Council: Skylight/Sloped Glazing Council

Acrylic
A light transmitting, easily fabricated thermoplastic material that is available in molding resin and sheet form for use in skylights. It can be cold bent for use in barrel vaults or thermoformed for use in shaped or domed skylights. Part of a class of thermoplastics characterized by light weight and flexibility for use as a substitute for glass. Special acrylic grades are available modified for improved impact resistance.

Aerogel
A light transmitting, nanoporous silica derived from a gel, in which the liquid component of the gel has been replaced with a gas. A synthetic porous material characterized by hydrophobicity (highly water repellent) and ultra-low thermal conductivity, used as a filler in architectural glazing.

Air Leakage
Air Leakage (AL) is indicated by an air leakage rating expressed as the equivalent cubic feet of air loss through a square foot of product area (cfm/sq ft).

Annealed Glass
Glass that has not been heat-treated and is essentially strain free; often referred to as “ float glass”.

Bent Glass
Glass that has been curved by heating to above its softening point and then bent by gravity or press molds; also termed “curved glass”.

Bite
Depth of glass engagement within the glazing channel; also termed “purchase” and “edge engagement”.

Cap or Counter Flashing
Used to protect and waterproof (by overlapping) terminated top edges at curb or base flashing.

Cladding
An exterior covering or skin applied to framing or a structure for aesthetic or protective purposes.

Condensation Gutter
A trough for carrying off condensed or infiltrated water; this may be drained to the exterior or allowed to evaporate.

Condensation Resistance Factor
Condensation Resistance Factor (CRF) measures the ability of a product to resist the formation of condensation on the interior surface of the product. The higher the CRF rating, the better that product is at resisting condensation formation. While this rating cannot predict condensation, it can provide a credible comparison of the potential of condensation formation between products.

Copolyester
A light transmitting, easily fabricated impact resistant thermoplastic material that is available in molding resin and sheet form for use in skylights. It can be cold bent for use in barrel vaults or thermoformed for use in shaped or domed skylights. Part of a class of thermoplastics characterized by high-impact strength, light weight, and flexibility, and used as shatter-resistant substitutes for glass.

Cricket
A ridged roof attachment that is designed to divert water on a roof around a penetration.

Cross Rafter or Purlin
In a skylight system, a structural framing member between rafters; generally at or near horizontal.

Curb or Base Flashing
Used for waterproofing at a curb or base.

Curb Mount
A skylight frame design that enables installation and anchoring of a skylight to a typically 1 ½” wide flashed wood curb, which is a permanent part of the roof structure. (This type of installation is typical on a low sloped roof.) Generally, curb mounted skylights are installed after roof construction.

Daylight Harvesting
The effective use of natural light from both the sun and the sky for meeting at least part of the lighting needs within an occupied space. Associated with this is an expectation that all or part of the installed energy consuming lighting system responds to some type of lighting control strategy driven by the available daylight.

Dead Load
Load from the permanent parts of a building or structure.

Dome Rise
The height of the dome above the perimeter flange of the dome. (Maximum strength for a free-blown dome is achieved with a rise of 20% to 25%.)

Dome Spring Line or Point of Curvature
The transition point at which the horizontal mounting flange of the dome begins to rise. (The spring line must be over the internal skylight gutter for condensation to be captured and eliminated through weep holes.)

Double Glazed
Any glazing consisting of two panes of glazing separated by an air space.

Dynamic Glazing
Any Glazing System/Glazing In-fill that has the fully reversible ability to change its performance properties, including U-factor, solar heat gain coefficient (SHGC), or visible transmittance (VT). This includes, but is not limited to, shading systems between the glazing layers and chromogenic glazing. (Per NFRC)

Edge Block
Blocks of elastomeric material used at the sides of the glass as support and to prevent direct contact with the framing member; mandatory for dry glazing systems.

Fiberglass Reinforced Polyesters (FRP)
Composite material that consists of a plastic matrix containing reinforcing glass fibers to increase strength or stiffness.

Flashing
Corrosion resistant material used for controlling, redirecting or preventing water from entering a structure.

Footcandle (fc)
A unit of illuminance (amount of luminous flux) incident on a surface, equal to one lumen per square foot (1 lm/ft2).

