LEED® Guidelines and Fenestration Design – Part 1

by Tom Minnon, LEED® AP, CDT, Eastern Region Sales Manager for Tubelite Inc.

Not every building is designed to achieve LEED® certification, but using the guidelines in the LEED Rating System can help lower utility costs, minimize the impact on our environment and improve occupant comfort levels. In this two-part blog, we’ll take a look at how “smart” fenestration designs and applications can significantly improve a building’s performance. Part one focuses on Energy & Atmosphere, Materials & Resources and Indoor Environmental Quality.

Energy & Atmosphere Credit 1: Optimize Energy Performance

Intent: To achieve increasing levels of energy performance to reduce environmental and economic impacts associated with excessive energy use.

Strategies:
* Design the building envelope and systems to maximize energy performance. Utilize aluminum and glass manufacturers’ most energy efficient products.
* Determine required minimum total system U-Factor based on aluminum framing system and glass type. Reference National Fenestration Rating Council (NFRC) 100-2010: “Procedure for Determining Fenestration Product U-Factors.”
* Determine required maximum Solar Heat Gain Coefficient (SHGC). Reference NFRC 200-2010: “Procedure for Determining Fenestration Product Solar Heat Gain Coefficient and Visible Transmittance at Normal Incidence.”

Recent improvements in thermal break technology have helped aluminum glazing systems become more energy efficient due to conductive heat loss. The graphics below show a true thermally broken curtainwall, thermally broken entrance with frame, and a fiberglass pressure plate for conventional curtainwall. The fiberglass provides a significant improvement over the more common aluminum pressure plate.

Energy and Atmosphere Credit 2: On-Site Renewable Energy

Intent: To encourage and recognize increasing levels of on-site renewable energy self-supply to reduce environmental and economic impacts associated with fossil fuel energy use.

Strategy:
Consider integrating photovoltaic (PV) panels as part of the storefront and/or curtainwall glazing systems. Where natural daylight is desired, some PV panel manufacturers offer semi-transparent building integrated photovoltaic (BIPV) modules that can generate electricity and transmit light.

The Tiger Woods Learning Center incorporated a 21-by-65-foot curtainwall system by Wausau Window and Wall Systems utilizing photovoltaic modules from SCHOTT North America, Inc. The lites varied in opacity and power-generation: The top panels of the PV array produce 72 watts each with an opacity of 5%, while the lower panels offer 25% opacity and produce 60 watts of energy. The BIPV system can produce 3,800 kilowatts of energy per year.

 

Materials and Resources Credit 4: Recycled Content

Intent: To increase demand for building products that incorporate recycled content materials, thereby reducing impacts resulting from extraction and processing of virgin materials. This credit requires the total recycled content of the building based on cost be 10% for one point or 20% for two points.

Strategies:
* Use materials with recycled content such that the sum of postconsumer recycled content plus half of the pre-consumer content constitutes at least 10% or 20% of the total value of the materials in the project.
* Identify aluminum framing manufacturers that provide significant recycled aluminum content in their systems.

Aluminum requires significant amounts of energy to convert bauxite to the finished goods. The “Embodied Energy” in prime aluminum is more than 100,000 BTUs per pound. However, it only takes 1/5 of that energy to process recycled aluminum. By recycling aluminum, we recover the energy that was used in converting bauxite to aluminum in the smelting process.

 

Indoor Environmental Quality Credit 4.1: Low-Emitting Materials – Adhesives and Sealants

Intent: To reduce the quantity of indoor air contaminants that is odorous, irritating and/or harmful to the comfort and wellbeing of installers and occupants. All adhesives and sealants used on the interior of the building (i.e., inside of the weatherproofing system and applied on-site) must comply with the following requirements as applicable to the project scope.

Strategies:
* Specify low volatile organic compound (low-VOC) materials in construction documents. Ensure that VOC limits are clearly stated in each section of the specifications where adhesives and sealants are addressed.
* Adhesives, sealants and sealant primers must comply with South Coast Air Quality Management District (SCAQMD) Rule #1168. VOC limits listed in the table below need to be adhered to for storefront and curtainwall installations:

Application  –  VOC Limit (grams/liter less water)
Structural Glazing Adhesives  –  100
Architectural Sealants  –  250
Sealant Primers, nonporous  –  250
Sealant Primers, porous  –  775

Indoor Environmental Quality Credit 4.2: Low-Emitting Materials—Paints and Coatings

Intent: To reduce the quantity of indoor air contaminants that is odorous, irritating and/or harmful to the comfort and wellbeing of installers and occupants.

