A Practical Guide to LED Lighting in Residential Application

By: Andreas Dankelmann

Introduction: 

LED lighting solutions are on the rise. There are more LED products and alternatives available on the market already than there ever have been for traditional incandescent and compact fluorescent (CFL), energy efficient bulbs.

While some LED products might just look like any other light bulb or fluorescent tube, the variety of products, new terminology introduced by the lighting industry and the fact that LED’s are a different technology from what we have been used to for decades can make the switch to LED lighting quite challenging.

This article explains the “must-know” terms that homeowners or contractors should be aware of when buying LED products, provides guidance on how to choose products for different areas in a residential environment and points out some of the pitfalls to avoid and be aware of to make the switch to LED lighting a success.

Why make the change to LED?

Besides being much more energy efficient than incandescent and CFL options, thus able to provide significant energy savings, they last much longer, don’t contain Mercury like CFL’s and provide a lot more options for brightness and light appearance (warm vs. cool).

When living in California, every new construction or renovation project is subject to the 2013 California Energy Efficiency Standard, also known as Title 24. LED products are a very good solution to meet or exceed the stringent energy consumption requirements outlined in this standard.

In addition, LED’s don’t only come in a traditional light bulb shape. Due to their compact shape, LED lighting solutions come in all forms, shapes and sizes, providing an almost unlimited amount of ways light can be used and added to a home environment.

Terminology

When buying traditional incandescent light bulbs, all we needed to pay attention to was the bulb shape, wattage which indicated the brightness of the bulb and the screw base size to make sure it fits into the lamp.

With CFL’s came the option of choosing the light appearance described mostly as soft white, bright white and daylight. Soft white resembles the warm tone of an incandescent bulb whereas bright and daylight being more crisp and cooler with a blueish appearance.

When using LED’s it is important to understand three concepts

  • Brightness
  • Light appearance
  • Color rendering

After all, LED products are still more expensive than comparable incandescent products and they will be a much longer lasting appliance, so we want to make sure we are buying the right product for the job.

Brightness:

First off, we have to let go of the misconception that wattage equals brightness. While for incandescent bulbs wattage and brightness had a direct correlation, this is not true for LED products and since LED’s consume much less power (Watts), it’s impossible to compare brightness of an incandescent and an LED bulb based on wattage.

So the only factor to pay attention to when looking for brightness of an LED light is Lumens. Lumen is the unit of measure for brightness and tells us how much light a particular lighting product emits.

For reference, a typical incandescent 60 W bulb emits approximately 800 lumens.

Light Appearance:

The color appearance or correlated color temperature (CCT) of light is measured in kelvin (K). When we want to know if a lighting fixture or bulb creates a warmer or crisper, cooler light we need to look for the kelvin number. The lower the number, the warmer the light will be and the higher the number the more cool and blue the light will appear. A typical incandescent bulb has a color temperature between 2700K and 3000K. The sun at noon on a clear day produces a light of approximately 5500K.

People often complain about the cool, sterile light appearance of CFL bulbs compared to incandescent bulbs. The issue here is that they chose a high kelvin, cool color temperature instead of a warmer color temperature.

Color Accuracy

Have you ever been to a store and thought that you are color blind, because you couldn’t quite make out if the piece of clothing you were looking at was a dark green or blue? If so, then you experienced poor color rendering by the light fixture inside that store.

Light sources differ in their ability to display the colors of objects “correctly”. And by correctly we mean compared to a natural light source like the sun or an incandescent bulb.

The color rendering is expressed as the Color Rendering Index or short CRI. The scale goes from 0 to 100. A 2700K incandescent light bulb has a CRI of 100.

A value of above 80 is with current LED technology considered a good CRI and will be sufficient for most applications. However, for some areas, better color rendering of 90 or above can be desirable, we explain that in the next section.

Choosing the right light for different light functions and areas in your home

 Functions of Light

Lighting is typically categorized in ambient, task, accent and decorative lighting. Each category provides a different purpose. When planning the light for a home, it is helpful to understand how these different light levels can complement each other.

Ambient Lighting:

Ambient (or general) lighting provides a uniform amount of lighting throughout an area or room for general vision and orientation.

Recessed down lights, cove lighting or pendant-hung fixtures are typical examples for ambient lighting.

Task Lighting:

To provide light in an area where an activity takes place, e.g. the kitchen counter top where meals are prepared a reading lamp or a make-up mirror. It is meant to highlight a specific area in addition to the ambient light in that room.

Accent Lighting:

It’s used to highlight objects like works of art, architectural features or plants, by creating contrast in brightness. This is often achieved using recessed or surface mount adjustable fixtures or track lighting, wall grazing and wall washing.

Decorative Lighting

This is the jewelry for the home; the main function of decorative lighting fixtures is to look pretty. Chandeliers and wall sconces are typical examples.