Fully Tempered Glass
Glass that has been heated and quenched in a controlled operation to provide a high level of surface compression. ASTM Standard C1048-85 specifies that the surface compression be a minimum of 10000 psi. Generally considered to have four times the strength of annealed glass and two times the strength of heat-strengthened glass.

Haze Factor
The percentage of light through a glazing material that is diffused. (A 100% haze factor would equate to 100% of the light being diffused. Codes require skylights to have a minimum 90% haze factor.)

Heat-Strengthened Glass
Glass that has been heated and quenched in a controlled operation to provide a degree of surface compression. ASTM Standard C1048-85 specifies that the surface compression be between 3500 and 10000 psi. Generally considered to have two times the strength of annealed glass.

High Impact Acrylic
Glazing material which has an impact modifier blended with the acrylic resin to meet specific impact requirements.

Insulating Glass Unit
Factory fabricated double glazing with the periphery of the air space sealed to minimize infiltration of water vapor.

Laminated Glass
A sandwich of two or more glass plies bonded together with resilient plastic interlayers, normally polyvinyl butyral (PVB).

Light or Lite
A single glazing pane; use of “lite” is preferred to avoid confusion; most often referred to as “pane.”

Light Diffusion
The scattering of light caused by passing through a non-transparent material or by bouncing off semi-reflective surfaces. Diffusivity of a glazing material is represented by measurement of its “haze factor.”

Live Loads
Loads from people and non-permanent parts of a building; loads from window washing and glazing rigs are live loads.

Low Emittance (Low E) Coating
A coating that has a reduced ability to radiate heat energy; when facing an air space this property reduces the amount of heat transfer across the space.

Lumen (lm)
The unit of luminous flux in the International System, equal to the amount of light given out through a solid angle (steradian) by a source of one candela (cd) intensity radiating equally in all directions. The lumen (lm) is a measure of the total “amount” of visible light emitted by a source. Luminous flux differs from power (radiant flux) in that luminous flux measurements reflect the varying sensitivity of the human eye to different wavelengths of light, while radiant flux measurements indicate the total power of all electromagnetic waves emitted by a source, independent of the eye’s ability to perceive it.

Lux (lx)
The SI unit of illuminance, equal to one lumen per square meter (1 lm/m2).

Model Building Code
A construction code developed from input from industry, building officials, and others for use as a guide for the development of state and local building codes. Model building codes have not legislative or jurisdictional power.

Multi-wall Sheet
A light transmitting thermoplastic glazing material with a cellular internal structure for increased thermal insulation.

Muntin
A non-structural dividing member between glass panes.

Pane
(see “Light or Lite”)

Passive Heating (solar)
Occurs when solar energy  enters a building through the thermal envelope and heat the air, floors, walls, furniture, etc. Some materials, such as stone, brick and plaster, more effectively absorb the heat. The absorbed heat is slowly released, impacting the load on HVAC equipment.

Point of Curvature
( see “Dome Spring Line”)

Polycarbonate
A light transmitting, impact resistant thermoplastic material that is available in molding resin and sheet form for use in skylights. Sheets can be cold bent for use in barrel vaults or thermoformed for use in shaped or domed skylights. Part of a class of thermoplastics characterized by high-impact strength, light weight, and flexibility, and used as shatter-resistant substitutes for glass.

Prismatic Sheet
Thermoplastic sheets with embossed pyramidal patterns that refract and diffuse light. Commonly used in skylights and other light diffusing applications.

Purlin
(see “Cross Rafter”)

Rafter
For sloped glazing, a main nominally sloped framing member.

Roof Monitor
Another form of top-lighting; a projecting portion of the roof with a vertical glazing component, sometimes referred to as clerestory windows.

Saddle Flashing
Flashing that is used on the head (upper) end of unit skylights, for the purpose of unrestricted water drainage around the skylight. Can be an alternative to a cricket.

Seismic Load
Building movement and forces caused by earthquake motion.

Self-Flashing
A skylight base that mounts directly to the roof without requiring a curb.

Setting Block
Blocks of elastomeric material used at the bottom edges of the glass as support and to prevent direct contact with the framing member; mandatory for dry glazing systems.

Skylight
A glazing and framing assembly consisting of sloped and (sometimes) vertical surfaces; the assembly is generally inserted into the roof of a building to admit daylight.

Side-lighting
Side-lighting from windows and doors provides daylight and solar energy along the perimeter of a building.

