Best Practices for Designing Modular Skylight Systems for Suspended Ceilings

Transcription

1 Best Practices for Designing Modular Skylight Systems for Suspended Ceilings By Jon McHugh, Lisa Heschong, Puja Manglani, Rocelyn Dee Heschong Mahone Group June, 2003 California Energy Commission Public Interest Energy Research (PIER) Program

2 Table of Contents TABLE OF CONTENTS I LIST OF FIGURES IV LIST OF TABLES VI PREFACE VII A CASE FOR SKYLIGHTS AND SUSPENDED CEILINGS 1 Why Use Skylights? 1 Better Light Quality 2 Energy Savings 2 Productivity Increase 3 Sales Increase 3 Why Use Suspended Ceilings? 3 Flexibility 4 Acoustic Absorption 4 Concealment of Plenum Systems 4 Market Potential 5 Skylight Market 5 Suspended Ceiling Market 6 Product Delivery Options 7 Current Building Practice 8 Current Applications 8 Obstacles to Mass Application 8 Need for Modular Light wells 10 Future Skylighting Trends in California 10 organization of guidelines 10 NOMENCLATURES AND FUNCTIONS Skylight Throat Splay Light Control Devices Suspended Ceiling Other Accessories (not shown in figure) 15 SYSTEM DESIGN 16 Systems Coordination 16 Coordination Strategies During the Design Phase 17 Coordination Strategies During the Construction Phase 18 HESCHONG MAHONE GROUP i

3 Design Process for skylight Wells 19 Design Process Flowchart 20 Skylight Well Sizing and Geometry 22 Photometric Analysis 27 COMPONENT REQUIREMENTS 32 Skylight 32 Minimum Performance Requirements 32 Design Options 33 Throat 34 Minimum Performance Requirements 35 Design Options 36 Splay 37 Minimum Performance Requirements 38 Design Options 39 Light Control Devices 39 Minimum Performance Requirements 39 Design Options 40 Suspended Ceiling System 41 Minimum Performance Requirements 42 PRODUCT EVALUATION AND APPROVAL 43 Plan Review by Building Officials 43 International Code Council Evaluation Services (ICC-ES) 44 Code Requirements 44 Applicable Tests 45 Future Evaluation Standards 45 Performance Metrics 45 CONCEPTUAL SYSTEMS 46 Systems Descriptions 46 System 1: Flexible threaded rod Throat -Fixed Splay System 46 System 2: Fixed Metal Throat Adjustable Splay System 47 System 3: Tubular Adjustable Throat Fixed Splay System 48 System 4: Fixed Throat Flexible Connector Fixed Splay System 49 Sample Project 49 Schematic Design 49 Design Development 59 Component Specifications 61 REFERENCES 64 GLOSSARY 66 APPENDIX I Appendix 1: Acronyms i Appendix 2: National Construction Volume ii Appendix 3: Market Potential for Suspended Ceiling Systems in Splay Applications iii Assumptions iii HESCHONG MAHONE GROUP ii

4 Calculations iii Summary iii Appendix 4: Skylight Sizing Chart iv Appendix 5: Code Requirements v Plastic Skylights v Glass Skylights v Appendix 6: Applicable Tests vi Plastic Skylights vi Glass Skylights vi Skylights with Plastic Frames vii Miscellaneous Tests vii Appendix 7: Well Assembly Schedule ix Condition A: Owner-occupied New Construction Option 1 ix Condition B: Owner-Occupied New Construction Option 2 ix Condition C: Tenant-occupied Construction as Tenant Improvements x Condition D: Remodel of existing building x HESCHONG MAHONE GROUP iii

