The Benefits of Natural Daylighting – Part 1 of 3

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

mattophoto architectural photographyAs winter approaches, and the amount of daylight decreases, it’s important to realize the positive effects of natural daylight. The lack of daylight has been documented to cause Seasonal Affective Disorder (SAD), maladjustment of our body clocks (circadian rhythms) and consistent periods of reduced productivity and enthusiasm. One solution is providing a well-lit space, with as much natural light as possible. Daylighting provides superior quality, full-spectrum, flicker-free light that positively impacts behavior. In study after study, daylighting is correlated to dramatic improvements in human performance in retail, workplace, educational and health care facilities.

Daylight is a full spectrum source of visible light. That is, it imparts the same spectral distribution as sunlight. Unlike electric lights, which sometimes provide a limited spectral range that is concentrated in the blue/green or yellow/green range, daylight is best suited to human vision. Daylight can also provide various illumination levels through proper design. These inherent characteristics of daylight contribute to improved lighting quality by enhancing color discrimination and rendering. Working by daylight is believed to result in less stress and discomfort.

Turn Off the Lightsmattophoto architectural photography

Daylighting saves dollars by using controls to automatically turn off the electric lights when interior daylight levels are sufficient for the task. This reduces both lighting and cooling costs, since reduced electric lighting cuts cooling loads. Daylight is inherently more efficient than electric light, contributing substantially less heat to a space for the same amount of light.

Electric lighting comprises 515,000,000 MWh or 20 percent of the nation’s electricity consumption. Of this total, approximately 10-15 percent is used to light a building’s perimeter zone where daylight is already present. For daytime-occupied commercial buildings, research projections show that total electricity and peak demand savings of 20-40 percent in lighting and its associated cooling energy can be achieved with the proper use of dimmable daylighting controls throughout the United States. Daylighting a building properly is like adding an alternative energy power plant that produces zero carbon emissions.


mattophoto architectural photographyDesigning for Daylight

Daylighting strategies and architectural design strategies are inseparable. Daylight not only replaces artificial lighting, reducing lighting energy use, but also influences both heating and cooling loads. Planning for daylight therefore involves integrating the perspectives and requirements of various specialties and professionals. Daylighting design starts with the selection of a building site and continues as long as the building is occupied.



Architects’ Perception of Daylighting in Commercial Building Design

Daylighting Collaborative

Energy Design Resources

Concepts for daylight harvesting (PDF)

Watch for part two and three on daylighting in December and January and in “Architect’s Guide to Glass and Metal.”


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.


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International Green Construction Code & Building Design

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

The International Green Construction Code (IgCC) is the first national green model code. It is flexible, enabling jurisdictions to choose additional requirements that make the code a deeper shade of green, while paying close attention to the local climate and local regulatory requirements.

This new code is intended to provide “minimum requirements to safeguard the environment, public health, safety and general welfare;” to reduce the negative impacts and to increase positive impacts of the built environment on the natural environment and building occupants. As such, it covers natural resources, material water and energy conservation, operations and maintenance for new and existing buildings, building sites, building materials and building components (including equipment and systems). The IgCC applies to all occupancy-types, except low-rise residential buildings under the International Residential Code.

The IgCC can have a major, immediate impact. According to the Energy Information Administration, buildings generate almost 40 percent of all greenhouse gas emissions and 76 percent of all power plant generated electricity. Buildings can, and should, be designed to operate with significantly less than today’s average energy levels.

How does this complement existing rating systems or other guidelines?

Rating systems, such as LEED, are voluntary guidelines for cutting-edge applications of green building design. The IgCC establishes minimum requirements for all buildings, providing a natural complement for voluntary rating systems that extends beyond the IgCC’s baseline. Rating systems are voluntary. In contrast, a model code adopted by the jurisdiction is enforceable and has the weight of law. The U.S. Green Building Council, creator of LEED, has participated in the development of the IgCC and endorses its usage as a viable option for communities that wish to regulate minimum green building provisions.

To fully appreciate the position of the IgCC in the advancement of building performance, it is important to understand the distinction among three modes of regulation: prescriptive, performance-based and outcome-based.

* Prescriptive codes, as the term suggests, prescribe specific materials, systems or configurations, such as the R-value of insulation or the percentage of exterior surface that may be glazed.

* Performance-based codes establish performance expectations, such as a maximum amount of anticipated energy use, and proposed building designs demonstrate compliance with these expectations through computer modeling. The IgCC offers both prescriptive- and performance-based paths to compliance.

* The third, emerging mode is outcome-based. While performance-based methods predict — but do not absolutely ensure — a level of performance, an outcome-based code would require that a building actually perform to expectations as determined through the monitoring of the completed building in operation.