Sloped Glazing
Glass or other transparent or translucent glazing material installed at a slope of 15 degrees (0.26 rad) or more from vertical. Glazing material in skylights, including unit skylights, solariums, sunrooms, roofs and sloped walls are included in this definition. (Per 2012 IBC)

Sloped Roof
A roof slope greater than two units vertical in 12 units horizontal (17 percent slope). Up to four units vertical in 12 units horizontal (33 percent slope) is considered a low slope; above this slope is considered high slope. (Per 2012 IBC – Chapter 15)

Snow Load
Load imposed on a building wall, roof, or skylight by the accumulation of snow; generally a long-term load.

Solar Heat Gain Coefficient
A measurement of how well a product blocks heat from the sun. (SHGC) is the fraction of incident solar radiation admitted through the glazing, both admitted through and directly transmitted, and absorbed and subsequently released inward. The lower a product’s SHGC, the less solar heat it transfers.

Stack Effect
The natural tendency of warmer air to rise above cooler air. In a building air will flow upward if there is a lower inlet and a high outlet, thereby accelerating the cooling effect of natural ventilation.

Stepped Flashing
Sections of overlapping flashing pieces usually woven into tile or shingle roofs at curb or base conditions.

Tempered Glass
(see “Fully Tempered Glass”)

Top-lighting
Top-lighting from roof-top fenestration systems can provide daylight and solar energy throughout the interior of a low rise building, on the top floor of a building or in an atrium.

Translucent Insulating Panels
A lightweight structural sandwich panel that combines a translucent inner and outer glazing element with an insulated internal cavity. They are typically flat but can be shaped to a large radius.

Tubular Daylighting Device (TDD)
A non-operable fenestration unit primarily designed to transmit daylight from a roof surface to an interior space via a tubular conduit. The basic unit consists of an exterior glazed weathering surface, a light- transmitting tube with a reflective interior surface, and an interior-sealing device such as a translucent diffusing panel. The unit can be factory assembled or field-assembled from a manufactured kit.

A TDD product line can be tested and rated differently, based upon insulation location, and product configuration (closed or open ceiling). (Based on 2012 IBC)

U-Factor
A measurement of how well a product prevents heat from being transmitted. The lower the U-factor, the better the product’s insulating value.

Unit Skylights
A factory-assembled, glazed fenestration unit, containing one panel of glazing material that allows for natural lighting through an opening in the roof assembly while preserving the weather-resistant barrier of the roof.

Unit skylights are either fixed (non-operable) or venting (operable). (Per 2012 IBC)

Ventilation
The process of supplying and removing air by natural or mechanical means to and from any space. Such air may or may not be conditioned. Proper ventilation improves indoor air quality by allowing air changes within the indoor environment.

Visible Light Transmittance (TVIS or VT)
Visible Light Transmittance (VT) measures how much light comes through a product. The visible transmittance is an optical property that indicates the amount of visible light transmitted.

Weep Hole
A hole placed in a framing member to allow condensed or infiltrated water to drain to the exterior of the structure.

Wind Load
Short duration load on a structure and its components due to the effects of the wind.

There are more than a dozen trades in which workers are permitted regular access to flat or low-sloped roofs, including but not limited to roofing, building maintenance, HVAC, electrical, plumbing and telecommunications personnel.

According to the FGIA (previously known as AAMA) 2015/2016 U.S. Industry Market Study, there are nearly 275,000 commercial unit skylights sold annually. Nearly all commercial unit skylights installed on roofs accessed regularly by workers are aluminum framed and most use some form of plastic glazing (acrylic is most common).

It is difficult to determine how many workers are exposed to the fall hazards on a roof every day. According to the Bureau of Labor and Statistics, there are more than 120,000 roofers alone who are obviously at risk. Add in the other trades that frequently access flat or low-sloped roofs and MILLIONS of existing unit skylights on the roofs…the risk exposure is significant.

Periodically, fatalities attributed to skylights (which may include uncovered roof openings) are highlighted in industry publications and outside media. As illustrated in the graphics below, the actual number of fatalities associated with skylights and skylight openings is very small when compared to other workplace injuries and fatalities. It is important for all workers that access the roof to be aware of all the hazards, including the potential to fall into a skylight, and how to prevent such incidents.

NOTE: A child should never have access to a roof where they could fall. 

Click here to view a PDF of infographic

The risk exposure of falling through a skylight opening is SIGNIFICANT.

