How can I minimize my heat signature?

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IR imaging cameraInfrared cameras are widely used by law enforcement for border patrol, grow room confirmation, and other surveillance operations. There is legal debate as to whether this technology is intrusive or non-invasive.

Growers fear IR because it?s difficult to ?hide? invisible heat. Protecting yourself against excessive heat emissions is a good defensive measure. This FAQ focuses on masking heat emissions.

What is infrared?
Light and heat energy warm objects, which then re-radiate excess energy. Some of this excess energy is emitted as low-energy infrared. IR is invisible to the naked eye, but can be displayed and measured by specialized cameras.

What does Leo look for?IR imaged residence
Officers are trained to look for hot spots on walls and windows, unusually warm foundations, exhaust emissions from vents and chimneys, and warming trends typical of marijuana grow operations. Leo will wait until evening or early morning (when the grow is up to full temperature and the air is cool). He will also look for light leaks, smells and other info at this time.

Note: Leo will try to image a suspected grow-op from all angles, but is only legally able to do so from public property (ie. Sidewalks, roads, public paths, etc).

Note: power companies occasionally image power pole transformers to see if they are abnormally hot (problems), and to source power theft.

Legal implications
(ExpensiveCloset) "A thermal imaging scan does not intrude in any way into the privacy and sanctity of a home?the privacy associated with a home, are (not) threatened by thermal imagery." (US supreme court ruling)

"The Supreme Court ruled 5 to 4 on June 11 [2001] that police cannot use infrared heat-detecting technology to gather evidence from a private home without a search warrant" High Times, October 2001 (Pg.20)

In Canada, IR is used in the pre-investigation phase. Positive results can then be used to obtain a search warrant.

Will Insulation help?
Conventional insulation will help block IR, but it is probably not enough by itself. A fully insulated wall (R 40) will hold heat much longer than a window (R 2). Concrete is a good conductor of heat; after hours of HID lighting, foundations will become abnormally warm.

Most growers flower at night to take advantage of the naturally cooler air; unfortunately, a warm grow house will radiate lots of thermal energy compared to the cool night air.

How do I mask my heat emissions?
Note: Small grows (under 2000w) would probably not emit enough heat to warrant the effort or expense.

Note: Reducing grow room temperature will reduce heat emissions; however, the grow room will still be warmer than surrounding basement rooms.

This technique creates a false wall to contain cold air. Interlocking rigid foam panels prevent hot grow room air from contacting and warming house walls. Cold air is blown into the gap between the foam and the walls for maximum protection. The wall?s exterior will appear ?cold? to an IR camera, indicating a negative for internal heat.

"Partial room" (insulate exposed walls only)
"Room in a room" (entire rooms are insulated)

*Floor. Concrete foundations absorb heat readily. Build a sub floor to raise the entire grow off the floor.

*Walls. Use interlocking 1.5 or 2? foam insulation along all exposed walls. Place the insulation 1-4? away from walls, fit foam panels from floor to ceiling (some cutting may be required), and blow cold air into the gap. Seal seams and corners with tape. Cover walls with Mylar to reflect heat back into the room.

*Windows. Windows are essentially uninsulated, so you must fill the gap with insulation. Draw the curtains/blinds, add black poly behind, then add insulation.

Drawing descriptionpartial 'Room-in-a-room'
A ? Public property that Leo can image from

B ? Internal basement room. Grow room heat will still be noticeable, and this side needs protection.

C -- ?Safe? basement rooms. Put ballasts and reservoir outside to minimize heat

D ? Partially insulated growroom. The pink band is the interlocking foam insulation, the blue band is the cold air contained between the insulation and the house walls. The window on the bottom of the picture can be open to allow cold air to enter the air gap. Room temperature air can also be blown in from an adjacent basement room through a hole in the foam panels.

Hiding the Exhaust
Safely exhausting hot air is difficult; Leo looks for unusual heat emissions coming from opened windows, chimneys, dryer vents and other handy places. Note: running exhaust to outside sheds, barns and tree stumps is well known to Leo.

Exhaust down the sewerThanks to JonJaffer

Every house has a sewer vent standpipe. By venting down the sewer, the exhaust will be chilled and smell is distributed amongst you and your neighbors. The sewer cleanout access is often a 3-way 4? abs ?T? with a threaded cap somewhere in the basement. Remove cap, and hook your blower to the T (A 4? to 3? adapter funnel may be required) and run blower 24/7. This will not affect normal use of the sewer

Cool exhaust with water
Place a wet towel (wicking water from a tray underneath) partially over the end of the exhaust. Spraying water inside the exhaust pipe works as well.

Underground exhaust
Running the exhaust through a long, buried pipe helps to cool the air. Perimeter drains can be used for this.

Water-cooled lights
Running water cooled lights is very effective; IR heat from the lights are washed down the drain. Water cooled light systems are currently difficult to source, and have drawbacks including cost, condensation and leaks.

Tools for the grower:
Note: most ?night vision? devices use UV (ultraviolet) and not longwave IR detection.

Engine heat ?guns?. +/- 1F. Numerical readout, laser pointer.
"Night Vision" scopes, cameras and camcorders.
Infrared film (Kodak High Speed Infrared Film 2481)

Consumer IR engine guns:
Infrared film usage

  Last modified: 20:55 - Sep 18, 2002  

faq:1305 "How can I minimize my heat signature?"