Patent Publication Number: US-2018045430-A1

Title: Energy recovery assembly, energy recovery ventilation system comprising an energy recovery assembly and method of operation for same

Description:
TECHNICAL FIELD OF THE INVENTION 
     The present invention relates to the field of energy recovery. More particularly, it relates to an energy recovery assembly, to an energy recovery ventilation system including such an energy recovery assembly and to a method of operation for the same. 
     BACKGROUND 
     In the field of ventilation, it is known to use ventilation systems in order to help maintaining adequate indoor air quality in buildings, such as industrial buildings, commercial buildings, farming facilities, residential houses and the like. Such ventilation systems are commonly used to, amongst others, prevent stagnation of the inside air of the building via the intake of fresh outside air and the corresponding exhaust of inside air. 
     Given that, in many cases, there is a temperature and/or humidity difference between the supply air brought into the building by the ventilation system and the outgoing exhaust air exhausted by the ventilation system, the ventilation systems are commonly required to control the temperature and/or humidity level of the supply air brought inside the building in order to maintain a constant temperature and/or humidity level inside the building. Such control substantially impacts the energy consumption of the ventilation system, as it commonly requires, for example, the heating/cooling of the supply air before it is distributed inside the building. 
     Over the years, many types of heat recovery ventilation systems have been developed in order to minimize the energy consumption required to regulate the temperature and humidity level of the supply air brought into the building by the ventilation system. In such ventilation systems, heat exchange and/or humidity exchange is performed between the outgoing exhaust air and the incoming supply air, for example through the use of heat recovery wheel, non-rotating cross-flow heat exchangers, and the like. 
     Known heat recovery ventilation systems however tend to suffer from several drawbacks. For example, such drawbacks include high maintenance costs (e.g. maintenance costs due to the periodical replacement/cleaning of filters or cassettes to remove the accumulated dust and/or debris) and/or extended down time periods periodically required to proceed to maintenance thereof. Moreover, these systems commonly lack the capacity to provide free cooling, when the outside air is warmer than the inside air (i.e. when the temperature outside of the building is greater than the inner temperature of the building). 
     Similar drawbacks regarding the above described maintenance issues also apply to heat recovery assemblies used to minimize the energy consumption required to regulate the temperature and/or humidity in high heat apertures having intake/exhaust of air therefrom, such as, for example and without being limitative, industrial ovens. 
     In view of the above, there is a need for an improved energy recovery assembly to be used in an energy recovery ventilation system, for an energy recovery ventilation system including such an energy recovery assembly and for a method of operation for the same, which would be able to overcome or at least minimize some of the above-discussed prior art concerns. 
     BRIEF SUMMARY OF THE INVENTION 
     According to a first general aspect, there is provided an energy recovery assembly for transferring thermal energy between outgoing exhaust air and incoming supply air, in an energy recovery ventilation system having at least one air transfer path through which the outgoing exhaust air and the incoming supply air flow sequentially. The energy recovery assembly comprises a plurality of beads, a bead receiving conduit section, at least one bead inlet for each bead receiving conduit section and at least one bead outlet for each bead receiving conduit section. Each one of the plurality of beads is made of thermal conductive material. The bead receiving conduit section is positioned across each one of the at least one air transfer path of the ventilation system. The bead receiving conduit section is configured to receive and retain corresponding ones of the plurality of beads therein. Each one of the at least one bead inlet is configurable between an open configuration allowing introduction of the corresponding ones of the plurality of beads in the bead receiving conduit section and a closed configuration where the at least one bead inlet closes the bead receiving conduit section and prevents introduction of the corresponding ones of the plurality of beads therein. Each one of the at least one bead outlet is configurable between an open configuration allowing removal of the corresponding ones of the plurality of beads from the bead receiving conduit section and a closed configuration where the at least one bead outlet closes the bead receiving conduit section and prevents removal of the corresponding ones of the plurality of beads therefrom. 
     In an embodiment, each bead receiving conduit section comprises at least two bead receiving chambers. Each one of the at least two bead receiving chambers is configured to receive and retain a subset of the corresponding ones of the plurality of beads. 
     In an embodiment, each one of the at least two bead receiving chambers is operatively connected to one of the at least one bead inlet and one of the at least one bead outlet. 
     In an embodiment, each one of the plurality of beads has a substantially spherical shape. 
     In an embodiment, each one of the plurality of beads comprises at least one through hole extending therethrough. 
     In an embodiment, each one of the plurality of beads has a substantially isogonal polyhedron shape with at least two open faces and a hollow core. 
     In an embodiment, each one of the plurality of beads has a substantially O-ring shape. 
     In an embodiment, the plurality of beads is divided in at least two bead material subsets, each comprising beads made of a distinct thermal conductive material. The beads of each one of the at least two bead material subsets are received in a distinct bead receiving conduit section. 
     In an embodiment, the plurality of beads is divided in at least two bead size subsets, each comprising beads having a distinct size. The beads of each one of the at least two bead size subsets are received in a distinct bead receiving conduit section. 
