Preliminary Considerations

Before heading to the hardware store, consider what you are trying to illuminate and why. Is your lighting for security, increased visibility, or aesthetics? Do you really need to cover your entire yard, or just specific areas next to your house? The intended use of the light affects how bright it needs to be. Usually low-wattage fixtures suffice for an entryway or for decorative illumination, while something stronger might be warranted to light up a patio or parking area. As shown below in “Bulb Basics,” some sources create light more efficiently — or have longer lifetimes — than others.

The intended purpose also determines how long a fixture should remain on each night. For example, you may have decorative lighting to accent your home’s exterior or landscaping. If so, consider installing a timer so it operates only while members of your household are awake.

With few exceptions, no security light needs to be on from dusk to dawn. Unless you’re in the habit of looking out your bedroom window all night long, such continuous operation merely provides the means for a criminal to survey your home’s exterior from afar or, worse, to show where to break in. If you’re concerned about safety, choose a motion-sensing fixture, because by turning on it alerts you and your neighbors that someone (or something) is moving around outside. Most models have manual override switches to keep them turned on (or off) continuously.

Ideally, everyone would choose to install full-cutoff fixtures, which emit no light above horizontal. Let’s be realistic, however. Most homeowners are unlikely to put up poles in the middle of their yards just so they can illuminate the surrounding areas with full-cutoff lighting. Instead, you’re going to attach a fixture to the side of your house, then point it to shine the light outward. So if illuminating your entire yard is important, at least try to minimize the damage: aim the fixture and use glare shields to fine-tune exactly where the light shines, and place it high on your house so that it can be aimed down as much as possible and still illuminate the yard. Attach the light to a motion sensor, and always use the lowest light output that you need.

Sometimes the offending light isn’t yours but a neighbor’s. Obviously, such situations need to be approached diplomatically. Offering a little guided tour of the night sky through your telescope can be used to bring up the subject, or you can always take a more direct — but friendly — approach. (Don’t forget to emphasize the possible cost savings.) If your neighbor agrees that some modification is in order, you could try to shield the existing light. Unfortunately, shields are almost never available for residential outdoor lighting — you will probably need to fashion one yourself. If it’s worth it to you to have glare-free nights, just consider buying your neighbor a new fixture!

Bulb Basics
Bulb Type	Watts	Mean Lumens	Lifetime (years)1 dusk-to-dawn	Lifetime (years)2 motion-sensor	Power cost 1-yr3 (d-to-d)	Power cost 1-yr3 (m-s)	Power cost 5-yr3 (d-to-d)	Power cost 5-yr3 (m-s)
Incandescent (flood)	150	2,000	0.5	11	$61.50	$2.75	$307.50	$13.75
Mercury vapor	100	3,2304	6	—5	55.35	—	276.75	—
Quartz halogen	100	1,400	1.5	20+	41.00	1.85	205.00	9.25
Incandescent (frosted)	100	1,690	0.2	5	41.00	1.85	205.00	9.25
Incandescent (frosted)	60	840	0.2	5	24.60	1.10	123.00	5.50
High-pressure sodium	50	3,600	6	—5	27.10	—	135.50	—
Compact fluorescent	25	1,750	2.5	—5	10.25	—	51.25	—
1Based on an average use of 11.25 hours per day (4,100 hours per year).  2Based on six 5-minute cycles per night.  3Based on actual wattage used by fixture and electricity costing $0.10 per kilowatt-hour.  4Initial lumen output is 4,100; output decreases significantly over time.  5Long warm-up time precludes use in motion-sensor applications.