Strategies:
* For projects that require on-site painting or repair of a buildings interior, specify low-VOC paints and coatings in construction documents. Ensure that VOC limits are clearly stated in each section of the specifications where paints and coatings are addressed.
* Track the VOC content of all interior paints and coatings during construction.
Note: With the exception of possible field repair of finishes, this requirement does not pertain to architectural aluminum anodizing or paint. All finishes are applied off-site and will not contribute to contaminants in the building.

Kynar® paint has been the proven mainstay in the architectural market for decades. The primary environmental concern with liquid paints is the solvents used to deliver the paint to the part; some of the solvents used are considered VOC content and must be destroyed. Environmentally conscious finishers, such as Linetec, use a 100% air capture system and destroy the VOCs with a regenerative thermal oxidizer, so there is no adverse environmental impact.

 

Next month’s blog will continue with LEED credit categories 5, 6 and 8.

**

Resources:
LEED 2009 for New Construction and Major Renovations Rating System (PDF)
U.S. Green Building Council
Tubelite Inc.
Wausau Window and Wall Systems
SCHOTT semi-transparent photovoltaic modules
Linetec aluminum finishing
Kynar 500® FSF® paint

**

Tom Minnon, LEED® AP, CDT, is the eastern region sales manager for Tubelite Inc., serving clients from Maine to Georgia. With nearly four decades of industry experience and many professional accreditations, he regularly provides educational and consultative support to architects, buildings owners and glazing contractors regarding storefront, curtainwall, entrances and daylight control systems.

###

...[View full article]

Shared Learnings: Controlling Storefront and Curtainwall Water Infiltration

by Tom Minnon, LEED® AP, CDT, Eastern Region Sales Manager for Tubelite Inc.

Most architectural aluminum glazing systems are not designed to be totally waterproof. Rather, most systems are designed to control water infiltration under extreme conditions and weep that water back to the exterior. Storefront and curtainwall systems differ in many ways: appearance, profiles, wind load resistance, glazing, thermal performance and how they weep water. This discussion focuses on how storefront and curtainwall handle water disbursement differently.

Storefront

Storefront systems control water infiltration by directing all moisture to the sill flashing (1). It is imperative that the sill flashing be installed correctly. Most aluminum manufacturers have introduced high-performance sill flashing designs that allow the installer to fasten the flashing to the bottom of the opening prior to installing the storefront framing. A watertight seal can then be applied over the fastener head (2). The sill then sets on top of the flashing with no need for fasteners penetrating the sill flashing. Unlike the old sill flashing designs, these high-performance sill flashings utilize two weep holes in the sill flashing at each lite of glass (3). These extrusions also have a much higher back leg for better water performance, and it is important to make sure that sealant is applied to the top of the back leg prior to installing the sill (4).

Improper sill flashing

Assuming that the sill flashing is installed correctly, the most important element in controlling water penetration with storefront is the proper fastening and sealing of end dams (5). Without end dams, water will intrude into the jamb locations of the building. In the photo below you can see where improperly (or missing) end dams have caused significant water damage to the interior drywall, even though sill flashing was present.

Storefront water deflector

Water deflectors must be installed wherever a horizontal mullion occurs in storefront. These direct any water that reaches the horizontal over to the vertical mullion where it weeps out at the sill flashing. Deflectors are necessary to ensure that the water bypasses the lite of glass below the horizontal. Without water deflectors, moisture likely will settle on the top of the glass, allowing water to enter the interior and causing possible failure of the insulating glass unit.

 

Curtainwall

With curtainwall, we want to prevent any water from reaching the vertical mullion. Each horizontal mullion must have zone dams (sometimes called “joint plugs”) properly installed and sealed at the vertical. Any water that makes its way to the vertical mullion ultimately will end up on the interior of the building.

Unlike storefront, which directs all water to the sill, curtainwall weeps water at each individual lite of glass through holes in the pressure plate. Because most curtainwall systems are used on taller elevations with higher wind loads, the amount of water entering the system is typically greater than the capacity of strorefront mullions and sill flashing. This is why each lite of glass is individually weeped. There are critical steps that must be taken to ensure that no water penetrates a curtainwall system.

Each pressure plate must have two weep holes ABOVE the horizontal tongue (1). Similarly, each face cover requires two weep holes (2). All too often, field failures of curtainwall are directly due to improperly installed zone dams or incorrect placement or missing weep holes.

Since water is not directed down the vertical mullions to the sill, curtainwall does not require sill flashing. However, care must be taken in handling the caulk joints at the sill. The exterior caulk joint must be behind the face cover since water is weeping out of the bottom (3). A common installation error is mistakenly applying caulking to the exterior sill and blocking the weep holes.