     According to another general aspect, there is provided an energy recovery ventilation system having at least one air transfer path through which outgoing exhaust air and incoming supply air flow sequentially. The energy recovery ventilation system comprises a ventilation assembly and an energy recovery assembly. The ventilation assembly comprises at least one ventilation unit operating to generate an airflow along the at least one air transfer path and at least one conduit defining the at least one air transfer path. The energy recovery assembly comprises a plurality of beads, a bead receiving conduit section for each one of the at least one conduit defining the at least one air transfer path, at least one bead inlet for each bead receiving conduit section and at least one bead outlet for each bead receiving conduit section. Each one of the plurality of beads is made of thermal conductive material. Each bead receiving conduit section is configured to receive and retain corresponding ones of the plurality of beads therein. 
     In an embodiment, each one of the at least one bead inlet is configurable between an open configuration allowing introduction of the corresponding ones of the plurality of beads in the bead receiving conduit section and a closed configuration where the at least one bead inlet closes the bead receiving conduit section and prevents introduction of the corresponding ones of the plurality of beads therein and each one of the at least one bead outlet is configurable between an open configuration allowing removal of the corresponding ones of the plurality of beads from the bead receiving conduit section and a closed configuration where the at least one bead outlet closes the bead receiving conduit section and prevents removal of the corresponding ones of the plurality of beads therefrom. 
     In an embodiment, the energy recovery ventilation system is an energy recovery ventilation system of a building. 
     In an embodiment, each bead receiving conduit section comprises at least two bead receiving chambers. Each one of the at least two bead receiving chambers is configured to receive and retain a subset of the corresponding ones of the plurality of beads. 
     In an embodiment, each one of the at least two bead receiving chambers is operatively connected to one of the at least one bead inlet and one of the at least one bead outlet. 
     In an embodiment, each one of the plurality of beads has a substantially spherical shape. 
     In an embodiment, each one of the plurality of beads comprises at least one through hole extending therethrough. 
     In an embodiment, each one of the plurality of beads has a substantially isogonal polyhedron shape with at least two open faces and a hollow core. 
     In an embodiment, each one of the plurality of beads has a substantially O-ring shape. 
     In an embodiment, the plurality of beads is divided in at least two bead material subsets, each comprising beads made of a distinct thermal conductive material. The beads of each one of the at least two bead material subsets are received in a distinct bead receiving conduit section. 
     In an embodiment, the plurality of beads is divided in at least two bead size subsets, each comprising beads having a distinct size. The beads of each one of the at least two bead size subsets are received in a distinct bead receiving conduit section. 
     According to another general aspect, there is further provided a method for performing energy recovery in a building. The method comprises the steps of generating an airflow along at least one air transfer path; retaining a plurality of beads in at least one bead receiving conduit section; and transferring thermal energy between the outgoing exhaust air and the incoming supply air through the sequential flow of outgoing exhaust air and the incoming supply air in the at least one bead receiving conduit section where the plurality of beads are retained. The airflow provides outgoing exhaust air being exhausted outside of the building and incoming supply air being supplied inside the building in each one of the at least one air transfer path sequentially. Each one of the at least one bead receiving conduit section is located across one of the at least one air transfer path. Each one of the plurality of beads is made of thermal conductive material. 
     In an embodiment, the method of claim further comprises the steps of removing corresponding ones of the plurality of beads from one of the at least one bead receiving conduit section; and reintroducing at least a subset of the corresponding ones of the plurality of beads in the one of the at least one bead receiving conduit section. 
     In an embodiment, the method further comprises the steps of cleaning the corresponding ones of the plurality of beads. 
     In an embodiment, the step of removing corresponding ones of the plurality of beads from one of the at least one bead receiving conduit section further comprises the step of configuring a bead outlet in an open configuration. 
     In an embodiment, the step of reintroducing at least a subset of the corresponding ones of the plurality of beads in the one of the at least one bead receiving conduit section further comprises the step of configuring a bead inlet in an open configuration. 
     In an embodiment, the method further comprises the steps of: removing corresponding ones of the plurality of beads from one of the at least one bead receiving conduit section; and reintroducing a plurality of beads in the one of the at least one bead receiving conduit section. The beads being reintroduced are different from the removed corresponding ones of the plurality of beads. 
     In an embodiment, the step of removing corresponding ones of the plurality of beads from one of the at least one bead receiving conduit section further comprises the step of configuring a bead outlet in an open configuration. 
     In an embodiment, the step of reintroducing at least a subset of the corresponding ones of the plurality of beads in the one of the at least one bead receiving conduit section further comprises the step of configuring a bead inlet in an open configuration. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Other objects, advantages and features will become more apparent upon reading the following non-restrictive description of embodiments thereof, given for the purpose of exemplification only, with reference to the accompanying drawings in which: 
         FIGS. 1A and 1B  are schematic representations of an energy recovery ventilation system of a building, according to an embodiment where the ventilation unit includes two reversible fans operating in opposite directions sequentially, and wherein  FIG. 1A  shows a first operating sequence and  FIG. 1B  shows a second operating sequence. 
