April 2010


When we at Great Oak rented an infrared camera to try to find sources of heat loss in winter in our Common House, we took the opportunity to also do a “study” of the exteriors of our other buildings to try to find any surprising sources of heat loss. A set of pictures of each unit were provided to the owners. Here are some interesting things that were noted:

  • the temperature range of the picture is shown at the bottom with the corresponding colors — dark is coldest, yellow to white is hottest — so for outside pictures, you want to find the bright spots that show heat leaking from your home,
  • as far as possible, I tried to take the pictures at night, without including the sky to reduce the range of temperatures and thereby constrain the color  variation to make local details more visible — if the sky is included it will show up as “-40” at the low end…like this:  IR 0175 W side of Building for units 34-37
  • unfortunately, on bright days, concrete porches absorbed a lot of heat and radiated it back out during the night, overwhelming the image and reducing the detail, so I took some more pictures during the day hoping to do it before the sun hit the home or caused large reflections on the windows, but not always successfully – here are some taken at night (the timestamp on the second picture is wrong) after a bright (but not necessarily warm) day;
    IR 0187 Unit 24 front porch

    IR 0722
  • likewise, bright portch lights also can overwhelm the image
    IR 0728
  • the underside of overhangs are not well insulated, and often contain heat vents…little we can do about it unfortunately 
    IR 0737

    IR 0717

    IR 0188 Unit 24 front top
  • exposed cement foundation is a major source of heat loss — it conducts heat from your house all night long and in summer gets heatedup and conducts the heat into your house, so if the dirt is scraped away, put it back, and as you can cover it up
    IR 0682
  • you might see “sideways” plumes of heat, that is the exhaust from your water heater, or single large bright circles are typically the furnace vent;
    IR 0849 notice sunlight reflection on siding

    IR 0852
  • note the kitchen fan exhaust venting heat
    IR 0853
  • there might also be reflections of sunlight or my reflection in windows that minorly distort the true contrast               
    IR 0866 my reflection 
in window

    IR 1417
  • chimmneys seem pretty well insulated, though I couldn’t hover above the roofs to really see the heat loss from above
    IR 0940
  • double basement doors are terribly leaky in all cases
    IR 1419

    IR 1422
  • in general, as can be expected, doors and windows were the major cause of heat loss; thick curtains/blinds really do work to insulate your home and probably are the best investment we can make (note the blind on one side of the upstairs window)
    IR 1425
  • the rear of the units were harder to photograph as they were on a slope, or had a fence or there wasn’t much room to get far enough back
  • although building roofs routinely show a gap in the insulation between units during snow melt, the heat loss wasn’t significant enough to show using the IR camera
    IR 0822

    IR 0824

    IR 0827
  • and lest you think it wasn’t fun or funny
    IR 0924 Susan with Scruffy on leash and Dewey on porch

    IR 0925 Tim with coffee


It has been 5 years since the Great Oak common house was built and we have 5 years of heating bills. Unlike the factory built buildings with our individual units, the Common House is the sole, heated, stick-built building on campus and is comparatively very leaky. As a more affordable alternative to a full blown energy audit, we had an Infrared-only audit performed in November 2008. The auditors recommended we add insulation to our Common House attic as the quickest and least expensive step to reduce our energy bills. Unfortunately, they did not do a followup Infrared audit to see if that solved the most egregious problems. So, this year, Great Oak rented an Infrared camera (a Flir b50 from flir.com at $425+shipping  per week) to take pictures and compare. Here is a comparative set of pictures, with 2008 on the left and the 2010 on the right with a visible spectrum image in the middle of our sitting room fireplace mantle and above:

the before and after pictures look about the same, unfortunately, but the comparison is not entirely fair as different cameras were used and the auto-scaling of the colors to match temperature range might not be the same — the original 2008 audit pictures don’t have the temperature range shown so we can only guess that it is about the same as before or slightly better with the attic insulation. Which is disappointing.

A full table of comparisons may be found here.

Taking advantage of the camera, we also took picutres of the outside of all the buildings and various folks took pictures of the insides of their units.

