System for improving both energy efficiency and indoor air quality in buildings

Abstract

A building's Heating Ventilating and Air Conditioning (HVAC) system is made more energy efficient and the indoor air quality (IAQ) of the building's circulating air is improved by incorporating a greenhouse as an integral part of the HVAC system and by utilizing a novel feed forward control strategy that maintains the proper levels of temperature, humidity and CO 2 concentration in the building under varying conditions of day, time, use and occupancy. A portion or all of the exhaust air from the building is discharged into a greenhouse where the heat and humidity are recovered in the winter by heating the greenhouse and the air conditioning is recovered in the summer by cooling the greenhouse. Selected plants are used in the greenhouse to remove CO 2 and pollutants from the building's exhaust air while enriching the air with oxygen and beneficial negatively charged ions. The oxygenated, improved quality air from the greenhouse is then used to supply all or a portion of the intake air to the building's HVAC system.

1 . An HVAC system for buildings and other structures consisting of traditional HVAC components in conjunction with a greenhouse as in integral part of the system consisting of:
 a) a heating humidification section (oil, gas, coal, wood, electric, heat pump, geothermal, solar or any other type)   b) an air conditioning section (air conditioner, heat pump, geothermal or any other type)   c) Fans or any other type of air movers, preferably variable speed, for air circulation, exhaust air and inlet air.   d) Air circulating ductwork with appropriate air filters and grilles.   e) Controllable dampers and valves.   f) Individual room radiators (optional).   g) Sensors for temperature, humidity, CO 2 , air flow, hot water flow and for any heating and cooling medium flows.   h) A computer or any other type of programmable controller with algorithms to minimize air circulation rates, exhaust air rates and inlet air rates while maintaining the desired targeted room temperatures, humidity and CO 2  levels which will normally vary depending on day, time, use and occupancy.   i) An attached or separate greenhouse with appropriate ductwork to accept 0 to 100% of the building exhaust air and a means to supply 0 to 100% of the building's supply air requirements.   j) Selected plants in the greenhouse that have the ability to absorb CO 2  and other air pollutants at a high rate and plants that have the ability to emit oxygen and beneficial negatively charged ions into the air at a high rate.
 All of the above components are not necessary to practice the teachings of this patent. 
   
   
   
       2 . A system of  claim 1  whereby the greenhouse preferably has an enclosed volume of more than two times the design hourly flow of the building exhaust air. 
   
   
       3 . A system of  claim 1  whereby the greenhouse preferably has a plant growing area of more than 4 square feet for each 100 cubic feet of design hourly flow of building exhaust air. 
   
   
       4 . A system of  claim 1  where greenhouse plants are selected on the basis of high CO 2  and other pollutant uptake rates and their ability to emit oxygen and beneficial negative ions and for their commercial value or any combination. Typically these are leafy fast growing plants, trees, fruits or vegetables and preferably where the leaves have a large total surface area and account for a large portion of the above ground biomass of the plant. 
   
   
       5 . A system of  claim 1  whereby plants suitable for this purpose but not limited to are as follows: 
     
       
         
               
               
             
                   
               
                 Family 
                 Examples (Common Name) 
               
                   
               
                 
                   Nephrolepis 
                 
                 Boston Fern 
               
                 Dragaena 
                 Mothers In Law's Tongue, Snake plant and Janet Craig 
               
                 
                   Hedra 
                 
                 English Ivy 
               
                 Fieus 
                 Weeping Fig 
               
                 
                   Phoenix 
                 
                 Dwarf Date Palm 
               
                 Vegetables 
                 Lettuce, Spinach, Kale, Zucchini and other squash 
               
                   
               
           
              
              
              
             
             
              
              
              
              
              
              
              
             
          
         
       
     
     Or any other plants found to absorb CO 2  and other pollutants and emit O 2  and beneficial negative ions and have some commercial value or any combination. 
   
   
       6 . A system of  claim 1  whereby at night or during periods of low light or for any other reason when the CO 2  concentration of the greenhouse air available for inlet air makeup air to the building HVAC system is too high, high efficiency sunlamps can be turned on to enhance or extend the conditions for plant growth thereby increasing the rate of CO 2  removal from the greenhouse air and increasing the rate of O 2  and beneficial negatively charged ions addition into the greenhouse air. 
   
   
       7 . An HVAC system of  claim 1  whereby sensors for measuring temperature, humidity, CO 2  airflow and the flow of any other heating or cooling medium are located strategically throughout the system and continuously transmit the values of each of the parameters to a central computer controller where algorithms are stored and continuously updated to determine the slope of the curves for the changes in temperature, humidity and CO 2  levels in the building and in the greenhouse. 
   
   
       8 . A system of  claim 1  and  7  whereby the slope or the rate of change in any measured parameter is used to control the rate of any of the controllable factors such as air flow or other fluid flows, the temperature of the air and other fluids, the humidity of the air and the CO 2  level of the air. 
   
   
       9 . A system of  claim 1  and  7  whereby algorithms in the controller determine the regulation priorities so as to maintain the proper temperature, humidity and CO 2  levels at the lowest air circulation rate, lowest air exhaust rate and lowest makeup air rate to improve energy efficiency so as to maintain good air quality using the lowest practical total energy consumption based on the sum of the energy used by all the components in the entire system. 
   
   
       10 . A system of  claim 1  and  7  whereby the desired temperature, humidity and CO 2  level is used as a feed forward target and not as a set point subject to overshooting, undershooting and cycling which leads to occupant discomfort and lower energy efficiency. 
   
   
       11 . A system of  claim 1  and  7  whereby the amount of the building exhaust air discharged into the greenhouse is controlled at the minimum rate required to maintain the ASHRE recommended CO 2  level in the air in each room of the building or preferably below 0.4%. Preferably the exhaust air is directed to the lower portion at one end of the greenhouse so that the higher density CO 2  in the exhaust air comes quickly in contact with the ground level plants stimulating faster removal of the CO 2  and pollutants from the exhaust air, encouraging faster growth of the plants and promoting more emissions into the air of oxygen and beneficial negatively charged ions by the plants. 
   
   
       12 . A system of  claim 1  and  7  whereby the amount of makeup air from the greenhouse to the building's HVAC system is controlled at the minimum necessary to maintain the desired ASHRE recommended CO 2  level in the air of each of the rooms of the building or preferably below 0.4%. Preferably the makeup air to the building is drawn from the upper portion of the opposite end of the greenhouse from the exhaust air inlet so that the lighter density lower CO 2  and higher oxygenated air containing beneficial negative ions is drawn into the building's HVAC system. 
   
   
       13 . A system of  claim 1  and  7  whereby the air circulation rate and the flow rate of any other heating and cooling fluid in each of the rooms is controlled at the minimum necessary to maintain the proper temperature, humidity and CO 2  level dependant on day, time, use and occupancy. 
   
   
       14 . A system of  claim 1  and  7  where a two-way proportioning exhaust damper is used so that when ambient air conditions of temperature, humidity or CO 2  level may be beneficial, a portion or all of the exhaust air from the building can be divided between the greenhouse and the ambient air. 
   
   
       15 . A system of  claim 1  and  7  whereby a two-way proportioning inlet damper is used so that when ambient air conditions of temperature humidity and CO 2  levels are beneficial all or any portion of the inlet air to the building can be drawn from the greenhouse and ambient air.