Lighting of exterior environments not only provides for safe navigation during hours of darkness, but can reveal design elements, both built and natural, that are lost in daylight, returning delight to the hours without sun. With all of our energy focused on lighting the ground, the importance of vertical illumination is getting lost in the darkness.

Early versions of LEED SS Credit 8 (Light Pollution Reduction), with stringent requirements to limit all light above the horizontal plane with the exception of very low-brightness fixtures, was an effort to push dark-sky agendas forward without acknowledging what a well-lighted exterior environment actually requires, or what it contributes to the urban environment. Downlight with sufficient uniformity can facilitate movement across plazas and walkways, but where are people headed? Lighted pavement alone can provide orientation only without end or destination.

While obscuration of the heavens through urban sky glow is one of the most unfortunate results of the urbanization and industrialization of our planet, the metrics for nocturnal illumination cannot be based upon the assumption that the primary task of humans in an urban environment is to go and gaze at stars. Even when these standards are met, the results can still have a negative impact: a modestly lighted parking lot with light-colored concrete pavement lit to the minimum IES recommendations, using only cut-off fixtures, can substantially degrade a dark residential environment if that pavement is within view of residences – and the reflected light from the pavement is going into the sky, even though the fixture itself does not emit light above horizontal. (This is a great opportunity to advocate for tree cover – not only does it provide parking lots with cooling shade during the summer and soften their appearance during the day, but it blocks reflected light from trespassing upwards! That’s not accounted for in the requirements).

The Lighting Research Center at Rensselaer Polytechnic Institute has developed a metric for evaluating and designing exterior lighted environments, known as Outdoor Site-Lighting Performance (OSP), that accurately documents the effect of electric illumination on a project. OSP acknowledges that glare, light trespass beyond the physical limits of the site, and sky glow are all important factors that warrant consideration. However, by using modeling tools that measure the amount of uplight trespassing off the site – not only light emitted by fixtures, but also the reflected light off of surfaces such as the parking lot mentioned above – a more realistic picture of the lighting effect can be examined. Similarly, current and future versions of LEED SS Credit 8 do allow for some amount of uplight in the urban environment.

What about projects where reliance on cut-off downlight fixtures is not a good fit architecturally? Can they still meet the intent of a sensitively lighted nighttime environment? Lam Partners’ Hermann Park Lake Plaza project avoides pole-mounted fixtures, equipment that is, in effect, prescribed by LEED and other dark-sky guidelines. Determined not to use pole-mounted lighting along the water’s edge to avoid distracting reflections in the water, the designers devised a fully integrated approach. One-watt LED button steplights illuminate and guide, tracing the arc of steps around the lake; ground-recessed ceramic metal halide tree uplights create a welcoming border.

The graceful composition remains uncluttered by hardware, focusing solely on form and line. The arrangement is serene and contemplative in early evening, then emerges dazzling and energetic as night descends. Because awakening the appearance of surfaces and landscape forms was critical to attracting visitors after dark while fostering safety and security, tree trunks and wall surfaces are boldly illuminated.

The team deliberately relinquished the LEED light pollution credit (although the project did achieve LEED status), and yet, the uplit trees are magical during nighttime strolls. As darkness conceals architectural stonework, the wooded procession comes to life through light. From across the lake, the trees form an illuminated horizon, and indirectly lighted walls form the edges of this exterior room.

Photo Credits: Anton Grassl / Esto (1), Walmart Stores (2), Overland Partners (3, 4)

Controls: use them!

It’s really not acceptable to use simple switches and whole-floor relays anymore. Some energy codes may still allow it, but that doesn’t mean it’s good practice. Have you ever walked around a city at night and looked up at the skyscrapers to see entire floors, or even whole buildings, with all the lights on late at night? Chances are there are only a handful of people there, or none at all. Sensor technology has improved a lot over the years and should be applied liberally to take care of all those lights that no one is there to use. It not only saves electricity, but the time, effort, and additional energy it takes to replace lamps that burned out too soon from overuse.

