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.

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

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

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

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

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

I think I've worked out the identity of banksy

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

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.

Every day is a school day this is your best video yet Roger .lots of great info and delivered at speed which is a great bonus compared to lots of other slow laborious offerings keep up the good work.very informative

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.

Fabulous video as always - such a tremendous wealth of knowledge and understanding, delivered in a down to earth way, by someone who has direct hands-on experience. Thank you!

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

Another fabulous white board session from Roger. I know a bit from years being a maintenance engineer / home mender. What you and Robin do is de-mystify all the ballcocks spouted by charalatans for the pro and the home owner. I am entertained and learn something every time watching your tubes. I cant learn 30 years of carpentry or plumbing in a 10 minute vid, but you both have seen it all and want to share your journey. Thanks

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.

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!

As a carpenter i feel blessed that i designed and fitted my own underfloor heating and its the best thing i have ever done on my house renovation , cheers Roger i also put a 160 mm of silver foil insulation in my ceiling , top video many thanks .

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

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.

You are a very good teacher! I also loved the spot on reference to Dads who come over looking to fix everything - that was mine & I miss him every day, so thank you!

Top notch teacher, Roger is! You know this when you listen to a topic that would never normally interest you...never again will I say, "hot air rises"!

Roger Bisby! I bell your channel. It is so informing and beneficial to watch your down-to-earth explanations. Thank you so much.

Absolute magic, when Roger said "a couple of legs there as well" I nearly fell off my chair with laughter. Brilliant!!

It's good to see someone that knows what his taking about and love's his work. Cheers from Portugal!

I knew about the air gap between insulation and the roof slates, however despite looking at numerous videos of ways of loft conversions and the insulating, none have mentioned the air gap on the other side. Good tip!!! thanks

Hello Roger, I have just watched your video and it was really excellent, I learned so much from this and a lot about heat I didn't know! I was thinking of insulating my suspended ground floor with rockwool and you now have confirmed for me that I will definitely do this. Thanking you from Ireland a new subscriber. 🙂

That was a brilliant video Roger!VERY informative!The knowledge to learn about buildings seems endless!Many thanks 😊👍

Great video very informative, love your delivery, a layman can understand it and it's not boring either.

Found that very useful! Thank you. I’m a Handyman but also a homeowner and so glad I stumbled on your channel. I have an issue with damp in my kitchen and it’s very interesting theory regarding your spot light which I have lots of! I’ve been searching for a leak and unable to find one! I’ll also fit an extractor which I haven’t got either. Lots of good advice so thank you guys 😊

Brilliant video, I have an old house with floor boards and my feet feel cold but with only 10 inches below the floor joists I can't get under to put rock wool in. I am considering taking the whole floor up to insulate it . Maybe even looking into taking the "radiator" out and doing underfloor heating in the living room ........a job for next summer 😁

Another brilliant presentation. Knowledge, experience and common sense, so rare but so necessary. Many thanks.

One of the best videos on youtube thank you Roger.

This makes me feel good about spending the extra on underfloor insulation (taped Celotex panels, with ply on top, then the floorboards on top of that) when I had my late 1800s terraced house renovated (and also the ventilation bricks were redone properly). Really makes a difference, especially as I took some internal walls out and made the downstairs open plan, which is not the most favourable thing to do in terms of keeping heat in.

4:17 "Its radiating heat at the square root of ... stuff or .." lol classic great vid

I can listen to this man 24/7. Tonnes of valuable info beautiful explained

That was one the best presentations that I’ve heard on this.

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

Great video Roger and a useful indication for a hierarchy of minor improvements that together will effectively improve comfort while also reducing heating costs. I would love to hear your thoughts on the advisability or otherwise of installing 4mm thick Thermal Liner to the inside of 600mm thick external stone walls?

Another fantastic, detailed presentation, well done Roger !!

Absolutely brilliantly explained Roger, Thank you

Brilliant presentation Roger, thank you, so accessible for the masses. I have to quickly tell you my experience of my own hands on self build. Single storey, vaulted ceiling, suspended timber floor, insulated very much as you describe, 2x110mm Kingspan between rafters and floor joists. (Rafters are 12x2). Water underfloor heating from ASHP. HERE’S THE SIGNIFICANT BIT! I only need to heat the underfloor water to 25-30°C to maintain 21°C in the house no matter what the temperature outside. So two points to take from this, firstly the principles you are teaching are solid and proven to work. Second, I’ve noticed that ASHP underfloor water temperatures tend to be set too high. This doesn’t achieve a higher room temperature but just burns more fuel. I adjusted mine down and down over several days to find the lowest water temperature that maintained the 21°C room temperature. Best wishes, Jim. S Bucks.

