus selection, operation, and energy cost accountability to enable optimizing space heating using the limited daily solar induced heat. Methods include advantageous containment of thermal energy stored in building interior materials as gathered from attic-heated air for later release through diurnal temperature variation to augment space heating.

What is claimed is: 
     
         1 . Apparatus and methods for acquiring heated air from within the under roof enclosed attic airspace (or upper crawl space) of a building structure to include controlling the operation of a blower (also described as a fan, or air mover) selected for its effective output to supply such heated air contained therein for space heating. Such apparatus and methods identified as an ‘attic air heat reservoir’ system (AAHR system or present invention) is for use principally during the heating season in geographic locations having adequate solar energy. The present invention utilizes such blower(s) to transport heated attic air through a preferred closed loop network of HVAC components and supply duct terminating at a diffuser leading into a building structure interior space comprising:
 A building attic air space generally sealed from outside ambient air with attic air ventilation openings mostly closed to become a reservoir for the solar heated air thus preventing heated air from communicating with a large volume of colder ambient air through the attic air vents generally placed in the roof or the attic exterior walls. Such attic air ventilation openings being mostly covered ensures adequate heat retention within the attic air space thus allowing air temperature to rise substantially in the attic peak area, which promotes increase of Btu measure for optimum space heating performance; 
 Furnace air filter(s), commonly designed for HVAC use, placed at the heated air intake for filtrating attic air to an acceptable quality prior to entering the present invention HVAC ducts for the intended space heating purpose; 
 A plurality of thermostatic control devices communicating with remotely located temperature sensors to transmit real time reading of temperature within the attic as well as temperature reading within the building interior. Such thermostatic devices regulate the flow of heated attic air under management of user-controlled parameters programmed therein to maintain a desirable interior space temperature level. Remote temperature sensors communicate temperature signals to solid-state digital temperature programmable control devices set with parameters for start/stop temperatures and hysteresis (differential temperature) to manage the building interior environment suitable for humans, animals, equipment, agricultural enterprise, etc.; 
 Economical and scalable HVAC network components including blower(s)/fan(s) [air mover(s)] selected to supply attic-heated air at a normally predetermined constant volume airflow. Such blower airflow volume, expressed in cubic feet per minute (CFM), is published in specifications and literature by the manufacturer to enable the user to select an appropriate blower unit. The blower regardless of the location's altitude typically moves at a constant volume during operation, with such airflow transported through an HVAC duct of suitable volume dimension for capacity to supply the heated air. The HVAC blower(s) selected is capable of supplying the heated attic air in volume sufficient for space heating during sunlight hours of the day, throughout the heating season when solar generated heat is available. Such HVAC components and air movers are readily available “off the shelf” in commonly scalable sizes up to and including industrial size air movers and components; 
 Methods to include computer programs using formulas incorporated within a plurality of stepped analytical applications to determine the amount of solar heat energy available in the attic air obtained through temperature and relative humidity data logging. Such methods including computational programmed spreadsheets that can specify the required apparatus configuration of the present invention for space heating. The computer program methods provide data to determine economic accountability of energy savings when such energy is measured using thermodynamic formulas designed for analyzing space heating performance of the present invention apparatus; 
 Such configuration of the apparatus, computer programmed devices, and methods operate within the comprehensive system of the present invention for enablement and maximum utilization of the sun's available heat energy to raise temperature in attic air during sunlight hours for purpose of space heating with solar energy becoming the heating fuel source, which is claimed. 
 
     
     
         2 . A method to incorporate a particular component for solar energy used in space heating identified as thermal mass of structural elements within the interior building assemblies and contents. Specific heat capacity measured from thermal mass is included in a reconciliation of total heat supplied from the attic air heat reservoir, during its daily operation, as accounted for in the measured heat provided through space heating of the present invention. Accounting for total heat load within the building interior is important for optimum use of attic-heated air. Heat load (design heat loss) of a building is based on the building envelope assemblies that meet the outside air, ignoring interior assemblies and related elements such as interior wall surfaces and all interior components including décor (furniture, etc.), fixtures, interior walls and cabinets. Such interior assemblies and related elements have the ability to retain heat beyond that normally considered as heat load, but HVAC principled computations made for ‘design heat loss’ ignore thermal mass of interior assemblies. This thermal mass phenomenon manifests in the diurnal temperature effect made possible when the interior materials retain such heat. Although thermal mass for building interior elements is difficult to quantify accurately, because of enormous variance in their mass, nevertheless, such heat retention value can be determined from known data regarding thermal mass of building materials and other substances available from a wide range of sources in the fields of architecture and building science. The non-envelope interior assemblies and materials become heat storage elements during daytime operation of the present invention as it supplies the attic-heated air into the building interior. The present invention methods include calculations using specific heat capacity per square foot of area, translated into the mass volume of the building interior assemblies and contents, using values from reference sources showing specific heat value that can be stored in such material mass volume. This transfer of heat emulates a passive solar heating process when sunlight enters a window as solar radiation beams directly onto interior surfaces such as floors and walls. Btu measure as retained in the building interior materials becomes a supplemental heat reservoir for use by the present invention to offset normal heat loss through the building envelope. Such supplement heat contributes to increasing or maintaining interior air temperature when accounted for in the diurnal temperature variation, which is an important factor for efficient use of the heated attic air, for space heating, which is claimed. 
     