The actual number of fatalities attributed to skylights is comparatively MINIMAL.

BUT … every fall fatality is AVOIDABLE.

Currently, there is not a standardized method for testing a skylight for its ability to withstand an impact from a falling human. OSHA, and similar authorities, has established regulations – but the skylight industry generally agrees that these regulations are vague and open to different interpretations. ASTM has drafted a standard and test method to validate a skylight’s (or related product’s) ability to support the effect of the impact from a large male, and the extensive review process is underway.

Fall protection must be shared amongst the many parties involved with the design, construction and maintenance of roofs. The following established safety procedures for minimizing risk should be implemented and followed first as a strong foundation for mitigating the occurrence of all falls from roofs and roof openings. When the glazing is not proven to be sufficiently resistant to falls, the use of railings, security grids or safety screens (not to be confused with insect or glass retention screens) are recommended.

Courtesy of Wasco

1. Only construction and building maintenance professionals should ever be on a roof, as there are a number of potential fall hazards present, including skylights. Access to a roof is the responsibility of the building owner and should be limited to such personnel by whatever reasonable means necessary.
2. Applicable OSHA safety regulations should be complied with at all times when it is necessary for individuals to be on a roof. This may include, but is not limited to, the use of guards, PFAS (personal fall arrest systems) and warning signs.
3. All individuals allowed to be on a roof as described above must be fully trained on roof safety by their employer and should have the competence and sense of personal responsibility and personal safety to follow all roof safety practices. The employer should have qualified personnel identify all potential roof hazards and ensure that all precautionary measures and practices are implemented. This may include, but is not limited to, the use of temporary barriers, PFAS (personal fall arrest systems) and warning signs. The potential hazards and safety measures implemented specific to the site must be communicated to and understood by all personnel working on the roof.
4. Signage should be posted by the building owners and managers at each access point on to the roof communicating roof safety and inherent dangers.
5. Skylights, and the roofs they are mounted in, are designed to resist the applicable environmental load requirements such as snow loads, wind loads, dead loads and, in some cases, hurricane-induced wind-borne debris impact loads. Standard design practices do not dictate that they are to be manufactured for human impact or point loads. Warning labels on skylights indicate this, as required by some evaluation entities (such as International Code Council-Evaluation Service) since 1986. In some cases, signage properly placed at roof access points has been employed to communicate this as well.

More information regarding the bullet points above can be referenced from the National Institute of Safety and Health (NIOSH).

The FGIA Skylight/Sloped Glazing Council has worked diligently for over 30 years to establish technically solid performance standards and design guidelines in which safety has always been an important consideration. The issue of fall protection is not a new one. Manufacturer members of the FGIA Skylight/Sloped Glazing Council have been proactive in improving the safety performance of their products; as manufacturers of a product that is installed on a roof by customers, roof safety issues have been a consideration for some time.

As such, the Council’s mission is to look objectively at this issue and all its elements from which the data is derived. The FGIA Skylight/Sloped Glazing Council will continue its commitment to roof safety as presented here and will endeavor to pursue reasonable approaches in the future through the FGIA Fall Protection Task Group, along with continued participation in ASTM’s E06.51 .25 Sub-committee developing Work Item WK17797. This group’s draft document is entitled Standard Specification for Human Impact and Fall-through Resistance of Unit Skylights and Related Products Used on Skylight Openings on Non-Residential Buildings.

In January of 2017, the Occupational Safety and Health Act’s (OSHA Act) updated criteria, created by the Occupational Safety and Health Administration (OSHA), went into effect. The update included new criteria for protecting workers from falls through skylight openings. However, the state of California did not update their Cal/OSHA requirements (see endnote). The updated OSHA Act criteria for skylight openings allows for more flexibility for the building owner and contractors to comply, but also increases confusion on demonstrating compliance. This is largely due to removing the previous language without replacing it with more specific criteria. The previous language stated:

[29 CFR 1910.23 (a)(4)]
“Skylight screens shall be of such construction and mounting that they are capable of withstanding a load of at least 200 pounds applied perpendicularly at any one area on the screen. They shall also be of such construction and mounting that under ordinary loads or impacts, they will not deflect downward sufficiently to break the glass below them. The construction shall be of grillwork with openings not more than 4 inches long or of slat work with openings not more than 2 inches wide with length unrestricted.”

