Abstract:
A daylight fixture for replacing a 2′×2′ or 2′×4′ electric lighting fixture in a suspended ceiling grid that incorporates a lighting source. The fixture utilizes a diffuser that distributes sunlight emerging from the exit aperture of a skylit lightwell. The diffuser has multiple parts, including an element mounted above a light source for use in concomitant non-simultaneous distribution of daylighting and electric lighting into an interior space, and a diffusion element mounted below the electric lamp for lighting distribution thereby using diffusion and reflectance elements within the fixture to create desired illuminance distribution within an interior space. In one embodiment a light source and reflector may be positioned below the ceiling for directing illumination onto the ceiling plane for reducing the surface luminance of fixture components to within acceptable standards for interior illumination. Daylight is directed into a building interior from a horizontal roof plane instead of vertical wall planes.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application claim priority to U.S. Provisional Patent Application No. 61/082,386 entitled “COMBINED DAYLIGHT ELECTRIC LIGHT FIXTURE FOR BUILDINGS USING ELECTROCHROMIC AND MECHANICAL METHODS,” filed Jul. 21, 2008, the contents of which are hereby incorporated by reference. 
     
    
     FIELD OF THE INVENTION 
       [0002]    The present invention relates generally to rooftop daylight fixtures that integrate skylights, light wells, and electric lighting and the manner in which illumination passing through and generated by this system is distributed to an interior space. 
       BACKGROUND OF THE INVENTION 
       [0003]    Rooftop daylight systems are becoming increasingly popular as a means to displace utility-provided electricity consumed in producing interior illumination. Rooftop daylight systems displace utility-provided electricity consumed in producing interior illumination. Basic solar mechanics can demonstrate that, on an annualized basis, there is more radiative energy available for collection through a horizontal rooftop aperture of a given size than for a similarly sized aperture along a vertical wall on any side of a building. Conventional skylights project unmodified solar beams into an interior, and are characterized by excessive contrast and high luminance/illumination ratio of interior environments. In the past, skylight technology has been burdened by highly contrasting and varying illumination levels at the workplane throughout the course of the day and the year. Engineering the diffusion of illumination as it passes through and interacts with components in a skylight/light well/diffuser system enables a large percentage of the solar volume admitted by the solar aperture to be brought into a space without the intensity of a direct solar beam, thereby improving the suitability of top-lighting for interior uses. 
         [0004]    A large component of the radiative energy harvested by rooftop daylighting fixtures is diffuse sky radiation, whose behavior is highly predictable and largely uncontrollable. The directional component of the collected solar radiation can be optically controlled, but in the interest of ultimately diffusing this radiation for use as interior illumination, every attempt should be made to achieve diffusion without absorption and energy loss, and to do so in a manner that does not introduce any highly luminous surfaces or elements that would produce visual discomfort in the interior space. Diffusion may be introduced into the system at the skylight dome, along the surfaces of the light well, by elements placed at the exit aperture of the light well or below the aperture of the light well, or at any location in between. This disclosure relates to diffusion elements being placed within the fixture or below the exit aperture of a light well affixed to a skylight. 
         [0005]    Daylight emerging from the end of a light well can be described as a directionally diffuse source. There are limits to what can be accomplished optically to change the characteristics of diffuse lighting, but within this diffuse element is a much larger directional component that can be optically controlled and which can be described with photometry that varies throughout the course of the day and year. 
         [0006]    Diffusers placed at the exit aperture of a skylight or light well are not new. This application aligns a skylight/light well with a 2′×2′ or 2′×4′ suspended ceiling panel, which is constructed so that a conventional electric light fixture can be replaced with a natural light fixture of the same interior dimensions. 
         [0007]    Technology exists for increasing the optical collection efficiency of skylight apertures, and for increasing the throughput efficiency of light tubes and light wells. 
         [0008]    Generally, common ceiling-recessed 2′×4′ fluorescent downlighting fixtures are comprised of a reflective upper panel that redirects illumination downward through a louver or diffuser into a space to be lighted. The interaction between the reflector/diffuser/fixture geometries result in a specific photometric characterization for every lighting fixture. This invention replaces the reflectors used to redirect the illumination emitted from a lighting source in conventional lighting fixtures, and the rear supporting structure of the fixture, with diffusers, or some other combination of reflection and diffusion media, to allow photosensitive transformation in the passage of daylight and reflection of electric light. 
