WO2012161765A1

WO2012161765A1 - Insulated daylighting assembly

Info

Publication number: WO2012161765A1
Application number: PCT/US2012/025569
Authority: WO
Inventors: S. Riaz HASAN; Terence O'CONNOR; Michael Sexton
Original assignee: Firestone Building Products Co., LLC
Priority date: 2011-02-17
Filing date: 2012-02-17
Publication date: 2012-11-29

Abstract

An insulated daylighting assembly including a roof curb positioned adjacent to an opening in a roof surface and a domed daylighting dome secured to a top of the roof curb. A thermally resistant glass unit is positioned on an interior side of the daylighting dome and helps to reduce heat transfer through the insulated daylighting assembly. A fall-protection screen may be secured to the roof curb, and in certain embodiments may be secured to a bottom of the roof curb. The thermally resistant glass unit reduces thermal transfer through the insulated daylighting assembly without significantly reducing the light transmittance of the assembly.

Description

INSULATED DAYLIGHTING ASSEMBLY

[OOOl] This application claims priority from U.S. Provisional Application Serial No. 61/443,775 filed February 17, 2011, which is incorporated herein by reference in its entirety.

FIELD OF THE INVENTION

[0002] One or more embodiments of the present invention relate to an insulated daylighting assembly. In one or more embodiments, the insulated daylighting assembly may include an insulating glass unit positioned on the interior side of a daylighting dome to improve the thermal resistance of the assembly.

BACKGROUND OF THE INVENTION

[0003] Daylighting systems are used in both residential and commercial settings to provide natural light to the interior of a structure. The use of natural light, as opposed to electric lighting options, reduces costs, especially when used in conjunction with a lighting control usage system, such as infrared motion sensors, photo sensors, ect. Natural light may also provide improved lighting within the building as compared to electric lighting systems alone. Daylighting systems often incorporate windows, skylights, and/or daylighting domes positioned in the roof of the structure, which may include glass or composite domed panels that allow light to penetrate into the building. The system may also include structural curb supports to which the daylighting dome is mounted, and waterproofing components, such as flashings that seal the system against water infiltration. While these daylighting domes are effective at light transmission, they often have very low thermal resistance (e.g. R-2), resulting in unwanted heat transfer though the daylighting assemblies, potentially increasing heating and cooling costs.

[0004] The low thermal resistance of daylighting domes makes them less desirable in many circumstances. For example, in a cold-storage warehouse or freezer, the heat transfer through the daylighting dome to the warmer exterior of the building increases the cost of maintaining the interior temperature. However, use of electric lights is also not ideal because electric lights produce additional convective heat, often of a greater magnitude than the solar heat gain from the daylighting dome, and they also involve the consumption of electricity while operating. The low thermal resistance of daylighting domes may also present disadvantages in other circumstances and situations, thereby limiting the use of the systems.

[0005] Thus, there is a need for an improved daylighting assembly with improved thermal resistance.

SUMMARY OF THE INVENTION

[0006] In one or more embodiments, an insulated daylighting assembly according to the concepts of the present invention includes a roof curb adapted to be positioned on a roof substrate around an opening; a daylighting dome secured to the roof curb; and a thermally resistant glass unit for reducing thermal transfer between the daylighting dome and the opening in the substrate.

[0007] In one or more embodiments, an insulated daylighting assembly according to the concepts of the present invention includes an insulated roof curb including an outwardly extending top flange and an outwardly extending bottom flange; a thermally resistant glass unit positioned over the top flange of the roof curb; a daylighting dome positioned over the thermally resistant glass unit and secured to the roof curb; and a fall-protection screen secured to the bottom flange of the roof curb.

[0008] In one or more embodiments, a method of installing an insulated daylighting assembly includes the steps of securing a roof curb around an opening in a roof substrate; positioning a thermally resistant glass unit adjacent to the roof curb so that the glass unit covers the opening; and securing a daylighting dome to the roof curb.