Make sure you use sensors correctly, too. If a sensor is placed behind a bookshelf, it’s doing no good back there. If you put one right in front of a door and the light stays on all the time, how it that helping? There are a few simple tricks that the manufacturers can educate you about to create good sensor design.

And, consolidate your sensors. Most sensors can be used for both lighting control and HVAC control. Instead of two sensors in a space, use one.

K.I.S.S. – keep it simple, stupid!

Lighting controls can be daunting. Even the simplest systems have gadgets, widgets, and enough wiring diagrams to make the savviest engineer’s eyes go crossed. When selecting the system you want to use, make sure that price isn’t your only deciding factor – consider how easy it is to design, install, and program. Making people’s lives easier will result in a higher probability of your controls design being implemented the way you designed it.

Minimize the amount of wiring you need to make your system work correctly. Wiring in any given building can add up to hundreds or even thousands of miles, if you tied it together and stretched it out. Any way to reduce that raw material used (and the energy used to make it) helps. If one system uses 40% less branch wiring than another, consider it.

But is the current energy code the best way to save energy? Is lowering the allowable maximum connected load for lighting even enough to get us the savings we need to meet the national energy goals of 2030? Probably not.

Over the past decade, the allowable lighting power densities (LPD) have been lowered time and time again, sometimes logically, and other times less so. The mantra has been to increase energy savings by lowering the amount of connected electric lighting load – end users are then free to turn that connected load on and off at any time. The problem with this method is that it doesn’t account for real usage. How energy-efficient is a low-power lighting solution if it stays on all the time?

For example, take a typical ten-foot-square office space with 1.0 watt per square foot allowable LPD. You can use up to 100 watts in that particular office. Now, if you leave that office light on for 24 hours (i.e. you forgot to hit the switch on the way out), you’d have 240 watt-hours (that’s 0.24kW-h on your energy meter). But not everyone forgets to turn off their lights, so that scenario is the worst case.

A lighting design can thus easily be checked against the code while still on paper, and this is pretty straightforward, but it doesn’t take into account how the end user will use that lighting. The lighting is designed for a maximum load at a single point in time (power), but is then measured as energy (power x time) – there’s a disconnect between the design and the application. The kicker is that there is no simple real-world method to check or enforce codes once a space is occupied. Owners are free to burn the midnight electrons and no one will say boo about it.

Now take that same office space but, instead of designing only for power allowances, you design it for power and time. What if you make an allowance for the lighting to be on for only 12 hours per day (a standard assumption for all but the craziest workaholic American). You could use the same 100 watts but the total energy used is now half that of the worst-case scenario. What if that same office has windows and daylight dimming, and the lighting is only on for 4 hours each day, just 40 watt-hours – we just went from half to one-sixth of the energy used!

So how do we predict how occupants will use lighting, and how can we make sure they then keep using it as intended? Mandates and accountability. As much as we’d like to assume that everyone will hit the light switch on the way out, that’s a bit too much wishful thinking. Cost is no deterrent, either – major corporations have money they seem happy to spend, and with the cost of energy artificially low in this country, there’s not much incentive.

There’s a growing movement in the code world to actually factor anticipated duration of use into the equation, measuring compliance in kilowatt-hours rather than just watts. We’ll always need to reference watts in our design process, but eventually we’ll have squeezed out all the watts we can, and it still won’t be enough. Adding time into the equation doesn’t immediately guarantee energy savings, but it does put it in terms that we can identify, relate to, track, and react to. It’s time to think more about energy, and less about power.

Photo Credit: Steve Ryan

With the onset of the holiday season, we have also come to the end of the three-year energy code development season. The new 2010 version of ASHRAE/IES Standard 90.1 has been published, and IECC-2012 will be published in April 2011. (No, that’s not a typo. IECC-2012 will be published in 2011. Don’t ask, I have no idea.)

It will be a while – years, probably – before IECC-2012 is adopted by states, and at least a year before 90.1-2010 is incorporated into LEED, but the code development community is already looking towards the next versions of these model energy codes: 90.1-2013 and IECC-2015. So, while designers are currently practicing under energy codes that are at least three years old, code geeks have their heads three years in the future. So, what gifts might the next code development season bring us?