     
         3 . Methods employing mathematical formulas to optimize the collection of attic heated air determined by assessing the volume of airflow through the blower, measured in cubic feet per minute (CFM), as necessary for space heating. Such methods are atypical in normal HVAC heating system sizing. The methods for employing such mathematical formulas of the present invention is facilitated through use of thermodynamic principles to determine available heat energy in the attic air at the given altitude location of the building structure. The present invention methods determine the HVAC network for best system performance by employing mathematical formulas by computer program calculations or by manual calculations. The mathematical formulas include the thermodynamic variable ‘enthalpy’, to determine Btu measure of heated air flowing through the present invention apparatus as it supplies heat to the building interior. Such formulas calculate the present invention HVAC network character to perform best within a range of attic air space temperature and humidity levels through establishment of airflow volume required of the blower (air mover) for optimum gathering of the heat energy available within the attic air. The mathematical formulas use data obtained from interval measurement logging of temperature and relative humidity levels within attic air during sunlight hours of operation to determine the Btu total of available heat energy. The present invention methods includes heat loss calculations for the given building structure, for input into such mathematical formulas. Heat absorption properties (thermal mass) of interior building materials is also integral to the mathematical modeling formulas based on the specific heat calculation of such materials. Data elements from the actual building design heat loss are also necessary in the mathematical formulas for such modeling. The mathematical modeling provides a reconciliation of heat load of the building to balance with sufficient Btu measure supplied by the present invention apparatus. The formulas determine the potential output of Btu measure of attic-heated air moving through the blower to balance with interior air volume along with heat energy stored as specific heat in each material type in a reconciliation of the total Btu required for operation during a typical day of moderate outside temperature. The formulas also include provision to require an estimate of any moderate temperature gain in the building interior as planned for by the user during the daily solar heat excursion. The calculation formulas make up a comprehensive mathematical modeling vehicle performing specific steps for the elements of discovery. The calculation formulas includes the recognition of Btu measure of the specific heat absorbed by all types of materials within the building interior which are subsequently affected by the diurnal temperature variation. The present invention apparatus operation can contribute to sufficient temperature rise within the building interior to reach levels that meet guidelines for human comfort going as high as 24.5° C. (76° F.) with relative humidity level scaling from as high as 60% down to 20%, which is tolerable for humans, animals and plants. Allowing such temperature rise to occur inside the building helps promote increasing the effect of thermal mass, which contributes to diurnal temperature variation to the benefit of the overall space heating process. Such methods of utilizing mathematical formula applications are designed to model the present invention space heating contribution to benefit the prospective user to include necessary information from known and estimated variables, including specific heat capacity of materials, blower output, and expected energy cost savings within their building prior to installation which is claimed. 
     
     
         4 . A method employing computer programmed instructions integrated into a specialized attic/interior matching temperature controller to sense temperature of the building structure in two locations: (1) supply outlet diffuser (or attic supply duct near the diffuser), and (2) building interior living or working area, to manage the distribution of heat retained in the attic to avoid conflict of the two atmospheres' temperatures. The specialized attic/interior matching temperature controller periodically polls temperature to manage the building environment by area or zone to ensure optimum supply of heat from within the attic air heat reservoir. A temperature sensor polls attic heated air temperature as such heated air exits through the HVAC supply duct diffuser, to enable the temperature controller operatively to prohibit colder air of the attic from entering the interior when such interior air temperature (also polled by the controller using a separate temperature sensor) is higher than the attic air temperature at the end of the daily solar cycle. Determining when attic air temperature is lower than interior air temperature is required to avoid supplying the interior with colder air from the attic than that of the current interior temperature of the building. This specialized temperature controller requires minimal user intervention. The specialized attic/interior matching temperature controller permits use of the maximum amount of heat energy within the attic during the daytime operation without forcing the air in the interior to lose heat at the end of the daily operating cycle of the present invention, which is claimed. 
     
