News and Events

NREL Performance Graph

December 10 2019

National Renewable Energy Laboratory Research Support Facility
2018 Average Weekday Lighting Power density

The graph above is the weekday average lighting power density ( watts per square foot ) of the 360,000 square foot National Renewable Energy Laboratory Research Support Facility ( RSF ) located in Golden, Colorado. Almost all office areas of this net-zero energy office building are daylit with the LightLouver Daylighting System. Compared to a minimally-compliant ASHRAE 90.1 office building, the RSF’s lighting power density is 85% lower.

Also of note, is the consistency of the lighting power density throughout the year, which indicates the uniform performance of the LightLouver Daylighting System during the four seasons of the year and during various daily weather conditions.

Phase 1 of the RSF was occupied in 2010 while Phase 2 was occupied in 2014. The daylighting performance of the entire RSF has been consistent in the intervening years proving the long-term reliability and durability of the LightLouver Daylighting System. The significant contribution of the daylighting system to the overall building energy performance has enabled the RSF to achieve its net-zero energy goal.


3rd Floor of one of Wings of the NREL Research Support Facility – The LightLouver units are located in the upper portion of the punched windows on the right side of the image. Sunlight is being reflected over the 60 foot width of the floor plate.

Michael Holtz Attends 2019 Daylighting Symposium

May 01 2019

LightLouver LLC Founder and CEO Michael Holtz, FAIA attended the 2019 Daylighting Symposium held in Sacramento and hosted by: The National Electrical Manufacturers Association Daylight Management Council, the California Energy Codes and Standards Program and the Emerging Technologies Coordinating Council. The objectives of this Symposium were to help accelerate market adoption of proven, cost-effective daylight management technologies and practices, present case studies that convey the state of daylight management and glare mitigation in current practice and identify opportunities to improve daylighting design and operations success, and inform overall prioritization of daylighting measures for California’s Title 24 2022 code cycle and beyond.

In addition to Michael’s presentation, LightLouver LLC prepared a poster highlighting the performance benefits of the LightLouver Daylighting System.

Michael’s presentation notes are presented below.

First, let me give you my definition of “daylighting”:

Daylighting is the purposeful use of sunlight to meet the illumination requirements of occupants in an architectural space.

“Purposeful use” means there is a specific design intent to use sunlight to meet the illumination requirements of the occupants in a space. Not just happenstance of daylight entering the space from an aperture.

“Illumination requirements” means that the quantitative and qualitative aspects of using daylighting are met. That is, the proper amount of daylight is provided in a uniformly distributed manner in the space, and without visual discomfort due to glare or high contrast ratios.


Daylight apertures – windows, skylights, atria -- have been an integral part of architecture for centuries --  for obvious reasons, such as illumination, view, fresh air, emergency egress, and well-being.

However, with the oil shocks of the 1970s – specifically the 1973 OPEC oil embargo and the 1979 oil crisis – which gave rise to a national call for energy conservation, architects and their clients started looking at daylighting as an energy conservation measure – which was a big mistake.

In the 1960s and 70s, when Lighting Power Densities ( LPDs ) were 2 w/sf or greater with T-12 fluorescent lamps and incandescent lamps , making an economic argument for daylighting, especially daylight-responsive electric lighting controls, was fairly easy. Reducing electric lighting energy use 30 to 60 % resulted in significant energy savings, and a reasonable economic argument for daylighting could be made, even if daylight dimming lighting controls were fairly expensive. However, the non-energy related benefits of daylighting were ignored and not allowed to be included in any economic analysis of daylighting.

With the advent of T-8 lamps and compact fluorescent lamps in the 1980s and 90s, and more stringent energy codes, LPDs dropped to around 1 w/sf and the economic argument for daylighting and daylight dimming controls became more difficult to make. Saving 50% of electric lighting energy consumption or about 0.5 w/sf through daylighting, while helpful to overall building energy efficiency, was not sufficient to satisfy building owners who were now use to making decisions solely on the basis of the ROI of the energy saving measure. Thus, to many architects and building owners, daylighting could no longer be justified as a “cost effective” energy conservation measure, and once again the non-energy benefits of daylighting were totally ignored.

And with the advent of low cost LEDs in the 1990s and into 21st century, LPDs have dropped into the 0.5 to 0.3 range, and no rational economic argument could be made for investments in daylighting products based solely on electric lighting energy savings. Consequently, many building owners and developers would not even entertain a discussion of integrating aggressive daylighting strategies because the simple payback or the return on investment in these strategies just did not “pencil out”. And once again, the non-energy related benefits of daylighting were not allowed to be included in the calculation.

