Windows

 The greatest cause of regret for house builders and home owners. Watch this for more information. Watch out for the cameo by Ted Moult. 

Air and Water: Condensation and Humidity

Whenever I talk about humidity I have a strong sense that I don't really know what I'm talking about. I think this is normal, because humidity is not at all intuitive. I know that my glasses will steam up when I come into a warm room from the cold. But what goes on within walls and buildings is complicated and strange. When predicting which way the moisture will go, I end up just assuming it will go where we don't want it!

In today's video I attempt to explain. In doing so I realised I need to say a lot more about diffusion, and probably do a whole new lesson on summer humidity. I can also talk about traditional approaches to protect buildings against condensation. 

Also I suggested that high humidity could increase the risk of spreading viruses. In fact low humidity can increase the risk of spreading viruses. 

Heating and Cooling

Here's a lesson on heating and cooling. 

More about the lesson here.

And more about air conditioners here.

How to slow Down Heat Part 2: Confounded by Compound Insulation

The sums don't quite add up for the problem we looked at earlier. The two calculations for compound insulation give a slightly different answer. 

You can see the calculations with my terrible handwriting here. Or just go straight to the video below, which is much lighter on maths. 

This is the calculation looking at parts of the wall in parallel first.  

And this is how to calculate looking at the parts of the wall in series first.  

We don't get the same answer. Here's why and what we can do about it.

How to Slow Down Heat

 Now that we know it's impossible to stop heat, let's see if we can slow it down!

More about the lesson here.