Very interesting. I always wondered about radiators next to windows etc.

Brilliant video, heat loss simply explained. Well done, I shall watch more of your skill builder videos.

Thanks for this - my living room is exactly how you drew the example and it's *Baltic* at the moment, might be a jaunt down to b&q once payday comes 🤣

This is actually incredible, informative and the bit about the ‘dad and the radiator story’ was hilarious... “Radiator needs bleeding son” 😂😂 I watch a lot of videos on the channel but this is probably one of my favourites for many reasons on Skill Builder so thank you 👍

A ceiling fan set to winter settings can also help considerably. It helps to push warm air down.

Roger what a great video , full of great information , You would make a great teacher , Keep them coming mate , Cheers .

Always learn a lot and it's in plain English so easy to understand. Thanks.

You're always on a heat with your skills keep it up I always enjoy your skills you're a top man👍keep going!.. God bless!!!.

Talking to an old man who lives alone, in the pub at the weekend how the high energy prices and insulation are affecting him. He said they are not affecting him at all, all he does is not put any heating on and sit in a coat, he said it doesn't really get all that cold in the UK anyway, the trouble is most people are just soft these days.

Very informative Roger! Appreciated.

Fantastic as always. I really appreciate sharing your knowledge and learn a lot from your videos.

Great video. My best house investment was during a lower floor upgrade was to rip out all 90% of my downstairs radiators and install overlay underfloor heating and then tiling most of the lower floor. The only downstairs radiator was replaced with a very large aluminium radiator in the lounge because we wanted carpets. All upper radiator were left and smart WiFi valves were installed across the house. The whole house operates from a Central Honeywell tablet controller with multiple underfloor zones and bedroom zones. It is Internet linked to also know outside temperture and thus back off or increase heat as required. The difference in the comfort is incredible. As he says underfloor is a different but very nice type of heat. We now run the boiler at 55 Deg instead of 72 Deg for radiators. Underfloor wide mixer runs at 45Deg. We have a anti mould additive in the system but once a month I up temp to 60% just to make sure we get no growth. Lower bills better comfort and the ability to control the system from my phone. Cannot recommend it enough. We also have double loft insulation, cavity wall and full double glazing. It is a 1976 house but after the update our energy cost dropped by 50%. A further advantage is that during the summer the house is cooler due to the large tile area. If you do nothing else install underfloor heating and smart control your house.

This was a practical physics lesson that you should have had at school. I'm more informed now than when I was watching cat videos.

Such a knowledgeable chap, thanks Roger!

Really informative Roger, thanks. Love the idea of infilling the floor joists in our old house!

Thanks Roger, very informative. I've meaning to insulate my suspender timber floor for some time. I've been putting it off because of the hassle factor as you mentioned. I've heard that moisture can build up in the insulation if you get it wrong. I'd be interested in your view on this and whether there are any do's and don'ts. Ta.

The worst flaw I've found in my house's insulation was the air flowing through the 3/4" gap between the drywall and the concrete blocks. On the coldest day of the year, you could feel exactly where they were, so I'd start drilling rows of holes in the middle of the coldest area and injecting expanding foam in each hole until it came out a bit in the next hole. Over time, I've run out of such areas, so the job is mostly done. If the house had been built more carefully, this would not have been needed, but I think they left the gaps open at the top, allowing air from the attic to fall down through the gaps.

Great formula! I love the stories and drawings! Makes learning is easy and fun - Thank You!

Well explained Roger. Thanks

Brilliant video. Perfectly explained. You should do a review of skirting board heating. A less disruptive alternative to underfloor heating which can be plugged into existing central heating systems.