BRIEF DESCRIPTION OF THE DRAWINGS

[0009] Fig. 1 is perspective view of an insulated daylighting assembly according to the concepts of the present disclosure;

[0010] Fig. 2 is a top view of the insulated daylighting assembly of Fig. 1;

[0011] Fig. 3 is a side view of the insulated daylighting assembly of Fig. 1;

[0012] Fig. 4 is a section view of the insulated daylighting assembly of Fig. 1 taken generally along line 4-4 of Fig. 3; [0013] Fig. 5 is an enlarged section view of a portion of the insulated daylighting assembly as indicated in Fig. 4;

[0014] Fig. 6 is a section view of a thermally resistant glass unit suitable for use in embodiments of the insulated daylighting assembly of the present invention; and

[0015] Fig. 7 is a section view of an alternative thermally resistant glass unit suitable for use in embodiments of the insulated daylighting assembly of the present invention.

DETAILED DESCRIPTION OF THE ILLUSTRATIVE EMBODIMENTS

[0016] Aspects of the present invention are based on the discovery of daylighting assemblies including a daylighting dome and a thermally resistant glass unit. In one or more embodiments, the daylighting dome may provide improved light transfer at low sun-angles, improved strength, and reduced weight as compared to conventional glass unit skylights. The daylighting dome may be secured over a roof curb that is positioned around or within an opening in the roof surface. In one or more embodiments, the thermally resistant glass unit may be positioned within, above, or below the roof curb, and may include a hermetic thermal seal or gasket to prevent thermal transfer around the glass unit from the building's interior to the exterior, or from the exterior to the interior. In certain embodiments, one or more louvered vents may be provided in the daylighting dome frame to prevent the buildup of condensation. In certain embodiments, the thermally resistant glass unit allows for a visible light transmittance that is equal to or greater than the visible light transmittance allowed by the daylighting dome. Advantageously, the thermally resistant glass unit provides a technologically useful increase in thermal resistance as compared to the daylighting dome alone, and thereby allows for use of the insulated daylighting assembly in environments that otherwise might not be suitable for daylighting systems.

[0017] Referring now to Figs. 1-5, an exemplary insulated daylighting assembly according to embodiments of the present invention is shown, and is indicated generally by the numeral 10. Insulated daylighting assembly 10 includes a daylighting dome 12 positioned over a roof curb 14 that is structurally mounted to a roof substrate 15 around an opening 16 in the substrate. Opening 16 may be of any desired size and shape, but is most often rectangular in shape with a width of between approximately 2 and 5 ft. and a length of between approximately 4 and 8 ft.

[0018] The roof curb 14 may include a plurality of connected walls, or a single circular wall, defining an inner area. Roof curb 14 may be manufactured in a size and shape to fit in or around opening 16 or may be built on site to the desired dimensions, and may be made of metal, wood, or other suitable materials. In certain embodiments, the roof curb 14 may be a modular roof curb, and as such may be manufactured as a plurality of separate components (e.g. wall portions) adapted for assembly on an installation site.

[0019] In one or more embodiments, the roof curb 14 may have a height from a bottom edge 14a to a top edge 14b of between approximately 5 and 24 inches (12.7 and 61.0 cm), in other embodiments between approximately 8 and 20 inches (20.3 and 50.8 cm), and in other embodiments between approximately 12 and 18 inches (30.5 and 45.7 cm). In these or other embodiments, the roof curb 14 may have a length of between approximately 4 and 8 ft (122 and 244 cm). In the same or other embodiments, the roof curb 14 may have a width of between approximately 2 and 5 ft (61 and 152 cm).

[0020] In one or more embodiments, the roof curb 14 may be an insulated roof curb to reduce heat transfer through the roof curb. In one or more embodiments, the roof curb 14 may be of single wall construction and include an insulation layer 18 on an exterior surface to increase the thermal resistance of the roof curb, as shown in Figs. 4-5. In other embodiments, the roof curb 14 may be of single wall construction without an insulation layer 18. In still other embodiments, the roof curb 14 may be of double wall construction including an insulation layer between the two walls to increase the thermal resistance of the roof curb. Assemblies of this nature are known in the art as shown in U.S. Patent No. 4,418,166, which is incorporated herein by reference. As will become more apparent from the description to follow, the presence of insulation on or in the roof curb 14 may be dictated by the positioning of the thermal resistance glass unit relative to the roof curb.