 

So, how can you ensure that a storefront and/or curtainwall system is being installed correctly?

  • Have the manufacturer’s installation instructions be included with the glazing subcontractor submittals. This will provide the architect, engineer and or general contractor a resource for field checking the installation, and they become part of the Construction Documents.
  • Carefully review submitted shop drawings. Ensure that the details correspond with the manufacturer’s recommended installation instructions.

**

Resources:
Glass Association of North America
National Glass Association
Whole Building Design Guide, Building Envelope Design Guide

 

Tom Minnon, LEED® AP, CDT, is the eastern region sales manager for Tubelite Inc., serving clients from Maine to Georgia. With nearly four decades of industry experience and many professional accreditations, he regularly provides educational and consultative support to architects, buildings owners and glazing contractors regarding storefront, curtainwall, entrances and daylight control systems.

###

...[View full article]

Shared Learnings: AIA 2012 Preview

by Tom Minnon, LEED® AP, CDT, Eastern Region Sales Manager for Tubelite Inc. As the

American Institute of Architects (AIA) 2012 National Convention and Design Exposition opens in Washington, D.C., exhibitors will be showcasing new technology and products for use in the glass and glazing industry. One focal point will be increasing the thermal performance of commercial glazing systems. This has become paramount as new energy codes continue to be adopted and enforced. Here are some highlights from the exhibit floor.

Viracon’s VE 1-2M has these characteristics: 63% Visible Light Transmission 0.21 U-Value, 0.34 Solar Heat Gain Coefficient

 

Triple Glazing

Viracon, and other glass fabricators, offer triple-glazed units that minimize heat transfer improving overall thermal performance. However, while a third pane of glass adds to the insulating value of the assembly, it also reduces the visible light transmission (VT) and the solar heat gain coefficient (SHGC). Adding a low-E coating to a surface, or multiple surfaces, of the triple-pane unit will also increase the energy performance, but it may (depending on the type of low-E coating) affect the SHGC and VT. Filling the space between the panes of glass with argon and/or krypton gas will also improve energy performance.

A third pane of glass increases the weight and thickness of the unit, which can make mounting and handling more difficult and transportation more expensive. There are physical and economic limits to the number of glass panes that can be added to a window assembly and the thermal performance benefits diminish as well. Care should be taken to ensure that the architectural aluminum framing system can support the additional weight of triple-glazed units, which average about 10 pounds per square foot.
Booth 3825

 

Suspended Films

A suspended plastic film can be substituted for the middle layer of glass in a triple-glazed unit. The light weight of the plastic film is advantageous. Because it is very thin, it does not increase the unit thickness substantially.

Southwall Technologies’ Heat Mirror® technology is based upon a very thin coated film, which reflects heat back to its source. They offer 12 different films, which provide varying levels of VT and SHGC to meet the diverse requirements of the commercial market place.

Heat Mirror units can be produced with a wide range of glass substrates including clear glass, tinted glass and low-E glass. By taking advantage of the benefits of film-based coatings and glass-based technologies, they can create superior insulating performance and outstanding solar control, while blocking UV radiation, and reducing outside noise more effectively than double-pane glass.

 

Electronically tintable glass

Electronically tintable glass can be specified for windows, skylights and curtainwalls. It is an effective way to control sunlight without shades or blinds, so you can manage glare and heat, while maintaining a connection to the outdoors. SageGlass® offers a solution (electrochromic) that can be adjusted based on the end-users’ preferences. Pleotint, on the other hand, offers a solution (thermochromic) that automatically adjusts based on the sun’s heat.

Electronically tintable glass increases design freedom by removing sun control from the equation. Buildings can be infused with daylight without shades, blinds or louvers.
Booth 2003 and Booth 2318

 

Advanced Aluminum Glazing Systems

Manufacturers of aluminum storefront, curtainwall and windows have responded to the need for increased thermal performance by designing systems that will accommodate glass in thicknesses greater than the typical 1-inch units. Triple glazing is usually 1.75-inch thick (three each 0.25-inch panes of glass and two each 0.5-inch air spaces).

Wausau Window and Wall Systems, and others, can provide curtainwall and windows that will accept this glazing.
Booth 313

 

Lumira Aerogel

Cabot Corporation’s translucent Lumira™ aerogel maintains and enhances energy efficiency, while enabling a wide range of commercial and residential building design choices.

Aerogels are the lightest and best insulating solids in the world. Cabot’s Lumira aerogel is a hydrophobic aerogel produced as particles. Each particle consists largely of air (more than 90 percent) and is contained in a structure with pore sizes less than the mean free path of air molecules, which severely inhibits heat transfer through the material.

