Heat Transfer in the Building Envelope

Question 1

List the heat transfer effect’s that should be included in a good model of an external
wall

Answer 1

Conduction, convection, radiation, Air infiltration and exfiltration, thermal mass, Thermal bridging, Dynamic boundary conditions

Question 2

What heat transfer effects are considered in the U-value model?

Answer 2

Conduction, thermal bridging, Surface resistances

Question 3

Why should the building’s outdoor air temperature sensor be shaded for solar
radiation?

Answer 3

Because direct solar radiation on the sensor will give inaccurate temp reading, inconsistent data, not as reliable HVAC operation and sensor degradation.

Question 4

What does the acronym EMCS mean?

Answer 4

Energy management and control system. It’s a building automation system that is designed to monitor, control and optimize building performance management.

Question 5

Briefly discuss simplifications in the IDA ICE model of the external wall.

Answer 5

Layered structure: a series of Homogenous layers with uniform properties.
Steady state assumptions: certain calculations (like U-values) are based on steady state assumptions.
Thermal bridges are considered, but in a simple manner.
Radiation effects: Simplified, such as averaged over time or approximated.
Material properties: Assumed to be constant