Watch the IECC

Historically, the IECC relied on 90.1 for energy code content. With IECC-2012, the IECC lighting section takes on a life of its own. Expect that trend to continue. While 90.1 will likely remain influential, since the IECC is the actual code that states adopt, the IECC may be where the action is in the future.

Stretch Your Codes

Energy codes only set a minimum acceptable performance (the worst possible building that you can legally build?). Institutions, corporations, and governments that understand this are looking for ways to push their energy use even lower. One way to do this is with “stretch codes” such as the Massachusetts Stretch Energy Code which has been adopted by over forty Massachusetts communities. This Stretch Code is an appendix to IECC-2009 that increases stringency.

Another way to go beyond the minimum is through green building codes such as the new International Green Construction Code (IGCC). Green building codes are intended to have energy performance provisions that are more stringent than base energy codes. Because of this, new energy regulation ideas are being proposed in the IGCC development process. Keeping an eye on the development of the IGCC’s energy chapter may give us an idea of what future energy codes will look like.

These advanced code programs, if adopted widely, will make the designer’s job more complex. Not only will they have to keep track of the applicable energy code in each state, but they will have to know if the municipality is using a stretch energy code or has adopted a green building code with its own separate energy provisions. And they may struggle to design to different and potentially conflicting requirements.

Squeeze Out More – a Lot More!

The pressure is on and will almost certainly continue for the energy codes to be more “efficient”. For the last code cycle, the goal was 30% more “efficient” than 90.1-2004. We don’t know what the target off of 90.1-2010/IECC-2012 will be, but I wouldn’t be surprised if we see a proposed target of 30%. Those of us who have been thinking about this don’t see how this will be possible with typical building technology, design solutions, and energy code methodology.

Lighting Power Density is currently the preeminent tool for regulating lighting energy use. The push for more efficiency in codes means pressure to lower LPDs even more. But barring an unforeseen leap in technology, we can probably only squeeze a little bit more out of LPDs if we are to maintain high-quality lighting. We may be able to eke out some more savings by expanding even further the requirements for occupancy sensors and daylight responsive controls. But how do we make big reductions – 30%, 50%, eventually all the way down to net-zero?! Daylighting.

In order to significantly reduce lighting energy use, we’re going to have to really use daylight to extensively light our buildings. If codes require this, a radical change in mindset will need to take place – resulting in major changes in building footprints, orientation, and envelope design.

Guaranteeing the Outcomes?

If energy codes are supposed to reduce building energy use, then shouldn’t we be directly regulating it? The common prescriptive code methods use blunt instruments such as LPDs, minimum equipment efficiencies, and R-values to affect how a building is designed. These methods do indirectly affect the energy use of the building, but the energy use itself (how the building is operated) is not regulated.

In an ideal world, the energy code should just tell us what the end result needs to be, and let us decide how to get there. Expect to hear more about EUI (Energy Use Intensity), measured in kBtu per square foot per year. An effective building energy performance-based code will require more robust, but easier to use, energy modeling software. It will also require a change in the way we design buildings – with a truly integrated design process where the whole design team is working together to get the most out of a limited building energy budget.

EUI may be the way to make the codes much more “efficient” and still allow high-quality buildings to be built – but many details, such as dealing with occupancy/operating hours, will have to be worked out. Look for energy codes to start requiring a building energy performance method for buildings of certain types or sizes.

Even if you perform complete energy modeling, and design to a specific annual building energy use limit, all you are doing is predicting how much energy the building will use on the day it opens, if properly commissioned and operated. Every lighting designer has their horror stories of carefully designed (and expensive!) lighting control systems that were never commissioned and/or operated correctly, leaving all the lights on, even when daylight is streaming in or when no one is around. The building meets energy code, but if it isn’t operated correctly and becomes an energy guzzler, then the code is ineffective. Realizing this, code geeks are starting to look at “outcome-based” codes.

An outcome-based code might require building owners to certify actual annual energy use. How will an outcome-based code be enforced? Will buildings someday need to get an annual energy certificate just like an elevator or health department inspection? And what would the penalties be for non-compliance? Will design professionals be held responsible for the performance of a building that they designed but do not operate?