       SUMMARY OF THE INVENTION 
       [0009]    Embodiments herein relate generally to skylights and the manner that illumination from skylights is integrated into an interior space. Embodiments herein relate to the characterization of a lighting fixture using daylight as a source, a transparent glazing element enclosing a solar aperture at the building envelope elevated above the roof plane by a curb element, and a light well, which is a mechanism for transferring solar illumination from an aperture exposed to that source to an illumination distributing fixture located at or below the ceiling plane in the interior of the building. The illumination distributing lighting fixture can closely approximate the form, function, and style of conventional electric lighting fixtures. 
         [0010]    Side-lighting naturally accommodates a time dependent upward illumination component for distribution within a space. Top-lighting most generally accommodates a downward, time dependent illumination component. The invention of the disclosure improves the feasibility of utilizing top-lighting for interior uses that the building and construction industry has to date reserved for side admitted daylighting. 
         [0011]    A large component of the radiative energy harvested by daylighting fixtures is diffuse sky radiation. The behavior of diffuse sky radiation is highly predictable and largely uncontrollable. The directional component of the collected solar radiation can be optically controlled, but in the interest of ultimately diffusing this radiation for use as interior illumination, every attempt should be made to achieve diffusion without absorption and energy loss, and to do so in a manner that does not introduce any highly luminous surfaces or elements that would produce visual discomfort in the interior. Diffusion may be introduced into the system at the skylight dome, along the surfaces of the light well, by elements placed at the exit aperture of the skywell or below the aperture of the skywell, or at any location in between. This disclosure relates to diffusion elements being placed within the fixture or below the exit aperture of a light well affixed to a skylight. 
         [0012]    Daylight emerging from the end of a light well can be described as a directionally diffuse source. There are limits to what can be accomplished optically to change the characteristics of diffuse lighting, but within this diffuse element is a much larger directional component that can be optically controlled and which can be described with photometry that varies throughout the course of the day and year. 
         [0013]    Diffusers placed at the exit aperture of a skylight or skywell are not new. This application positions a skylight/skywell that may be substantially aligned with a 2′×2′ or 2′×4′ suspended ceiling panel, which is constructed so that a conventional electric light fixture can be replaced with a natural light fixture of the same interior dimensions. 
         [0014]    To accommodate maximum utilization of skylighting within an interior space, the distributing light fixture is affixed to or suspended beneath the exit aperture of a skylit lightwell, which may be located at the ceiling plane, to receive emitted light. Through a combination of diffusing and reflecting surfaces, a direct/indirect, semi-direct/indirect, indirect/semi-direct illumination distribution can be attained for achieving for predictable illumination levels that satisfy pertinent IES Guidelines and Standards for specific lighting applications. Embodiments herein include a type of fixture that interacts with the end of a lightwell to attain specified illumination distributions. 
         [0015]    Energy losses within skylit lightwells contribute to diffusing the emission of daylight into building interiors. Interior inter-reflections that occur along the length of the lightwell contribute to a decrease in throughput efficiency of skylighting because of absorption that occurs at each bounce of light rays. Scattering improves the uniformity in daylight distribution emitted from the exit of a skylit skywell aperture, but is considered a loss factor because a portion of the scattered illumination is projected upward and back out of the collection system. 
         [0016]    Technology exists for increasing the optical collection efficiency of skylight apertures, and for increasing the throughout efficiency of skytubes and skywells. 
         [0017]    Generally, common ceiling-recessed 2×4 fluorescent downlighting fixtures are comprised of a reflective upper panel that redirects illumination downward through a louver or diffuser into a space to be lighted. The interaction between the reflector/diffuser/fixture geometries results in a specific photometric characterization for every lighting fixture. Embodiments herein replace the reflectors used to redirect the illumination emitted from a lighting source in conventional lighting fixtures, and the rear supporting structure of the fixture, with diffusers, or some other combination of reflection and diffusion media, to allow photosensitive transformation in the passage of daylight and reflection of electric light. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0018]      FIG. 1  is a top view of a combined daylight electric fixture. 
           [0019]      FIG. 2  is a side view of combined daylight electric fixture of  FIG. 1 . 
           [0020]      FIG. 3  is a building interior view of the underside of the combined daylight electric fixture of  FIG. 1 . 
           [0021]      FIG. 4  shows an embodiment of the combined daylight electric fixture of  FIG. 1  utilizing an electrochromic diffuser, the underside of which becomes reflective when photo-activated. 
           [0022]      FIG. 5  is a side cutaway view of an illumination distribution fixture of the daylight electric fixture of  FIG. 1   
           [0023]      FIG. 6  is a bottom view of the illumination distribution fixture in which the reflectors are in a retracted position. 
           [0024]      FIG. 7  is an illumination distribution fixture in which the reflectors are partially deployed. 