The FGIA Skylight and Sloped Glazing Council has previously expressed its concerns about such problematic language. The primary issues included, but were not limited to, the following:

1. The 200-pound load is not sufficient, nor is the description of how the load is applied. Relatively weak screen products have been shown to pass this requirement when sand bags are carefully stacked to apply the load. The load requirement should be a dynamic drop test, to more closely replicate the impact forces of a falling worker.
2. We questioned the need to protect the skylight glazing from breakage since the goal of the safety screen is not to protect the product, but the worker from falling through the skylight opening.
3. The skylight itself is often stronger than the ‘screen’ that is required to be installed on top. It does not clearly state that the skylight itself, could act as the ‘cover’ for the skylight opening.

We are glad to see that this language has been removed. However, as a result, the new criteria for protecting a skylight opening reverts to the general requirements of all “covers” for roof and floor openings (including skylight openings):

[29 CFR 1910.29(e)]
“Covers. The employer must ensure each cover for a hole in a walking/working surface:
[29 CFR 1910.29(e)(1)]
Is capable of supporting without failure, at least twice the maximum intended load that may be imposed on the cover at any one time; and
[29 CFR 1910.29(e)(2)]
Is secured to prevent accidental displacement.”

The lack of providing a well-defined load and impact rating leaves compliance open to considerable interpretation. The building owner and contractor look to the skylight and/or screen manufacturer who in turn looks to the building owner and contractor for their specifications. Of course, nobody wants to make the assumptions required, thus absorbing potential liability. And again, how should the load be applied, and over what area? Is it dynamically by a severe drop bag test or by carefully stacking sand bags until the desired load is achieved? These are critical questions that should not be left open.

Due to a lack of a standard for testing “covers”, members of the FGIA Skylight and Sloped Glazing Council have worked diligently for several years with other concerned individuals and safety organizations in the development of an ASTM standard tentatively titled, “Human Impact and Fall-through Resistance of Unit Skylights and Related Products Used on Skylight Openings on Commercial Buildings.” This work is scheduled for a third and likely final ballot with publication shortly thereafter.

The ASTM standard is intended to qualify the skylight opening cover in the event of a single worker accidentally falling, for most cases. However, the results obtained from use of this standard may or may not provide sufficient information in all scenarios.

At this time, it is not possible for a skylight or screen manufacturer to claim a product is “OSHA Compliant.” The criteria set forth, as outlined above, does not provide a clear definition of all the requirements. This is problematic for not just building owners but, the entire industry including manufacturers, suppliers and contractors. The FGIA Skylight and Sloped Glazing Council is committed to addressing this issue, which of course will take time. As changes are made, this web page will be updated in an effort to communicate the current status to all who are impacted by this issue.

EndNote: Cal/OSHA still exists with a different set of criteria, which states:

(b) Floor and roof opening covers shall be designed by a qualified person and be capable of safely supporting the greater of 400 pounds or twice the weight of the employees, equipment and materials that may be imposed on any one square foot area of the cover at any time. Covers shall be secured in place to prevent accidental removal or displacement, and shall bear a pressure sensitized, painted, or stenciled sign with legible letters not less than one inch high, stating: “Opening -Do Not Remove.” Markings of chalk or keel shall not be used.

(e) Any employee approaching within 6 feet of any skylight shall be protected from falling through the skylight or skylight opening by any one of the following methods:

(1) Skylight screens installed above the skylight. The design, construction, and installation of skylight screens shall meet the strength requirements equivalent to that of covers specified in subsection (b) above. They shall also be of such design, construction and mounting that under design loads or impacts, they will not deflect downward sufficiently to break the glass below them. The construction shall be of grillwork, with openings not more than 4 inches by 4 inches or of slatwork with openings not more than 2 inches wide with length unrestricted, or of other material of equal strength and similar configuration.

The AAMA SKY-3, Skylight Selection and Daylighting Design Guide including Unit Skylights, Tubular Daylight Devices (TDD) and Sloped Glazing is intended to provide the user with a better understanding of the features and performance characteristics necessary for the effective use of skylights and sloped glazing in today’s building environment.

Key concepts covered include:

• The design considerations and selection criteria needed for the various roles of skylights, from building aesthetics to functional top-lit daylight design
• Summarizing the building code criteria and environmental factors to consider
• Product and component available options

It is the industry’s first comprehensive document to cover all these concepts together.

