The Benefits of Integrating Daylighting Systems with Metal Panels

When metal roofing and wall systems of insulated metal panels, or IMPs, are combined with integrated daylighting and electrical lighting systems (such as with skylights, windows and translucent panels) it can improve occupant wellness and overall building performance. Are you curious if the return would be worth your investment? Uncover the recent advancements in daylighting technologies, the benefits and how to measure your building’s success.

Advancements in Daylighting Technologies and IMPs

In recent years, IMP assemblies have seen significant improvements, including more effective seals and thermal breaks as well as better thermal performance.

A range of novel daylighting products and technologies have been introduced in recent years that aid in the deployment of natural illumination for a multitude of occupancies—maximizing daylighting effectiveness while also maintaining the envelope’s barrier and thermal performance. These tools include pre-engineered, integrated metal envelope and roof solutions with compatible curbless skylights, light tubes, pan-type prismatic skylights, automated dimming controls for lighting, motorized shades and other components.

One example of how new tools are replacing more traditional products is the use of domed and pan-type units with prismatic embossing, which refracts and directs two to four times as much illumination into the indoor spaces when solar incidence angles are more acute, such as in the early morning and late in the day. These prismatic elements also help eliminate “hot spots” and reduce glare and ultraviolet (UV) deterioration from daylighting.

Daylighting with Metal Roofing

Benefits of Investing in Daylighting

Overall, using the current crop of novel skylight products in combination with a highly thermally efficient base system of metal panel walls and roofing will reduce excessive solar heat gain as they reduce the electrical base load for lighting. Highly diffusing acrylic and polycarbonate lenses and spectrally selective glass openings are very effective for maximizing functional visible light indoors while inhibiting unwanted heat gain. Many of the skylight aperture designs block 85% of infrared (IR) and 99.9% of UV light, which also reduces the unwanted degradation of products and materials inside the buildings. Additionally, the new generation of skylights also optimizes solar harvesting because many of the lenses have a minimal effect on VT.

In this way, the use of skylights with metal roofing and IMPs can be an effective way to meet the requirements of IECC 2012 and state energy codes. The skylights reduce overall electrical loads without adding unacceptable levels of solar heat gain, and their small relative area means the overall roof U-values remain low.

How to Measure the Success of Daylighting

Building teams will encounter a number of key variables that help measure the effectiveness of proposed daylighting designs. The most common (and valuable) daylighting performance metrics in use today include the following:

• Daylight factor
• Window-to-wall ratio, or WWR
• Effective aperture, or ea.
• Daylighting depth
• Solar heat-gain coefficient, or ShgC
• Haze factor
• U-factor

Using the above tools and terminology, building teams can better assess the benefits of daylighting strategies with skylights, prismatic pan-type products and solar light pipes, among others. In particular, these are important for meeting the widely used 2012 International Energy Conservation Codes (IECC) and ASHRAE 90.1 as well as state energy codes and “reach targets” such as green building certifications, the Passive House standard and others.

How to Learn More

The use of building systems combining metal roofing with skylights and integrated lighting provide significant life-cycle performance. Much of this is due to the research and development behind the individual products and materials used for these applications.

For a more in-depth look at daylighting within the context of metal roof and wall systems, please refer to MBCI’s whitepaper, Shining Light on Daylighting with Metal Roofs, which showcases the strong rates of return of using integrated daylighting systems with novel prismatic optics and high-efficiency lighting on metal envelopes with good thermal and barrier performance.

Download the White Paper, Daylighting with Metal Roofs

Thermal Bow vs. Thermal Expansion: A Look at Thermal Efficiency in Insulated Metal Panels

Insulated metal panels  (IMPs), a type of lightweight factory-fabricated metal panel,  are a compelling alternative to more conventional roof panel choices. IMPs have a continuous insulating core that works together with metal skins to create a barrier against air, water vapor, and thermal conditions. One major benefit of IMPs, is their thermal efficiency, averaging R-7.0 to 7.2 per inch as compared to R-5.6 per inch for unfaced urethane board stock. Insulated metal roof panels are commonly available in thicknesses ranging from two- to six-inches which generally correlates to R-14 to 42.

Structure of IMPs

IMPs consist of two single skin metal panels and a foamed-in-place core. The foam insulation is made of non-chlorofluorocarbon (non-CFC) polyurethane foam. As an example, MBCI’s IMPs consist of closed cell structure and nominal density of 2.2 pounds per cubic foot. Its closed cell structure also prevents the foam from absorbing water.

Thermal Bow in IMPs

Thermal Efficiency of IMPs
Thermal expansion of insulated metal panels is accommodated by thermal bowing.