The Gift That Keeps On Giving

As you can see, energy codes are likely to get tougher, get more complicated, and adopt unfamiliar new methods. Building design professional organizations such as the IALD, AIA, IES, and ASHRAE are all actively involved with energy code development. If you are interested in getting involved with code development and are a member of one of these organizations, you can contribute. Happy holidays!

Photo Credit: Phillie Casablanca

Readers of this blog have already heard about the new Green Building codes, but there are new versions in the works, both of the energy code standard ASHRAE/IES 90.1, and of the International Conservation Code (IECC). What will these codes look like, and how will they affect the work of architectural lighting designers?

The 2010 version of ASHRAE/IES 90.1 will be published this fall. Standard 90.1 is the benchmark model energy code. Although rarely adopted directly as code, it is an alternative path for IECC compliance; it’s also the energy performance reference for both the US Department of Energy and the LEED rating systems, and is highly influential, like California’s Title 24, as a trendsetter.

ASHRAE’s goal for the 2010 version of 90.1 is to be 30% more stringent than the 2004 version. Standard 90.1-2010 will have lighting power allowances that are significantly lower than the 2004 and 2007 versions. Additionally, there will be many new controls requirements such as mandatory use of occupancy sensors in some spaces, incentives for daylight responsive controls, exterior lighting after-hours shut-off, and controls commissioning requirements, among other things.

The IECC is currently in the middle of its three-year development cycle. IECC-2012 will be published in April 2011. The goal of the Department of Energy and other stakeholders in IECC development is for IECC-2012 to be 30% more stringent than the 2006 version. It’s a little early to know for sure what will be in the next version, but expect reduced power allowances, and the addition of a space-by-space method for determining lighting power densities. Another concept that’s been proposed is the “Additional Efficiency Package Options”. To comply, the project will have to pick one option from a menu of energy-efficiency provisions like more efficient mechanical equipment, onsite renewable energy, or reduced lighting power allowances.

But here’s the thing to keep in mind: even though these new standards will be published soon, they don’t become code until they are adopted by individual states. By federal law, the DOE must evaluate each new version of 90.1 to determine if it is more efficient than the previous version (and because IECC offers 90.1 as an alternative compliance path, it piggybacks on the DOE determination). If the standard is found to be more efficient (and it will be), states are required to adopt an equally stringent code within two years.

But, enforcing this provision and getting the states to adopt the latest code is easier said than done. Currently, only ten states have adopted the most recent standard, IECC-2009/90.1-2007. At the other end, eleven states have either no statewide energy code at all, or are using standards older than 90.1-1999. The remaining states use something in between. This lag is typical, but I expect it will decrease, given the global push to reduce energy consumption and greenhouse gas emissions. If states follow the example of my home state of Massachusetts, then code lag will be very short in the future. Last year, Massachusetts not only adopted IECC-2009, but wrote into law that newer versions of the IECC will automatically become code soon after publication.

One school of thought says that these new standards will be overly stringent and will make it impossible for designers to produce quality results. I don’t agree with this opinion. Through my work as Chairman of the IALD Energy and Sustainability Committee, I’m pretty familiar with what is likely to be in these standards. We’ve been working hard to make sure that the codes are as aggressive as possible, but without prohibiting quality design. I believe that the new standards will only codify what any responsible designer should already be doing to reduce the negative environmental impact of their design. And, I do not think that they will prevent us from producing effective, comfortable, and beautiful spaces.

Yes, it will be harder. The “cushion” will be gone; we will have to be very careful with our use of energy in order to meet code. Competency in lighting design will require deep knowledge of code requirements, the skill to get the most out of limited power budgets, and expertise in lighting controls technology and system design.

Image Credit: D-32

It’s pretty safe to say that people like daylight and sunlight. Daylight is good for people, since it sets our biological rhythms, gives us a connection to the weather and time, keeps us physically and mentally healthy, and obviously allows us to perform visual tasks. It’s no wonder then, that architects through the ages have designed architecture to effectively introduce sunshine and daylight into building interiors – not only to sustain human life, but to allow it to flourish.