         FIGS. 2A and 2B  are schematic representations of an energy recovery ventilation system of a building, according to another embodiment where the energy recovery ventilation system includes a supply duct and an exhaust duct, and wherein  FIG. 2A  shows a first operating sequence and  FIG. 2B  shows a second operating sequence. 
         FIG. 3  is a schematic perspective representation of a portion of an energy recovery ventilation system, in accordance with an embodiment, and wherein bead receiving conduit sections of the energy recovery ventilation system are shown without beads inserted therein. 
         FIG. 4  is a schematic elevation representation showing one bead receiving conduit section of the energy recovery ventilation of  FIG. 3 , with beads retained therein and showing partial views of an insulation layer and outer covering of a corresponding building. 
         FIG. 5  is a schematic elevation representation showing a cross-section of the bead receiving conduit sections of the energy recovery ventilation system shown in  FIG. 3 , with beads retained therein. 
         FIG. 5A  is an enlarged view of a subset of the beads retained in one of the bead receiving conduit sections shown in  FIG. 5 . 
         FIG. 6  is a schematic top plan representation of bead receiving conduit sections of an energy recovery assembly of the energy recovery ventilation system, according to another embodiment. 
         FIG. 7  is a schematic front elevation representation showing a cross-section of the bead receiving conduit sections of the energy recovery assembly of the energy recovery ventilation system shown in  FIG. 6 . 
         FIG. 7A  is an enlarged view of a subset of the beads retained in one of the bead receiving conduit sections shown in  FIG. 7 . 
         FIGS. 8A to 8C  are schematic perspective views of beads which can be used in the present energy recovery ventilation system, wherein  FIG. 8A  shows an embodiment in which a bead has a substantially spherical shape,  FIG. 8B  shows an embodiment in which a bead has a truncated icosahedron shape with open faces and a hollow core, and  FIG. 8C  shows an embodiment in which a bead has a substantially O-ring shape. 
     
    
    
     DETAILED DESCRIPTION 
     In the following description, the same numerical references refer to similar elements. The embodiments, geometrical configurations, materials mentioned and/or dimensions shown in the figures or described in the present description are embodiments only, given solely for exemplification purposes. 
     Moreover, although the embodiments of the energy recovery assembly and the energy recovery ventilation system including such energy recovery assembly and corresponding parts thereof consist of certain geometrical configurations as explained and illustrated herein, not all of these components and geometries are essential and thus should not be taken in their restrictive sense. It is to be understood, as also apparent to a person skilled in the art, that other suitable components and cooperation thereinbetween, as well as other suitable geometrical configurations, may be used for the energy recovery assembly and the energy recovery ventilation system including such energy recovery assembly, as will be briefly explained herein and as can be easily inferred herefrom by a person skilled in the art. Moreover, it will be appreciated that positional descriptions such as “above”, “below”, “left”, “right” and the like should, unless otherwise indicated, be taken in the context of the figures and should not be considered limiting. 
     Referring generally to  FIGS. 1A to 2B , there are shown alternative embodiments of energy recovery assemblies  30 ,  130  operative to transfer thermal energy between outgoing exhaust air  15 ,  115  and incoming supply air  16 ,  116 , wherein similar features are numbered using the same reference numerals in the  10  series in  FIGS. 1A and 1B  and in the  100  series in  FIGS. 2A and 2B . In the embodiments shown, the energy recovery assembly  30 ,  130  is operative to transfer thermal energy between outgoing exhaust air  15 ,  115  and incoming supply air  16 ,  116 , in an energy recovery ventilation system  10 ,  110  of a building  20 ,  120 . The energy recovery ventilation system  10 ,  110  includes a ventilation assembly  11 ,  111  with a ventilation unit  12 ,  112  operating to generate an airflow and at least one conduit  13 ,  113  which defines at least one air transfer path  14 ,  114  where the outgoing exhaust air  15 ,  115  and the incoming supply air  16 ,  116  flow sequentially, as a result of the airflow generated by the ventilation unit  12 ,  112 . As will be easily understood, the outgoing exhaust air  15 ,  115  is exhausted outside of the building  20 ,  120 , from the inside, and incoming supply air  16 ,  116  is supplied inside the building  20 ,  120 , from outside, to counterbalance the exhausted outgoing exhaust air  15 ,  115 . 