5 List of Figures Figure 1. Skylight application in an office (SMUD office building, Sacramento) 1 Figure 2. Ralph's Grocery. 2 Figure 3. Energy savings of Ralph s Grocery. 3 Figure 4. Suspended ceiling installation in an office (source: 4 Figure 5. California new and retrofit construction floor area by occupancy. 5 Figure 6. Column going through light well splay. 9 Figure 7. Ill-fitting acoustic panels in splay. 9 Figure 8. Section of skylight well (refer to text for definitions). 12 Figure 9. Typical spacing of systems within the plenum. 16 Figure 10. Typical spacing of systems installed on the ceiling. 17 Figure 11: Flowchart showing design process of skylight wells 20 Figure 12: Plan showing primary and secondary structural members 22 Figure 13. Skylight spacing with splay. 23 Figure 14: Skylight spacing without splay. 23 Figure 15: Large versus small skylights 24 Figure 16. Skylight without splay results in darker surfaces. 25 Figure 17: Skylight with splay has better light distribution with well-lit walls. 25 Figure 18. Isolux contour. 27 Figure 19. Detailed skylight visualization using Radiance simulation software. 28 Figure 20. Photometric report for a skylight. 28 Figure 21. Using photometrics to evaluate appropriate luminance levels. 29 Figure 22. Evaluation of uniformity using photometric analysis. 30 Figure 23. Photometric analysis of uniformity due to skylights and electric lights. 30 Figure 24. Details of a skylight. 32 Figure 25. Light distribution of a clear skylight. 33 Figure 26. Light distribution of a diffused skylight. 33 Figure 27. Different skylight shapes for plastic glazing. 34 Figure 28. Glass skylight. 34 Figure 29. Cut section of throat. 35 Figure 30. Lightwell made of acoustic tiles 36 Figure 31. Gypsum board lightwell 37 Figure 32. Cut section of splay. 37 Figure 33. Acoustic tile splay in a classroom (Olive Ranch School, CA). 39 Figure 34. Gypsum board splay (SMUD office, Sacramento) 39 HESCHONG MAHONE GROUP iv

6 Figure 35. Diffusers in AgTAC kitchen in Tulare, CA. 40 Figure 36. Reflectors in Stop and Shop Supermarket in Walpole, MA. 40 Figure 37. Louver for Olive Ranch School in Roseville, CA. 40 Figure 38. Photosensor installation. Error! Bookmark not defined. Figure 39: Skylight well dimensions 50 Figure 40: Data inputs in Skycalc to get the SFR 51 Figure 41: Well efficiency graph 52 Figure 42: Total well efficiency of light well with splay (WE1 x WE2 x Tvis of diffuser) 53 Figure 43: Well efficiency of throat using Skycalc 54 Figure 44: Well efficiency of splay using Skycalc 55 Figure 45: Total annual energy savings from skylights (Kwh/yr) 56 Figure 46: Total energy cost savings from skylights ($/yr) 56 Figure 47: Well efficiency of light well without splay using Skycalc 57 Figure 48: Total annual energy savings from skylights-light well without splay (KWh/yr) 57 Figure 49: Total energy cost savings from skylights-light well without splay ($/yr) 58 Figure 50: Spacing layout of light well with splay 58 Figure 51: Layout without splay, 12 skylights ( 3 x 4 ) with SFR 3.3% 59 HESCHONG MAHONE GROUP v

7 List of Tables Table 1: New construction floor area under roof in the United States (annual average from 1990 to 1999). 6 Table 2: Advantages and disadvantages of product delivery options (multiple and single manufacturers) 7 Table 3: Tables showing differences between small and large skylights 24 Table 4: Comparison of skylight wells with and without splay. 25 HESCHONG MAHONE GROUP vi

8 Preface The California Energy Commission s (CEC) Public Interest Energy Research (PIER) program supports research that will bring affordable and energy-efficient products to the marketplace. It is funded by California ratepayers through California's System Benefit Charges. In fulfillment of the PIER objective, this design guideline aims to energize the market for modular skylight well systems. It provides guidelines for manufacturers, designers, and contractors in the development and design of skylight well products for suspended ceilings. The main building types that will benefit from this are new and retrofit constructions of lowrise offices, retail stores and classrooms installed with suspended ceiling systems. These building types will have these characteristics: Flat or low-slope roofs, with built-up or membrane roofing Non-fire rated assemblies Unit skylights, with maximum dimensions of 8 or less This design guideline is produced as a public non-proprietary product and is not targeted to a specific construction method or a particular manufacturer. It only discusses requirements of components and connections related to the skylight system and not of adjacent systems, such as the roof assembly or suspended ceilings. Submitted to: New Buildings Institute Integrated Energy Systems Productivity & Building Science Program HESCHONG MAHONE GROUP vii