The inclusion of Lumira in daylighting systems virtually eliminates the historical trade-off of insulation vs. natural light by providing three to six times the thermal performance of traditional insulated fenestration products, while maintaining optimal light transmission. As a result, even large daylight surface areas can maintain high energy-efficiency by reducing thermal loads.
Several companies that offer Lumira will be exhibiting at the AIA Design Exposition.

 

 

Resources:

**

Tom Minnon, LEED® AP, CDT, is the eastern region sales manager for Tubelite Inc., serving clients from Maine to Georgia. With nearly four decades of industry experience and many professional accreditations, he regularly provides educational and consultative support to architects, buildings owners and glazing contractors regarding storefront, curtainwall, entrances and daylight control systems.

###

...[View full article]

Shared Learnings: Glazing and Energy Codes

by Tom Minnon, LEED® AP, CDT, Eastern Region Sales Manager for Tubelite Inc.

Architects and building owners face growing challenges in balancing aesthetics and daylighting design needs with increasingly stringent building and energy code requirements. This month’s discussion will focus on ways to reduce heat loss and heat gain to comply with commercial energy codes. Thermal energy performance of glass can be improved several ways; many of them are just now beginning to be incorporated into the commercial segment.

 

Warm Edge Technology
(Conductive heat loss)

Several products have been introduced that will help reduce conductive heat loss through the edge of insulating glazing units (IGUs). Warm Edge technology will also help reduce condensation that typically occurs around the edge of glass near the frame. Below are some of the different types of IG spacers available.

1. Metal spacers
Made from stainless steel or aluminum. Dessicant consists of tiny beads which absorb any moisture trapped in the unit during manufacturing. Stainless steel offers better performance than steel.

2. Hybrid spacers
Changing metal spacers from a tube to a U-shaped channel reduces the flow of heat through the spacer.

3. Thermal break spacers
Thermal barrier technology creates a warm-edge IGU that reduces thermal conductivity.

4. Foam & Thermoplastic spacers
Non-metal spacers include a foam material that has dessicant entrained within it and thermoplastic spacers consisting of a single-component polyisobutylen with included desiccant material.

 

Argon and Krypton Gas Fill
(Convective heat loss)

An improvement that can be made to the thermal performance of IGUs is to reduce the movement of air between the panes of glass. Typically, the space is filled with air or flushed with dry nitrogen just prior to sealing. In a sealed IGU, air currents between the two panes of glazing carry heat to the top of the unit and settle into cold pools at the bottom. Filling the space with a less conductive, more viscous, or slow-moving gas minimizes the convection currents within the space, conduction through the gas is reduced, and the overall transfer of heat between the inside and outside is reduced.

Argon is inexpensive, nontoxic, nonreactive, clear and odorless. The optimal spacing for an argon-filled unit is the same as for air, about ½-inch (11-13 mm). Krypton is nontoxic, nonreactive, clear, and odorless and has better thermal performance, but is more expensive to produce. A mixture of krypton and argon gases is also used as a compromise.

 

Low-e Coatings
(Radiant heat loss)

A great deal of winter heat loss (and summer heat gain) is due to radiation. In winter, low-e coatings help “reflect” heat energy back into the building. They also increase the surface temperature of the interior glass. This is very important when considering human comfort levels. People lose body heat in four ways:

  • conductive heat loss between the air and exposed skin,
  • convection heat loss due to air moving across the skin (think wind chill factor),
  • evaporative heat loss due to moisture on the skin evaporating (you feel hotter on a humid day because the skin cannot evaporate as much moisture), and
  • radiant heat loss due to the human body being warmer than the surrounding surfaces. More than 50% of body heat loss is due to radiation. The warmer we can make our surroundings, the less heat we will radiate to those surfaces and the warmer we will feel. This is referred to as “Mean Radiant Temperature.” Increasing the surface temperature of the glass will result in a higher mean radiant temperature and ultimately a greater feeling of human comfort.

In summer, and year round for most commercial buildings, we want to limit the amount of solar radiation entering the building, which increases air conditioning loads. Low-e coatings are very effective at minimizing the amount of solar radiation entering the building. In order to meet the 2012 Energy Code, areas of the southern U.S. in Zones 1, 2 and 3 will need to have a fixed glazing system Solar Heat Gain Coefficient (SHGC) of 0.25 or less. This can best be achieved with IGUs and low-e coatings. The days of ¼-inch single glazing in storefront and curtainwall are pretty much in the past.