     With reference to  FIGS. 1A and 1B , where features are numbered using reference numerals in the  10  series, in the embodiment shown, the ventilation unit  12  includes two reversible fans  21   a  and  21   b  operating in opposite directions sequentially (i.e. one of the fans  21   a  operates continuously in a first direction for a definite time period and in the opposite direction for another definite time period, with the other fan  21   b  operating simultaneously in the directions opposite to the operating direction of the first fan  21   a ). One skilled in the art will understand that, in an alternative embodiment (not shown), different types and/or quantities of air circulation apparatus can be used for the ventilation unit  12 .  FIG. 1A  shows a first sequence where the first fan  21   a  operates in the supply direction, thereby supplying incoming supply air  16  inside the building  20 , and the second fan  21   b  operates in the exhaust direction, thereby exhausting exhaust air  15  outside of the building  20 .  FIG. 1B  shows a second sequence where the first fan  21   a  operates in the exhaust direction and the second fan  21   b  operates in the supply direction. The first sequence and the second sequence are continuously performed alternately, each sequence lasting a definite time period, such as, without being limitative, between about 1 minute and about 10 minutes. In an embodiment, the fans  21   a  and  21   b  are operatively connected to a control assembly (not shown) controlling the operation thereof. 
     Still referring to  FIGS. 1A and 1B , in the embodiment shown, gravity shutters  22   a ,  22   b  are provided to open or close the air inlet  23  and air outlet  24  of the conduit  13  associated with the corresponding fan  21   a ,  21   b , depending on the direction in which the fan  21   a ,  21   b  operates. Inwardly opening gravity shutters  22   a  are provided at the air inlets  23 . The inwardly opening gravity shutters  22   a  open towards the inside and are driven in an open configuration when the fan  21   a ,  21   b  operates in the exhaust direction (see fan  21   b  in  FIG. 1A  and fan  21   a  in  FIG. 1B ) and are driven in a closed configuration when the fan  21   a ,  21   b  operates in the supply direction (see fan  21   a  in  FIG. 1B  and fan  21   b  in  FIG. 1B ). In contrast, outwardly opening gravity shutters  22   b  are provided at the air outlets  24 . The outwardly opening gravity shutters  22   b  open towards the outside and are driven in the closed configuration when the fan  21   a ,  21   b  operates in the exhaust direction (see fan  21   b  in  FIG. 1A  and fan  21   a  in  FIG. 1B ) and are driven in the open configuration when the fan  21   a ,  21   b  operates in the supply direction (see fan  21   a  in  FIG. 1A  and fan  21   b  in  FIG. 1B ). In the embodiment shown, filters  25  are also provided at the air inlets  23  and air outlets  24  of the conduits  13  in order to minimize the amount of dust and debris entering the conduits  13 . One skilled in the art will easily understand that, in an alternative embodiment, no filters could be provided or alternate means to the above described shutter mechanism could be used to open/close the air inlets  23  and air outlets  24  of the conduits  13 . Moreover, in an embodiment (not shown), the same opening in the conduit  13  could be used for both the air inlet  23  and air outlet  24 . 
     Now referring to  FIGS. 2A and 2B , where features are numbered using reference numerals in the  100  series, there is shown an energy recovery ventilation system  110  for a building  120 , according to an alternative embodiment where the energy recovery ventilation system  110  includes a supply duct  117  and an exhaust duct  118 . The energy recovery ventilation system  110  once again includes two reversible fans  121   a  and  121   b  operating in opposite directions sequentially.  FIG. 2A  shows a first sequence where the first fan  121   a  operates in the supply direction to generate incoming supply air  116  and the second fan  121   b  operates in the exhaust direction to generate outgoing exhaust air  115  in the conduits  113 .  FIG. 2B  shows a second sequence where the first fan  121   a  operates in the exhaust direction and the second fan  121   b  operates in the supply direction. The first sequence and the second sequence are once again continuously performed alternately, each sequence lasting a definite time period, such as, without being limitative between about 1 minute and about 10 minutes. Once again, in an embodiment, the fans  121   a  and  121   b  are operatively connected to a control assembly (not shown) controlling the operation thereof. 
     In the embodiment of  FIGS. 2A and 2B , the conduits  113  are connected to a supply duct  117  and an exhaust duct  118  of the building  120 . Each one of the supply duct  117  and the exhaust duct  118  includes a plurality of openings used respectively as air inlets  123  in the exhaust duct  118  and air outlets  124  in the supply duct  117 . The supply duct  117  and exhaust duct  118  include gravity shutters  122   a ,  122   b  at opposed ends thereof, proximate to the first fan  121   a  and second fan  121   b . The gravity shutters  122   a ,  122  are opened/closed depending on the direction in which the fan  121   a ,  121   b  operates and are used to direct the outgoing exhaust air  115  in the exhaust duct  118  and the incoming supply air  116  in the supply duct  117 . Inwardly opening gravity shutters  122   a  are provided at opposed ends of the supply duct  117 . The inwardly opening gravity shutters  122   a  open towards the inside of the supply duct  117  and are driven in an open configuration at the end proximate to the fan  121   a ,  121   b  operating in the supply direction (see fan  121   a  in  FIG. 2A  and fan  121   b  in  FIG. 2B ) and in a closed configuration at the end proximate to the fan  121   a ,  121   b  operating in the exhaust direction (see fan  121   b  in  FIG. 2A  and fan  121   a  in  FIG. 2B ). In contrast, outwardly opening gravity shutters  122   b  are provided at opposed ends of the exhaust duct  118 . The outwardly opening gravity shutters  122   b  open towards the outside of the exhaust duct  118  and are driven in a closed configuration at the end proximate to the fan  121   a ,  121   b  operating in the supply direction (see fan  121   a  in  FIG. 2A  and fan  121   b  in  FIG. 2B ) and in an open configuration at the end proximate to the fan  121   a ,  121   b  operating in the exhaust direction (see fan  121   b  in  FIG. 2A  and fan  121   a  in  FIG. 2B ). In the embodiment shown, filters  125  are also provided at the opposed ends of each one of the supply duct  117  and the exhaust duct  118 , to minimize the dust and debris reaching the fans  121   a ,  121   b . Once again, one skilled in the art will easily understand that, in an alternative embodiment, no filters could be provided. 