Request a free download now.

What exactly is FGIA?

FGIA is the leading trade association representing glass, window, door, skylight, curtain wall and storefront manufacturers, suppliers and test labs. Members address issues of critical importance, share experience and knowledge and participate in efforts to shape the future for the industry. FGIA is a key industry voice that consistently addresses technical issues for the skylight market through the guidance of the dedicated Skylight/Sloped Glazing Council.

While product certification is a great first step to involvement, engaging as a member brings enhanced value including input on the certification process. Through paid memberships, companies establish technical performance requirements for their products in standards, codes and regulations.

Valuable services provided by FGIA include:

• Standards development
• National, regional and state building code and regulatory advocacy
• Industry representation at ASHRAE, ASTM, NFRC and more
• Professional education opportunities

Why me? Why now?

FGIA membership is strong and growing, but skylight manufacturer involvement is minimal. Greater participation strengthens the consensus process.

Skylight manufacturers of all sizes need to be present and engaged to drive requirements for their products, ensuring they are set by those directly impacted. Otherwise, the standards and regulations will change without skylight industry input.

What has FGIA done for the skylight industry?

FGIA regularly participates in code hearings. One example of a significant code change that FGIA influenced for the skylight industry is the increase in allowable skylight area in commercial buildings from 3 to 5 percent of the roof area. Other notable efforts include mitigating unrealistic energy code proposals and overly ambitious ENERGY STAR^® criteria. Each code cycle, FGIA submits proposals to strengthen the skylight industry and clarify previous code issues. Working together, FGIA skylight members have provided strong data supporting these code initiatives.

If I’m not a technical expert, what could I contribute?

The entire skylight industry is strengthened by more manufacturer participation, especially for standards development. Though expertise on building codes and testing protocols is important, equally critical is participation by those who know skylight products and how they are used in the marketplace. Involvement by those regularly engaged in the industry ensures appropriate requirements are established. We need you at the table.

“Currently, there are so many organizations trying to set guidelines for our products, it can make your head spin. FGIA keeps a watchful eye on all these organizations and then reports back to the membership on items that attempt to regulate our products. This information is invaluable to my company in keeping one step ahead of changes, as well as providing a powerful ally in turning back some of these proposed code and regulations.”
— Randy Heather VELUX

Is there more to FGIA than technical performance requirements?

Yes. Members participating in FGIA become more knowledgeable and create greater connections. Member education is a key component to FGIA’s core values.

Educational opportunities include, but are not limited to, the following:

• Other Industry Organization Initiatives
  • ASHRAE, ASTM and NFRC are just a few of the organizations that greatly impact our industry. Monitoring these groups as an individual manufacturer can be overwhelming. FGIA informs members of critical action, providing the opportunity for companies to act accordingly. FGIA’s delivery of this information saves both time and money.
• Green and Sustainability Updates
  • Environmental product declarations (EPDs), life cycle assessments (LCAs) and product category rules (PCRs) are critical requirements for certifications under LEED^® and other green building programs. Awareness is important for any product manufacturer because there is the potential for this to become increasingly relevant to the marketplace in the future.
  • At conferences and through webinars, FGIA provides seminars from experts who explain compliance paths, changing requirements and relevant code changes such as:
    • Significant LEED v4 changes impacting the commercial market
    • Revised California Prop 65 labeling requirements
    • The California AB 262 legislation requiring EPDs for specific products in government projects
  • These updates eliminate the need for companies to research green and sustainability efforts on their own.
• Guest Speakers
  • Guest speakers are an added bonus at FGIA conferences, addressing topics directly related to the fenestration industry, manufacturing, professional development and the economy.
• Valuable Resources
  • Resources and materials provided during conferences are available to reference and share with co-workers after FGIA events.

Networking opportunities at FGIA are also very important. FGIA provides a unique forum for engaging with industry peers. Your issues are not uncommon, and FGIA members are helpful and glad to share knowledge to raise the industry as a whole.

How much is this going to cost?

FGIA membership offers multiple levels of participation and a dues fee that fits your needs. FGIA hosts three national conferences per year. Members generally invest an average of $2,000 to $3,000 per event, including registration, travel and hotel fees. Some may see this as a significant amount; however, not engaging is more costly and the potential return on investment is extensive.

Think you don’t have the time?