9 A CASE FOR SKYLIGHTS AND SUSPENDED CEILINGS WHY USE SKYLIGHTS? No space, architecturally, is a space unless it has natural light. - Louis Kahn, architect Figure 1. Skylight application in an office (SMUD office building, Sacramento) Numerous studies have shown the benefits of skylights and daylighting like aesthetics and better light quality. Apart from this, skylights also provide other functional benefits. In commercial building applications, skylights and daylighting also result in energy savings, productivity increases, sales increases and performance improvements. Skylighting is successfully being applied to a wider range of everyday buildings, such as schools, offices, and retail stores. HESCHONG MAHONE GROUP 1

10 Better Light Quality The most apparent benefit of a skylight is its ability to introduce daylight into the interior space. It provides light that is without flicker and has high color rendering qualities essential for commercial building occupancies. In retail applications, good color rendering is important for accurate product representations, especially for those that require customers to make color choices, such as paints or cosmetics. Better color choices result in higher customer satisfaction. In office environments, a properly designed daylit space provides better lighting conditions under which to work. This can result in fewer task-related errors. At the same time, there is a psychological comfort associated with daylighting that can result in improved worker morale. Studies also discuss an increase satisfaction as a result of employees perception of employers concern regarding their well-being. Energy Savings Skylights can result in energy savings due to daylight displacing electric lighting. This requires the use of daylighting controls, such as photosensors, in conjunction with skylight installations, to automatically turn down lights when daylight is available. In a retail case study funded by PG&E of Ralph s Grocery in Valencia, CA (see Figure 2), the installation of skylights and daylighting controls resulted in a 30% decrease in lighting energy demand 1 (See Figure 3). This figure illustrates light energy profile during most of the hours of the day and shows that two thirds of the light can be shut off due to daylight. Figure 2. Ralph's Grocery 2. 1 PG&E Daylighting Initiative: Retail Applications: Ralph s Grocery Case Study. See Reference section. 2 PG&E Daylighting Initiative: Retail Applications: Ralph s Grocery Case Study. See Reference section. HESCHONG MAHONE GROUP 2

11 Figure 3. Energy savings of Ralph s Grocery 3. Productivity Increase The daylight provided by skylight applications has also been credited with higher test scores in schools. A study funded by the Pacific Gas & Electric Company (PG&E) surveyed the performance of three school districts in California. It showed that improvements in student performance as high as 25% on test scores is strongly correlated to the presence of daylight in the classrooms 4. Sales Increase In big-box retail stores, skylights are associated with increased sales. A Walmart store in Lawrence, Kansas was outfitted with skylights on half of the store. Information derived from monitoring the sales registers showed that products located under the skylit areas had significantly higher sales than the products sold in the non-daylit areas of the store 5. Meanwhile, the PG&E also funded a survey of 108 retail stores. Two-thirds of them were daylit with skylights while the other third were not. The study showed that the daylit stores had 40% higher sales than the others 6. WHY USE SUSPENDED CEILINGS? Suspended ceilings are desirable because of their aesthetics, inherent flexibility, access to equipment, and acoustic properties. Office and retail spaces require flexibility due to regular tenant changeovers. Offices and schools require acoustic control for a good work 3 PG&E Daylighting Initiative: Retail Applications. 4 Cooper, Kenneth. November 26, Natural Classroom Lighting Can Aid Achievement. Washington Post. Page A14. 5 Wall Street Journal, November 20, Heschong Mahone Group for PG&E. Skylighting and Retail Sales. HESCHONG MAHONE GROUP 3

12 environment. In the majority of these projects, the most effective solution is a suspended ceiling system. Figure 4. Suspended ceiling installation in an office (source: Flexibility Office and retail spaces experience regular tenant turnovers and often require changes in space layout. Ceiling solutions, such as gypsum board construction on studs, require extensive work and material replacements to accommodate the constant change in space requirements, lighting layouts and air duct relocations. The modular nature of a suspended ceiling system allows for changes without needing expensive new materials or installation labor. Acoustic Absorption Recognizing that good acoustics is indispensable for verbal learning, a new ANSI standard for classrooms was issued that has strict acoustic specifications for educational spaces 7. This standard places reverberation limits on rooms that essentially require sound absorbing surfaces in classrooms. In office environments, acoustics also affect the work space. Noise in the environment affects worker concentration and comfort. A survey of 400 building managers estimated that improvements in acoustics would increase productivity by 26% 8. Concealment of Plenum Systems In offices, high-end retail stores and classrooms, aesthetics is an important design issue. An exposed ceiling solution requires coordinated design of the mechanical ducts and other systems to produce an organized-looking ceiling design. A suspended ceiling system allows the designer to conceal the plenum without resorting to a more extensive design process and additional finishing costs. 7 ANSI S Acoustical Performance Criteria, Design Requirements and Guidelines for Schools. 8 Guest article. Achieving Effective Office Acoustics. Archoustics West. HESCHONG MAHONE GROUP 4

