This happens time and time again. The promotion of light coloured rooftops in summer periods.... and I'm all for it - but we need the whole picture. How do these rooftops perform in winter times? I have been told that a darker roof yeilds a better energy rating for winter time due to increased solar absorption. Which is tough because its a win loss situation, and requires balance to the ratio of hot and cold climate time periods for each particular climate zone.
I'm definitely no expert but I feel the affects of the summer sun would be much stronger than the influence of the sun during winter. Example would be I found the winter sun made practically no difference in my home without a thermal mass to absorb that low heat. A bit off the topic of this post though. Would be interesting to see some data from the affect of colour on the roof space temperatures during colder weather.
@@josephcheung3964 Ah it makes sense now, in winter your always losing (heat). With a dark coloured rooftop it only slowed the net heat loss during the day (if sunny). But I also remembered that dark colours also emit more radiant heat, so any gains are quickly reduced to a point where heat will begin to radiantly leak outwards. So in conclusion light colours help prevent radiant heat absorption during summer AND radiant heat leakage during winter (as long as its paired with an appropriate insulation system). Man I love it when I learn something new, thanks Joseph.
It’s much cheaper to heat a home than it is to cool a home. Fighting the thermal load during the cooling times will yield the best overall/annual result. (Depending on geographic location, of course.)
Slightly disappointed not to use a factory coated White panel (e.g. colorbond surfmist, I know you intentionally are avoiding brand names). Probably wouldn't be much different given the other results but in the spirit of a physical demo like this I think it would be helpful for the average person. I also would have included a sheet of monument and shown the factory claimed emissivity values to compare that with the green and factory white. Data logging a graph of the temperature of all 5 samples over a day (preferably a mostly full sun day) and showing that would also be great. Good starter but would love to see you re-do this with those additions and make a follow-up video!
We made the decision NOT to use factory-coated white panel because we want to make an "apple to apple" comparison including the "application technique" and the imperfect finish.😉
What about Barium Sulphate emissive paints? The reflective properties of paints and colours are well known. The emissive properties to REMOVE heat rather than reflect it is a different matter all together. The science behind them is good., but so far I have not found any properly commercially developed and evaluated paints.
That's an interesting product. However, we are not able to find an off-the-shelf product on the Australian market. We want to focus on commercially available.
I've had sunshield, a ceramic roof coating on an outbuilding of mine for 4 years. It's 8 degrees cooler than the white roof next to it. I use a high quality heat gun from work to get my readings. You can feel the difference
Prove it, make your own video. Show us all how much better your paint is than Dulux Vivid white! Freshly painted, with both. And use your heat gun, we would love to see it.
@ecoevo yes, I should have Acknowledged that. I'm a simple man. I can walk barefoot on my ceramic coated (4years old) on a 110 degree day. On my white metal roof, its extremely uncomfortable. The ceramic roof has never been washed either. And it's just about flat.
How did the prices differ? I’d imagine with NASA technology on the can, they’d want a lot more for it. But as mentioned it’s inconclusive, because a verdict would require the longevity test also. By the way that pastel green wasn’t even very dark, but still it was 25% hotter. I wonder how much hotter those maroon/terracotta color barns would be.
NASA tech paint that we obtained over AUD1,400 (yes! over au$1.4K) for 15L; AUS ceramic AUD378 (light colours) for 10L; Normal outdoor paint ~ AUD 310 (depending on brand and which hardware store you are getting it from white colour only).
@@josephcheung3964 Waw, almost 5 times as much. So if the normal paint lasts even 1/5th of the time (which it probably do better), it would still cost the same as NASA. Cool 👍
The Nasa coating is for high reflectivity plus high emissivety. White paint is generally less thermally emissive so it will not radiate heat away as easily. This doesn't matter much when your main heat source is the sun but if you had a building producing a lot of heat it might start to matter. This is also made more important for nasa since you don't have an atmosphere to be conducting heat away in space.
i Should add this nasa coating probably makes it the worst option for variable weather since it should lose heat at a greater rate as well while white normal paints will emit at a slower pace.
Yeah, well, in this experiment the nasa coating was either not reflecting as well as white or not ditching energy fast enough to maintain a cooler temperature than plain white.