Notable pictures taken in the Common House are shown below (all were taken after dark, after 9pm on a night when it was around 22 degrees Farenheit outside and the Common House is pretty much heated to 65 degrees inside). This first picture shows the residual heat in an uninsulated section of pipe coming from the solar hot water heater tank that feeds into the main hot water heater (natural gas powered).

IR 0145 SDHW machinery

Almost without exception, outside corners were several degrees colder than adjoining walls or ceilings, suggesting that insulation was not “wrapped” around, this was true of the factory built units as well – this is the NW corner of the CH sitting room:

IR 0150 sitting room NW corner

The North side of the dining room ceiling, with peaked roof shows a bright stripe across it where the hot water pipe runs to the East side of the Common House from the hot water heater, so although the ceiling is around 65 degrees, there is a 9 degree or so heat loss out of that water pipe and at least half of it radiates skyward no doubt pushing up our hot water bill — perhaps we should consider having a separate hot water heater on the East side?

IR 0153 dining room N ceiling

IR 0158 dining room N side with water pipe?

The next pictures are the water pipe coming down to the hallway
sink on the East side with one showing the heavily insulated attic
access panel (so heavily insulated now that I couldn’t push it up and
get in there to take “after” pictures).
IR 0169 W outside sink corner

IR 0168 E attic accesss

The 52 windows in the Common House are the major source of heat loss, though the blinds help to reduce the heat loss by almost half (just looking at surface temp) so we need to make sure we pull the blinds at night (or during the day in the summer) as it does really help. This is a North-facing window with a blind pulled half way down.
 IR 0184 dining room N windows showing effect of blinds

The pictures on the left are some dining room windows and the one on the right shows the play room windows — the middle one is clearly leakier than the other two:

IR 0155 dining room south windows

IR 0156 dining room south windows with peak

IR 0162 playroom window, contrast

The skylight in the game room is just a bit leakier than most windows, so likely a major source of heat in the hot summer:

IR 0166 game room skylight

and even though the LCD projector is in “standby” it is always warm, consuming a trickle of energy:

IR 0165 game room ceiling

the outside doors are particularly leaky, especially as they age fast and warp in the corners given the heavy use — this one is the NE door and the South main door (which is new but doesn’t seem to be terribly better than the original doors we had in 2008 other than it latches more firmly):
 IR 0167 NE door corner

IR 0129 south main door

A running laundry machine is a good source of radiant heat so we should keep the laundry door closed in summer, to the right is the aquarium, with around the same surface temperature:
IR 0170 laundry room (note extra cold window)

IR 1458 aquarium

Outside, the laundy vents aren’t particularly notable compared with the heat loss from the rest of the building, though having the sky in the picture does throw off the automatic ranging:

IR 0186 laundry dryer vents not leaking as much as joints 

the solar hot water panels don’t hold much heat at night:

IR 0181 Solar hot water
 panels not leaking heat 

and doors from the outside are somewhat leaky (notice my “heat” reflection in the glass):

IR 0176 N side main 
door from outside (notice my reflection)
a major source of heat loss seems to be the uncovered parts of the cement slab foundation, otherwise it is as expected, windows and doors are the major sources of heat loss and blinds do help. Some additional pictures of the North side:

IR 0182 east wing, notice slab leakage as bad as window

IR 0828 NW main doors

IR 0829 N side door

IR 0830 N side door and media room

and some of the South side:

IR 0172 general view, windows leak most

IR 0173 W wing, windows and doors leak most

In summary, adding the insulation to the ceiling made some difference but it is hard to be more specific. Given the structure that was probably the simplest change to make. The next best steps would be to see if can cover the exposed slab with insulation or at least some dirt (a building expert friend suggested that the best course of actoin would be to dig around 8-12 inches below the slab and then horizontally up to two feet underneat the slab and place foam insulation, but given the massive amount of labor and cost that would incur, it probably would not be cost-effective) and to try to cover as many of the windows as possible to minimize daily heat loss or gain as appropriate for the season.