13 In a suburban office case study 9, an exposed ceiling design would have cost the project $ $0.60 more than a suspended ceiling installation because of the additional duct design work and the finish material. Thus, removing suspended ceilings is not always a cost-saving measure. At the same time, it sacrifices the flexibility, aesthetics and acoustics of suspended ceilings. MARKET POTENTIAL Current design and construction practices indicate that there is a demand for modular skylight well products (see next section on Current Building Practice), while an analysis of the building market shows that there is a substantial volume of potential clients for such products. Information in this section is especially valuable for manufacturers interested in expanding their market share of the building industry. Skylight Market The potential market for modular skylight well products includes the building types that can take advantage of daylight benefits and that require the use of suspended ceiling systems. These building types are low-rise commercial buildings, such as offices, retail spaces, grocery stores, and schools. Data from the Dodge New Construction database shows that they make up 45% of all new and retrofit construction in California (see Figure 5). With an estimated annual commercial construction market of 84.8 million sq ft in California 10, this means a potential market of the target building types of 38.2 million sq ft. a year. Restaurant 3% Other 16% Warehouse 18% Medical 4% Hotel 5% Education 8% Lg Office 20% Retail 16% Sm office 6% Grocery 4% Figure 5. California new and retrofit construction floor area by occupancy 11. The national construction market size is estimated at 1,109 million sq ft annually. Educational, retail and office spaces make up million sq ft or 46% of the total 9 For complete case study details, please refer to the research report entitled Integrated Design of T- bar Ceilings with Skylight Wells. It can be accessed through the New Buildings Institute website: 10 Brook, Martha "California Electricity Outlook: Commercial Building Systems". See Reference section. 11 Ibid. Small office buildings are defined as having floor area under 30,000 sq. ft. HESCHONG MAHONE GROUP 5

14 construction volume. 12 This percentage figure is comparable to the California construction market. The market size for skylights can also be determined by the amount of floor area that can be installed with skylights, that is, area directly under a roof. In data gathered from the Commercial Building Energy Consumption Survey (CBECS), 68% of all built floor space is directly below a roof (See ). This means that 68% of built floor area can be installed with skylights. With a new construction of office, retail and educational space of million sq. ft. a year, there is a potential market for skylight installations of million sq. ft. of floor area annually. Table 1: New construction floor area under roof in the United States (annual average from 1990 to 1999) 13. Floors Million sq. ft. Fraction of Area Under Fraction Under Total Roof Roof % % % % % 32 3% 4 to % 22 2% > % 3 0% Total 1, % % Suspended Ceiling Market The suspended ceiling system is widely used in the commercial building sector. According to a study conducted by Armstrong Industries in 2002, suspended ceiling systems are installed in: 68% of all educational facility floor space 45% of all office floor space 46% of all store floor space There is an evident dominance of the system s application in these building types. But as evidenced by existing case studies 14, there is potential for the product application to extend to the modular skylight well, especially for splay construction, as discussed in the later sections of this guideline. Each skylight installation within a building using a suspended ceiling results in the loss of the total suspended ceiling installation area. For example, in a building with 40,000 sq ft of floor area, installed with suspended ceilings and 4 ft x 4 ft skylights with 45 splays, 36% of the total ceiling area 15 will be allocated to skylight wells. This translates to a loss of 36% of 12 Energy Information Administration Commercial Buildings Energy Consumption Survey: Building Characteristics Tables. See Appendix for details. 13 Ibid. 14 For complete documentation of case studies, please refer to the research report entitled Integrated Design of T-bar Ceilings with Skylight Wells. It can be accessed through the New Buildings Institute website: 15 Assuming 4% SFR. HESCHONG MAHONE GROUP 6