Prescriptive vs. Performance Paths for Energy Compliance

The prescriptive path is a set of pre-determined, simple and easy-to-follow guidelines and assembly performance values that address energy performance features in the design of a building. They do not require extensive analysis or technical support. Intended to be easily understood and applied, prescriptive requirements are basically a building assembly component checklist of required performance values that, when applied, will be accepted as having met the minimum code requirements.

The performance path defines a process by which an architect can design a building that will achieve energy code compliance with custom architectural assemblies, energy values and features, instead of a set of prescribed values. On the performance path, energy modeling is required to demonstrate that the overall reduction in energy use of the proposed building is at least as good as the minimum code requirement.

In response to the need for greater energy conservation, prescriptive path elements continue to become ever more restrictive to the point of significantly limiting design flexibility. And while relatively simple, the prescriptive path also doesn’t provide the flexibility needed to respond to integrated passive design strategies, such as maximizing daylight, strategic window placement or evaluating trade-offs of view-glazing placement with higher thermal performance assemblies.

Some examples of the fenestration limitations of the prescriptive path are:

  • Mandatory values for solar heat gain coefficient (SHGC) and window performance may not necessarily be beneficial in all climate zones, where in certain instances, solar gain coming into a building can offset heating needs. Restrictions on the amount of glass and SHGC requirements also severely limit daylight penetration that can afford reduction in electric lighting and associated cooling energy consumption.
  • The prescriptive path of the IgCC mandates that solar shading devices be permanently attached on specified building orientations; however, successful design of solar shading is likely better suited to the flexibility in the performance path rather than the prescriptive path.
  • The amount of glass on a building is restricted in the prescriptive path. For example, if a designer or building owner wants more transparency, or wishes to take advantage of views or unique site opportunities, the potential to compensate with higher performance in other building assemblies is only available using the performance path and energy-modeling. The performance path affords much greater freedom of design choice. It affords the opportunity to offset different system efficiencies against others, so long as the overall energy efficiency goals are met.


On-Site Renewable Energy Systems

Building project design shall show allocated space and pathways for future installation of on-site renewable energy systems and associated infrastructure that provide the annual energy production equivalent of not less than 6.0 kBtu/ft2 for single-story buildings and not less than 10.0 kBtu/ft2 multiplied by the total roof area in ft2 for all other buildings.


Daylit area of building spaces

IgCC has very specific requirements for daylighting a building. The designer must take into account any side-lighting (vertical fenestration), rooftop monitors, skylights and tubular daylighting devices. A daylight analysis must be conducted that includes:

  • Exterior shading devices, buildings, structures and geological formations on the fenestration of the proposed building and on the ground and other light reflecting surfaces.
  • Movable exterior fenestration shading devices.
  • Blinds, shades and other movable interior fenestration shading devices.
  • Automatic daylight controls.
  • Dynamic glazing.


Permanent Projections

For climate zones 1–5, the vertical fenestration on the west, south and east shall be shaded by permanent projections that have an area-weighted average Projection Factor (PF) of not less than 0.50. The building is allowed to be rotated up to 45 degrees to the nearest cardinal orientation for purposes of calculations and showing compliance. The PF is the ratio of the distance the overhang projects from the window surface to its height above the sill of the window it shades.

[Courtesy of]

Vertical Fenestration Area

The total vertical fenestration area shall be less than 40% of the gross wall area. This requirement supersedes the requirement in Section of ANSI/ASHRAE/IES Standard 90.1. Keep in mind that the vertical fenestration of a building may be allowed to exceed 40% by using the Performance Path for energy compliance.


Maximum U-Factors and Solar Heat Gain Coefficient

The table below shows the U-Factor and SHGC requirements for climate zone 5 per the IgCC (in green on the map below).

These performance requirements present a real challenge to the architectural aluminum industry. Many manufacturers are responding to the need for more energy efficient glazing systems by developing new and improved thermal break technology, such as: double pour and debridge, thermal strut and curtainwall fiberglass pressure plates.

The thermal analysis below shows that using standard storefront with a single thermal break and glass with a Center of Glass (COG) U-Factor of 0.30, does not meet the “Assembly U-Factor” code requirement of 0.35 of less.

The adoption of the IgCC is a step toward achieving the goal of carbon neutrality in building construction by 2030. The IgCC is the first model code to include sustainability measures for the entire construction project and its site — from design through construction, certificate of occupancy and beyond. The new code is expected to make buildings more efficient, reduce waste and have a positive impact on health, safety and community welfare. We will all need to become more familiar with this new code as it gets adopted by states and municipalities.


The American Institute of Architects’ Guide to the IgCC,

International Code Council (ICC) and the IgCC,

ICC PowerPoint – Overview of the 2012 IgCC,

ICC Book – Green Building: A Professional’s Guide to Concepts, Codes, and Innovation,

Windows for High Performance Commercial Buildings,


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.