Daylighting has been an integral part of the built environment throughout architectural history, and structures that are thousands of years old are still revered for their daylighting qualities. “The history of Architecture is the history of man’s struggle for light – the history of the window,” wrote Mies van der Rohe.

It’s only within the last 75 years or so that daylighting has been supplanted by electric lighting as the primary source of interior daytime illumination. Ever since the introduction of air-conditioning, and especially of modular gas-discharge lighting (i.e. modern fluorescent lamps), windows and skylights have been getting smaller and floor plates have been getting larger. Our luminous environments have been deemed adequate and appropriate based on a simple numerical criterion, horizontal footcandles. However, in recent years, especially with the ‘green’ movement, there has been much more pressure to re-introduce daylight back into our interiors and create daylit architecture once again.

But what exactly is ‘Daylit Architecture’? It’s difficult to define. For architects it may be about beauty and ergonomics; for engineers it tends to be focused on energy and economics. Fortunately, with recent studies, we finally have hard evidence showing that daylight in schools improves test scores, and daylight in the workplace improves productivity. In retail, it boosts sales; in hospitals, it reduces recovery time. These studies embolden the stance of the ‘quality’ seekers.

But, on the other side are the energy tyrants. They want to see fewer windows in architecture since windows are terrible insulators. The criticism is real. News stories are unfolding about LEED buildings and how they are not living up to their touted energy claims. But the LEED points for daylighting and views have nothing to do with saving energy. It’s all about interior environmental quality.

So now, there is a bigger push to improve energy usage and enforce ‘green’ building codes. LEED, CHPS, and other programs give you the option of getting daylighting points. A ‘green’ code will require it. There has been overwhelming support for some type of daylighting requirement or code, but the problem seems to be in writing one. Most would agree that, if introduced properly, daylighting can save energy associated with interior illumination. The more difficult aspect is quantifying quality. How do you require architecture to beautifully introduce daylight and sunlight into itself?

Codes requiring access to daylighting are relatively new to the United States. Title 24 in California already requires daylighting in certain buildings. There’s a rich history of codes requiring access to daylight. An English law dating back to 1663, Ancient Lights, is a form of easement that gives owners of a building with windows a right to maintain access to daylight. Justinian Code in the sixth century AD included sun rights, laws to ensure that every homeowner had reasonable access to the sun. And, many modern European codes require daylight and views for workspaces and classrooms.

Get ready for daylighting codes across the United States. Come late spring 2010, ASHRAE will have introduced its new Standard 189.1, which is basically a ‘green’ standard that goes beyond the energy-saving measures published in ASHRAE Standard 90.1. It also contains a lot of language about minimum amounts of windows and required illuminance from daylight. The other big player is the International Code Council, with their new proclamation, the IgCC, or ‘International Green Construction Code’. In that particular code, the daylighting portion will most likely be broken into two sections: energy and indoor environmental quality. This approach makes the most sense for both camps. We want enough daylight and views to elevate the human spirit, but not so much as to cause glare or unnecessary energy usage associated with excessive cooling loads.

It won’t just be footcandles and daylight factors anymore. Relatively new metrics such as Daylight Autonomy, Daylight Saturation Percentage, Useful Daylight Illuminance, and Daylight Glare Probability may become common language within these new daylighting codes.

It’s probably time that we have some sort of code that protects and even encourages our access to our greatest energy source, the sun. How it is written makes all the difference. It cannot reward poor design, or suffocate good design.

Great daylit architecture comes from the brilliant architects and designers who create it, not from a formula or code. But gone are the days of overly-glazed façades used in the name of ‘daylight’. Responsible practice must produce sustainable architecture, even if it has to be mandated.

Photo Credits: Elinnea (1), Roryrory (2), Stephen Lee (3), Lam Partners Inc (4)

Compliance with energy codes has become a regular part of the design process for lighting designers in recent years. Prior to the release of the 2004 version of the ASHRAE/IES 90.1 standard for energy codes, it was easy to design lighting without worrying about bumping into code limits. This was because codes had not yet caught up with energy-efficient technologies and current design practices. The ASHRAE 2004 standard was significantly more stringent in its limits on the total amount of connected lighting load allowed. It is still possible to produce quality lighting design under these limits, but much of the headroom went away. Frankly, you can’t be sloppy anymore, and this is a good thing. So, less energy use, more code compliance work for lighting designers – happy ending, right? Well, maybe.

