No matter whether Roger shows you how to bleed a radiator or explains you the 2nd Law of Thermodynamics, he is always a pleasure to listen to.

Poor bastard in that house, not only is his house cold, he's got rickets too!

This video should be on the National Curriculum to educate the next generation on how to minimise their energy usage.

"Wow a half hour long video...never gonna watch all this."
30 minutes later..."Where did that time go??"

"It's kind of like a rainbow and you are the pot of gold at the end of it."

Absolute poetry.

I think I've worked out the identity of banksy

At school, years ago when asked what 3 ways did heat travel one person answered sincerely "upwards, sideways and downwards" lol

Physics, explained by a builder! It's makes so much more sense coming from Roger.

You are National Treasure Roger.  Love your passion for the construction industry and always learn something

I absolutely love your videos. I’m a 75 year old woman who lives alone and I feel so much more competent after watching your tutorials! Thank you very much indeed. Stevie, York.

You could be a lecturer rather than a builder.
The way you explain in every clips are extraordinary and easy to understand.
You make us understand very well .

Best communicator on any subject — Sensitivity — Integrity — Clarity — Comprehensive — Methodical — Entertaining — Natural — Great morale booster! — Ought to be in Parliament or Privy Council — Admiral — Philosopher — Entertainer!

Great video for those who are considering using heat pumps instead of oil or gas boilers. Clearly a lot of older type properties aren't insulated to the levels you've demonstrated,  the fabric heat loss will undermine the required core temperature of the home and will never be met by refrigeration heat pumps supplying either underfloor heating or radiators. The COP of these machines in power terms cannot match the temperatures of conventional water boilers, and thus the heat loss would exceed the level of heat required  ... without the insulation methods you've mentioned.

I wish you'd been my science teacher at school, Roger. Thank you for yet another high quality video!

Really enjoy your videos. I would like to mention a couple of points on this one, as heat transfer is a subject of personal interest.
1) 6:02 For those interested in a bit more detail, essentially the greater the temperature of air, the less dense it becomes (ideal gas law). Temperature is a measure of how much molecules vibrate and jiggle around. The hotter the something is, the more its molecules vibrate and space apart, the less dense it becomes. If something is less dense it rises, if something is more dense it sinks. Perhaps the phrase 'hotter air rises' better describes these buoyancy-driven flows.
2) 12:07 I agree that conventional radiators are transferring heat through convection (which is buoyancy-driven), but I suspect convection is still responsible for a large part of the heat transfer from underfloor heating systems too. Radiation is not likely to transfer as much heat as you might think as it is only emitted in significant quantities at very high temperatures (as it scales with temperature to the power 4!).
3) 21:30 An air gap is a great thermal insulator because you've created basically something similar to the walls of a flask. Conduction and convection are both poor in a narrow air gap, and radiation is not effective at these temperatures. Also, anything solid is likely to be opaque to radiation, and it's typically absorbed within the first millimeter or so of hitting a solid body. Interestingly glass is transparent to visible radiation (light) but opaque to infrared!
95% on point! A great explanation of heat transfer within the home for the layman!

I have learnt more about physics in this video than I did all those years ago at school.
Or maybe I did learn it & forgot it but a fascinating & a very practical insight, thank you.

Roger is always a pleasure to listen to.  He should have been a University lecturer. Excellent.

We're about to buy a 1910s house that needs significant work to the subfloors and a suspected damp problem. This was a very useful video for me! I'm very keen to improve the warmth of the place as much as possible during renovation, knowing how heat moves in these different ways and how to insulate efficiently makes me a lot more confident choosing workmen or doing it ourselves.

This has to the most informative superbly presented video that I have ever watched regarding heat. I can’t believe how little I actually knew. To talk for so long about a physics subject and have me riveted says just how well you presented it.

I did enjoy physics lessons, but they weren’t this interesting at school! Brilliant, thank you.