Great video as usual! Underfloor heating is really good, but a few things some people may consider... You will have warm feet while your head is slightly cooler. Some people, like me, don't really like the feeling. I have heard about health problems related to that but can not confirm the truth of these claims. You will get some convection going and thereby eventually blow up dust that's laying on the floor. People with certain allergies may have problems with that. An alternative could be to put your heating pipes on the outer walls. The obvious downsides of that is that you should not put large furniture in front of the heated walls, blocking the radiation. Also an adequate insulation on the outer walls is necessary! I personally have set my heating pipes in a thick clay mortar on the outer walls and could not be happier. The tempering of the usually cold outside walls gives a fantastic feeling inside, I actually have lower temperatures now while feeling comfortable. Also the clay mortar has a high thermal capacity and great moisture regulation. No more condensing on my windows. Maybe some people find this informative, as many people I meet don't know about wall heating. Cheers 🍻

Your definitely not failing us lads, I love the videos guys, unbelievably helpful, keep up the good work, I might be able to build my house by myself soon😂

A pleasure to watch as always Roger.

Top lesson Roger ! I wish you’d been my physics teacher..... I would have got an O level 😂

I'm 5 minutes in and I think Roger has been on the Sherry lol

I've only just seen this. Best Skill builder video out there. Absolutely excellent

Best explanation of heat, its properties and the physics of it all.

In the case of your home with an air space under the ground floor. The Canadian approach (-25degC winters), would be to apply insulation as you did, but to also apply a 6mil thick vapour barrier across the joists, sealed (with acoustic seal) to adjacent walls and joined together with special tape, to ensure a completely draft-proof barrier. Then the floor boards would go over that. As you said, the reason why your room felt so much warmer (despite the fact that heat loss through the floor isn’t that great), is not because of the R value of the insulation, but because the insulation considerably reduced the drafts. If all you did was apply vapour barrier (and no insulation), you would also notice a very significant improvement. But both together work the best.

The heat is on,its on the street

Excellent explanation of a common problem. Thank you.

Another brilliant video Roger, so nice to hear someone talking intelligently and scientifically as regards heating and insulation, love the air gap tip in the ceiling, had not thought of that, will be doing it in future. All you builders and plumbers out there, take a leaf out of Rogers book, he's a clever bloke, obviously reads books, educates himself and makes full use of his brain. As i try to convey to my son, try and have a big brain not a big head. Obviously the country is struggling at the moment but there is huge volumes of work to be had improving household heating, ventilation and insulation.

Your videos are brilliant 👍🏻 and you’re a gifted communicator 👍🏻 thanks 🙏

Great tutorial nice and simple but in depth

A great easy to understand explanation 👏🏻

Like your stuff you come across very well, simply and well explained,thank you

Thanks for the video. Wanted to mention that when heating a room via a radiator or floor heating the solid part of the room is heated first, due to the molecule structure, but air will be heated to the set point temperature which is why all the home thermostats are measuring the air temperature and not the wall temperature or the floor.

Great clear explantion, thank you.

Brilliantly described and addictive viewing for anyone that knows the right end of a wrench or screw driver 👍🏻

Roger, amazing, informative and entertaining. Thank you so much, every day truly is a school day!

One of your best vids.. Love a bit of building science!

Amazing video many thanks for all your hard work putting this information together very interesting

Absolutely brilliant..fascinating and made completely understandable

This video is smashing fantastic! I learned so much ! Thanks 🙏🏻

BRILLIANT & VERY INTERESTING. Many Thanks.

Fantastic presentation!

Great video Roger (as always) - Thanks.

So cool explained! Thanks for the channel

Always learning something new with this guy

Great info again Roger. There are millions of people out there with no idea. Insulating tip for wooden floors, fix 2x1's to bottom of joist and slot celotex in between joists. Job done 👍

Great teaching . Keep up the good work

Brilliant explanations

Superb exclamation thanks

The back addition was built over crawl space. Plastic, gravel on dirt. Foam boards on walls. The space has lots of plumbing and runs to baseboard so reluctant to put insulation between joists and have pipes freeze. Floors are indeed cold in winter. I used heavy mats or rugs on most of the floor areas and that keeps them quite comfortable.

Superb explanation!

Fantastic explanation. Thanks 😊

Roger is absolutely wonderful, brilliant,he is like I dunno,can you imagine him ,as teacher,headmaster etc politician,, etc because this guy is so knowledgeable, clever ,these are the guys that should be running things,

Very informative scientific too thank you. Feeling toasty already listening to a visual explanation of heating. Cheers from Australia!

Excellent presentation well done

I just love the skills in teaching from across the ocean... frank.... funny... intelligent... honest... love it