The conferences are packed with valuable information, but with the scope of products that FGIA addresses, there are natural times in the schedule to step away to focus on emails and phone calls. Plus, the conference venues afford opportunities to experience new cities and social settings while expanding your professional network in a comfortable environment. Many members consider this a proactive time investment versus the time that would be spent on independent research or a reactionary response.

What are the next steps?

You have valuable experience to contribute to FGIA members, and your business is impacted by codes and standards. Skylight manufacturers need to come together to drive the future of the industry.

For more information about joining FGIA, visit our membership page, or to experience an FGIA conference, visit the FGIA Events page.

My company has been an FGIA member for 25 years and I’ve been participating for 15 of those. We are a small regional skylight manufacturer, so the time and monetary commitment is significant. We feel strongly about staying as active participating members, for all the reasons mentioned here, and other factors as well.

One of those other factors is networking. A recent example of this is when California’s Prop 65 changes were rolling out. I was sure we had our ducks in a row until we started to consider how our crating material might come into play. This is a gray area in the Prop 65 language but getting it wrong could be very costly.

However, by participating in FGIA, I knew I could ask some broad questions to the group; our issues are not unique. But more importantly, I knew who I could tap on the shoulder and ask more specific questions, knowing they would answer frankly and provide guidance. These are conversations that I wouldn’t have been able to simply pick up a phone or email other companies and talk about, but FGIA provides the appropriate forum for such conversations and opportunities for these connections to form. That type of networking is hugely beneficial and invaluable.
— John Westerfield CrystaLite

Good daylighting design saves energy in many ways. The obvious one is lighting energy, which can represent a major portion of the total energy consumed by many buildings.

With daylight comes free heat, which can save energy during the cooler seasons. Some products used mainly for providing natural light can also significantly reduce the amount of heat lost when substituted for more traditional products.

This daylighting-focused web page addresses key differences between fenestration products installed primarily vertically (windows, doors, curtain walls and storefronts) and those installed primarily overhead (skylights, roof windows and tubular daylighting devices [TDDs]) and their relation to daylighting and energy savings.

The common set of terms used by daylighting professionals for these two fenestration categories is side-lighting and top-lighting respectively. Generally, all fenestration products can be sources of quality daylight and passive solar energy; however, additional factors need to be considered when choosing side-lighting and top-lighting products.

The basis for the difference is quite simple; side-lighting products face the horizon and top-lighting products face the sky.

Side-lighting from windows and doors provides daylight and solar energy along the perimeter of a building. Good daylighting design should consider these side-lighting characteristics:

• Most daylight is provided through ambient lighting from the sky. The amount of daylight available will vary throughout the day depending on the direction the fenestration is facing. External obstructions may reduce access to the available daylight.
• Orientation (north, east, south, west) with respect to the sun’s path is a critical factor.
• Shading to avoid excessive glare may be necessary when the sun is low in the sky.

Top-lighting can provide daylight and solar energy throughout the interior of a low rise building, on the top floor of a building or in an atrium. It should complement side-lighting in any good daylighting design, where conditions permit:

• Daylight is consistently available throughout the day from both ambient lighting from the sky and direct exposure to the sun.
• Shading to avoid direct sun may be necessary when the sun is high in the sky. Modern transparent and/or translucent glazing can be utilized to avoid glare, aid in capturing sunlight at low angles and diffuse light to wider areas of floor space.
• Shading accessories can be used on many product options to manage light levels when desired or necessary.
• Even on a cloudy day, top-lighting can provide excellent daylight.

Effective daylighting design results in a system that includes side-lighting, top-lighting, electric lighting controls (automated if possible) and a building explicitly designed to optimize the usefulness of daylight.

In applications where daylighting is the primary goal, factors which impact the efficient application of side-lighting and/or top-lighting include:

Building Purpose

Non-residential
In a retail building, for example, daylighting is typically focused on the public retail areas and not on the lesser-used areas for storage and offices. Top-lighting can provide daylighting into any interior floor space area, a critical consideration for large floor plans.

Residential
Daylighting is most beneficial in common areas. Top-lighting is particularly useful further from the perimeter of the building.

Building Features

Ceiling height, surface colors and textures, light shelves, room dividers and partitions all impact the usefulness of the daylight available to the space and should be considered in daylighting design. All of the newest U.S. energy conservation codes specify that many suitable buildings must now use skylights (and automated lighting controls) over specified portions of the occupied floor area because of the energy savings that are achievable in such buildings.

