Mandatory Daylighting: Are You Ready?

May 14, 2012 / no comments

The long-awaited International Green Construction Code (IgCC) has been published. The International Code Council, the organization that produces building codes widely used in the United States, such as the IBC and IECC, produced the IgCC. Development began in 2009 with the American Institute of Architects on board as a sponsor. The International Association of Lighting Designers (IALD) was represented on the drafting committee and testified at all code development hearings. Along with our IALD colleagues, Lam Partners Principals Keith Yancey and I were intimately involved in the development of the electric and daylighting related provisions of the code. For more on green building codes, see my February 2010 article Will Green Building Codes Leave You Seeing Red?.

So now the question is, will the IgCC be widely adopted? One school of thought is that many municipalities are clamoring for a green building standard written in enforceable code language. The other asks why a municipality would add another very complex code to the enforcement responsibilities of their already overstretched inspectional services departments. Me? Well, I’m skeptical that IgCC will take off, especially considering the anti-regulatory tone in our political discourse these days. But don’t listen to me; I was surprised by the wildfire success of LEED.

What does this have to do with daylighting? Well, did you know that the IgCC has a mandatory provision requiring minimum daylighting of buildings? Surprise! We’re not talking about daylight responsive lighting controls to save energy; we’re talking about buildings having to be designed to ensure a minimum amount of daylight into the building. This is not a code requirement we are used to in the US.

So how does it work in IgCC? First, the requirement only applies to these building and space types:

  • Office, Higher Education, Labs
  • Retail (single-story and larger than 10,000 square-feet)
  • Schools
  • Manufacturing and Warehouse
  • Library reading areas, Transportation waiting areas, Exhibit halls, Athletic areas.

The IgCC says that in one-or-two story buildings, 50% of your floor area has to be daylighted and 25% in buildings three-floors and up. The trick is defining “daylighted”. IgCC does this with two options: a prescriptive method and a performance method. If your project is required to have a daylighted area larger than 25,000 square-feet, you must use the performance method.

Genzyme Lam Partners

Let’s look at the prescriptive method first. It defines your daylighted area based on the height and width of your windows and skylights. Then, assuming you have a sufficient daylighted area, you determine if you have a high enough “effective aperture” (EA). EA is just your window area multiplied by glass transmittance, divided by the daylighted area. The more window area you have and the higher transmission your glass is, the more daylight will enter. The minimum EA is given in a table and is based on the sky type for your location. There is also a nasty looking formula that lets you reduce the required daylighted area based on exterior shading obstructions, such as other buildings.

The performance method requires daylight computer modeling of the project. Simply put, the performance requirement says that you have to show that you will have at least 300lux and not more than 4500lux in the daylighted area. You show this under clear sky on the equinox for the either 9:00AM or 3:00PM.

Greenspace Lam Partners

Easy, right? Truthfully, both the prescriptive and performance requirements are more complicated than I have led you to believe and this will be especially true when applied to complex architecture. In many cases, designing a building to meet these requirements will require a daylighting design expert, and likely one with expertise in daylight computer modeling software. Those of us who deal with the LEED daylighting credit will find these daylighting requirements familiar, but if IgCC takes off we are going to have to pay attention to daylighting from the very beginning of the building design process. It’s one thing to say, “Hey, let’s see if we can get a LEED point.” With IgCC we’ll be saying, “If I don’t site, mass, and fenestrate my building properly, I’ll be in violation of code.”

Photo credit: Stephen M. Lee (1), Glenn Heinmiller/Lam Partners (2), Lam Partners (3)


Dispatches from Lightfair

May 31, 2011 / no comments

Every year, many of us here at Lam attend Lightfair® International, an annual lighting trade show and conference, allowing us to keep up to date with products from hundreds of lighting manufacturers, as well as design tools and technologies, standards and practices, and industry-wide trends and innovations.

The following are some of our impressions of this year’s event:


Lightfair seems to be turning into more of an electronics show than a lighting show. But, I saw a lot of LED products this year that gave me hope about LED lighting in general. My favorite: retrofit LED lamps that are actually a good replacement for incandescent lamps! Sure, these things have been around for years now. They cost a fortune, last about a month, produce hardly any light, and the light they do produce is garish. But what I saw at Lightfair was lamps that dim, have good color, produce useful light, and are affordable! This is very encouraging. There are lots of wonderful products that can produce a low-power-density lighting design for a new project – but the majority of square footage in the world is not new, it’s existing. Affordable retrofit products that are actually starting to look good is a great step forward. We may even be able to reach the Architecture 2030 Challenge!

Other LED products I saw that give me hope are interchangeable light engines. They’re like LED light bulbs. There’s an industry-wide movement, called Zhaga, that is trying to standardize the specifications for the interfaces of these light engines. So instead of throwing the whole luminaire into a landfill, we can now recycle and replace just the LED module.