[0021] In one or more embodiments, as shown for example in Fig. 4, the roof curb 14 may include nailers 19 (strips of wood) adjacent to the top and/or bottom edges of the roof curb to facilitate the attachment of various other components of the insulated daylighting assembly 10, such as, for example, the daylighting dome 12. The nailers 19 may also be used to secure waterproofing components around the insulated daylighting assembly 10, as will be described in more detail below. In certain embodiments, the roof curb 14 may also include a bottom flange 20 extending outwardly from a bottom edge thereof to facilitate attachment to the roof substrate. In the same or other embodiments, the roof curb 14 may include a top flange 21 extending outwardly from a top edge to facilitate attachment of the daylighting dome 12 and/or nailers 19. In one or more embodiments, a plurality of fasteners (not shown) may be used to secure the bottom flange 20 and the roof curb 14 to the roof substrate 15. In certain embodiments, a gasket or sealant (not shown) may be provided between the bottom flange 20 and the roof substrate to seal the interior of roof curb 14 from the ambient air.

[0022] In one or more embodiments, a fall-protection screen 23 may be provided above, below, or inside the roof curb 14 to span opening 16. Fall-protection screen 23 can be made of metal, and may be welded to form a grid-like fall-protection and safety barrier. In certain embodiments, the fall protection screen may comply with OSHA requirements as outlined in OSHA 1926.502 and OSHA 1910 regulations, and may be certified for fall protection. In one or more embodiments, the fall-protection screen 23 may be secured within the roof curb 14 as part of the manufacturing process, and may thereby be provided to the installation site pre-assembled within the roof curb 14. In other embodiments, the fall-protection screen 23 may be secured to or within the roof curb 14 during assembly or installation of the roof curb at an installation site. In certain embodiments, fall-protection screen 23 may be positioned adjacent the top edge 14b of roof curb 14, as is conventional in the art. In other embodiments, fall-protection screen 23 may be secured to roof curb 14 adjacent to the bottom edge 14a to render installation of the daylighting system 10 easier, as will be appreciated from the description to follow.

[0023] Daylighting dome 12 may be of any conventional construction known to those skilled in the art. As used herein, the term daylighting dome refers to skylights having a generally domed or otherwise non-planar configuration that is adapted to increase visible light transmittance and light diffusion through the fenestration. In certain embodiments, the shape or form of the daylighting dome may be irregular, including a plurality of "waves" or contours designed to increase the visible light transmittance at lower sun angles throughout the course of a day. In one or more embodiments, the daylighting dome 12 may be adapted for passive daylighting, which means the components of the daylighting dome 12 are stationary. In other embodiments, the daylighting dome 12 may be adapted for active daylighting, and include one or more mechanical devices used to track the sun and maximize the visible light transmittance and diffusion into the building throughout the course of the day. A suitable passive daylighting dome for use in the insulated daylighting assembly 10 of the invention is the SunWave™ Dome skylight, available from Firestone Building Products (Carmel, Indiana). A suitable active daylighting dome for use in the insulated daylighting assembly 10 of the invention is the SunWave™ SMRT™ Dome skylight, also available from Firestone Building Products (Carmel, Indiana). U.S. Patent No. 7,395,636 discloses the structure of a domed skylight in more detail, and is incorporated herein by reference for that purpose.

[0024] In certain embodiments, as shown for example in Fig. 5, daylighting dome 12 may be doubled glazed, including a first domed panel 24 arranged interiorly of a second domed panel 26, and a space 25 between the first panel 24 and second panel 26. First and second domed panels 24 and 26 may be encased in a frame 28 around the outer peripheral edges. In one or more embodiments, frame 28 may be made of extruded aluminum or other suitable metals.