An interesting phenomenon with IMP roof panels is that you don’t have to deal with thermal expansion the way you do with single skin panels. On wide, through-fastened roofs, you can have issues with panels slotting around the fasteners. And with standing seam roofs, you have to ensure that the panel clips can handle the anticipated thermal movement. However, insulated panels experience something called “thermal bow.”

An IMP’s exterior metal skin will still expand as it heats up. But, instead of causing the whole IMP to grow in length,  the exterior skin of the IMP will bow up slightly between purlins/joists because the interior metal skin of the IMP maintains a relatively constant temperature. The insulating foam that adheres to this metal skin flexes to allow for this bow. Because of this, thermal expansion is accommodated by the small incremental growth (and bowing up) of the exterior metal skin between each purlin/joist, which are usually spaced five to seven feet apart.

­­­­­Conclusion

Insulated metal roof panels are fixed roof systems that will experience thermal bow between the purlins as opposed to single skin systems, which are designed to allow for expansion and contraction in the panel. With its thermal efficiency benefits, IMP roofs are beginning to get noticed as an alternative for designers looking for a progressive choice to achieve flexibility and function.

Wellness and Envelopes: Four Ways Single Skin & Insulated Metal Panels Keep Us Healthy

SONY DSC

 

Is there a connection between building design and human health?

We know the answer must be yes, but figuring out how the connection works is the job of experts like the team behind the WELL Building Standard®, a new certification that takes on the question. Among the solutions that can help make a building better? Metal roofing and siding, according to many healthy building experts.

First, let’s learn about WELL. According to the International WELL Building Institute, the WELL Building Standard “takes a holistic approach to health in the built environment addressing behavior, operations and design.” Their performance-based system measures and monitors such building features as air, water, nourishment, light, fitness, comfort, and mind. Two ratings have been offered: WELL Certified™ spaces and WELL Core and Shell Compliant™ developments. Done properly, these “improve the nutrition, fitness, mood, sleep patterns, and performance of occupants.”

Pilot programs are currently available for retail, multifamily residential, educational, restaurants and commercial kitchens projects. In many of these projects, the use of metal claddings and insulated metal panels (IMPs) is recommended by many health-focused professionals. Why?

1. Occupant comfort

IMPs tend to have excellent R-values and very good thermal efficiency – including long-term thermal resistance, or LTTR, a key measure of how the building will perform over time. For the wellness factor from pure thermal comfort, IMPs are highly effective over conventional construction.

2. Nourishment of people and earth

IMPs are often made with recycled metals and improve the energy performance of the building. With energy cost savings ranging from 5 percent to 30 percent, they cut the carbon footprint of the facility. Plus the interior and exterior skins include up to 35 percent recycled content – and they are 100 percent recyclable – reducing impact on the global carbon load.

3. Daylight for all.

Using metal roofs with skylights or light-transmitting panels in conjunction with integrated dimming lighting is a highly cost-effective strategy, and IMP systems also have integrated window systems that increase available sunlight within building interiors. Light is essential for healthy buildings, and daylight is the best kind of all.

In addition, because rigid insulation per inch offers more R-value than per inch of fiberglass insulation and IMPs have metal liner skins, day-lighting fixtures such as light tubes can be integrated more easily with these roofs.

4. Proper moisture and air control.

Issues such as leaky walls and wet, moldy construction materials are anathema to wellness, and must be controlled for healthy building certifications. Mold has a negative impact on indoor air quality and indoor environmental quality, and one of the main culprits is trapped moisture. This can also corrode the metal studs and furring members, even if they are galvanized, leading to structural issues such as reduced fastener pullout resistance and leaks.

How Does a Building Become WELL Certified?

IMPs used as either rainscreens or as sealed barrier walls backing up a rainscreen are shown to protect against moisture issues and mold over time. They also serve as a continuous layer of insulation and air barrier. In this way, the single-component system can eliminate the need “for air barriers, gypsum sheathing, fiberglass insulation, vapor barriers, and other elements of a traditional multicomponent wall system,” says one industry executive. In fact, many masonry buildings are being upgraded with IMP retrofits on the exterior, directly over the old concrete, brick or stone.

All of these traits of IMPs certainly contribute to more healthy buildings, but do they add up to WELL Building certification levels, such as Silver, Gold or Platinum?

To get there, building teams must undergo an on-site WELL Commissioning process with rigorous post-occupancy performance testing of all the features. If it meets the “preconditions” — the WELL features necessary for baseline certification — WELL Certification is given. If the team pursues “optimization features,” the higher levels of achievement are granted.

Passive Aggressive: Metal Buildings Suit Passive House Standards

Today’s big push toward Passive House standards — the formerly German building certification that recently gave rise to a U.S. counterpart, Passive House Institute US, with its PHIUS+ certification — is also creating more interest in the highly efficient, highly insulated metal buildings. The projects range from metal-clad houses to IMP commercial facilities to the first Passive House high-rise in the world, Cornell University’s 26-story residence tower, clad in metal panels.

