Lecture 2 - Heat Transfer And Energy Balance

Question 1

What are the 3 components of Building energy performance?

Answer 1

1. Compactness (surface / volume)
2. Porosity (solid / empty space)
3. Slenderness (building footprint / height)

Question 2

Which value describes how the building form affects the building’s energy consumption?

Answer 2

The S/V ratio

Question 3

What does the heating/cooling demand represent for a building?

Answer 3

The difference between Heat LOSSES and Heat GAINS (usually minuscule, from appliances, people, etc.) in order to provide COMFORTABLE conditions in summer or winter.

Question 4

Why can U-values recommended for single-family buildings be higher than those recommended for multi-family buildings?

Answer 4

In single-family buildings:

• heated volume is lower
• S/V ratio is higher

Thus a more effective insulation is needed in order to contain heat losses

Question 5

EXAM: What is thermal transmittance (U)?

Answer 5

Rate of heat transfer of in Watts through 1sqm of a structure when there is a temp difference of 1 degree

Inverse of thermal resistance (R) thus:
Smaller U value = better thermal performance.

Question 6

EXAM: In the calculation of the U-value of a window, what does the Ψ value represent?

Answer 6

The linear heat transfer coefficient of the insulated glazing EDGE SEAL