Section 01 of 04
The order of magnitude
Most conversations about heat loss start at the glazing, which is where the least of it is. This section takes the paths one at a time — what a wall does, what a roof line does, what a U-value assumes — because the ranking has to come before anything else.
PLATE 1A cavity opened up. What the plane of the wall does is settled here, and it outweighs the glazing by a wide margin.
Photo: Cavity Wall · Wikimedia Commons
Start here
It was never the windows
An uninsulated wall and a leaky roof line dwarf the glazing question that most conversations start with, and the arithmetic is not close.
Everything in this section
It was never the windows
An uninsulated wall and a leaky roof line dwarf the glazing question that most conversations start with, and the arithmetic is not close.
U-values, and what they leave out
A U-value describes one square metre of an element in steady state, and a real wall is neither one square metre nor in steady state.
The order of magnitude
Ranking the heat loss paths before touching any of them is the whole of the discipline.
The other sections
Every guide, listed →
Section 01 of 04
The order of magnitude
Most conversations about heat loss start at the glazing, which is where the least of it is. This section takes the paths one at a time — what a wall does, what a roof line does, what a U-value assumes — because the ranking has to come before anything else.
PLATE 1A cavity opened up. What the plane of the wall does is settled here, and it outweighs the glazing by a wide margin.
Photo: Cavity Wall · Wikimedia Commons
Start here
It was never the windows
An uninsulated wall and a leaky roof line dwarf the glazing question that most conversations start with, and the arithmetic is not close.
Everything in this section
It was never the windows
An uninsulated wall and a leaky roof line dwarf the glazing question that most conversations start with, and the arithmetic is not close.
U-values, and what they leave out
A U-value describes one square metre of an element in steady state, and a real wall is neither one square metre nor in steady state.
The order of magnitude
Ranking the heat loss paths before touching any of them is the whole of the discipline.
The other sections