Let’s look at the structure of U.S. energy codes as they apply to lighting. They aren’t really energy codes, they are more like power codes. The main way that U.S. energy codes regulate lighting is by limiting the amount of power (watts) that your lighting system can use. This is done by giving you allowances for maximum lighting power density (LPD), measured in watts per square foot, for various building or space types. In other words, the amount of power you can draw with every light in the building turned on at full output – but it is the rare building that has every light turned on 24/7.

Energy = Power x Time, so an energy code needs to take power (watts) and time into consideration. This is why we pay for electrical energy by the kilowatt-hour (energy), not by just the total wattage of all the devices connected to the meter (power). To be fair, current energy codes do have provisions that address the time variable of the equation – but they only do it by requiring automatic controls to shut off the lights when not needed. There is no quantification or metric of what those controls get you in energy use reduction. A building with lights on 20 hours per day is treated the same by code as a building with lights on 10 hours per day. A building with the most rudimentary code-minimum controls is seen as identical to a building with sophisticated occupant-sensing and daylight-responsive controls.

We can see why lighting power as the metric for building lighting energy-efficiency is deficient, but is this a big problem? Yes, and here is why: energy use of our buildings must be reduced radically – the push to do that by improving the performance of envelope, HVAC, and lighting is strong and growing stronger, and rightfully so. For example, the energy bill working its way through Congress, at 1,000-plus pages, contains a section to institute energy codes enforceable at the Federal level with a target of 55% energy reduction (over the 2004 code baseline) by 2018, and 75% by 2030. Serious stuff! So when looking at lighting, the obvious thing is to just keep reducing the lighting power allowances, right? Wrong! The use of more efficient lamp and fixture technologies alone can’t achieve these targets. If we just keep pushing down power allowances, lighting quality will suffer and we will find ourselves sitting in dark rooms or bland white rooms lighted with bare, glary light bulbs. To truly reduce lighting energy use we need to figure out a way to write a code that actually regulates lighting energy, not lighting power.

Photo Credit: Isaac Bowen

You’ve heard the saying, “There are two things you will never wish to watch: the making of sausage and the making of legislation.” As the new chair of the Energy and Sustainability Committee of the International Association of Lighting Designers (IALD), I’ve been getting a glimpse into the kitchen.

Why, you might ask, would a Lighting Designer care about the making of legislation? Energy codes, light pollution ordinances, LEED, green building codes, Federal energy efficiency legislation, Department of Energy rulemaking, and on and on. Get the picture? All of these things affect our work as lighting designers, directly or indirectly.

Lighting Designers have a responsibility, and an obligation, to minimize the negative environmental impact of their design decisions. Mostly, this means energy! energy! energy! Making lighting more energy-efficient is the easy part. The hard part is doing it without destroying the quality of the visual environment – this is what we do.

So, back to the sausage. We get involved with the development of energy codes and standards and legislation to make them the best they can be. Don’t get me wrong, this isn’t about resisting or trying to make standards more lenient. This is about maximizing real energy savings while simultaneously maximizing lighting quality – no simple task. Too often, standards have been developed by people who do not understand this balancing act. A belief that simply limiting the available watts or setting efficiency standards on equipment is enough can lead to unintended consequences, such as the obsolescing of unique equipment, or increased glare and light pollution.

The energy bill winding its way through Congress has an outdoor lighting energy efficiency provision that is being negotiated by lighting manufacturers and environmental groups. Our committee has been following this process and making ourselves heard (see IALD position statement below). We provide an independent voice that understands how to reduce lighting energy use of the total lighting system and how to create quality luminous environments. You need to understand this if you are going to write an effective standard, right? This is what motivates me to watch, and sometimes help, make the sausage.

Photo Credit: Stephen M. Lee

RELEASE IALD POSITION STATEMENT OUTDOOR LIGHTING.pdf