Tag Archives: thermal imaging

Blinding out the cold

Do your window covers block out the cold? It turns out that horizontal blinds work pretty well, especially if you tilt the rails downwards, so that they open towards the floor, a bit like the feathers on a bird.

I used to think that it would be best to have the opening upwards, as I thought it would reduce the coldness falling from the window into the room. But it turns out that the bigger issue is to prevent warm air from inside the room from falling onto the window in the first place. Angling the rails down stops cold air circulating – a bit like feathers on a bird.

I took some thermal images to test this theory. I chose a cold night of about minus four degrees Celsius outside, after our  heater had been on for several hours, so it was about 20 degrees inside.

The following pictures show a series of close-ups in the same mid-section of the blinds. The thermal scale is the same in each picture, so you can compare the impact of tilting the rails. In these photos, blue and green are cold, and white is warmer than red.

The rails are tilted down in the first picture, which is the right way to do it. Here are some close ups. When the rails are angled down, there is a lot of white, quite a bit of red, and no green or blue. Rails tilted down stops cold air from circulating out from the centre of the blind.

In the next pictures, the rails are tilted upwards. There is less white and more red here. The blinds are still stopping a lot of the warm air leaking out the house, but not as much as when the rails are pointed down.

And in case you are thinking that maybe the blinds don’t do much at all, have a look at them when they are open. The heat loss is huge, with glaring great blue-cold glass leaking the warmth out right away. I could really feel it too, when I opened the blinds and the room felt colder right away.

It’s also worth thinking about the whole blinds. The photo from further back shows that there is still some coldness down at the bottom. These blinds would work even better if I could seal off the base, but I haven’t worked out how to do that yet.

Any suggestions?

Why LED lamps are best

There’s a lighting revolution underway. You can no longer buy the old incandescent lamps that are still the symbol of a good idea . Instead there’s a bewildering array of alternatives. So which ones should you buy?

https://pixabay.com/en/education-a-good-idea-an-array-of-548105/

Here are the lamps I saw for sale recently at the supermarket. So many options, each with most of the fittings you could want – including the standard screw and bayonet fittings that are still standard in most older houses like mine.

LEDs and other lamps for sale - whole rack

They have a wide range of wattages, lumens, hours and price tags. What does is all mean?

close up of lamps for sale

  • Watts are the amount of power used. The higher the watts, the great the energy being used.
  • Lumens are the amount of light emitted. The higher the lumens, the brighter the lamp. In some places, like kitchens, we want lots of light. We may want less from our bedside lamp.
  • Hours of operation differ between lamps. If a lamp lasts for many thousands of hours, you may not have to change it for a decade.
  • To really understand the price tag, you need to put all of this together. A lamp that uses minimal energy, emits lots of light, and lasts for a decade is cheaper in the long run than one that uses more energy and blows quickly.

LEDs, or light emitting diodes reportedly have the lowest watts per lumen for any lights available in Australia (see the light globe conversion table at the end of this link). A key reason is that they convert electricity into light, and not heat.

I tested this using a thermal imaging camera to compare an old incandescent with a compact fluorescent and LED lamp. Each had been on for half an hour before I tested their temperature.

The hottest point on the incandescent lamp was 161 degrees Celsius. That’s a lot of electricity being converted into heat, instead of light.

The hottest point on the compact fluorescent lamp (CFL) was 134 degrees Celsius. Still pretty hot.

The hottest point on the LED lamp was 65 degrees. Most of the power is going into light, not heat.

LEDs contain less toxins than other lamps, being free of mercury, lead and phosphorous and are also fully recyclable. So there are fewer waste problems with LEDs than with other lamps. CFLs in contrast, contain mercury so it is important to recycle those.

I’m convinced. I had already swapped all of my incandescents for CFLs. Now its time to change over to LEDs. And if the quoted hours are right on these new lamps they might outlive the house.

Hot and Cool with Thermal Pics

Here are some random thermal images with thoughts on what they show. Cats, dogs, chickens, noses, hands, gardens, tents beverages and injuries.

Cats have hot faces and cool bodies.

IR000320

Dog on a couch

Dogs have hot eyes and cold noses.

IR000013

Chickens roosting on a cold night.

Chickens have hot faces and feet.

Hot nose, cold nose.

Cool day, warm soil. Cool above the weed mat.

A folk festival in a heatwave. The dark parts of the tent are very much hotter than the light parts.

Hands!

Beverages!

Our sore bits are hot.

The hot dirt on compost

By Su Wild-River

It’s well known that compost generates heat. Clever people even heat their houses, run cookstoves and cars off compost. Here’s a little look at a humble backyard compost system through the lense of a thermal imaging camera.

A thermal imaging camera is really a heat sensor, not a camera which shows what you see with your eyes. In these photos, the hottest areas are shown in white, and a rainbow spectrum going through red, to yellow, green and finally blue, show colder areas.

The photographs were taken on a cool autumn morning, with an ambient temperature around 14 degrees Celsius (about 57 Fahrenheit). The yellow glowing thing is a ‘compost dalek’, or plastic drum with air vents at the top, and compost inside.

Its interesting to see in the first pair of photos, that the water-filled pot at the front, and the two ceramic pieces behind are the coolest spots around. These are the high thermal mass areas of the photographs, and I was surprised at first to see that they were so cold, as I usually think of thermal mass as warm. Of course the main feature of thermal mass is not that it stays warm, but that it moderates temperature changes. Large thermal mass elements, like water tanks insulated slabs change temperature so slowly that they stay around the long-term average ambient temperature.

Compost by Kath McCann. Photos by Su Wild-River

Compost by Kath McCann. Photos by Su Wild-River

The outside of the compost dalek registers a temperature of around 16.5 degrees Celsius. It is much warmer than everything around it, and only the vents are colder.

Looking inside without turning the compost gives us a look at even higher temperatures. The hottest parts here are about 20 degrees Celsius. They are the deeper parts of the compost, so we dug a bit further.

Compost by Kath McCann, Photos by Su Wild-River

Compost by Kath McCann, Photos by Su Wild-River

Only an inch or so down, the hottest temperature was 26.4 degrees Celsius. This is more than 10 degrees above the background temperature.

Compost by Kath McCann, Photos by Su Wild-River

Compost by Kath McCann, Photos by Su Wild-River

Now this compost is owned by Kath McCann, a keen gardener, and a good composter, but not someone who is using the stuff to heat her house. It seems as if even humble compost could make enough heat to warm us up, if only we plan and use it wisely.

So there you go. Compost really is warm. How could you be using yours?