Architects were now trapped by the energy economic argument and when challenged by their clients to demonstrate the cost effectiveness of daylighting, they could not, and thus daylighting redirection strategies and controls were not included in the building design and when they were they were value engineered out of one project after another.

Architects are now trying to get out of this energy economics trap by espousing the “wellness” argument. That is, it is the health, well-being and productivity of the building occupants that is important not solely energy savings.

So now we see architects trying to integrate daylighting into their designs with mixed results. In general, architects are not well versed in daylighting design principles and thus are not very proficient in integrating “aggressive, glare-free daylighting” into their projects. They tend to over-glaze their designs, rely on ineffective daylighting strategies –such as light shelves, create glary uncomfortable interior conditions, and do not understand the interdependency of the many components of an “integrated lighting system” ( daylighting / electric lighting / lighting controls / solar control ). So while the will is many times there, the knowledge of the most effective ways to daylight an architectural space is not. As a consequence, there are many buildings whose daylighting performance has been terribly compromised.

So as to the first of the two questions, “What is working?”, I would have to say not much. We have the tools, such as Radiance and Radiance based tools like SPOT, to effectively model and design daylit spaces but these tools are rarely used and the current daylighting performance metrics are rather crude and not well tested and verified. And the focus tends to be on new construction when it needs to be equally focused on existing commercial buildings.

As for the second question, “What needs to change?”, I would have a long list, but a few of the most significant changes would be:

  • Architect, engineer and lighting designer education of daylighting design principles and strategies must be improved.
  • Research must be undertaken to develop and verify comprehensive daylighting performance metrics, including glare / visual discomfort metrics, and the human factors issues associated with daylighting.
  • Building codes and standards need to include daylighting as a mandatory indoor environment quality requirement as part of the overall health and safety mandate of the code.
  • Daylighting design and analysis tools must be capable of modeling complex daylight redirection and distribution devises and solar control strategies, and generate the daylighting performance metrics necessary to assess the performance, including code compliance, of the proposed daylighting design solution.
  • And we must focus on integrating daylighting and other sustainable design strategies into existing commercial buildings.

And all the above is irrelevant unless every person in this room, and every person on the planet does their individual and collective part to combat climate change. The future of human habitation on the planet is at stake.

Design Industry Response to Climate Change

January 03 2019

In recent weeks, I have noticed an uptick in professional design journal editorials regarding industry response to climate change. These editorials may have been in response to the release of the latest Intergovernmental Panel on Climate Change ( IPCC ) Special Report on Global Warming of 1.5 °C (SR15 ) and of the Federal Government’s Fourth National Climate Assessment. Both of these reports indicate that if drastic and significant action in not take in the next decade, the environmental, human and economic impacts of climate change will be catastrophic. The design professions bear an enormous responsibility to address climate change in every project they undertake, these editorials are telling the design professions that they can no longer look the other way when it comes to doing something about climate change.

I want to share portions of several of these editorials with LightLouver LLC customers and friends to rally your continuing support of immediate and significant action on climate change.

Engineering News Record Editorial of November 5th, 2018

How to do Better on Climate Change

Our industry can no longer look the other way at the impacts of climate change. Whether or not you believe our crazy weather and increasing heat are caused by human activity, the facts are irrefutable – the world’s communities are experiencing more frequent flooding, stronger hurricanes with massive storm surges and intense and long-lasting droughts. The recent report from the United Nation’s IPPC says the world has just 12 years to get matters under control or the effects will be irreversible. If it doesn’t entire cities may have be walled in to protect them from sea-level rise; other cities may simply have to relocate to areas where there is less flooding or drought.

Since 2007, the architectural profession has made sustainable design a part of it ethical code. In 2018, the code was expanded to say architects should work with their clients to incorporate strategies to anticipate extreme weather events. The National Society of Professional Engineers and the American Society of Civil Engineers also encourage sustainability.

While designing for climate change can be expensive, the National Institute of Building Sciences  has shown that for every federal dollar spent on disaster mitigation, $6 on average is saved on disaster mitigation. Engineers and architects need to include those costs and benefits in their presentations and underscore that when it comes to the future, a penny saved isn’t necessarily a penny earned.

If we continue to rebuild without thinking about the future, we will continue the existing cycle of rebuilding, over and over again, wastefully, without longer-lasting structures and systems. We must do better at using new approaches and incorporating resilience into designs.

Pretending that climate change isn’t real, or doing nothing about it, goes against fundamental ethics.