     
         5 . A method as to  claim 1  utilizing attic air space as a reservoir of heat, rather than employing a costly manufactured solar heat collector apparatus comprising specialized material or unique design form necessary to retain such solar heated air. Solar generated heat energy contained within the attic air space generally has favorable temperature excursion from early morning into the early afternoon peak when sunlight contributes adequate heat energy as it rises to maximum temperature level then lowers as the sun recedes on the horizon. Such heat captured within the attic air space, which is the attic air heat reservoir, is subject to a daily time limit during which sufficient Btu measure becomes available for space heating when location, sunlight hours and weather conditions dictate. Hours of sunlight are uncertain due to variable weather patterns that can affect the buildup of necessarily sufficient heat from solar energy for absorption into a building's roofing materials and the surrounding attic structural materials. Such uncertainty and limited hours of sunlight make it necessary to operate the present invention in an effective manner to draw as much heat energy as possible from said attic air heat reservoir for space heating. The attic air heat is isolated therefore undisturbed from influences such as wind or rain. The circulation of attic air within a sealed attic space, by suction of the blower, causes a positive physical effect of fresh ambient air and waste heat to come in contact with the heated attic ceiling as suction of the blower accelerates heat transfer to induce convection coefficient of heat energy throughout the attic air. The attic air heat reservoir therefore relies on multiple thermodynamic features for efficient capture of heat energy contained therein for space heating, which is claimed. 
     
     
         6 . A method as to  claim 1  employing a digital temperature controller set for “cooling mode” to communicate with a remote temperature sensor strategically located in the attic. The controller functions in a manner similar to an attic air ventilator, with attic-heated air transported into the building interior rather than ventilated outside the attic. The attic temperature controller stores temperature parameters to start and stop the blower operation, as established by the user, when attic air is warm enough for space heating. The attic temperature controller is a device comprising (a) a digital processor; (b) a memory operatively coupled to the processor; and (c) a remote temperature sensor. The attic temperature controller contains an electric wire coil relay switch, typically a normally open SPST type (single pole, single throw), activated by the digital temperature controller's processor responding to the parameter settings programmed into the device. A more robust relay switch is necessary when operating blowers of higher energy load. The temperature controller features a wide range for its hysteresis adjustment to compensate for cooler HVAC components in the morning enabling the blower to start at a higher temperature than the stopping temperature. The attic temperature controller set to “cooling mode” feature is ideally suited to manage the present invention for space heating while the attic temperature rises and falls during sunlight hours, which is claimed. 
     
     
         7 . A method as to  claim 1  for determining attic air temperature using a negative temperature coefficient (NTC) sensor or thermistor strategically located in the attic to enable real time communication with a digital temperature controller containing multiple variable parameter settings for the efficient operation of the present invention. With solar energy being the unique heating fuel source, the excursion of temperature within the volume of heated air, so contained in the attic space as temperature increases then lowers, offers usable heat energy for an unknown period during sunlight hours. Such remote temperature sensor in communication with the temperature controller enables placement of such temperature controller console inside the building for convenience of user thermostatic management decisions. Remote location sensing of temperature coupled with differential temperature parameter setting thereby allows the attic temperature controller to manage operation with precision, which is claimed. 
     
     
         8 . A method as to  claim 1  whereby the present invention temperature controllers manage operation with minimal user attention during an entire heating season. The thermostatic control starts when attic temperature is high enough and stops when attic temperature can no longer be useful during sunlight hours. Changes to attic thermostatic control start and stop temperature settings, throughout the course of heating season weather pattern shifts, necessitate strategy change for optimum use of the heat energy that is available within the attic air heat reservoir as well as thermal mass of interior materials. Daily operation, during absence of occupants, can prevent the building interior from cool-down. The present invention apparatus supplies heated attic air into the building interior even while occupants are away from the premises, daily or intermittently, enabling pre-heating of the interior environment when the existing traditional heating appliance is off, to ensure optimum use of available attic heat, which is claimed. 
     