     For ease of understanding, in the description below, features which could be numbered using reference numerals in the  100  series will now be referred with the corresponding reference number in the  10  series. 
     One skilled in the art will understand that the ventilation assembly  11 , including the ventilation unit  12  and the conduits  13  (defining the transfer paths  14 ) of the energy recovery ventilation system  10 , is adapted to the required airflow of the associated structure. Therefore, in the case of a building, the number of conduits  13  defining different air transfer paths  14 , where the outgoing exhaust air  15  and the incoming supply air  16  flow sequentially, the number of ducts  17 ,  18 , and the type of ventilation unit  12 , depends on the required airflow and can vary greatly depending on the size and architecture of the building  20 . Hence, the ventilation unit  12  used and the size, shape and/or configuration of the conduits  13  defining different air transfer paths  14  and connected ducts  17 ,  18  can differ from the embodiment shown, the illustrated embodiments being given herein only for exemplary purposes. 
     Moreover, it will be understood that even though in the embodiment shown, the ventilation assembly  11  is adapted for a building  20 , in alternative embodiments (not shown), the ventilation assembly  11  of the energy recovery ventilation system  10  can be adapted to other structures and/or apparatuses, such as high heat apertures having intake/exhaust of air therefrom. For example and without being limitative, in an embodiment (not shown), the ventilation assembly  11  of the energy recovery ventilation system  10  can be adapted to industrial ovens or the like. 
     In view of the above, it will be understood that the incoming supply air  16  and the outgoing exhaust air  15  flow in opposite directions, through each one of the transfer paths  14  sequentially. Therefore, in order to perform the transfer of thermal energy between the outgoing exhaust air  15  and the incoming supply air  16 , the energy recovery ventilation system  10  is configured such that each one of the incoming supply air  16  and the outgoing exhaust air  15  flows through an energy recovery assembly  30  thereof, positioned across the corresponding ones of the transfer paths  14 . 
     In reference to  FIGS. 3 to 5 , the energy recovery assembly  30  will now be described in more details below. The energy recovery assembly  30  includes a bead receiving conduit section  32  for each conduit  13  which defines an air transfer path  14  and where the incoming supply air  16  and the outgoing exhaust air  15  flow sequentially. The bead receiving conduit section  32  is a section of the corresponding conduit  13 , positioned proximate to the entrance of the conduit  13  for the incoming supply air  16  and the exit of the conduit  13  for the outgoing exhaust air  15 . One skilled in the art will understand that, the bead receiving conduit section  32  can have various sizes and shapes which allow a plurality of beads  34  to be inserted and retained therein, as will be described in more details below. 
     In the embodiment shown, each bead receiving conduit section  32  has a substantially rectangular parallelepiped shape. One skilled in the art will however understand that, in alternative embodiments, the bead receiving conduit sections  32  can have many different shapes for containing the plurality of beads, which can differ from the substantially rectangular parallelepiped shape of the embodiment shown. 
     Moreover, in the embodiment shown, the bead receiving conduit sections  32  extends substantially vertically along a portion of an external wall  19  of the building  20 , under the outer covering  19   a  and the insulation layer  19   b  thereof (See  FIGS. 4 and 5 ). The outer covering  19   a  and the insulation layer  19   b  provide thermal insulation from the outside environment of the building  20 . One skilled in the art will understand that even though the bead receiving conduit sections  32  of the embodiment shown are substantially vertical, in an alternative embodiment (not shown), the bead receiving conduit sections  32  can also be angled from a substantially vertical position or be substantially horizontal. 
     One skilled in the art will also understand that, in alternative embodiments, the bead receiving conduit section  32  can also be positioned in a location different than along the portion of an external wall  19  of a building  20  and/or can use different insulating means or methods in order to thermally insulate the beads from the environment. As mentioned above, in an embodiment the ventilation assembly  11  of the energy recovery ventilation system  10  can be adapted to a structure and/or apparatus, different than a building and can therefore extend along a section of this structure/apparatus. 