The trade show itself was also encouraging. I was in New Orleans to attend the AIA convention the week prior, where the floor was dead compared to Lightfair. Is it because architecture is still hurting economically and there were just not as many people attending? Or is it that architects are chasing CEUs and attending more seminars rather than walking the trade show floor? Either way, Lightfair was wonderfully crowded and vibrant this year. People in almost every booth gave me hope that the industry is coming back. I ran into a lot of colleagues who said work was picking up, or that they were very busy. A sense of optimism seemed to be the brightest luminaire at Lightfair this year.

– Keith

I had two basic missions at Lightfair. The first was to check out innovations in current and upcoming lighting design software, and the second was to attend the IES Daylighting Metrics Committee meeting.

Tools to evaluate lighting are in a state of flux. Some lighting and daylighting metrics have progressed in sophistication, but the software has not yet been developed to employ all of them. Revit is becoming not only popular, but required on many projects, however, coordination of lighting into Revit models is still far from commonplace. This was clear in the short session I attended about BIM modeling, which showed many important capabilities of a variety of softwares, while also showing that in practice, transferring information between programs can be tedious and time-consuming (though one particularly bright spot revealed at Lightfair is a plug-in being developed for Revit which allows lighting analysis of Revit models without manually transferring the model into AGi32 and back).

On the other hand, there are good software tools available, but most designers have not yet learned how to use them. Researchers have developed robust and valuable new daylighting metrics that can only be used by a select few with advanced expertise of difficult, esoteric software. This is especially problematic when working with codes like IgCC and LEED. Better metrics can help foster better design, but it’s impractical to require compliance based on software that’s not widely known or easily available. Furthermore, as the Daylighting Metrics Committee discussed, there is a need to standardize metrics so that everyone is working from the same basic assumptions.

The rise of Revit and BIM provides new opportunities as well as challenges. In principle, it should facilitate coordination among architects, engineers, and consultants, but in its nascent stages, there are still a lot of hurdles to clear.

– Kera

After walking the many aisles of lighting booths at Lightfair, I was left with a feeling of brightness. Not with a sense of novelty or originality, but literally, glaring brightness. There was a vast display of LED site lighting pole fixtures looming above, packed with bright LEDs, and causing overpowering glare at almost every corner. As manufacturers touted the universal suitability of LEDs, the fixtures actually on display overwhelmingly revealed some of their biggest disadvantages, with high-angle glare and excessively cool color temperatures.

Even though it was slightly frustrating to walk around the exhibition hall, squinting my eyes to dodge bright LED fixtures, I found the experience to be, in a way, eye-opening, as the ever-present LEDs on display demonstrated the need for much continuing development and innovation before these products become practical.

On the other hand, it was interesting to see some of the manufacturers that are implementing LEDs into thin forms and planar fixtures, taking advantage of LEDs’ unique characteristics and compact quality.

The part of Lightfair I enjoyed the most, the part that left the biggest impression on me, was the keynote speaker luncheons. I enjoyed the camaraderie of sharing design experiences, and learning about the design process from visualization to concept to schematics, mock-ups, and final design. It’s great to simply get to know other designers, and to appreciate the projects from various points of view, with more than just a final photo of the result.

– Amber

My biggest impression at Lightfair was “who are these guys”? There were so many companies that I had never heard of. Seems like everyone sees this big market opportunity in LEDs, and if they can stick a chip into something and make it glow, they are a lighting company!

I was happy to see the development of small-aperture LED recessed fixtures with a choice of beam-spreads, as an alternative to MR halogen fixtures. They are still much more expensive, but the price should come down, and potential payback in energy savings can help. Of course, the lack of standardization in outputs and beam-spreads continues to be frustrating.

Speaking of lack of standards, let’s talk about controls. Unfortunately in this country there is no standard lighting control architecture or protocol. Add to this some really fascinating out-there control systems (low-voltage DC power, power-line carrier, wireless) and it gets really crazy. It will be interesting to see how this will settle out – but in the meantime, we’ve got to design control systems… sigh.

As usual I was disappointed by the lack of new, innovative fixture designs – sure, there were a few things, but none of my colleagues I bumped into were saying “you’ve got to go see this!”. And when it comes to LED (which is pretty much all anyone was showing), this means that I saw very few fixtures that took advantage of the unique form and electrical characteristics of LED. Sure, we need (cost-effective) LED downlights and troffers – but come on guys, use a little imagination!

– Glenn

Meh. Let me put my curmudgeon hat on:

Unfortunately, I feel this way more and more about each successive Lightfair I attend. Perhaps it’s because Lightfair happens too often (try a two-year rotation), but the last three I’ve seen have been dominated by the same theme: everyone trying to convert their standard products to LEDs. The problem is that LEDs are STILL only half-baked as replacements for standard sources and, until the industry agrees on some basic standards (like a replaceable LED module), it’s just the Wild West out there.