15 potential ceiling tiles sales as a result of presence of skylight splays. In contrast, if the skylight splay is made of acoustic tiles, ceiling manufacturers stand to gain 45% of the total ceiling area as additional sales volume 16. Product Delivery Options Manufacturers interested in entering the market for modular skylight wells have different options for product delivery: by fabricating only one or two components of the system and integrating with other manufacturers providing other components, or by providing the whole modular well system as a kit. Each option has advantages and disadvantages, for both the manufacturer and the consumer. Table 2: Advantages and disadvantages of product delivery options (multiple and single manufacturers) Description Multiple Manufacturers Different manufacturers will supply the unit skylights, and lightwell components Advantages Manufacturers can use existing manufacturing expertise and equipment, without having to expand their manufacturing capabilities Consumers can have multiple sources of interchangeable parts Promotes competition among component suppliers Disadvantages No single point of responsibility and liability for consumers Requires industry standards for connectors to allow components from different manufacturers to fit together seamlessly T-bars should be able to be fairly standardized Will require more coordination work during construction Greater uncertainty in the assembled product s overall performance Single Manufacturer One single manufacturer will supply all components associated with a skylight well system as a kit Single point of responsibility and liability. Less coordination required between different manufacturers Connections between components can be better designed or even be completely eliminated Allows manufacturers to differentiate products Requires expansion of manufacturing capabilities of suppliers beyond their current expertise Consumers must buy proprietary systems from a single supplier 16 See Appendix for calculation. HESCHONG MAHONE GROUP 7

16 CURRENT BUILDING PRACTICE Information on current building practice and needs are gathered from case studies on existing buildings with integrated skylight wells and from a series of Technical Advisory Group (TAG) meetings conducted with various industry representatives. The case studies consisted of twenty existing projects that have integrated skylight installations with a suspended ceiling system 17. Evaluations were based on plan reviews, site visits, and interviews with project managers and construction managers. The TAG meetings are brainstorming sessions conducted by the research group to receive inputs from the industry regarding their needs from a modular skylight well market. Participants are architects, lighting designers, and manufacturers of skylights and suspended ceiling systems. These interactions with industry representatives indicate that there is a demand in the building industry for a modular skylight well product. Current Applications Existing applications of integrated skylight wells are in both new and retrofit construction work. These projects include classrooms, chain grocery store, big-box retailers and offices. The existing systems were mostly custom-designed and site-built systems. The only premanufactured systems used were tubular skylights. Obstacles to Mass Application Depending on their success in integrating skylights and suspended ceilings, project and construction managers of the case studies gave their feedback on the design and construction process. The major obstacle to the mass application of skylight wells is that due to lack of prefabricated components, these systems have to be custom-designed and site-built. Problems associated with this include cost, difficulty of quality control, performance uncertainty, and difficulty in maintenance. Quality Control Site-built systems require on-site construction of components. The use of manual workmanship can result in inconsistency of quality, which can affect the aesthetics of the space, or in the worst case, safety of occupants. In the case of a grocery store chain, suspended ceiling system was used for the skylight splay construction. Due to lack of prefabricated splay components, tiles and runners had to be cut and bent on-site. Though the general aesthetics of the sales area was unaffected, a closer inspection would reveal incongruent sizes and shapes of components. Figure 6 and Figure 7 below shows examples of these issues. 17 Heschong Mahone Group Integrated Design of T-bar Ceilings with Skylight Wells. See Reference section. HESCHONG MAHONE GROUP 8