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Shared Learnings: Shedding Light on Photovoltaics

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

Photovoltaics convert light energy into electrical energy. The word “photovoltaic” is derived from photo, the Greek word for light, and volt, relating to electricity pioneer Alessandro Volta.

In 1954, Bell Labs in the U.S. introduced the first solar photovoltaic (PV) device that produced a useful amount of electricity, and by the late 1950s solar cells were being used in small-scale scientific and commercial applications, especially for the U.S. space program.

The International Space Station relies on PVs for its electrical needs.
Photo Courtesy NASA.
The Mars Rover is powered by photovoltaics. PVs work on other planets!

When PVs were first introduced into the marketplace back in the late 1970s they were very expensive, not very efficient and not for the average residential or commercial construction project. In recent years, PVs have seen a huge surge in popularity and integration into building designs. The cost per “peak watt” continues to decline as the efficiency of solar cells continues to improve and more firms are manufacturing PV panels. We’ve seen a new industry of local solar companies sprout up to meet the demand for design and installation services.

The graph below shows the cost of PVs in dollars per watt has fallen from over $10 in 1998 to less than $6 in 2012.

Graph courtesy of National Renewable Energy Laboratory.

The opportunity for building integrated photovoltaics (BIPV) looks extremely promising. BIPV is set to become one of the fastest-growing segments in the solar industry with up to 4.6 GW of installations forecast through 2017. Pike Research sees BIPV as one of the fastest growing solar markets.

Building Integrated Photovoltaics (BIPV) utilize the PV panels as part of the envelope of the building. Instead of installing PV panels to existing roof or wall areas, with BIPV, the panels are the roof or wall. This reduces the net cost of the PV system by deducting for the cost of the glass, spandrel panel or skylight that is being replaced. Building Applied Photovoltaics (BAPV) do not have this benefit.

The graphic below shows that BIPV/BAPV revenues have the potential to grow from about $600 million in 2012 to $2.5 billion in just five years.

With expectations of 4.6 GW worth of installations of the coming five years, Pike Research sees BIPV as one of the fastest-growing solar markets. That will be especially true during the next two years, while the global market should reach close to $2.5 billion by 2017 in the analyst company’s “base” scenario. Figures: Pike Research.

Reproduced with permission. ©2012 Navigant Consulting, Inc. All rights reserved.

BIPV installations require coordination among several entities. The general contractor, glazing contractor, electrical contractor, aluminum framing manufacturer, PV panel manufacturer and solar energy consultant must all understand what is required and who is responsible for each portion of work.

  • Who will install the PV panels in the glazing system?
  • How will the electrician wire the PV panels as they are installed?
  • Will wiring be routed within the framing system? Will the framing system need to be modified to accept the wiring?
  • Do the bidding documents clearly define who will bid what portion of the work?

The diagram below shows how PV panels were installed in the Tiger Woods Learning Center in California. The curtainwall was fabricated with access holes in the tongues to allow for the wring to be run down the mullion.
Diagram compliments of Wausau Window and Wall Systems.

How cost effective BIPVs can be depends on several factors, such as:

  • Anticipated amount of sunlight at the building site. Is there the potential for shading from other buildings or trees? Some areas of the U.S. get much more sunlight than others. By the way, PVs work with sunlight, not solar heat. A cold climate has no adverse affect on the performance of the solar cells. In fact, a bright, clear, cold winter day will show improved performance over a hot summer day.

The map below shows the potential for PV performance across the country.
Map courtesy National Renewable Resource Laboratory.

  • Are the panels facing due south for maximum efficiency?
  • Are the panels on a slope or are they in a vertical wall. Tilted panels will perform better.
  • How much was saved by eliminating other building fenestration products and replacing them with PVs?
  • Is “net metering” allowed? This allows the building owner to sell back to the utility any excess solar energy being generated. In some cases, you can literally watch the electric meter spin backward!
  • Are there local and/or state tax incentives or grants? This site has a wealth of information on renewable energy financial incentives:
  • Is their special financing available?
  • Does the electrical utility provide any funding or rebates? Some utilities are willing to help fund PV installations in return for them getting Renewable Energy Credits (RECs) for the installation. These RECs can be used by the utility to show that they are generating a certain portion of their power from renewable energy.

Many times, it’s not just the “payback” that interests building owners to opt for BIPV. What’s the return on investment (ROI)? Most solar PVs will last 25 years or more. How much will electricity cost in 2020, just eight years away? Is depreciation allowed on the installation?

Sometimes, in the end, building owners simply see this as the right thing to do for them and the environment by generating non-polluting, renewable, made in the U.S., domestic energy.


National Renewable Energy Laboratory (NREL),
Database of State Incentives for Renewables and Efficiency (DSIRE),
Pike Research,


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.