Metal? That’s right. While this surprises few design and construction professionals, consider these facts: (1) IMPs and metal roofs protect their insulation backup better than many kinds of construction methods, ensuring good long-term thermal resistance, or LTTR. (2) Passive House requires airtight construction with minimal air infiltration, which is ideal for the tight, engineered construction and inherent air barrier quality of metal panels. (3) Metal roofs and walls are available with high-efficiency Energy Star windows and skylights that are designed to integrate with the cladding and roofing systems.

Photo courtesy of www.phius.org
Photo courtesy of www.phius.org

These reasons also explain why IMPs have been used extensively for net-zero energy buildings in recent years, which also demand highly energy-efficient enclosures along with the means to produce energy with solar heating, photovoltaics, geothermal and wind turbines.

So when it comes to Passive House and the PHIUS+ certification, often the choice of insulated metal panel (IMP) systems is among the first major project choices. Two immediate benefits arise, says the Metal Construction Association, for solar reflectance (SR) and thermal emittance (TE). “Metal cladding has very dependable and high SR and TE values, and it employs polyurethane foam, one of the most efficient types of insulation, which maximizes building energy efficiency,” says Ken Buchinger, general manager of Technical Services with MBCI.

Coupled with the robust barrier provided by coil metal and the tight construction afforded by pre-engineered, prefabricated panel systems, the resulting enclosure type is among the most efficient available. And that’s not just for new construction: A large number of Passive House projects have retrofitted IMPs over leaky existing buildings of masonry, brick or stucco. In its certification guide for PHIUS+, the Passive House Institute US specifically cites metal roofing and metal cladding systems to meet the rigorous criteria.

For the net-zero approach, Buchinger adds that solar photovoltaic systems and solar water heating systems can be installed on a metal roof, penetration-free, resulting in high performance with minimal risk. “Metal roofing, known to last 60 years or longer, is the only roof type that can outlive a PV system mounted on it, meaning zero maintenance and low in-place cost for the roof and PV system together,” he explains.

Whether the approach is passive or zero, we’re seeing a new generation of super-efficient buildings today. New certification rules were unveiled this year for the Passive House standard have lots of buzz. And the latest projects, many with metal wall and roof panels, have resulted in facilities using as little as 10% of the energy required for comparable projects, according to PHIUS.

That’s why passive design sounds pretty aggressive for going green.

Sustainability Begets Resiliency…In Practice

McMahaon Centennial Complex, Cameron University

Sustainability is the buzzword started by USGBC that is pushing us to design and build environmentally friendly buildings.  And that’s a good thing.  However, from a practical—and roofing—standpoint, what we can most readily do with roofs is design them to be resilient.  Roof system resiliency is the tangible aspect of sustainability that the “regular” population can get their heads around.  Resiliency—the ability to bounce back—is understandable.

Loosely speaking, a resilient building can withstand an extreme weather event and remain habitable and useful.  It follows that a resilient roof system is one that can withstand an extreme weather event and continue to perform and provide shelter.

What makes a metal roof system resilient?  It needs to be tough and durable, wind and impact resistant, highly insulated and appropriately reflective, and perhaps be a location for energy production.

An extreme weather event typically means high winds.  A resilient metal roof system needs to withstand above-code wind events.  Remember, codes are minimum design requirements; there is nothing stopping us from designing metal panel roofs above code requirements!  If a building is located in a 120 mph wind zone, increase the design/increase the attachment as if it were in a 140 mph wind zone.  And, very importantly, increasing the wind resistance of the edge details is critical to the wind resistance of a roof system.

Toughness is important.  Increasing the thickness of a metal panel roof system increases resistance to impacts and very likely increases service life (of the metal panel, at least).  Tough and durable seams are important, too.  A double-lock standing seam is one of the best seam types for metal roofs.  A little bit of extra effort at the seam can go a long way for durability, weatherproofing, and longevity.

Highly insulated and appropriately reflective are also traits of resiliency.  High R-value means less thermal transfer across the roof assembly.  Two layers, staggered or crisscrossed, provide a thermally efficient insulation layer.  Using thermal breaks between the metal panels and the metal substructure adds to the thermal efficiency.  Reflective roofs help reduce heat transfer through the roof assembly.  The effectiveness of a roof’s color and reflectivity to save energy depends on many items, such as location, stories, and building type.

Enhanced wind resistance, improved impact resistance and toughness, high R-value, and reflectivity and color are passive design elements that increase the resiliency of a building’s rooftop.  And let’s not forget that rooftop energy production can provide electricity to critical components of a building, such as a freezer section of a grocery store.  Hurricane Sandy put resiliency on the public radar; resilient buildings are here to stay.