17 Figure 6. Column going through light well splay. Figure 7. Ill-fitting acoustic panels in splay. Performance Uncertainty The electric lighting industry is mature, with fixtures and luminaries mass-produced in a factory and every manufacturer providing photometric reports and light output test results. This information allows designers to predict luminaire performance and to design space lighting accordingly. Meanwhile, outputs of skylight well systems are predicted based on relatively crude calculations by the designer. Their performances are unpredictable and do not conform to any performance standards. The TAG participants have stressed their need for such a standard. The existence of prefabricated systems will allow for tests to be conducted on prototype systems where the final mass-produced product will perform at levels close to the tested results. The lower level of sophistication of skylight calculations is mainly due to scarcity of skylight photometric data available for use. Maintenance Problems Maintenance problems result due to the use of custom parts. Any replacements that are required would have to be special order or have to re-cut or re-bent, causing inconvenience and delays in the construction schedule. Higher Cost One of the retail case studies 18 evaluated different methods of incorporating a skylight with suspended ceilings, and found the available options too expensive. While material costs of site-built lightwells may be less than a pre-manufactured skylight well system, their installation costs could be higher. There is a trade-off between material costs, installation costs and number of skylights required. In a custom-designed system, there will be a longer design schedule due to increased coordination work among system designers. In a site-built system, there will be a longer construction schedule due to on-site cutting and adjustments. Some construction managers interviewed would like to see about a 50% reduction in cost and the availability of a kit of parts skylight system that will make it easier to install. 18 Heschong Mahone Group Integrated Design of T-bar Ceilings with Skylight Wells. See Reference section. HESCHONG MAHONE GROUP 9

18 Need for Modular Light wells Among the retailers interviewed 19, one is currently considering using skylights, but is uncertain about hoe to specify light wells that are compatible with suspended ceilings. Two other retail stores do not use skylights if their stores have dropped ceilings. A major big-box retailer is currently integrating skylights with suspended ceilings, but has not been doing it on a wider-scale because of lack of a better coordination solution with other building systems like HVAC, sprinkler, etc. These case studies show that there is a demand in the building industry that needs to be addressed. The problems associated with the current method of custom-designing and building skylights can be resolved through the use of prefabricated skylight wells. These issues present a challenge for product manufacturers to develop an alternative more flexible well system that will achieve the required performance criteria while accommodating these inconveniences and improving the coordination process. FUTURE SKYLIGHTING TRENDS IN CALIFORNIA The market for skylights will be greatly affected by revisions that have been proposed for the California Energy Code (Title 24). The new 2005 Title 24 Nonresidential Standards will be made mandatory in the year The most notable change that will impact the industry is the establishment of skylights as a prescriptive measure 21 for low-rise nonresidential buildings that have spaces larger than 25,000 sq ft directly under a roof and a with a ceiling height greater than 15 ft. For these buildings, at least half of the space is required to be daylit. In spaces with less than 1 W/SF lighting power density, the required skylight to floor area ratio (SFR) must be at least 3%. In spaces with greater than 1 W/sq.ft lighting power, the required SFR must be at least 3.6%. The code also places a prescriptive upper limit on SFR of 5% for all buildings, except atria greater than 55 feet high. The standards will have a mandatory automatic light controls requirement for skylit spaces greater than 2,500 sq.ft. These controls have to be multi-leveled either by multilevel steps of control or continuous dimming. ORGANIZATION OF GUIDELINES The modular skylight guidelines are organized as follows: Nomenclature and Functions The second chapter establishes a common nomenclature so that industries members can begin to communicate ideas and create understanding among themselves. Functions 19 Heschong Mahone Group Integrated Design of T-bar Ceilings with Skylight Wells. See Reference section Building Energy Efficiency Standards for Residential and Nonresidential Buildings. Draft 3, February 2003, P D3. 21 Non-residential buildings can comply with the Energy Code by using either of two approaches: prescriptive or performance approach. Buildings that choose to comply using the performance method will be compared to the efficiency of a building using the prescriptive measures. They should use an alternative measure to achieve the same energy savings as a building using skylights. HESCHONG MAHONE GROUP 10

19 associated with each component are also included to define the functional basic requirements. System Design The third chapter lays out the process of designing a skylight well. Preliminary design is done by using rules of thumb and by accommodating other building services. More in-depth analysis can be accomplished by using photometrics and isolux graphs. This section also discusses the coordination of skylights with other systems from the design to the construction stages of a project. Component Requirements The fourth chapter discusses the geometry and physical properties required of each component to satisfy their performance goals. Product Evaluation and Approval The fifth chapter explains the approvals and evaluation process that will allow modular skylight well systems to be installed in buildings. It addresses the building permit plan check, third-party product evaluation and applicable codes and tests. Conceptual Systems Lastly, the sixth chapter presents four conceptual systems that were developed through brainstorming and design sessions with industry professionals. A detailed step by step design process is explained through one example as a sample project. HESCHONG MAHONE GROUP 11