     In the embodiment shown in  FIG. 3 , each bead receiving conduit section  32  includes sub-sections configured to receive and retain a subset of the beads  34  of the bead receiving conduit section  32 . In the embodiment shown, each bead receiving conduit section  32  includes four bead receiving chambers  33 , but one skilled in the art will understand that, in an alternative embodiment (not shown) a different number of bead receiving chambers  33  (or no bead receiving chambers  33 ) can be provided. Moreover, even though in the illustrated embodiment the bead receiving chambers  33  are positioned in a parallel configuration, in an alternative embodiment (not shown), the bead receiving chambers  33  can be configured in a series configuration, or in a combination of parallel and series configurations. The division of the bead receiving conduit section  32  into multiple bead receiving chambers  33  allows a smaller quantity of beads to be retained in each chamber  33 , thereby facilitating the insertion and removal of the beads in each chamber, for example, for maintenance purposes, as will be described in more details below. 
     In the embodiment shown, each bead receiving conduit section  32  includes an inner (top) bead blocking member  36  and an outer (bottom) bead blocking member  37  configured to retain the beads  34  in the bead receiving conduit section  32 . Indeed, in the embodiment shown, the outer bead blocking member  37  prevents the beads from being released at an outer end of the conduit section  32  (e.g. a bottom of the conduit section  32  in the embodiment shown), for example by gravity, and the inner bead blocking member  36  prevents the beads from being released towards the corresponding fan  21   a ,  21   b  at an inner end of the conduit section  32  (e.g. a top of the conduit section  32  in the embodiment shown), for example, as incoming supply air  16  flows through the conduit section  32 . In the embodiment shown, the inner bead blocking member  36  and outer bead blocking member  37  are support grids, but one skilled in the art will understand that, in alternative embodiments (not shown), other components or mechanisms for retaining the beads  34  in the bead receiving conduit section  32  can also be used. 
     Referring to  FIG. 5 , in an embodiment, each bead receiving conduit section  32  includes at least one bead inlet  38  which allows selective introduction of the beads  34  in the bead receiving conduit section  32  and at least one bead outlet  39  which allows selective removal of the corresponding ones of the plurality of beads from the bead receiving conduit section  32 . Each one of the at least one bead inlet  38  is configurable between an open configuration (shown in  FIG. 5 ) allowing access to the bead receiving conduit section  32  and introduction of the beads  34  in the bead receiving conduit section  32  and a closed configuration (not shown) where access to the bead receiving conduit section  32  is prevented and introduction of the beads  34  in the bead receiving conduit section  32  is consequently also prevented. Each one of the at least one bead outlet  39  is also configurable between an open configuration (shown in  FIG. 5 ) allowing access to the bead receiving conduit section  32  and removal of the beads  34  from the bead receiving conduit section  32  and a closed configuration (not shown) where access to the bead receiving conduit section  32  is prevented and removal of the beads  34  from the bead receiving conduit section  32  is consequently also prevented. 
     In the embodiment shown, the bead inlet  38  and bead outlet  39 , each are manual trap doors selectively openable and closeable, for example and without being limitative, from outside the building  20 , and which can be locked in the closed configuration when the beads are retained inside the bead receiving conduit section  32 . One skilled in the art will understand that several locking mechanisms known in the art can be used to lock the manual trap doors in the closed configuration. One skilled in the art will also understand that, in an alternative embodiment, the bead inlet  38  and bead outlet  39  can be positioned differently than in the embodiment shown. For example and without being limitative, in an embodiment (not shown) the bead inlet  38  and/or bead outlet  39  can be located in the corresponding one of the top bead blocking member  36  and bottom bead blocking member  37 . Moreover, one skilled in the art will also understand that, in alternative embodiments, other components or mechanisms which allow selective introduction/removal of the beads in/from the bead receiving conduit section  32 , distinct from the above described manual trap doors, can also be used. 
     In embodiments where the bead receiving conduit section  32  is divided in multiple bead receiving chambers  33 , one bead inlet  38  and one bead outlet  39  can be provided for each bead receiving chamber  33 . 
     Advantageously, each bead outlet  39  and corresponding bead inlet  38  allows easy selective access to the corresponding bead receiving conduit section  32  or bead receiving chambers  33  and therefore allows easy removal and reintroduction of the beads  34  into the corresponding bead receiving conduit section  32  or bead receiving chambers  33  of the bead receiving conduit section  32 , for example and without being limitative, for cleaning purposes, bead replacement purposes or the like. 
     In an embodiment, the cleaning process of the beads  34  contained in one of the bead receiving conduit section  32  or bead receiving chambers  33  of the bead receiving conduit section  32  can be performed manually, by configuring the bead outlet  39  in the open configuration, removing the beads  34  from the corresponding bead receiving conduit section  32  or bead receiving chambers  33 , through the bead outlet  39 , and cleaning the beads. Subsequently the beads  34  can be reinserted in the corresponding bead receiving conduit section  32  or bead receiving chambers  33 , by configuring the corresponding bead inlet  38  in the open configuration (with the corresponding bead outlet being previously reconfigured in the closed configuration). 