     
         9 . A method as to  claim 1  of the present invention comprising versatile, robust and scalable apparatus employing commonly produced HVAC components that are affordable for the user to benefit from a respectable economic payback for their investment outlay. The present invention apparatus components are readily available as “off the shelf” in the marketplace to include common and easily understandable parts and materials for those who may desire to perform a “do it yourself (DIY)” home or business installation. Professional solar device installers, HVAC jobbers and electricians would prefer the versatility and scalability features. Such professionals are normally conversant in the present art technology with an advantage of ease in implementing present invention apparatus for their customer needs. The simplicity of the system offers potential for wide adoption where solar heating energy is practical. The versatility and affordability of the present invention shows by example using an ordinary electric timer, or even just a simple electric switch, to turn on or turn off the air supply blower, instead of using digital thermostatic devices, which may further reduce installation expense. Respectable economic payback is a benefit through the present invention novel approach in configuring components of lower cost than that suggested for most present art devices. Versatility, affordability and scalability is known in the selecting of HVAC components within the present invention, while also offering flexibility to allow for modification or enhancement of space heating apparatus, which is claimed. 
     
     
         10 . A method as to  claim 1  to reduce inherent static pressure and velocity pressure within the present invention HVAC network of components in favor of a simplified rigid duct configuration for gathering the available, but limited, heated attic air efficiently. The attic air heat reservoir has a limited time in which heat is available throughout the sunlight hours of operation. Air friction inside the air handling equipment is a critical element for efficient movement of such limited available heated air. The present invention use of low friction rigid ducts with very few duct turns reduces static pressure and velocity pressure that would cause air mover and HVAC network inefficiency. Reducing static and velocity pressure in the HVAC duct network thereby enables conserving as much heat as possible during peak hours when solar energy heating reaches its maximum level, which is claimed. 
     
     
         11 . A method as to  claim 1  to optimize containment of heated air in the attic air space whereby a majority of attic air ventilation openings are covered by shutters, panels or other suitable materials to enable solar generated heat to substantially increase attic air temperature during the hours of sunlight. Blocking the attic ventilation openings reduces outside colder ambient air from exchange within the attic air space. However, air exchange will accelerate during operation in sunlight hours when sufficient heat is available and contained to the advantage of the present invention as the blower sucks in such heated air. Therefore, when covering the ventilation opening at the perimeter of, or at the ceiling of the attic structure, the air temperature resists cooling by ambient air of a lower temperature entering through any open attic air vents. Covering air ventilation openings would also avoid any wind accelerating the cooling effect upon such cooler air entering the attic air space. The preferred method of closing attic air vents for containment of heat and humidity enables the present invention to perform adequately as a space-heating appliance during heating season, which is claimed. 
     
     
         12 . A method as to  claim 1  for employment of the attic air space under the roof structure of common architectural design and suitable roofing materials that absorb heat. Such roof structure becomes an ad hoc solar heat collector protected from outside weather conditions. Although roofing materials enable absorption of solar insolation at varying efficiencies, such materials nonetheless become a receptacle for solar heat with such heat conducted into the attic ceiling and throughout the structural elements of the voluminous attic without requiring partitioning or any major building structural changes. Roof slopes in normally colder climates are very steep and attics more voluminous, but such attics can retain necessary heat near the attic peak area. The present invention draws heated air from near the attic ceiling peak to benefit from the attic area of warmest temperature and optimum Btu measure during the sunlight hours of the day. Typical roofing materials facilitate good solar absorption and heat transfer. A preponderance of material types presently used on building structures such as asphalt shingles, concrete tile, and a number of other well-qualified roofing material types facilitate heat conduction and convection inside the attic air space; therefore, such attic air space ideally functions as the reservoir for heated air, which is claimed. 
     
     
         13 . A method as to  claim 1  to make use of relative humidity normally resident in the attic air during the nighttime, such humidity is subject to weather conditions and changing dew point during heating season. The present invention draws warm humid air contained within the attic space during its daily sunlight operation with such warm humid air having increased level of Btu measure for supply to the building interior as the day begins. The relative humidity level within the attic space gradually falls during sunlight operating hours as humidified air moves to the drier and colder interior of the building structure during action of the present invention. Removing humidity from the attic air can reduce mold, mildew and stagnation through better ventilation of the attic, when moist warmer attic air transports into the building interior while being agitated by action of the present invention blower. Intake air filters ensure cleansing the humid air in normal HVAC fashion before supply to the building interior. There is a benefit to human comfort, during heating season, as humidity mixes with drier air inside a building structure. Interior air dryness is endemic during the heating season as traditional heating appliances operate in poorly ventilated building interior conditions closed to outside fresh air and lack of natural ventilation as windows are usually closed. Closing attic air vents therefore helps to reduce humidity in the attic air as a benefit while operation of the present invention also cause some increase of humidity in the building interior by transfer of such humidity, both desirable traits in the respective atmospheres of a building attic and interior space during the heating season, which is claimed. 
     