[0025] Panels 24 and 26 may be made of synthetic materials such as plastic or other resin. In particular embodiments, one or more of the panels 24, 26 are made of acrylic or polycarbonate materials. In one or more embodiments, both panels 24 and 26 may be substantially clear. In other embodiments, the exterior second panel 26 may be substantially clear and the interior first panel 24 may be more translucent. In a particular embodiment, interior first panel 24 is tinted white to provide a soft yet bright light to the interior of a structure, while reducing the solar heat gain through the daylighting dome 12. In one or more embodiments, first panel 24 and/or second panel 26 may include additional coatings and/or additives to provide improved UV resistance, light diffusion, and visible light transmittance with less solar heat gain.

[0026] Frame 28 may include a mounting flange 32 to facilitate attachment of the daylighting dome 12 to roof curb 14. A plurality of fasteners may pass through the mounting flange 32 and into the roof curb 14 to secure the two components together. In one or more embodiments, a gasket or sealant (not shown) may be provided between frame 28 and/or mounting flange 32 and the roof curb 14 to seal the interior of the roof curb 14 from the exterior. In certain embodiments, one or more vents (not shown) may also be provided in frame 28 to prevent condensation from forming on the interior of the daylighting dome. In a particular embodiment, the vents may be louvered.

[0027] In one or more embodiments, and as discussed above, a thermally resistant glass unit 34 may be provided to increase the thermal resistance of the insulated daylighting assembly 10 and reduce heat transfer from daylighting dome 12 and roof curb 14 into and from the interior of a structure. The glass unit 34 may have a relatively high R-value to provide improved thermal resistance. R-value refers to the ratio of the temperature difference (ΔΤ) across an insulator and the heat flux, which is the heat transfer per unit area (Q_A) through the insulator. R-value, under uniform conditions, is represented by the following formula:

The glass unit 34 may also have a relatively low U-value, which relates to the thermal absorption of the unit. The U-value, which may also be referred to as the U-factor or the overall heat transfer coefficient, is the inverse of the R-value and is represented by the following formula:

where k is the material's thermal conductivity, and L is it's thickness. In addition, the glass unit may have good visible light transmittance properties so as to not negatively affect the lighting abilities of the insulated daylighting assembly 10. Visible light transmittance refers to the ratio of visible light transmitted through a substance to the total visible light incident on its surface.

[0028] In one or more embodiments, and as shown in Figs. 4-5, the glass unit 34 may be positioned adjacent to the top edge 14b of the roof curb 14, which facilitates installation of the glass unit. In these embodiments, the glass unit 34 may be positioned over and secured to the top flange 21 of the roof curb 14 and/or the nailer 19. A gasket or sealant 35 may be provided between the roof curb 14 and the glass unit 34 to reduce thermal transfer from the interior of the building and through the daylighting dome 12 and roof curb 14. In particular embodiments where the glass unit 34 is positioned at the top 14b of the roof curb 14, the roof curb 14 may be insulated (e.g. includes an insulation layer 18) to further reduce thermal transfer through the insulated daylighting assembly. In these embodiments, the thermal resistance (R value) of the insulated daylighting assembly 10 is only as high as the thermal resistance of the glass unit 34 or the roof curb 10, whichever is lower. Accordingly, in certain embodiments, the insulated daylighting assembly 10 may be designed so that the thermal resistance of the roof curb and glass unit are substantially the same.

[0029] It is also contemplated that in other embodiments the thermally resistant glass unit 34 may be sized and shaped to fit within the roof curb 14. In one or more embodiments, a plurality of brackets may be provided within the roof curb 14 to support and retain the glass unit 34. A gasket or sealant may be provided between the brackets and glass unit 34 to prevent thermal transfer between the interior of the building and the daylighting dome 12 and roof curb 14. In one or more embodiments, the glass unit 34 may be positioned adjacent to the bottom edge 14a of the roof curb 14 (as opposed to the upper edge 14b or in the middle) so that heat transfer through the roof curb 14 may be reduced regardless of the thermal resistance of the roof curb itself. In a particular embodiment, the glass unit 34 may be positioned over or above fall-protection screen 23, which allows the glass unit to be easily secured within roof curb 14 after the roof curb and fall-protection screen have been secured in or around opening 16.