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Tubelite’s LEED Professionals Share Sustainable Design Knowledge

As members of the U.S. Green Building Council (USGBC), Tubelite Inc. supports building projects that are designed and constructed to meet LEED® Rating Systems’ criteria. Exemplifying the company’s commitment to sustainable design, Tom Minnon, eastern regional sales manager, and Brian Tobias, estimator, are LEED Accredited Professionals. Gerard Schoeb, a structural and applications engineer, is a LEED Green Associate.

They share their knowledge of green building products and practices through presentations and articles, such as with the USGBC, Architects’ Guide to Glass and Metal, Metal Architecture, the American Institute of Architects (AIA), and the Construction Specifications Institute (CSI).

Tubelite provides storefront, curtainwall, entrance and daylight control systems to commercial building teams. These products can contribute to projects pursuing certification through the LEED Rating Systems in the areas of daylighting and views, thermal comfort and energy efficiency, low-emitting materials and recycled content. The aluminum used to produce these products can be extruded by Tubelite using EcoLuminum™, a high recycled-content aluminum billet composition with eco-friendly, durable finishes.


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LEED® Guidelines and Fenestration Design – Part 2

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

In the second half of this two-part blog, we continue our look at how “smart” fenestration designs and applications can significantly improve a building’s performance using the guidelines in the LEED® Rating System. This month we’ll take a look at Thermal Comfort, Daylighting and Views to the Outdoors.

Materials and Resources Credit 5: Regional Materials

Intent: To increase demand for building materials and products that are extracted and manufactured within the region, thereby supporting the use of indigenous resources and reducing the environmental impacts resulting from transportation.

Strategy: Use building materials or products that have been extracted, harvested or recovered, as well as manufactured, within 500 miles of the project site for a minimum of 10% or 20%, based on cost, of the total materials value.

Note: Aluminum is manufactured from mined (extracted) bauxite. There are no bauxite mines in the United States. Therefore, regardless of where the manufacturer is located, aluminum framing systems do not qualify for this credit. LEED version 4.0, due out next year, will require manufacturers and their raw material suppliers to meet disclosure and responsible sourcing requirements.

Indoor Environmental Quality Credit 6.2: Controllability of Systems – Thermal Comfort

Intent: To provide a high level of thermal comfort system control by individual occupants or groups in multi-occupant spaces (e.g., classrooms or conference areas) and promote their productivity, comfort and wellbeing. Operable windows may be used in lieu of controls for occupants located 20 feet inside and 10 feet to either side of the operable part of a window.

* Design the building and systems with comfort controls to allow adjustments to suit individual needs or those of groups in shared spaces.
* Designs can include operable windows or hybrid systems integrating operable windows with mechanical systems.


Indoor Environmental Quality – Daylight and Views
Credit 8.1: Provide daylight to 75% of regularly occupied spaces
Credit 8.2: Provide direct line of sight to the outdoors for building occupants in 90% of all regularly occupied areas

Intent: To provide building occupants with a connection between indoor spaces and the outdoors through the introduction of daylight and views into the regularly occupied areas of the building.

* Design the space to maximize daylighting and view opportunities.
* Daylighting strategies to consider include exterior sun shades, interior light shelves and high-performance glazing.
* Views strategies to consider include interior glazing partitions.

The photo below shows Tubelite’s Max/Block™ exterior sun shades installed on a storefront system. Note that the sun shades are installed about 2 feet below the top of the opening. This allows for natural daylight to be transmitted through the glass above the sun shades. Using an interior light shelf will help disperse daylight farther into the room and minimize glare near the windows.

Complying with LEED requirements does not have to be a daunting experience. It is important for all parties involved to know upfront if the project will pursue LEED certification. In some cases, the architectural aluminum manufacturer will need to know if there is a specific requirement for recycled content. Total system U-Factors and Solar Heat Gain Coefficients will need to be calculated to ensure that the thermal performance of the fenestration meets the design intent. Substituting products must be carefully reviewed – installing a different type of glass than what was specified may have adverse effects on the heating and cooling loads and daylighting.

The best way to determine if a project is following LEED guidelines is to review Division 1 of the specifications. AIA MasterSpec® Section 01 81 13 Sustainable Design Requirements reads: “This Section includes general requirements and procedures for compliance with certain U.S. Green Building Council‘s (USGBC) LEED® prerequisites and credits needed for the Project to obtain LEED [Certified] [Silver] [Gold] [Platinum] certification. Other LEED prerequisites and credits needed to obtain LEED certification are dependent on material selections and may not be specifically identified as LEED requirements. Compliance with requirements needed to obtain LEED prerequisites and credits may be used as one criterion to evaluate substitution requests.”


LEED 2009 for New Construction and Major Renovations Rating System (PDF)
U.S. Green Building Council
Tubelite Inc.
Wausau Window and Wall Systems


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.


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