All Those Sustainability Acronyms Mean Something, Right?

PCR, LCA, EPDBy now I’m sure you’ve heard about PCRs, LCAs, and EPDs.  Simply put, a PCR is a set of product category rules; an LCA is a life cycle analysis; and an EPD is an environmental product disclosure.  But what do they mean and what’s the purpose of it all?  In the broadest sense, these are mechanisms used for the sustainability movement.  The most granular is the EPD, which is a product-based discussion (i.e., disclosure) of the environmental effects caused by a specific product or product type.   Architects and building designers use EPDs to compare products in order to select the most environmentally friendly products to be used in environmentally friendly buildings.

Developing an EPD can only happen after the creation of a set of product category rules (PCR).  A PCR sets the rules for creating LCAs and EPDs.  An example of a PCR is “Product Category Rules for Preparing an Environmental Product Declaration (EPD) for Product Group: Insulated Metal Panels & Metal Composite Panels, and Metal Cladding: Roof and Wall Panels,” which was developed by UL through the efforts of the Metal Construction Association (MCA).

Only after a PCR is developed can a verifiable LCA or EPD be developed.  An LCmA and EPD are similar but different.  An LCA uses industry-average data, and an EPD is specific to a product or product type.  For example, “LCA of Metal Construction Association Production Processes, Metal Roof and Wall Panel Products” provides industry-average information about the environmental aspects of three key products: steel insulated metal panels, aluminum metal composite material panels, and steel roll-formed claddings.  This LCA is based on 24-gauge material.

EPDs are typically more product specific.  (An EPD is typically based on an LCA, so most often LCAs are developed prior to EPDs.)  For example, the EPD titled “Roll Formed Steel Panels For Roof and Walls” provides similar environmental data as an LCA, but includes information about 29-, 26-, 24-, 22-, 20- and 18-gauge materials.  This provides additional product specific information that can be used by designers when an industry average is not adequate.  And importantly, more LEED points are garnered from a product-specific EPD than an LCA because of the specificity.  LEED is certainly a driver of this!

LCAs and EPDs used in the roof industry are often focused on cradle-to-gate analysis, and exclude the use phase and end-of-life phase.  Ideally, an LCA or EPD should include the use and end-of-life phases so architects and designers have a complete cradle-to-grave analysis.  Without the use phase, designers are allowed to freely select the service life of a metal roofing product, for better or worse, without industry guidance.  And, the advantages gained through metal recycling at the end of life are also omitted from MCA’s LCA.

It’s all about standardized disclosure of environmentally based product data.

Learn more about MBCI’s LCA, EPDs and other sustainability efforts, here.

Metal Roofs & Walls a Big Plus When It Comes to Net Zero Energy

Kickapoo Tribe Government & Community Building
Kickapoo Tribe Government & Community Building features MBCI’s CF Architectural Insulated Metal Panel

Are you familiar with “Net Zero Energy?” No, it’s not that sense of power you got from using that early dial-up Internet browser of the 1990’s (The company, by the way, is still in existence, and comes up in searches for the term Net Zero. Who knew?). The Net Zero Energy I’m speaking of is the enviable, sustainable state achieved when the creation and use of energy within the same building system are equal.

Though achievable, the cost and capacity for producing energy within a building system is greater than that of creating energy efficiency in one. The good news is that metal roofing and ,a href=”http://www.mbci.com/products/wall-products/”>wall panels are extremely useful on both sides of the equation.

On the energy efficiency side, insulated metal panels (IMPs) provide roof and wall systems with the thermal and radiative performance needed for sustainable design. Insulated wall and roof panels provide continuous insulation and eliminate thermal bridges. As building and energy codes become increasingly more stringent, insulated metal panels are an ideal choice for thermally efficient building envelopes.

Baker Hughes features MBCI’s CF Mesa Insulated Metal Panels

On the other side of the equation, a common method of generating energy is through the use of photovoltaics (PVs), and metal roofs provide the best possible surface to host a photovoltaic (PV) array. Solar photovoltaic systems and solar water heating systems can be installed on a metal roof, penetration-free, resulting in high performance with minimal risk. Both the use of IMPs and the installation of PVs on metal roofs can be used with proper designs to maximize building energy efficiency.

Of course, metal roofing, known to last 40 years or longer, is the only type of roof that can be expected to outlive the PV system mounted on it, which results in virtually zero maintenance and a very low in-place cost for the roof and PV system together.  A sustainability win, a durability win, and, of course, an aesthetic win.  The result is anything but a zero sum game.

Find out more about MBCI’s Insulated Metal Panels

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