Do a black and dark gray compared to surfmist ect also does solar production increase on white roof.. and doea solar undo some of the white roof or not...
How would a galvanised iron sheet roofing compare to the white sheeting .I have recently reroofed my 100 year old house with galvanised corrugated iron and it feels a lot cooler inside this summer compared to last year.
That's not a real test. They are in the exterior. Material heat with the sir temperature, they should build a storage, paint all around it, and measure the temperature inside . Has to be in the morning and wait until middle of the day to see which one stay cooler, my garage door was green, getting hit by the sun light, garage temperature was about 125 f. Painted white,temperature dropped to 98, 109 at most.
Ceramic coating needs to be at least 1mm thickness anything less is a waste of time and money. Ceramic microspheres when correctly coated will result in a 40% reduction in ambient temperature below the surface of the sheeting.
Just like white paint can reduce solar gain. As a side note. Temperature scale is an arbitrary scale that cannot be presented as % reduction. E.g. a 10 degree Celsius reduction from 40degree Celsius cannot be said as a 25% reduction in temperature.
i should paint the roof of my factory white
With anti-fungal additive.
Thanks for these informative videos. As an average home owner interested in renovations for energy efficiency I've learnt so much from them.
A well-explained simple comparison trial. I'll going to Bunnings right now for a tin of white outdoor paint!!!
It's all about using white since white has the highest Albedo effect across the color spectrum. Have applied this principle on our own roof 😊
This happens time and time again. The promotion of light coloured rooftops in summer periods.... and I'm all for it - but we need the whole picture. How do these rooftops perform in winter times? I have been told that a darker roof yeilds a better energy rating for winter time due to increased solar absorption. Which is tough because its a win loss situation, and requires balance to the ratio of hot and cold climate time periods for each particular climate zone.
For winter, the key is your insulation. with long and cold nights, the benefit of a "solar heated" roof is not enough to cover your losses at night.
I'm definitely no expert but I feel the affects of the summer sun would be much stronger than the influence of the sun during winter. Example would be I found the winter sun made practically no difference in my home without a thermal mass to absorb that low heat. A bit off the topic of this post though. Would be interesting to see some data from the affect of colour on the roof space temperatures during colder weather.
@@josephcheung3964 Ah it makes sense now, in winter your always losing (heat). With a dark coloured rooftop it only slowed the net heat loss during the day (if sunny). But I also remembered that dark colours also emit more radiant heat, so any gains are quickly reduced to a point where heat will begin to radiantly leak outwards.
So in conclusion light colours help prevent radiant heat absorption during summer AND radiant heat leakage during winter (as long as its paired with an appropriate insulation system).
Man I love it when I learn something new, thanks Joseph.
Right on!
It’s much cheaper to heat a home than it is to cool a home. Fighting the thermal load during the cooling times will yield the best overall/annual result. (Depending on geographic location, of course.)
Slightly disappointed not to use a factory coated White panel (e.g. colorbond surfmist, I know you intentionally are avoiding brand names). Probably wouldn't be much different given the other results but in the spirit of a physical demo like this I think it would be helpful for the average person. I also would have included a sheet of monument and shown the factory claimed emissivity values to compare that with the green and factory white. Data logging a graph of the temperature of all 5 samples over a day (preferably a mostly full sun day) and showing that would also be great. Good starter but would love to see you re-do this with those additions and make a follow-up video!
We made the decision NOT to use factory-coated white panel because we want to make an "apple to apple" comparison including the "application technique" and the imperfect finish.😉
We have another video coming soon with Dover white, and other common colour bond colours with and without a ceramic addition.
Totally agree
If you are doing another video I'd be interested in standard zincalume/silver colorbond.
Please include zincalume in this test
What about Barium Sulphate emissive paints? The reflective properties of paints and colours are well known. The emissive properties to REMOVE heat rather than reflect it is a different matter all together. The science behind them is good., but so far I have not found any properly commercially developed and evaluated paints.
That's an interesting product. However, we are not able to find an off-the-shelf product on the Australian market. We want to focus on commercially available.