     
         14 . A method as to  claim 1  whereby the present invention HVAC apparatus is enclosed within the attic to provide a safe haven from outside weather elements and harmful solar radiation while also eliminating the need for ordinarily costly installation methods such as those required to secure externally mounted solar collector apparatus to rooftops or other building assemblies. Housing of the present invention HVAC elements within an enclosed attic avoids the cost of significant study and planning by professional engineers to determine weight factors and stress points of a building construction including calculations of capacity to hold weight during earthquakes, high winds, or snow conditions. A typical attic is already engineered and designed to support the heavy weight of roofing material with its structural and load bearing members, while the attic floor or ceiling structure is often used to contain HVAC appliances, duct systems, and storage of personal effects that would weigh much more than present invention HVAC components. Exterior mounted solar equipment is subject to effects of outside airborne chemical contaminants and dust that can be extremely harsh on such equipment. Further, externally mounted solar energy apparatus exposed to direct solar insolation and hot and cold temperatures can limit its operating lifetime affecting the long-term economics of the equipment. The current invention employs standard HVAC components designed for temperature extremes inside an attic where cooling season temperature excursions can increase to 60.0° C. (140° F.) or more, and heating season temperatures would dip below −18.0° C. (zero ° F.). Such HVAC components generally operate in a majority of building structures that contain attics/upper crawl spaces. The present invention demonstrates utility for the user by including components of reasonable cost that can withstand extremes of temperature and humidity to reduce potential for operational problems while being sheltered inside the attic with minimal weight distributed over the building structure, which is claimed. 
     
     
         15 . A method as to  claim 1  whereby scalability of the present invention apparatus enables collaboration with other solar heating modality such as a solar heat collector device for supplemental preheating to include the glazed or unglazed perforated solar heat collector (TSAC). The user can also combine the present invention system with a surface mounted solar collector placed outside the building to intake solar heated air through a duct inserted into a building structure attic vent with such heated air then merged. Supplemental heated air in the attic from external sources comes from concentrated form when using a heat exchanger or other externally mounted solar collector. Use of heat exchangers for heated air containment may be from a variety of solar heating units available in the marketplace. The user must be aware that solar collectors may provide only minimal Btu measure based on thermodynamic conduction and convection expected from such devices. Such collectors, however, would enhance solar heat gathering in partnership with the present invention apparatus regardless. The present invention system in partnership with other modality solar heating devices can result in increased solar space heating performance, which is claimed. 
     
     
         16 . A method as to  claim 3  using present invention computer programs to account for space heating energy cost savings versus cost of heat energy consumed in the resident traditional artificial heating appliance with such heat energy replaced by solar generated heat. Energy cost savings using the present invention requires measuring the psychrometric variable enthalpy, which determines the Btu/ft 3  of air gathered by the system during operation. With such method, the consumer has the ability to calculate energy cost saving from measurement of attic air temperature and relative humidity monitored at their location by making recordings over relevant monthly periods during heating season. Such measurement enables determining energy value captured throughout the sunlight hours from start time to stop time of operation using the CFM airflow rate of the HVAC blower in the calculation. Monitoring of the temperature and relative humidity employs an inexpensive remote or wireless logging device that measures temperature and relative humidity in short intervals. The temperature/humidity logging device connects to a laptop or a desktop computer USB port for download of logged data. A dollar value in savings is determined from such logged data by measuring cost of heating fuel typically used to produce the same amount of Btu measure supplied at virtually zero cost for fuel using solar energy heated air. The cost savings of the present invention is readily accounted for using methods provided within the present invention computer programs for the benefit of the consumer, which is claimed. 
     
     
         17 . A method as to  claim 1  for selection of an air mover (blower) to produce required airflow velocity change of such blower thereby modifying heated air supply volume during space heating. A changing CFM airflow results through action of a variable speed control type motor engaged inside the blower activated by an independent controller that is computer programmed with necessary parameter HVAC operational factors. Variable airflow delivery can thereby provide additional flexibility in managing withdrawal of the limited resource of solar heated air within the attic, which is claimed.