     In an embodiment, the cleaning process can also be automated, for example and without being limitative, through the use of an automated washing device (not shown). In an embodiment, the automated washing device can be configured to automatically configure the bead outlet  39  in the open configuration, remove the beads  34  from the corresponding bead receiving conduit section  32  or bead receiving chambers  33 , though the bead outlet  39 , clean the beads and subsequently reintroduce the beads  34  in the corresponding bead receiving conduit section  32  or bead receiving chambers  33 , through the corresponding bead inlet  38 , by configuring the corresponding bead inlet  38  in the open configuration (with the corresponding bead outlet being previously reconfigured in the closed configuration). It will be understood that, in an embodiment, the automated washing device can operate automatically to proceed with the cleaning of the beads  34  of the different bead receiving conduit section  32  or bead receiving chambers  33  sequentially, when required or at predetermined intervals. 
     One skilled in the art will understand that a process similar to the cleaning process, can also be used for replacement of a portion of the beads from the corresponding bead receiving conduit section  32  or bead receiving chambers  33  or all of the beads therefrom. In other words, the bead outlet  39  can be configured in the open configuration to remove the beads from the corresponding bead receiving conduit section  32  or bead receiving chambers  33 , though the bead outlet  39 , and the corresponding bead inlet  38  can be configured in the open configuration (with the corresponding bead outlet being previously reconfigured in the closed configuration), to introduce new beads, with or without previously removed beads, in the corresponding bead receiving conduit section  32  or bead receiving chambers  33  through the corresponding bead inlet  38   
     Referring now to  FIGS. 6 and 7 , it is shown a non-limitative alternative configuration for the conduit section  232  in an energy recovery ventilation system  210  for a building  220 , wherein similar features are numbered using the same reference numerals in the  200  series. In the alternative embodiment shown in  FIGS. 6 and 7 , each bead receiving conduit section  232  has a substantially cylindrical shape. In the embodiment shown, the bead receiving conduit section  232  is located in an external structure having an outer covering  219   a  and an insulation layer  219   b  thereof, such that the bead receiving conduit section  232  is thermally insulated from the outside environment of the building  220 . In the embodiment shown, each bead receiving conduit section  232  includes three bead receiving chambers  233  configured to receive and retain a subset of the beads  234  of the bead receiving conduit section  232 . Once again, the division of the bead receiving conduit section  232  into multiple bead receiving chambers  233  allows a smaller quantity of beads to be retained in each chamber  233 , but it will be understood that, in alternative embodiments, another amount of bead receiving chambers  233  or no bead receiving chamber  233  could be provided. Once again, one skilled in the art will understand that even though the bead receiving conduit sections  232  of the illustrated embodiment are substantially vertical, in an alternative embodiment, the bead receiving conduit sections  232  could be angled from a substantially vertical position. 
     Once again, for ease of understanding, in the description below features which could be numbered using reference numerals in the  200  series will now be referred with only the reference number in the  10  series. 
     Hence, one skilled in the art will understand that, in other possible alternative embodiments, the bead receiving conduit sections  32  can also have sizes, shapes, configurations and/or positioning which differ from the illustrated embodiments. The size, shape, configuration and/or positioning of the bead receiving conduit sections  32  is adapted according to the structures and/or apparatuses for which the energy recovery ventilation system  10  is installed. For example, in the case of an energy recovery ventilation system  10  for a building such as the embodiments shown, the size, shape, configuration and/or positioning of the bead receiving conduit sections  32  is adapted to the architecture of the building  20  and the required airflow of the corresponding conduits  13  thereof. In alternative embodiments, an energy recovery ventilation system  10  can include multiple bead receiving conduit sections  32 , each having sizes shapes and/or positioning which differ from one another in order to adapt to the required airflow of the corresponding conduits  13  of the structure or apparatus for which the energy recovery ventilation system  10  is installed. Moreover, it will be understood that even though the embodiment shown shows the bead receiving conduit sections  32  being connected to the remainder of the ventilation assembly  11 , by a top section of the bead receiving conduit sections  32 , in an embodiment the bead receiving conduit sections  32  can be connected to the remainder of the ventilation assembly  11  by a bottom section or a side section thereof. 
