Lighting Auditing and LED Replacements

About this section:

This page will prepare you to audit residential lighting and potentially install LED lighting replacements

How to use this page:
Read through this page to get the executive summary of each topic. If you’re interested to learn more, click on any link for suggested readings or resources, all of which will open in a separate tab (in other words, don’t worry about losing this page). You can use the “back to top” at the bottom of each section to come back to the top of the page, and then use the table of contents at right to pick and choose a topic to read. But *please note*, depending on your browser and settings, the table of contents might send you slightly below the section heading for that topic. Sorry for the inconvenience.

Lighting, energy, and safety

As we discussed in the Clean Home Technology Basics Module, lighting is one of the bigger energy users in the average home. The calculations we did there showed that an average 60 watt equivalent LED bulb could save the average American household about $7.25 per year (and these days, as the cost of LEDs have dropped, that translates into a less than one year payback period). But the picture gets better when you consider the life cycle. LEDs can last 25,000 to 50,000 hours, vs. ~1000 hours for incandescents. This means you’ll replace those incandescents 25-50 times over the same period of time. Those purchase prices (let alone the trip to the store) add up over time, and in addition to the extra money someone would spend on energy, LEDs become an absolute no-brainer. But there’s an even better option in some cases, which we’ll cover next in the lighting audit section.

Further reading:

The true costs of lightbulbs

Notes on Safety

Lighting has several aspects that require attention from a safety standpoint. First, there’s the obvious challenge of breakage. A lot of lighting is made of glass, metal, and other potentially sharp objects that can become worse after breakage occurs. Gloves and protective eyewear are a must when handling lightbulbs and other lighting.

In addition, lighting, like all products that use electricity, is hazardous if not handled properly during installation or in any other time when coming in contact with the sockets and/or circuitry. Many people think that getting shocked by putting your finger in a light socket is just a myth. IT IS NOT. There are very real consequences, potentially including death. So don’t do it. When you are working on any electrical device, it is a good idea to turn the power off to the socket/fixture prior to working on or changing lighting. You can do this at the breaker (best option) and the light switch (good additional option).

The other major concern with lighting regarding safety is mercury. All fluorescent lighting contains mercury gas. Mercury is a neuro (brain) toxin (deadly stuff). You do not want mercury in your body, as it can decrease your cognitive abilities (make you dumb), among other things. The mercury gas in a fluorescent lightbulb will be more virulent (dangerous) when it is hot (the bulb is turned on), so if you happen to be around when a fluorescent lightbulb breaks, you are going to be breathing in mercury. In the “healthy home” module, we covered what to do if this happens.


It is common for rooms to be over (too bright) or under-illuminated (too dim). Low lighting levels can be dangerous on multiple levels, and over-lighting can cause headaches and eyestrain. In addition, overlighting is a financial and environmental cost that is easy to avoid.

So how would one go about finding overlit or underlit spaces? A device called a light meter is a simple diagnostic tool that measures the amount of light in a given area. The three basic measurements that a light meter can give are Lumens, Foot Candles, and Lux. A Lumen is the “amount” of illumination given off by a source of light. A foot candle is the amount of light that falls on an object one foot away from a light source, a lux is the amount of light falling on an object from one meter away.

Regardless of which unit of measure is used, there are standard levels of lighting suggested by the Illuminating Engineering Society, and those guidelines are what architects use to design lighting for rooms. The suggested level of light will vary by the function of that room. So a hallway, where the primary function is simple navigation, will need a certain amount of light to allow people not to walk into walls. A countertop where people will be chopping vegetables will need more light. A bathroom vanity where people will be applying eye makeup or putting in contact lenses may need even more. A surgical operating room will need the most! In other words (and in industry parlance), the higher precision of task needed for an activity the higher will be the recommended lux or footcandles.


To conduct a light audit, simply take several readings on a light meter (as pictured above), and compare the average to the recommended amount of light in that type of room (or better, for the type of activity that will be done in that room, which may be obvious, but it’s always best to ask a customer just to double check they’re not doing high precision activities in a room where you might not expect them to). This process can help determine if lamps should be removed to bring lighting into healthy levels through “delamping.”

Delamping: How to

Delamping can be done by removing the bulb, but the best thing to do is to unscrew it enough and let it hang in the fixture safely (still in enough to not fall out on its own, but unscrewed just enough to not be turned on by the light switch with the rest of the bulbs controlled by that switch). Laundry rooms, hallways, and bathroom vanities tend to be vastly overlit, and are areas where delamping can be done fairly regularly. This reduces energy use, preserves lightbulbs, and reduces eye strain. Just make sure you educate the customer about what you’re doing, and show them that if they want more light on any given day/time, they simply need to screw the bulb back/tighter into the fixture.

To compensate for outside light (rooms with open blinds or windows), use your light meter to measure amount of light at a task area with lights on and shades open as normal, then measure with lights off. Subtract the latter number from the former to determine how much artificial lighting you have and if it is too high for that space (that will tell you whether that artificial lighting will provide enough light at night).

Further reading:

Proper lighting levels for various activities

How To: Use a light meter to measure and set appropriate light levels

Increasing lighting’s effectiveness by cleaning Light Fixture Covers

In many cases, a light meter will record a strong jump in the amount of lux being put out by a light fixture after the cover is cleaned. Thus, with any delamping, we recommend light fixture cover cleaning.

There’s no standard fixture, but most can simply be deconstructed with a twist or a gentle pull or nudge. Make sure that you are on stable footing when you begin, and that you have a hand on both the screw/attachment piece, as well as the glass fixture itself.
Screen Shot 2015-08-19 at 11.34.39 AM

Cleaning the covers is usually as simple as wiping them out, but depending on how long it’s been since they were cleaned, it may require running them under water in a sink and scrubbing the caked on debris off.

