Nashville, TN


Lighting Design Consultants

Lighting Design Consultants

Lighting Design ConsultantsLighting Design Consultants

design announcement

DHS Lighting Design Adds Revit and BIM360

                                                                                                                                                                                                        June 25, 2019

In order to be a more valuable partner for the design community, DHS Lighting Design now provides lighting design in Revit, as well as AutoCAD and Sketchup formats. In addition, we are also capable of full BIM360 collaboration with your entire design team.

Should you like more information, please call our office at the number above or go to


Three steps to a better lighting renovation

                                                                                                                                                             Published Feb 7, 2018

Many times throughout my career, I’ve heard stories of renovations that didn’t meet the expectations of the architect, designer or owner because the new lighting was inadequate, mostly due to light levels that were lower than promised or anticipated. It’s a frustrating experience for everyone involved. After all, how could new lighting be inadequate? It usually comes to this: the conditions of the space weren’t properly documented beforehand, so every step that came after was based on inaccurate assumptions. 

So, how is this remedied so that anticipation doesn’t turn into disappointment? Here are three steps a lighting designer will take to ensure a better lighting renovation:

1. Don’t Guess in the Dark

In fact, there shouldn’t be any guesswork. It’s always a good idea to be knowledgeable about the existing light sources AND light levels. Whether designing to maintain the current light levels, or increasing them, knowing the current footcandle levels is crucial and a good starting point to any lighting retrofit.

2. 80/50/20—A Good Rule to Break

All too often, these type projects are initiated with only room measurements and replacement fixture selections. Calculations are quickly performed using the default reflectance values of the lighting software and inaccurate light loss factors. 80/50/20 cannot be used for every application. What is 80/50/20? These are the default reflectance values incorporated into most lighting calculation software programs. The software assumes that the finishes selected for the ceiling, walls and floor will have light reflectance values of 80%, 50% and 20% respectively. This is a faulty assumption and should almost always be modified since white ceilings and white walls are no longer commonplace.

3. Light Loss Factor (LLF) – What happened to the light?

Most fixture manufacturers run photometric tests on the luminaires they introduce to the market. These photometric tests are then used for reports and specification sheets, and for producing IES files used for evaluating the performance in lighting calculations. The light output of the luminaire is measured in “initial lumens”. Initial lumens represent 100% light output of a new luminaire. There are a number of environmental influences that will affect the light output of a luminaire (dirt, temperature, etc.), and over the life of the installation, initial lumens will diminish. These conditions need to be applied to the initial lumen output to simulate the expected loss of light. 

The first calculation of a renovation or retrofit project should be an effort to recreate the original conditions. This is accomplished by modifying reflectance values to match the space and by making adjustments to the light loss factor until the model calculations are in line with the footcandle readings recorded at the site. The lighting designer will now apply the percentage adjustments to the new luminaire with considerations for the physical properties of the source.

When using Google Maps to reach a destination, one needs to know where they are to get where they are going. Likewise, to achieve a good lighting renovation (destination), the lighting designer (1) must first know where he is by visually inspecting the site and recording the current light level readings and fixture locations, (2) know the actual finishes so that the true reflectance values can be considered, and (3) factor in environmental conditions that affect light output. By taking these three steps, the designer can now proceed with confidence that the lighting design will reflect expectations and receive approval. 

Danny Streit is an independent lighting designer, lighting educator and advocate, residing in Nashville, TN. As design principal of DHS Lighting Design, he is Lighting Certified (LC) through NCQLP, is an Associate Member IALD, Member AIA, USGBC, and past President of IES Nashville. You may reach him directly at


The problem with lumen output

                                                                                                                                                           Published Oct 23, 2017

 When comparing the performance of LED downlights, lumen output alone doesn’t tell the whole story.  On a recent hospitality project, the contractor wanted to substitute another light fixture that met the minimum lumen output requirement. It's a familiar story, but an incomplete one. In this case, however, the lighting designer showed that the would-be substitution did not, in this application, provide the uniformity of the original, specified fixture. Demonstrating this to the electrical engineer and architect confirmed that the original fixture should stay on the job. 

Fixture manufacturers are continuing to improve their products by upgrading luminaire light engines resulting in higher lumen outputs. This is especially true with manufacturers of LED downlights. These improvements allow fixture manufacturers to offer smaller aperture downlights with lumen outputs that previously were only available in larger apertures. Most of the major manufacturers of downlights now offer a 6-inch downlight with 3000 lumen output or higher. 

A common misconception among many lighting specifiers is that an equal lumen output from a substitute manufacturer of equal quality is an acceptable alternative. This is not always the case.


In the hospitality application, Luminaire A was specified as a 6-inch downlight utilizing a 2500 lumen light engine with delivered lumens of 2264. The application was a 20' x 40' room with a 9ft ceiling height and a 50 footcandle design criteria. However, Fixture B was submitted as a substitute. It utilizes a 3000-lumen light engine with delivered lumens of 2564. Comparing only lumen outputs, this might appear to be an acceptable substitution, but a closer look at the comparative performance tells a different story.