References

**

Tom Minnon, LEED® AP, CDT, is the eastern region sales manager for Tubelite Inc., serving clients from Maine to Georgia. With nearly four decades of industry experience and many professional accreditations, he regularly provides educational and consultative support to architects, buildings owners and glazing contractors regarding storefront, curtainwall, entrances and daylight control systems.

###

...[View full article]

Shared Learnings: Thermal Barriers

by Tom Minnon, LEED® AP, CDT, Eastern Region Sales Manager for Tubelite Inc.

Aluminum remains the framing material of choice for architectural fenestration products used in non-residential applications. Aluminum has many excellent qualities from recyclability to engineering versatility to corrosion resistance. It also is an excellent conductor of temperature.

Therml=Block entrance systems

Adding a barrier or “break” to insulate between the inside and outside aluminum surfaces, reduces the transfer of hot and cold temperatures. This minimizes the potential for interior condensation and frost build-up in cold weather and helps save energy.

Slot thermal break

The most common types of thermal breaks used in aluminum-framed fenestration products are:

* Slot thermal breaks remove 1-inch-wide by 6-inch-long sections of aluminum extrusion with only one inch between these slots. This typically is reserved for vertical framing members. Slotted horizontals are typically not strong enough to handle the dead load of glass.

* Clip thermal breaks use a small, plastic “clothespin” clip to separate the interior and exterior aluminum surfaces.

Clip thermal break

* Strut thermal barrier systems insert thin fiberglass reinforced “struts” into the aluminum extrusion.

* Pour and debridge thermal barriers involve pouring a two-part, chemically-cured resin into a cavity in the extrusion. After it hardens some of the aluminum is cut away creating the break. The pour and debridge area can also be “lanced” to provide an additional bond between the metal and thermal break.

“Double” pour and debridge are emerging in response to new energy code requirements. This barrier system utilizes two pour and debridge cavities, thus reducing the amount of conductivity between inside and outside. Most manufacturers have developed these systems in order to meet new, more stringent, energy codes.

Strut thermal barrier

When thermally-broken aluminum framing is matched with high-performance glass, performance is further improved in all categories, including lower U-Factors and higher Condensation Resistance Factors (CRF). CRF is a dimensionless ratio of surface temperature to ambient temperature difference that is determined through surface temperature measurement in guarded hot box testing. A non-thermal single-glazed unit may have a CRF 29; a standard, uncoated insulating glass unit may have a CRF 52 and the highest-performing curtainwalls may reach a CRF 80.

CRF is especially important in cold-climate, high-humidity applications such as multi-family and mixed-use buildings, hotels, kitchens, computer rooms and hospitals. Hospitals may require a CRF as high as 72 or more. For instance, with an outdoor temperature of 0°F, indoor temperature of 70° and relative humidity of 50%, condensation will occur at about

Pour and debridge thermal barrier

50°, requiring a CRF of 72. Below 32 °F surface temperature, condensation forms as frost, which can persist even when temperatures moderate. For additional CRF information and calculations, please visit the American Architectural Manufacturers Association (AAMA) website.

Tubelite’s 300ES Series Curtainwall systems using high-performance glass with Therml=Block™ Insulbar® technology can reduce U-Factors as low as 0.25 and increase frame CRFs as high as 72. This combination achieves a 31% reduction in thermal construction (Uc) compared with standard, pressure bar curtainwall systems that use rubber insulators. Many curtainwall manufactures are beginning to offer fiberglass pressure plates to further increase their thermal performance.

300ES Series Curtainwall

The benefits presented by fenestration systems using thermal barriers is attractive from an energy and cost savings perspective, and also creates a comfortable thermal environment that supports the productivity and well-being of building occupants. These characteristics also align with the U.S. Green Building Council’s LEED® Rating System’s criteria for Indoor Environmental Quality (EQ).

Along with the improved comfort and performance, the aluminum frames’ thermally-broken construction utilizing thermal struts or snap-on face covers also allows some manufacturers to offer dual finishes, where different colors and techniques may be specified for each side of the aluminum’s visible surface. As examples: a curtainwall system could be ordered to match different exterior and interior color schemes, or an entrance system could be finished with a durable anodize on the exterior and a brightly painted surface on the interior.

Innovative manufacturers continue to develop new products and technologies to enhance both the appearance and the performance of their products, meeting the needs for best-in-class building envelope performance in any Climate Zone.

**

Tom Minnon, LEED® AP, CDT, is the eastern region sales manager for Tubelite Inc., serving clients from Maine to Georgia. With nearly four decades of industry experience and many professional accreditations, he regularly provides educational and consultative support to architects, buildings owners and glazing contractors regarding storefront, curtainwall, entrances and daylight control systems.

...[View full article]