Lighting tech specs

Bulb styles

There are four modern styles of light bulb technology. In order of lowest to highest efficiency and technological age: Incandescent, halogen, Compact Fluorescent (CFL), and Light Emitting Diode (LED) (organized left to right in the below photo).

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To give you an idea of efficiency, the equivalent bulb types will use 60 watts (Inc) 47 watts (halogen) 13 watts (CFL) and 9 watts (LED). The halogen pictured above is a different type (it’s an MR16, rather than an A19 as the other three bulbs are, which we’ll explain below), but the picture of an A19 halogen bulb is the same, basically, as an incandescent. It’s very hard to visually tell them apart, so we put the MR16 photo here to document what a halogen more or less looks like inside.

Incandescents and halogens will generate a lot of waste heat, which is a very effective selling point when you’re replacing bulbs for people and you can tell them that their Air Conditioners, fans, etc., won’t have to battle incandescent bulbs after you give them an LED lighting upgrade. The bulbs inside refrigerators also tend to be incandescents, and swapping those out for an LED not only cuts the energy down, typically from 40 watts to 5, but also stops making your fridge fight against the light inside the fridge.

Further reading:

Bulb style

Common Bulb Shapes and Sizes

There is a huge diversity of lighting in terms of shapes, sizes, color spectrums, etc. For residential and small business applications, though, there are 8 or 9 “most common” bulb shapes found:

picture 45

Abbreviations found on the bulbs (e.g., A19) refer to the shape (A) and size/diameter (19). The diameter is measured in eighths of an inch. A T12, for example, is 12/8ths wide, or 1.5 inches. Bizarre? Overly complicated? Like measuring distances by the length of an old king’s foot? Yep, not the most intuitive. But it is what it is, and it has become the industry standard.

Here are some samples:

common residential and small business lighting

Further Reading:

Shapes and Sizes

Bulb Color and Temperature

The color of a light bulb is measured in Kelvins to illustrate the temperature of the color produced. These numbers shouldn’t be mistaken for how hot the bulb gets. We know…this makes about as much sense as the measurement of 1/8ths of an inch. But again, this is the industry standard, so this is what you’ll need to know.

There are 3 main color temperature categories for most light bulbs: Soft White (2,700K – 3,000K), Bright White (3,000k – 4,800k), and Daylight (5,000k and up to 7,000). There are many different descriptions of these colors, so, when in doubt, stick to the Kelvin scale provided with the bulb. A “warmer” color will be a lower K, and “cooler” or white-blue color will have a higher K. In terms of their application, soft white is typically used indoors for most bulbs except for the T8s and T12s, which are often 4000K. T8s and T12s are typically found in places where the brighter white is helpful–laundry rooms and kitchens–and not where people want a softer hue (bathrooms, bedrooms, and the like). The higher K bulbs tend to be used mostly for security lighting–outside by the garage, for instance. This provides a little extra security for night-time viewing, but the light is usually far too harsh for indoor use, and customers tend to much prefer 2700K or 3000K for indoor uses.

Further Reading:

Color and Temperature

Base Types

There is a much smaller variety of base types in use throughout your home.

bulb bases
From left to right, Medium Screw Base, Candelabra, GU10 and GU5.3.

Typically these correspond with a usage. For instance, candelabra bases are typically for accent lighting. GU bases are typically for track lighting, etc.

Further Reading:

Base Types

LEDs vs. CFL vs. Incandescents: Dimmers, Wattage and other considerations

When comparing lightbulbs, it’s important to use light output as a comparison. You may see “Lumens per watt” as a common measure of light production. As a general ballpark, though, CFLS use roughly 1/4 the electricity of equivalent incandescents, and LEDs use about 1/8 the electricity of an equivalent incandescent.

CFL bulbs don’t typically work in fixtures controlled by dimmer switches. The bulb must be specified as dimmable. LEDs come in both dimmable and non-dimmable varieties. Dimmable ones should work in most any fixture controlled by a dimmer switch. Exceptions do occur in lighting fixtures with old wiring.

LEDs last far longer than either incandescents or CFLs, meaning their lifetime cost is far lower than other types of bulbs in most applications.

Further Reading:

LEDs vs. CFLs

3 Way Bulbs – How and When

These types of bulbs, typically used in lamps, allow you to choose between three levels of light output (for instance, 30w/60w/100w). Thus, if someone is reading by the lamp, they might want more light output, whereas if they’re just having coffee with a friend, they might click the bulb into the lowest light output setting. There are replacement LEDs for 3 way bulbs, though at the time of this writing, they are prohibitively expensive.

Further Reading:

3 way bulbs–how and when

Dimmer Switches – considerations

Dimmer switches are not uncommon in residential lighting. They work by rapidly turning the electrical circuit running to your lightbulbs “on” and “off”. The idea is that the current is reduced to the light fixture by the switch on the wall (which typically has a sliding tab):

The lower current going to the fixture the less light output will result. While most people might think of these as mood lighting, they can also help reduce energy use. The lower the light output, typically, the lower the energy consumed.

Further reading:

How dimmer switches work, plus styles, LED compatibility, etc.


Tube lighting (commonly found in laundry rooms, kitchens, offices, schools and public buildings) is typically controlled be either a magnetic or electronic ballast. Electronic ballasts are more energy efficient than magnetic ballasts, but magnetic ballasts have one major advantage–when used outside in very cold climates, they tend to outperform electric ballasts in terms of life expectancy.

It used to be the case that upgrading these types of lighting fixtures required major re-wiring in order to install LEDs (magnetic ballasts had to be removed and replaced with electronic). Now, however, there are plug and play LED T-8’s that can work with either type of ballast, and cut upwards of 50% of the energy used by the fixture.

Further reading:

Ballasts–magnetic vs. electric