Building Siting/Orientation

Optimizing exposure to the sun’s path is critical to any daylighting system. Top-lighting obtains consistent exposure for long periods of the day.

Multi-story vs. Single-Story

Side-lighting is easily provided on all floors of a multi-story building. However, through proper building design and/or use of integral light wells or TDDs, top-lighting potential still exists for lower floors in multi-story buildings.

Typical Climactic and Daylight Conditions

Even in moderate climates with typically cloudy weather trends, top-lighting provides excellent daylighting potential all day long.

Interior Climate Control System

Appropriately designed HVAC systems are critical in any energy conservation effort.

Non-residential
Automated lighting controls are critical in multi-user environments such as offices and retail spaces to ensure lighting energy is not used when daylighting is sufficient. Annual energy modeling approved for code compliance on these buildings takes lighting energy into account, so it is feasible to justify good daylight on this basis alone.

Residential
Although automated systems are becoming more readily available, generally no additional automated controls are required as homeowners are increasingly conscious about energy conservation and savings. In contrast to non-residential applications, energy modeling for residential code compliance only accounts for heating and cooling energy. This makes official recognition of the value of daylighting harder to obtain. However, one manufacturer has published a study using those modeling tools that was designed to evaluate the changes to heating and cooling energy use when fenestration is optimized for good daylighting and efficient natural ventilation. One of the outcomes of that study shows that using toplighting where appropriate allows the total fenestration area in the modeled buildings to be reduced significantly, thereby saving annual energy in every climate zone of the U.S.

Fenestration Design

Advances in both glass and plastic glazing, as well as other system components, have improved thermal performance characteristics, such as insulation and solar heat gain control. Modern glazing can reduce the amount of glare resulting from direct sun exposure and/or diffuse the light into a larger area of interior spaces.

For top-lighting, light well design and/or TDD products can be useful in directing/reflecting light into larger areas of floor space.

Remember, the overriding goal of any daylighting design is how well it uses the available light. However, uncontrolled daylight may result in excessive heat gain and potential discomfort. It is important to ensure that the fenestration is appropriately sized and located and that the correct glazing and accessories are selected. Use the fenestration area wisely to help insure the energy benefits balance the costs.

Further considerations for proper daylighting design are health, comfort, solar tuning and other design aspects. For more information about daylighting, visit the Skylight/Sloped Glazing Council Resources. Another resource is the FGIA Window and Door Selection Guide, which is available in the online store.

DDGA, Daylighting Design Guidelines for Roof Glazing in Atrium Spaces
Purchase Document

1607, Installation Guidelines for Unit Skylights
Purchase Document

SKY-1, Skylight Fall Protection Position Paper
Purchase Document

GDSG-1, Glass Design for Sloped Glazing
Outlines design considerations necessary for choosing the proper glass for non-residential skylight and sloped glazing applications and describes the minimum requirements for sloped glazing as specified in the major building codes
Purchase Document

TIR-A7, Sloped Glazing Guidelines
Purchase Document

SDGS-1, Structural Design Guidelines for Aluminum Framed Skylights
Purchase Document

TSGG, Two-Sided Structural Glazing Guidelines for Aluminum Framed Skylights
Purchase Document

1600/I.S. 7-00 (AAMA/WDMA), Voluntary Specification for Skylights
Purchase Document

AAMA/WDMA/CSA 101/I.S. 2/A440-22, NAFS – North American Fenestration Standard/Specification for windows, doors and skylights
Purchase Document

AAMA/WDMA/CSA 101/I.S. 2/A440-17, NAFS – North American Fenestration Standard/Specification for windows, doors, and skylights
Purchase Document

AAMA/WDMA/CSA 101/I.S. 2/A440-11, NAFS – North American Fenestration Standard/Specification for windows, doors, and skylights
Purchase Document

AAMA/WDMA/CSA 101/I.S. 2/A440-08, NAFS – North American Fenestration Standard/Specification for windows, doors, and skylights
Purchase Document

AAMA/WDMA/CSA 101/I.S. 2/A440-05, Standard/Specification for Windows, Doors and Unit Skylights
Purchase Document

ANSI/AAMA/WDMA 101/I.S. 2/NAFS-02, Voluntary Performance Specification for Windows, Skylights and GlassDoors – A North American Fenestration Standard
Purchase Document