This layered approach to lighting is useful to create a comfortable, visually balanced atmosphere.

Once it is decided what type of fixture will be placed where for the various functions, it’s time to think about the color temperature.

The light should compliment the interior design, furniture, colors and other decoration in your home.

In general, color temperature is very much a personal choice and preference, however there are a few rules that can be applied to help choosing a light that compliments the interior design.

Color Temperatures for Ambient Light

The ambient lighting in a room is typically the main source of light and therefore a key element in setting the overall mood and ambience for a room.

Warm white lighting fixtures are often preferred in living rooms and bedrooms to create a cozy atmosphere.

The kelvin numbers offered for LED lights are typically 2700K and 3000K. These warm white lights are a good choice to compliment earthy tones and wood furniture.

If more than one type of ambient light is installed, e.g. down lights and cove lighting, choose the same color temperature for both to ensure an even, harmonic effect.

Though many people seem to prefer warm white, rooms that are decorated with light colored furniture and crisper colors, like white, blue and light grey e.g. in a modern kitchen, can benefit from a more neutral, cooler light.

Lighting with kelvin numbers in the range from 3500K to 4000K are considered neutral white and accentuate lighter colors better than warm white lights.

In addition, studies show that neutral and cool white light has an energizing effect on people, and is therefore are a good choice for home offices and studies.

Since neutral and cool white light creates better contrast than warm white, they are also a good choice for the main ambient light in bathrooms. The cooler light will provide a more realistic idea on what we look like in the real world. Look for kelvin numbers between 4000K and 5000K for your main ambient bathroom fixture.

If the bathroom features a bathtub and you want to be able to create a warm atmosphere as well, consider using an additional layer of light, e.g. a wall sconce with a warm white light in the range of 2700K that can be switched separately from the main light.

Color Temperatures for Task Lighting

Task lighting is used to provide an additional, higher level of light than the surrounding area where a visual task takes place.

It is therefore important that the light is able to create good contrast, which is best achieved with a neutral to cool white in the 3500K to 5000K range.

Besides the color temperature the color rendering index (CRI) and brightness are particularly important for task lighting.

While for ambient lighting a CRI of 80+ is often sufficient, for task lighting a CRI of 90 and above should be considered.

Food that gets prepared on a kitchen counter will look much more appealing when rendered well by the under cabinet light.

A make up light with good color rendering will also paint a more realistic picture.

Dimming

Dimming is an important feature of ambient and task lighting. It enables us to set the light level to create the desired atmosphere in an area or create the ideal brightness for a task. In addition, dimming provides energy savings by reducing the electric load of a light fixture.

As opposed to a standard incandescent lamp, not all LED fixtures are built to be dimmable, it is therefore important to look at the product label and ensure that the fixture is marked as dimmable.

When making the switch to LED, be prepared to also change out your dimmer switches. Most dimmers were built for incandescent, bulbs, however LED’s are based on a very different technology and therefore these two don’t necessarily work well together. It’s like trying to connect your old rotary phone to your digital phone outlet.

Most manufacturers provide a compatibility list that shows dimmer manufacturers and models that have been tested and are compatible with the LED fixture.

To ensure an optimal lighting experience, it’s highly recommended to stick to the manufacturer's recommendations. Using incompatible dimmers can lead to flickering lights or insufficient dimming levels.

Installation

Though most LED lighting fixtures are considered low-voltage, that means they either have a transformer build in or require an external transformer, the good news is, it is not necessary to rewire a house to use LED’s. All the wiring that is commonly used in houses is perfectly fine for use with LEDs.

Many LED fixtures have a transformer already built in and can be connected to a standard electrical outlet. Some LED products, i.e. LED strip lights, require an external power supply. These come in two formats, either with an AC cord attached, similar to a laptop power supply or they need to be connected to an outlet.

It is recommended to have a licensed electrician perform any installation that requires electrical connections to the line voltage.

Do pay attention to the product label, it will indicate if a power supply is required or not.

How to choose quality product

There are many LED products on the market, however they are not all built the same. To ensure the product is safe to use and has been tested by an independent laboratory, look for the UL or ETL mark on the product or packaging. Though, the so called UL or ETL listing is not a requirement to sell products in the US, if the installation is subject to an electrical inspection as part of a renovation or new construction project, the product can be rejected by the inspector if it has not been tested for safety.

Due to the generally long lifetime of LED products, the warranty should be at least 3-5 years. Though this is a long time, do keep your receipts for proof of purchase in case the product fails prematurely.

Do take a look at the product label. These specifications should be clearly outlined:

  • Light Output (Lumens)
  • Power Consumption (Watt)
  • Lumens per Watt (Efficacy)
  • Color Accuracy (CRI > 80)
  • Color Temperature (Kelvin, should be stated as a number, i.e. 2700K not just warm white or cool white)
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