The Zonal Lumen Summaries of the two photometric reports shown in Figure 1, to the right,  highlight the 0-20-degree zone of each luminaire. Luminaire B distributes 48.7% of the total lumens in to the 0-20-degree zone. For higher ceiling heights, this would be desirable. However, for this application with a 9-foot ceiling, it was not an acceptable substitute.


The calculation summary in Figure 2, to the right, reveals a maximum footcandle level of 81.4 FC for Luminaire B on the work plane compared to 60.6 FC for Luminaire A. This is due to the higher concentration of lumens in the 0-20-degree zone of Luminaire B. The Pseudo Color Rendering below also illustrates the better overall uniformity Luminaire A provides. The Average-to-Minimum Ratio and Maximum-to-Minimum Ratio also confirms that Luminaire A is the better solution.


In summary, both fixtures meet the design criteria of 50 footcandles maintained on the work plane. However, horizontal footcandle levels should never be the only measure of performance. Uniformity should always be included in the performance specification and photometric data should be closely examined. The Zonal Lumen Summary gave clues that further comparison was needed but the Calculation Summary and Pseudo Color Rendering revealed the facts. 

Danny Streit is an independent lighting designer, lighting educator and advocate, residing in Nashville, TN. As design principal of DHS Lighting Design, he is Lighting Certified (LC) through NCQLP, is an Associate Member IALD, Member AIA, USGBC, and past President of IES Nashville. You may reach him directly at  


5 Reasons to Consider a Lighting Designer

                                                                                                                                                     Published June 7, 2017

There are 5 Reasons your may want to consider a lighting designer on your next project. There's no question that lighting design has become much more complex, requiring more design time and coordination. If you're an architect, electrical engineer, developer, owner, or facility manager, you are seeing this already. How do you incorporate all the moving pieces when it comes to proper illumination--function, aesthetics, mood, codes, environmental concerns, cost, maintenance, controls, etc.--and still maintain the vision? Maybe it's time to consider an independent lighting designer. Below are 5 factors to bear in mind when you are beginning your next project.

#1 Independent means Independent
An independent lighting designer does not sell lighting fixtures and therefore is not obligated to any manufacturer, distributor or agent, nor is he tied to any specific product line. The designer is free to recommend the best solution for your project regardless of who manufactures it. A good lighting designer understands the value of independent, unbiased research and verification, and does not rely solely on manufacturer representations.

#2 Lighting and Lighting Controls are Complicated
LED has changed the landscape. The characteristics of LED lighting are different from traditional light sources. Energy codes and lighting ordinances vary between states and municipalities and lighting controls are now a major consideration on nearly every project. Add to that the rapid changes in products and technologies, and you can see how difficult it is to stay up to speed. Lighting designers spend a large amount of time on education, research and training. With the rapid pace of technological advances and complexities now associated with LED lighting and control systems, expert lighting designers are needed now more than ever before.

#3 Lighting Design is both Art and Science
There is both a creative and technical aspect to lighting design. An experienced lighting designer understands how to create moods, use color, accent objects, enhance textures, and utilize natural light. He also understands the physics of light and how it is produced and controlled. Your lighting designer has the knowledge and expertise to evaluate products, manufacturers, sources and techniques to structure the best solution and creative design for the application.

#4 Not an Added Cost
Contrary to what many believe, an independent lighting designer isn't just another fee added to the project. The professional services your designer provides will in many cases save time and money both in the short- and long-term. The value that an independent lighting designer brings to the project exceeds the fee. Good lighting design affects safety and security, productivity, and in many cases profitability, to name just a few. A lighting designer is able to: a) develop a lighting plan that prevents spending unnecessary lighting dollars, b) facilitate the architect in getting off the job faster by eliminating or easing unforeseen costs and delays, and c) produce an effective, creative lighting design that can set the architect apart from the firm’s competition and satisfy the client. 

You have a vision for your project and want to work with those who share that view. A good lighting designer becomes a valuable member of the design team, performing specific tasks for a pre-determined time schedule, meaning that the lighting designer is not on the firm's permanent payroll.

#5 The Lighting Designer Solves Problems
Problem solving may be the biggest reason to hire a lighting designer. Someone that has been in the industry for a while has, without a doubt, seen his or her share of common and not-so-common lighting dilemmas. A lighting designer works through a myriad of lighting problems every day, catching those small oversights throughout a project that can become huge problems in the end. How and when those problems are remedied can impact your bottom line and client relationships.

Final Word
In short, an independent lighting designer works with your design team to see your vision realized, assists you in navigating lighting complexities, brings up-to-date technologies to your project, and provides unbiased lighting and lighting control systems expertise. Maybe it's time to take your architectural designs to the next level by bringing in an expert in lighting and lighting controls to work on your next project.

Danny Streit is an independent lighting designer, lighting educator and advocate, residing in Nashville, TN. As design principal of DHS Lighting Design, he is Lighting Certified (LC) through NCQLP, is an Associate Member IALD, Member AIA, USGBC, and past President of IES Nashville. You may reach him directly at