I've had sunshield, a ceramic roof coating on an outbuilding of mine for 4 years. It's 8 degrees cooler than the white roof next to it. I use a high quality heat gun from work to get my readings. You can feel the difference
Prove it, make your own video. Show us all how much better your paint is than Dulux Vivid white! Freshly painted, with both. And use your heat gun, we would love to see it.
@ecoevo freshly painted doesn't prove anything. You need a few years to see how each will perform over the long haul.
@deelarry2137 Agreed, and we do talk about that.
@ecoevo yes, I should have Acknowledged that. I'm a simple man. I can walk barefoot on my ceramic coated (4years old) on a 110 degree day. On my white metal roof, its extremely uncomfortable. The ceramic roof has never been washed either. And it's just about flat.
How did the prices differ? I’d imagine with NASA technology on the can, they’d want a lot more for it. But as mentioned it’s inconclusive, because a verdict would require the longevity test also. By the way that pastel green wasn’t even very dark, but still it was 25% hotter. I wonder how much hotter those maroon/terracotta color barns would be.
NASA tech paint that we obtained over AUD1,400 (yes! over au$1.4K) for 15L; AUS ceramic AUD378 (light colours) for 10L; Normal outdoor paint ~ AUD 310 (depending on brand and which hardware store you are getting it from white colour only).
@@josephcheung3964 Waw, almost 5 times as much. So if the normal paint lasts even 1/5th of the time (which it probably do better), it would still cost the same as NASA. Cool 👍
The prices were in the vid
@@drjimbarnes Ops, I must’ve looked away at that point.
The Nasa coating is for high reflectivity plus high emissivety. White paint is generally less thermally emissive so it will not radiate heat away as easily. This doesn't matter much when your main heat source is the sun but if you had a building producing a lot of heat it might start to matter. This is also made more important for nasa since you don't have an atmosphere to be conducting heat away in space.
i Should add this nasa coating probably makes it the worst option for variable weather since it should lose heat at a greater rate as well while white normal paints will emit at a slower pace.
Yeah, well, in this experiment the nasa coating was either not reflecting as well as white or not ditching energy fast enough to maintain a cooler temperature than plain white.
Do a black and dark gray compared to surfmist ect also does solar production increase on white roof.. and doea solar undo some of the white roof or not...
How would a galvanised iron sheet roofing compare to the white sheeting .I have recently reroofed my 100 year old house with galvanised corrugated iron and it feels a lot cooler inside this summer compared to last year.
There is a video coming soon, comparing a whole range of colours, including gal sheet. We will produce a table of results on a web page too.
Do solar panels also reduce roof heat since they intercept the sunlight?
They can indeed. The more coverage you have, the cooler your roof for sure.
What about using the shiny metal roof with no paint ?
We cover that, in this video. ua-cam.com/video/EyL48OMns9o/v-deo.htmlsi=vD4-duDQUTwQGNsY
Does paint sheen matter? I've heard that high-gloss reflects more sun.
It may vary the emissivity, which may improve IR reflectivity.
That's not a real test. They are in the exterior. Material heat with the sir temperature, they should build a storage, paint all around it, and measure the temperature inside . Has to be in the morning and wait until middle of the day to see which one stay cooler, my garage door was green, getting hit by the sun light, garage temperature was about 125 f. Painted white,temperature dropped to 98, 109 at most.
@@PlanetNegative White makes massive difference. Indeed it does, and this videos shows it.
Ceramic coating needs to be at least 1mm thickness anything less is a waste of time and money. Ceramic microspheres when correctly coated will result in a 40% reduction in ambient temperature below the surface of the sheeting.
@@Grokit-br7np unfortunately, That was not found with this testing.
Just like white paint can reduce solar gain. As a side note. Temperature scale is an arbitrary scale that cannot be presented as % reduction. E.g. a 10 degree Celsius reduction from 40degree Celsius cannot be said as a 25% reduction in temperature.
@@josephcheung8311 Then if you experience a 40% reduction in temperature in comparison to ambient, how do you describe the difference?
None of these are in a box like they'd be on a roof. The tests are meaningless.
Please explain what you mean by this?
@@ecoevo A metal roof will hold more heat on a roof than simply sitting in the air.
Enconcrusive
common sense ?