What’s more is that everyone is jumping on the bandwagon and copying everyone else. Where there were once two or three LED downlights, now there are 50, all making crazy claims of energy savings and unrealistic lifespans. The copy-catting was so bad this year that I had to walk up and down the aisles ignoring any company I hadn’t heard of before, because the probability is high that you won’t see them at the next Lightfair.

It’s not even a fad, it’s a frenzy. Most don’t even try to innovate – they just use the same old housings and stuff LEDs into them. Those that did their LED homework and are doing some ground-breaking stuff command some respect, and I was impressed to see their recent improvements. Still others, who have built their companies around standard light sources, are proceeding more cautiously, and I can respect them for that as well. But those that simply do it because everyone else is doing it – both specifiers and manufacturers – may end up getting burned in five years when everything needs to be replaced. There will be a glut of crap out there for several years to come. I’m not an LED hater. They have their time and place, but proceed with caution – now more than ever.

Curmudgeon hat off, optimist hat on:

I did see noted improvement in the more design-ey LED stuff. Some manufacturers have embraced the LED’s discreet nature and have developed fixtures around new forms. I saw some three-dimensional forms, curves, planes, stuff sandwiched between panes of glass, and other crazy shapes that really catch your eye (not like those that try to snare you into their booths by impairing your vision with LED headlights). That’s the kind of ingenuity we need to see.

As for controls, I saw a marked improvement in promotion of digital addressable systems, which are definitely game-changing technology. Just like for LEDs, there is currently no regulation or standardization out there, but those manufacturers that really get it are making significant headway. It’s a lot to sort out, but we’re finally seeing progress where for twenty years there had been none. Keep it coming.

– Matt

Image credit: LIGHTFAIR® International (photo by Lam Partners)

Heliodon 4.0

August 10, 2009 / no comments

In an era when computer speed and software capabilities are constantly improving, one might wonder why any lighting design firm would bother with physical model-testing for daylight analysis anymore. There are many different types of software available today that can be useful for studying daylight in architectural spaces, but there are still compelling reasons why studies performed by traditional methods will never be completely replaced by computers.

The cornerstone of these methods is a multi-axis device known as a heliodon. A scale model is first secured to the table, oriented correctly north-to-south, and then the table is angled to match the latitude of the real building’s location on earth. A solar sundial is positioned next to the model to identify time of day and time of year.

Rotating and locking one axis of rotation then establishes time of year, while rotating the angled table recreates the changing time of day. Once these variables are set, one can immediately see daylight interacting accurately with the model any time of day, any time of year, anywhere on earth.

The newest heliodon at Lam Partners is a testament to the belief that physical model-testing continues to be indispensable in evaluating daylight. Easy video integration, fast modifications to the model, perfect rendering of materials, and a comprehensible interface are all reasons why we decided that upgrading our heliodon was worthwhile, and this fourth-generation model incorporates new design features gleaned from 35 years of daylight analysis experience.


The primary feature is the motorized table that allows for precise rotation, used in conjunction with a digital video camera. A heliodon is able to quickly cycle through sunrise to sunset, so smooth rotation at a consistent speed is critical for high-quality video output.

Another feature is a wide, stable, and adjustable base platform that is removable and can be field-leveled for the most accurate results. Part of the overall design objective was to make the entire heliodon easily broken down and portable, with three easily reassembled components that all use the same size bolt. All necessary tools are stored neatly within the frame and easily accessed.


The improved precision of the new heliodon required a sundial that was equally precise. We designed a new one and had it CNC machined from solid aluminum, like the heliodon (yes, the chips were all recycled!). The new construction features an adjustable and lockable latitude angle, as well as a removable and replaceable gnomon that can be safely stored within to prevent damage. A polar sundial design was then laser-etched onto the front for durability.

Together, the new heliodon and sundial provide a level of exactitude never before realized in earlier designs. After the initial set-up, an architectural model can easily run through an entire year’s worth of sun-angles in barely an hour on the heliodon. Since sunlight works the same at any scale, measured footcandle levels inside the model, when factored to account for local latitude and season, are accurate and reliable.

This breadth of valuable information takes far longer to gather using computer software which usually lacks the intuitive feel and quick adjustments that physical modeling offers, and most daylighting software continues to struggle in accurately representing complex materials and textures or multiple reflections.

So, while Lam Partners certainly does use software for some aspects of daylight study such as basic sun-angle geometry, the qualitative advantages inherent to heliodon analysis make it an extremely useful tool for daylight-intensive projects.


Photo Credits: Anna Baranczak / Lam Partners Inc (1, 4), Justin Brown / Lam Partners Inc (2, 3)