           [0025]      FIG. 8  is an illumination distribution fixture in which the reflectors are fully deployed, providing indirect illumination. 
           [0026]      FIG. 9  is a cross-section of an illumination distribution fixture of the daylight electric fixture of  FIG. 1  with a diffuser placed above deployable reflective panels. 
           [0027]      FIG. 10  is a cross-section of a fixture with the reflective louver in an open position. 
           [0028]      FIG. 11  is a cross-section of a fixture with the reflective louver in a partially retracted position. 
           [0029]      FIG. 12  is a cross-section of a fixture with the reflective louver in a closed position with the exterior illumination rejected and electric illumination reflected below. 
           [0030]      FIG. 13  is a perspective view of an embodiment of an electric daylight fixture that provides indirect electric illumination. 
           [0031]      FIG. 14  is a partial cross-sectional perspective view of the daylight fixture of  FIG. 13 . 
           [0032]      FIG. 15A  is an enlarged partial cross-sectional perspective view of the embodiment of  FIG. 13 . 
           [0033]      FIG. 15B  is an enlarged perspective view of the upper diffuser segment of  FIG. 15 . 
           [0034]      FIG. 16  is a perspective view of an additional embodiment of a daylight fixture. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0035]    A daylight fixture  10  of the invention has light well  12  that defines solar aperture  14  on an upper end and defines exit aperture  16  ( FIGS. 3-16 ) on a lower end. Lightwell  12  may extend above roof plane  18 . Lower end of lightwell  12  is preferably coplanar with ceiling plane  20 . An interior of lightwell  12  is reflective. A portion of light well  12  that extends above roof plane  18  is referred to herein as curb portion  22  ( FIGS. 1 ,  2 ,  10 - 16 ). Skylight  24  ( FIG. 1 ) or transparent glazing portion is provided to cover solar aperture  14 . 
         [0036]    Illumination distribution fixture  26  ( FIGS. 5 ,  9 - 12 ,  15 A) is affixed to light well  12  adjacent to exit aperture  16 . Illumination distribution fixture  26  includes first side wall  28 , second side wall  30 , first end wall  32  and second end wall  34 . Illumination distribution fixture  26  further includes integrated electric light assembly  36  ( FIGS. 5-9 ). 
         [0037]    Integrated light assembly  36  includes light assembly support  38  having first support end  40 , second support end  42 , first support side  44  and second support side  46 . First support end  40  of light assembly support  38  is affixed to a lower middle portion of first end wall  32  of illumination distribution fixture  26 . Second support end  42  of light assembly support  38  is affixed to a lower middle portion of second end wall  30  of illumination distribution fixture  26 . Reflector  43  ( FIGS. 5 ,  9 ) may be affixed to an underside of light assembly support  38 . Reflector  45  ( FIGS. 5 ,  9 ) may be provided to cover the length of light assembly support  38 . Lighting element  48  ( FIGS. 5 ,  9 ) is affixed to a lower surface of light assembly support  38 . Protective member/diffuser  49  ( FIGS. 5 ,  9 ) may be affixed to light assembly support  38  and extend below lighting element  48 . 
         [0038]    In one embodiment, electro-chromatic diffusers are provided to selectively allow light to pass through the diffusers or to provide reflective surfaces on an underside of the diffusers, as is best seen in  FIG. 5 . First electro-chromatic diffuser  50  has a first side  52  and a second side  54 . First side  52  of first electro-chromatic diffuser  50  is supported by first side wall  28  of illumination distribution fixture  26 . Second side  54  is supported by first support side  44  of light assembly support  38 . First electro-chromatic diffuser  50  is selectively actuatable to be either substantially transparent (see, e.g., left side of  FIG. 4 ) or substantially reflective (see, e.g., right side of  FIG. 4 ). 
         [0039]    Referring back to  FIG. 5 , second electro-chromatic diffuser  56  has a first side  58  and a second side  60 . First side  58  of second electro-chromatic diffuser  56  is supported by second support side  46  of light assembly support  38 . Second side  60  is supported by second side wall  30  of illumination distribution fixture  26 . Second electro-chromatic diffuser  56  is selectively actuatable to be either substantially transparent (see, e.g., left side of  FIG. 4 ) or substantially reflective (see, e.g., right side of  FIG. 4 ). 
         [0040]    In a second embodiment, reflective panels are provided that may be positioned in a deployed configuration for reflecting light off of a lower surface or the reflective panels may be positioned in an non-deployed configuration to allow light to pass through exit aperture  16  of light well  12 . As may be best seen in  FIG. 9 , first reflective panel  62  has first side  64  and second side  66 . First reflective panel  62  is supported on first side  64  by first side wall  28  of illumination distribution fixture  26 . First reflective panel  62  is supported on second side  66  by first support side  44  of light assembly support  38 . First reflective panel  62  may be selectively positioned to be either in a deployed or non-deployed configuration. 