ARCHITECT, The Journal of the American Institute of Architects, October 2018

A Positive New-Zero Attitude

The 2016 Paris Agreement focused on the effects of a 2-degree C ( 3.6-degree F ) increase in average global temperature, and gave the world a deadline of 2100 for reducing greenhouse gas emissions to zero. A new U.N. report, undertaken the behest  of island nations concerned about sea-level issue, looks  more conservatively at a 1.5-degree C ( 2.7-degrree F ) increase. The findings are alarming, to put it mildly: the outcomes of even this lower temperature hike will still be disastrous, and we will be all but resigned to that fate in little more than a decade unless we act immediately. To minimize the catastrophic risk, humanity must reduce emissions by 45% by 2030, and achieve total carbon neutrality by 2050.

It’s net-zero hour, folks.

If you think the internet has been disruptive, just wait until rapid decarbonization takes hold. Of course, we already know that achieving carbon neutrality is technically possible. The process calls for an estimated clean energy investment through 2035 of 2.5 percent of global GDP. While that’s a staggering amount of money – roughly $2.4 trillion per year – financing humanity’s survival may seem easy compared to the social and political challenges the  task entails.

….in a net-zero energy economy, there’s no avoiding the fact that there will be likely be limits on growth. But that doesn’t mean there will be limits on opportunity…….

Decarbonization isn’t about constraints, it’s about smarter decision-making, based on better information.

….The terrible consequences of inaction are increasingly evident – just ask the residents of the Florida Panhandle. Now we must focus on the essential value of taking action, beyond survival.

ARCHITECT: The Journal of the American Institute of Architects, October 2018

Existing Buildings: The Elephant in the Room ( Carl Elefant, FAIA, 2018 AIA President )

For those who knew of me before I became AIA President, it is probably for coining the phrase: “ The greenest building is …one that is already built.”

…..Building-sector statistics are compelling, architects have been busy beavers since World War II. From coast to coast, the U.S. has accumulated to many buildings that economic projections estimate that over the next 30 years more than twice as many will be renovated than newly constructed. To put it another way, today’s early-career architects will spend more time renovating buildings than designing new ones.

Existing buildings are a resource for tackling climate change. Buildings represent “embodied carbon.” Keeping and using existing buildings avoids the release of massive quantities of greenhouse gases, emissions caused by needlessly demolishing and replacing existing buildings. Retrofitting existing buildings to meet high-performance standards is the most effective strategy for reducing near- and mid-term carbon emissions, the most important step in limiting climate disruption. Existing buildings are also a resource for leaning about life before buildings were addicted to fossil fuels, and cities and towns were addicted to automobiles in the name of progress.

For the next generation of architects, embracing the opportunities and challenges of existing buildings is the elephant in the room. How long before our profession notices?

ARCHITECT, The Journal of the American Institute of Architects, November 2018

Percent of Design Activity Devoted to Existing Building Projects

The results of the 2018 AIA Firm Survey Report reveal that 44 percent of design activity is dedicated to improving existing buildings. Typically, existing building work shrinks during strong construction markets ( like the one we are currently experiencing ), but this time it has continued to hold steady. The persistent activity demonstrates the shift in owner focus to making current assets as valuable as possible – and the impact of incentives for investment in improvements versus replacement. Through existing buildings work, architects can continue to have a tremendous impact on improving the efficiency of structures, combating the impact of climate change, and preserving history.

These editorials have one thing in common, they speak to the immediate and critical need to address climate change in every conceivable way imaginable. There is no single solution: there must be multiple solutions in every sphere of life and living. The causes of climate change – greenhouse gas emissions -- occur in all facets of life, and thus the solutions to climate change must be found and implemented within all facets of life. As architects, engineers and planners of the built environment, we must play our part in developing and implementing strategies that are sustainable and mitigate climate change.

We must always rememberWe do not inherit the earth from our ancestors; we borrow it from our children.”

Fort Collins Utility Administration Building Wins Award

October 01 2017

Engineering News Record ( ENR ) has selected the Fort Collins Utility Administration Building as the best sustainable building project of 2017. Designed by RNL Design and constructed by Adolfson & Peterson Construction, the three-story, 37,500 square foot office building is only the fourth project in the world to be certified LEED Platinum for new construction under the U.S. Green Building Council’s version 4 standard. The building integrates numerous sustainable design features such as wall panels that combine framing and insulation; fiberglass high performance window frames and glazing; photovoltaic modules for power generation; a rain garden; and the LightLouver Daylighting System for deep, glare-free daylighting.

The LightLouver Daylighting System was selected over other side-daylighting strategies that were considered because it provided uniform, glare-free daylighting deep into the office areas. A unique mounting strategy was developed because of the fiberglass window frames that were used for the high performance windows.

See images of the project in the Portfolio section of the LightLouver web site.