20 Nomenclatures and Functions The skylight well system refers to the set of components necessary to deliver daylight from the exterior, through the plenum space, into the building interior. It encompasses the following components: Figure 8. Section of skylight well (refer to text for definitions). 1. Skylight A skylight is a glazed opening in a roof to admit light. HESCHONG MAHONE GROUP 12

21 It encompasses the following sub-components: 1a. Frame The skylight frame is the structural frame supporting the glazing of the skylight. It includes the condensation gutters and the seals and gaskets necessary for its installation. 1b. Glazing The glazing refers to the glass or plastic lenses used as to cover the skylight opening. 1c. Skylight-Curb Connection The skylight-curb connection is the interface between the skylight frame and the rooftop curb. It includes all accessories required for the proper attachment of the skylight, such as fasteners, and flashing. 2. Throat The light well is composed of two components, the throat and the splay. They both serve as conveyances of daylight from the skylight into the interior space. The throat is the tubular component (can be rectangular or circular in section) connecting the skylight to the splay. In the absence of a splay, it is attached directly to the ceiling plane. It is comprised of the following components: 2a. Throat Attachment to Structure This connection refers to the interface between the throat and the building structure. This attachment holds up the throat by providing support. 2b. Throat Interconnector This refers to a component that attaches two pieces of throat material (e.g. gypsum board, acoustic tile, or sheet metal tubes) together. It may be a rigid connection, or an adjustable component that allows for vertical, horizontal or angular displacement of the throat. 2c. Throat Structural Support This refers to the throat support that provides lateral and seismic stability. It may be a rigid brace, hanger wire or other alternative types of support system. 3. Splay The splay is the second component of a light well. A splay is the oblique transitional component of the light well that starts at the bottom of the throat and connects to the ceiling. The use of a splay will provide better light distribution into the interior space. 3a. Splay-Throat Connector The splay-throat connector attaches the splay to the throat. It can be a simple attachment or it can incorporate an adjustable assembly that allows for horizontal, vertical or angular displacements. HESCHONG MAHONE GROUP 13

22 3b. Splay Interconnector The splay interconnector joins two pieces of splay material (e.g. gypsum board, acoustic tile or sheet metal tubes). It may be a rigid member or an adjustable component that allows for horizontal, vertical or angular displacements. 3c. Splay Structural Support This refers to the support that provides lateral and seismic stability for the splay. It may be a rigid brace, hanger wire or other alternative types of support system. 4. Light Control Devices Light control devices are attachments to the light well that modulate the amount of daylight coming through the skylight. One or more devices can be used at the same time in a light well system, depending on the design requirements. Types of light control devices are: 4a. Louvers Louvers are slanted metal slats attached to the throat that controls the amount of daylight coming through. They can be installed as an integral part of the skylight frame. 4b. Interior Diffusers A diffuser is any kind of glazing material installed within the light well that diffuses the light from the exterior into the interior. The most commonly used diffusers are prismatic acrylic lenses installed at the bottom of a skylight well. 4c. Suspended Reflectors (not shown in figure) Reflectors are lighting accessories made of reflective material installed at the bottom of the light well to diffuse daylight by bouncing it off the ceiling or splay. 4d. Baffles (not shown in figure) Baffles are opaque or translucent plate-like protective shields used against direct observation of a light source. 4e. Device connectors These connectors attach the light control devices onto the throat or splay, as their design requires. 5. Suspended Ceiling A suspended ceiling is a ceiling grid system supported by hanging it from the overhead structural framing. 5a. Runners Runners are cold-rolled metal channels used to support ceiling tiles. HESCHONG MAHONE GROUP 14

23 5b. Ceiling Tile A ceiling tile is a preformed ceiling panel composed of mineral fiber or similar material with good acoustical and thermal properties, and a textured finish appearance. 5c. Ceiling-Splay Connector The ceiling-splay connector joins the splay to the ceiling. It can also serve as concealment for this junction. 6. Other Accessories (not shown in figure) Electric light fixtures, air diffusers or grills, sprinkler heads, other devices like smoke detectors, security cameras, etc. HESCHONG MAHONE GROUP 15