         [0041]    Still referring to  FIG. 9 , second reflective panel  68  has a first side  70  and a second side  72 . Second reflective panel  68  is supported on first side  70  by second support side  46  of light assembly support  38 . Second reflective panel  68  is supported on second side  72  by second side wall  30  of illumination distribution fixture  26 . Second reflective panel  68  may be selectively positioned to be either in a deployed or non-deployed configuration. 
         [0042]    Diffuser  74  may be positioned above integrated electric light assembly  36 . Diffuser  74  is positioned a distance above electric light assembly  36  sufficient to permit first reflective panel  62  and second reflective panel  68  to open fully into a non-deployed configuration. 
         [0043]    In a third embodiment, louver tray  76  is located above light assembly support (not shown) that supports protection member/diffuser  49  that houses light source  48 . Louver tray  76  has a plurality of louvers  78  that extend from first end wall  32  to second end  34  wall of illumination distribution fixture  26 . Each louver  78  is pivotal about a longitudinal axis from an open vertical orientation ( FIG. 10 ) to a closed horizontal orientation ( FIG. 12 ). 
         [0044]    The surfaces of the fixtures, e.g., first electro-chromatic diffuser  50 , second electro-chromatic diffuser  60 , first reflective panel  62 , second reflective panel  64 , and louvers  78 , may have optical characteristics that partially transmit or partially reflect light, or may be perforated to allow simultaneous transmission from above and reflection from below. Since light enters solar aperture  14  from above during sunlight hours, and light entering the system  10  from below is during non-sunlight hours, two methods for accommodating complimentary operational modes are described below. The first method is electrically based, the second is mechanically based. 
         [0045]    In the first embodiment, shown in  FIGS. 4 and 5 , electro-chromaticity enables daylight fixture diffusers  50 ,  56  to retain transparency and distribute sunlight when non-activated and to function as electric lighting fixtures when sunlight is unavailable. Silvered electro-chromaticity is defined here to refer to a material applied to, or within, a rigid or semi-rigid substrate that will change from clear to highly reflective when a photo-sensitive voltage is applied. In  FIG. 4 , silvered electro-chromic diffusers ( 50 ,  56 ) are de-activated in the left illumination distribution fixture  26  and when photo-sensitively activated, become reflective on their undersides, as shown in the right illuminated distribution fixture  26  of  FIG. 4  to distribute electric lighting into the interior space below the light fixture. 
         [0046]    Electric light  48  may be a linear lamp protected by translucent louver  49  on its underside, as shown in  FIG. 5 . The electro-chromic diffusers  50 ,  56  rest upon the side of an integrated electric light assembly  36  within an illumination distribution fixture  26 . The electric light assembly is comprised of lamps  48  whose backward directed light (A) is reflected downward by reflector  43  and an activated silvered electro-chromic reflector  56 . Downward directed light (B) and reflected light (A) pass through diffuser  49  so that the brightness or intensity of light is reduced before entering into the space below fixture  10 . When photo-sensitively activated, to become reflective on the undersides of electro-chromic diffusers  50 ,  56  and become part of the supplemental electric lighting system, which could be a linear lamp  48  protected by a translucent louver  49  on its underside. 
         [0047]    In a second embodiment ( FIGS. 6-8 ), fixtures are to be fitted with reflective panels  62 ,  68  that pivot down onto light assembly support  38  when activated. In a preferred embodiment, deployment of reflective panels  62 ,  68  are photo activated. As shown in  FIG. 6 , retractable reflective panels  62 ,  68  are positioned in an open un-deployed position when the system  10  is delivering sunlight to the building interior. Reflective panels  62 ,  68  may be hinged along the long sides of illumination distribution fixture  26  and lay on top of a portion of light assembly support  38  when fully deployed ( FIG. 8 ). The fully deployed configuration shuts off the daylight component and enables efficient reflection of the indirect lighting component of electric source  48 . Since reflective panels  62 ,  68  could be fitted with thermally insulting material, and since low light exterior conditions occur at the same time as heat loss through the fixture/light well is highest, these reflective panels will increase the U-Value of the daylight system, and significantly improve their thermal performance.  FIG. 7  illustrates a partial deployment of the reflective panels. 