[0030] In one or more embodiments, glass unit 34 may have an R-value of at least 8 ft²-°F-h/BTU (1.409 m²K/W), in other embodiments an R-value of at least 12 ft²-°F-h/BTU (2.11 m²K/W), in other embodiments an R-value of at least 16 ft²-°F-h/BTU (2.82 m²K/W), in still other embodiments an R-value of at least 20 ft²-°F-h/BTU (3.52 m²K/W), in other embodiments an R-value of at least 25 ft²-°F-h/BTU (4.40 m²K/W), and in yet other embodiments an R-value of at least 30 ft²-°F-h/BTU (5.28 m²K/W). In particular embodiments, the glass unit 34 may have an R-value of 40 ft²-°F-h/BTU (7.04 m²K/W) or more. The R-value may be measured according to ASTM C1363-11 (Standard Test Method for Thermal Performance of Building Materials and Envelope Assemblies by Means of a Hot Box Apparatus^') .

[0031] In certain embodiments, glass unit 34 may have a visible light transmittance of at least 30%, in other embodiments a visible light transmittance of at least 35%, in other embodiments a visible light transmittance of at least 40%, in other embodiments a visible light transmittance of at least 45%, in other embodiments a visible light transmittance of at least 48%, in still other embodiments a visible light transmittance of at least 50%, and in yet other embodiments a visible light transmittance of at least 55%. The visible light transmittance may be measured according to ASTM D1003-llel (Standard Test Method for Haze and Luminous Transmittance of Transparent Plastics^') and/or ASTM E1348-11 (Standard Test Method or Transmittance and Color by Spectrophotometry Using Hemispherical Geometry),

[0032] In one or more embodiments, glass unit 34 may have a U-value of less than 0.10 BTU/h °F ft² (0.568 W/m²K), in other embodiments a U-value of less than 0.09 BTU/h °F ft² (0.511 W/m²K), in other embodiments a U-value of less than 0.08 BTU/h °F ft² (0.454 W/m²K), in other embodiments a U-value of less than 0.07 BTU/h °F ft² (0.397 W/m²K), and in yet other embodiments a U-value of less than 0.06 BTU/h °F ft² (0.341 W/m²K) . The U-value refers to the overall heat transfer coefficient, and is a measure of the heat transfer through a building element over a given area. The U-value may be measured according to ASTM C1363-11 (Standard Test Method for Thermal Performance of Building Materials and Envelope Assemblies by Means of a Hot Box Apparatus) .

[0033] In one or more embodiments, the thermally resistant glass unit 34a, as shown in Fig. 6, may include a first glass pane 36, a second glass pane 38, and a plurality of heat reflecting films or coatings 40 spaced between the panes and oriented generally parallel to the panes. It is also contemplated that more than two glass panes may be provided, with heat reflecting films positioned between each of the glass panes. In a particular embodiment, three reflecting films may be provided, although more or less reflecting films may be included.

[0034] A plurality of internal spaces or voids 42 are formed between the glass panes 36, 38 and the reflecting films 40. The internal spaces 42 extend between adjacent panes 36, 38 and/or reflecting films 40 and have a hermetic seal at the periphery of the thermally resistant glass unit 34a, which may be formed by a sealant and optionally an adhesive tape positioned on the exterior of the sealant around the outer edges of the thermally resistant glass unit 34a. In certain embodiments, the sealant used may be a curable sealant, which may also act to secure adjacent panes and reflecting films together. In the same or other embodiments, the adhesive tape provided around the periphery of the thermally resistant glass unit 34a may be a metal backed adhesive, and may also act to secure the components of the glass unit together. U.S. Patent No. 5,156,894 describes the structure and assembly of a suitable thermally resistant glass unit having heat reflecting films or coatings in more detail, and is incorporated herein by reference for that purpose.

[0035] In one or more embodiments, a gas may be provided in the internal spaces 42 of the glass unit to improve the thermal resistance of the glass unit. Use of gasses in windows having multiple panes is well known, and any suitable gas may be employed. In a preferred embodiment, the gas may be a mixture of Xenon and Krypton. In a particular embodiment, the gas may include 50% Xenon and 50% Krypton. A suitable thermally resistant glass unit 34 for use in the insulated daylighting assembly of the invention including heat reflecting films is Eco Insulating Glass, made by Eco Insulating Glass Inc. (Mississauga, Ontario Canada).