     Now referring to  FIGS. 5A, 7A and 8A to 8C , as mentioned above, a plurality of beads  34  are retained in each bead receiving conduit section  32 . Each one of the beads  34  is made of thermal conductive material, such as, without being limitative, aluminum, glass, granite, river rock, copper, iron, stainless steel, brass, bronze, or the like. The beads  34  are sized and shaped to allow the incoming supply air  16  and the outgoing exhaust air  15  to flow through the bead receiving conduit section  32 , while performing thermal transfer with the beads  34 . In an embodiment, each bead  34  has a substantially spherical shape (see  FIGS. 5A, 7A and 8A ) and has a diameter ranging between about ¼ inch and 6 inches. One skilled in the art will however understand that, in an alternative embodiment, the beads  34  can have a shape distinct from the illustrated substantially spherical shape of  FIGS. 5A, 7A and 8A . In an embodiment, the beads  34  can include one or more through hole extending therethrough, thereby allowing airflow through the beads  34 . For example and without being limitative, in an embodiment, the beads  34  can have a polyhedron shape, with at least two open faces and a hollow core between the open faces to allow the passage of the air through the beads  34 .  FIG. 8B  shows such an embodiment where the bead has a truncated icosahedron shape with open faces and a hollow core between the faces, such that the bead  34  is essentially composed of the edges of the truncated icosahedron. One skilled in the art will however understand that, in alternative embodiments (not shown), the bead  34  can also have a different polyhedron shape. In another alternative embodiment the beads  34  can have a substantially O-ring shape (see  FIG. 8C ). In view of the above, one skilled in the will understand that the beads  34  can have multiple shapes which allow the incoming supply air  16  and the outgoing exhaust air  15  to flow through the bead receiving conduit section  32 , while performing thermal transfer with the beads  34  and should not be restricted to a specific bead shape. 
     In an embodiment, the material of the beads  34  may be selected to perform humidity exchange between the outgoing exhaust air  15  and incoming supply air  16  or simply to resist to high humidity and/or acidity of the outgoing exhaust air  15 . 
     One skilled in the art will understand that, in an embodiment where multiple conduits  13  are provided, each defining a different air transfer path  14  (thereby resulting in multiple bead receiving conduit sections  32  where beads  34  are retained) the size and/or shape and/or material of the beads  34  of each one of the multiple bead receiving conduit sections  32  can be different, for example to be adapted to one of the temperature, humidity level, or acidity level of the outgoing exhaust air  15  and incoming supply air  16  of the particular bead receiving conduit sections  32  in which they are introduced and retained. It will also be understood that the size and/or shape and/or material of the beads  34  of each bead receiving chamber  33  within a bead receiving conduit section  32  can also be different to be adapted to the specific air characteristics of the outgoing exhaust air  15  and incoming supply air  16  for the specific position of each bead receiving chamber  33 . 
     Advantageously, when used in a ventilation for a building, the above described energy recovery assembly and energy recovery ventilation system comprising the energy recovery assembly can allow heating of the outside air before it is supplied inside the building, using the thermal energy of the exhausted inside air transferred to the beads retained in each bead receiving conduit section  32 . In cases where the internal temperature of the building is colder than the external temperature, such energy recovery assembly and energy recovery ventilation system can also perform free cooling, i.e. cooling of the outside air before it is supplied inside the building, using the low temperature of the exhausted inside air transferred to the beads retained in each bead receiving conduit section  32 . Moreover, the energy recovery assembly and energy recovery ventilation system comprising the energy recovery assembly allows maintenance (i.e. cleaning or recycling of the beads  34 ) to be performed on a portion of each conduit section  32  at the time (i.e. each bead receiving chamber  33  at the time), therefore leading to no down time of the system. 
     The energy recovery assembly and energy recovery ventilation system comprising the energy recovery assembly having been described above, a method of operation for the energy recovery ventilation system will now be described. In an embodiment the method comprises generating the airflow along the at least one air transfer path where outgoing exhaust air is exhausted and incoming supply air is supplied in each transfer path sequentially. The method further comprises retaining a plurality of beads in at least one bead receiving conduit section and transferring thermal energy between the outgoing exhaust air and the incoming supply air through the sequential flow of outgoing exhaust air and the incoming supply air in the at least one bead receiving conduit section where the plurality of beads are retained. In the above mentioned method, each bead receiving conduit section is located across one of the at least one air transfer path and each bead is made of thermal conductive material. 
     In an embodiment, the method also comprises steps related to the cleaning or replacement of the beads. Such steps include the steps of configuring the bead outlet in the open configuration, removing corresponding ones of the plurality of beads from one of the at least one bead receiving conduit section, cleaning the corresponding ones of the plurality of beads (the case of cleaning purposes), configuring the bead outlet in the closed configuration, configuring the bead inlet in the open configuration and reintroducing the beads in the bead receiving conduit section. As mentioned above, the reintroduced beads can be the beads previously removed, a subset thereof, or completely new beads (in the case of a replacement for example). 
     Several alternative embodiments and examples have been described and illustrated herein. The embodiments of the invention described above are intended to be exemplary only. A person skilled in the art would appreciate the features of the individual embodiments, and the possible combinations and variations of the components. A person skilled in the art would further appreciate that any of the embodiments could be provided in any combination with the other embodiments disclosed herein. It is understood that the invention may be embodied in other specific forms without departing from the central characteristics thereof. The present examples and embodiments, therefore, are to be considered in all respects as illustrative and not restrictive, and the invention is not to be limited to the details given herein. Accordingly, while specific embodiments have been illustrated and described, numerous modifications come to mind without significantly departing from the scope of the invention as defined in the appended claims.