What does ‘IR’ mean in halogen bulb descriptions?

Have you ever wondered what the IR means in some halogen bulb codes?

Here are two examples: 100PAR38/IR/NFL25,  37MR16/IR/FL40.

IR Halogen CoatingThe IR (or sometimes HIR) in the description code means ‘infrared’, as you might have guessed, but it does not mean these bulbs are for heat lamp applications. The IR refers to a coating on the halogen capsule which is located inside the reflector of PAR or MR halogen light bulbs.

This diagram shows the capsule inside an MR16 reflector.  Several layers of durable, thin interference film are added to the capsule wall. This coating reflects otherwise wasted infrared radiation back onto the bulb filament. By recycling the radiant heat, less energy is required to raise the filament temperature to the optimum level. The result is a more efficient light bulb.

IR technology is useful if you are looking for longer halogen bulb life or increased energy efficiency. The following two examples illustrate these benefits.

A standard 100PAR38/NFL25 has a rated life of 1500 hours.  With the IR version, 100PAR38/IR/NFL25, the rated life doubles to 3000 hours.

In the second example, assume you currently use a number of 50MR16/FL40 bulbs.  To cut energy costs without sacrificing the quality of the light, select the lower wattage, IR version of the same bulb, 37MR16/IR/FL40. and get the same light output using about 30% less energy.

You will pay a little more for the IR technology halogen bulbs, but it is usually a very cost effective choice because of the extended life and higher efficiency benefits.

One note of caution: IR halogen bulbs should not be located in enclosed or semi-enclosed fixtures. IR coatings may result in higher bulb temperatures. Limited airflow around the neck of the bulb can compromise any potential benefits.

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Dave Burtner

Dave has been active in the lighting industry since 1994. Formerly a member of the Illuminating Engineering Society of North America and certified by the National Council On Qualifications for Lighting Professionals, Dave now writes blog posts, lighting tips and provides lighting product assistance for the Topbulb website.