[0036] In other embodiments, the glass unit 34 may be a vacuum insulated glass unit, indicated by the reference numeral 34b in Fig. 7. The vacuum insulated glass may include at least two panes of glass 50, 52 separated by thin separating members 54 arranged between the panes at the peripheral edges. In certain embodiments, more than two glass panes may be provided. In one or more embodiments, an array of support pillars or spacers 55 may also be provided between the panes of glass 50, 52.

[0037] A small inner cavity 56 is created between the panes 50, 52, which may be sealed at the periphery of the panes by the separating members 54. In certain embodiments, the separating members may be fused solder glass, which act to provide a hermetic seal around the inner cavity 56. In the same or other embodiments, a sealant or gasket (not shown) may be provided between the panes around the periphery of the inner cavity 56 to seal the cavity against fluid transfer. A hermetically sealed pump tube 60 is provided that communicates with the inner cavity 56 and is used to create a vacuum between the panes of glass 50, 52. After a vacuum has been attached to the pump tube 60 to create a low pressure area within the inner cavity 56, the pump tube 60 may be sealed against further air transfer therethrough. U.S. Patent Application Publication 2010/0279038 discloses the structure and method of assembly of a suitable vacuum insulated glass unit, and is incorporated herein by reference for that purpose.

[0038] The low pressure inner cavity 56 substantially eliminates conduction and convection heat transfer through the glass unit 34b. The vacuum insulated glass 34b unit also provides good light transmittance through the panel and has a decreased thickness as compared to other glass units having high R- values. An example of a vacuum insulated glass unit suitable for use in the insulated daylighting assembly 10 is manufactured by Qingdao Hengda Glass Technology Co. Ltd. (China).

[0039] In one or more embodiments, the insulated daylighting assembly 10 may have a relatively low solar heat gain coefficient, which relates to the heat generated within the building or structure by the assembly. The solar heat gain coefficient is the ratio of the solar heat gain entering the space through the daylighting assembly to the incident solar radiation. In one or more embodiments, the insulated daylighting assembly 10 may have a solar heat gain coefficient of less than 0.50, in other embodiments less than 0.45, in other embodiments less than 0.40, in other embodiments less than 0.35, and in yet other embodiments less than 0.30. The solar heat gain coefficient may be measured according to NFRC 201 :2001 (National Fenestration Rating Council - Interim Standard Test Method for Measuring the Solar Heat Gain Coefficient of Fenestration Systems Using Calorimetry Hot Box Methods^').

[0040] In one or more embodiments, the insulated daylighting assembly 10 may have a relatively low air leakage through the system. Air leakage refers to the volume of air flowing per unit time per unit area through the daylighting assembly, between the interior and the exterior environments, due to air pressure or temperature differences. In one or more embodiments, the insulated daylighting assembly 10 may have an air leakage of less than 0.07 cfm/ft² (0.356 L-sec/m²), in other embodiments less than 0.06 cfm/ft² (0.305 L-sec/m²), in other embodiments less than 0.05 cfm/ft² (0.254 L-sec/m²), in still other embodiments less than 0.04 cfm/ft² (0.203 L-sec/m²), and in yet other embodiments less than 0.03 cfm/ft² (0.152 L-sec/m²) . The air leakage may be measured according to ASTM E283-04 (Standard Test Method for Determining Rate of Air Leakage Through Exterior Windows, Curtain Walls, and Doors Under Specified Pressure Differences Across the Specimen).

[0041] A method of installing the insulated daylighting assembly 10 will now be described. In one or more embodiments, the roof curb 14 may first be assembled, if provided in modular form. In certain embodiments, the fall-protection screen 23 may be secured to the roof curb prior to attachment of the roof curb to the roof substrate around the opening 16. In one or more embodiments, the fall-protection screen 14 may be secured to the roof curb 14 by attachment tabs 25 provided on one or more of the flanges 20, 21 of the roof curb. The roof curb may then be secured to the roof substrate around the opening 16, and in certain embodiments may be secured by driving fasteners through a portion of the roof curb and into the roof substrate.

