Week 8 - Passivhaus Design Blog

  Passive Design

Heat Energy
  • Average indoor temperature is 20°
  • Average outdoor temperature is 10°
  • The heat from inside the home is trying to escape to the cooler area which is outside.
  • To prevent this happening we have to fully insulate our homes, but some level of heat energy will always escape through thermal conductivity.
Thermal Conductivity
  • thermal conductivity is the measure of the rate at which heat energy is conducted through a material.
  • measured in watts per meter kelvin.
  • when talking about thermal conductivity we are talking about a sample cubic meter of the material.
  • The building regulations provide us with the thermal conductivity of common materials, seen below.


Thermal resistance
  • Thermal resistance is the term used to describe a materials ability to resist or prevent the flow of heat.
  • the thermal resistance of each material depends on its thickness and the rate at which it can conduct heat.
Surfaces resistances
  • In construction studies we use standard values for surface resistance.
  • The level of resistance at the surfaces depend on:
  • surface properties
  • direction of energy flow
  • climate


U- Values
  • Thermal transmittances is the term used to describe the rate of heat energy transfer through a structure.
  • this is what we call our U-Value.
  • For a building to reach passivhaus standards it has to be below a certain U-Value, these standards are listed below:
  1. Roof - less then or equal to 0.15
  2. window - less then or equal to 0.08
  3. Walls - less then or equal to 0.15
  4. Floor - less then or equal to 0.15
Here are the U-Values for my building.

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