         [0048]      FIG. 9  further illustrates the physical organization of a hybrid electric light fixture  10  with retractable panels  62 ,  68 . Retractable downwardly reflective panels  62 ,  68  are shown in open, partially open, and fully closed positions. The fully open and fully closed positions are functioning positions. The intermediary position occurs during activation and deactivation of electric source  48 . Light rays (A) emitted from electric lamp  48  are reflected by reflector  43  within the integrated light assembly  36  of the illumination distribution fixture  26 , and by the deployed retractable reflective panels  62 ,  68 . Light rays (B) emitted by the electric lamp in downward direction are diffused by a lamp diffuser  49  so that lamp brightness is reduced before entry into the interior space below the fixture. Sunlight diffuser  74  may be placed far enough above the deploying reflectors  62 ,  68  to allow them to move from a vertical (de-activated) position to a horizontal (activated position). 
         [0049]    In an alternative configuration of the second embodiment of this disclosure, diffuser  74  is placed far enough above the deploying reflectors  62 ,  68  to allow reflectors  62 ,  68  to move from a vertical (de-activated) position to a horizontal (activated movement, see cutaway of  FIG. 9  for illustration of partial deployment). The underside of reflectors  62 ,  68  would redirect upward components of illumination from electric source  48  downward into the space below. Reflective surfaces could also be placed on the upper sides of the deploying reflectors  62 ,  68  to send radiation back out of the building envelope, when used as a solar shading device, to reduce the amount of solar illumination reaching the interior space. Diffuser  74  may be constructed of a highly insulative material, as may the substrate of reflectors  62 ,  68 , so that the overall convective and conductive heat loss/gain characteristics of fixture  10  are minimized. 
         [0050]    An alternative configuration of the second embodiment would utilize a system of adjustable louvers  78  ( FIGS. 10-12 ). This would enable diffuser  74  to sit lower in illumination distribution fixture  26 , but is functionally equivalent to the embodiment of  FIG. 9 .  FIG. 10  illustrates a cross section of fixture  10  with reflective louvers  78  in an open position.  FIG. 11  illustrates the same system in a partially retracted position. In either of these positions, daylight is admitted into the interior space below, and much of the illumination generated by the electric source  48  would escape through the top of the fixture.  FIG. 12  illustrates the louvers  78  in a closed position such that exterior illumination is rejected out of the system and electric illumination (A, B) is reflected into the interior space of the building. 
         [0051]    Referring now to  FIG. 15A , in an additional embodiment of the invention, a daylight fixture has a lightwell  12  that defines a solar aperture  14  on an upper end. Lightwell  12  additionally has an exit aperture  16  on a lower end that is proximate a ceiling plane  20 . A diffuser  80  is located within lightwell  12  proximate to exit aperture  16 . A light source  48  is suspended below diffuser  80  on a vertical member  51 . An upper diffuser segment  82  is affixed to the lower end of vertical member  51 . Upper diffuser segment  82  is located adjacent to light source  48  and has an opaque center section  84 . A lower diffuser segment  86  is also located adjacent to light source  48 . Opaque center section  84  is sized to prevent upwardly directed light from light source  48  from projecting on aperture  16  of lightwell  12 , but is sized to allow other upwardly projecting light to shine on ceiling plane  20  through translucent section  86 . Additionally, opaque center section  84  is preferably provided with a reflective upper surface to redirect light passing through lightwell  12  and diffuser  80  upwardly toward roof plane  20 . 
         [0052]    Exit aperture  16  of daylight fixture  79  can incorporate components described previously in the disclosure, such as silvered electrochromic, drop down reflectors, or simple diffusers, for effecting various electric/solar light distributions. 
         [0053]    Another embodiment of a hybrid daylight electric light fixture that provides non-simultaneous electric light and engineered diffuse daylight is shown in  FIG. 16 . The fixture creates an upward component of sunlight within the fixture with a lightwell  12 , a clear, translucent or transitional electrochromic diffuser  90  through which sunlight A passes, a double sided downwardly concave reflector  92 , the top surface of which reflects sunlight A passing through the diffuser  90  in an upward direction, and the bottom surface of which reflects, in a generally downward direction, electric light B generated by an electric lamp  48  placed below it, and an optional diffuser (not shown) placed below the electric lamp  48  for diffusing the downwardly directed illumination produced by the lamp  48 . 
         [0054]    Thus, the present invention is well adapted to carry out the objectives and attain the ends and advantages mentioned above as well as those inherent therein. While presently preferred embodiments have been described for purposes of this disclosure, numerous changes and modifications will be apparent to those of ordinary skill in the art. Such changes and modifications are encompassed within the spirit of this invention as defined by the claims.