[0042] Once the roof curb has been secured to the roof substrate, the insulated glass unit 34 may be positioned within or over the roof curb. In one or more embodiments, the glass unit 34 may be positioned on the top flange 21 of the roof curb. In certain embodiments, a sealant may optionally be applied between the top flange 21 of the roof curb 14 and glass unit 34 to create a hermetic seal therebetween. In one or more embodiments, the daylighting dome 12 may then be positioned over the glass unit 34, and secured to the roof curb 14.

[0043] In one or more embodiments, waterproofing components may be installed over and around the roof curb of the daylighting system to prevent water infiltration. In certain embodiments, flashings 36 may be used to seal the daylighting system to a roofing membrane 38 covering the remainder of the roof substrate. Flashings are well known to those skilled in the art, and any known flashing suitable for the intended purpose and for use with the roofing system may be used. In one or more embodiments, the roof flashing may be secured at one end to the nailer of the roof curb.

[0044] Various modifications and alterations that do not depart from the scope and spirit of this invention will become apparent to those skilled in the art. This invention is not to be unduly limited to the illustrative embodiments set forth herein.

Claims

CLAIMS What is claimed is:

1. An insulated daylighting assembly comprising:

a roof curb adapted to be positioned on a roof substrate around an opening;

a daylighting dome secured to the roof curb; and

a thermally resistant glass unit for reducing thermal transfer between the daylighting dome and the opening in the substrate.

2. The assembly of claim 1, wherein the roof curb includes a top flange extending outwardly from a top edge.

3. The assembly of claim 2, wherein the thermally resistant glass unit is

positioned over said top flange of said roof curb.

4. The assembly of claim 3, wherein a sealant is positioned between the thermally resistant glass unit and the top flange of the roof curb.

5. The assembly of claim 1, wherein the roof curb is insulated.

6. The assembly of claim 1, wherein the roof curb is a metal roof curb.

7. The assembly of claim 1, wherein the roof curb includes a bottom flange

extending outwardly from a bottom edge to facilitate attachment of the roof curb.

8. The assembly of claim 1, further comprising a fall-protection screen secured to the roof curb.

9. The assembly of claims 1, wherein the daylighting dome includes a first domed panel and a second domed panel.

10. The assembly of claim 9, wherein the daylighting dome includes a frame secured around a periphery of the first and second domed panels.

11. The assembly of claim 9, wherein the first and second domed panels include an acrylic.

12. The assembly of claim 9, wherein the first domed panel is positioned to the interior of the second domed panel, and wherein the second domed panel is substantially clear, and the first domed panel is tinted white.

13. The assembly of claim 1, wherein the thermally resistant glass unit has an R- value of greater than approximately 8.0.

14. The assembly of claim 1, wherein the thermally resistant glass unit has a

visible light transmittance of greater than approximately 40%.

15. The assembly of claim 1, wherein the thermally resistant glass unit has a U- value of less than approximately 0.10.

16. An insulated daylighting assembly comprising:

an insulated roof curb including an outwardly extending top flange and an outwardly extending bottom flange;

a thermally resistant glass unit positioned over the top flange of the roof curb;

a daylighting dome positioned over the thermally resistant glass unit and secured to the roof curb; and

a fall-protection screen secured to the bottom flange of the roof curb.

17. A method of installing an insulated daylighting assembly comprising:

securing a roof curb around an opening in a roof substrate; positioning a thermally resistant glass unit adjacent to the roof curb so that the glass unit covers the opening; and securing a daylighting dome to the roof curb.

The method of claim 17, further comprising the step of securing a fall- protection screen to the roof curb.

The method of claim 17, where the step of positioning the thermally resistant glass unit includes positioning the thermally resistant glass unit over the roof curb.

The method of claim 17, further comprising the step of applying a sealant between the glass unit and the roof curb.