AdvancedTopic 98 of 105Thermodynamics & Fluids
Building thermal analysis
Heating and cooling loads from conduction, solar gain and ventilation.
In depth
Loads come from conduction through envelope, solar gain, ventilation and infiltration, occupants and equipment. Heat loss Q=UAΔT. Design aims: insulation, glazing, airtightness, thermal mass, shading, heat recovery. Degree-days estimate annual energy use.
Key points
- U-values
- Psychrometrics for latent loads
- Passive house standards
ExampleUpgrading windows from U=5 to U=1.2 cuts glazing heat loss by 76%.
Building thermal analysis finds the heating and cooling loads, which determine the size of heating, ventilation and air conditioning equipment.
What is Building thermal analysis?
Heating and cooling loads from conduction, solar gain and ventilation.
Why is it important to understand building thermal analysis?
Building thermal analysis finds the heating and cooling loads, which determine the size of heating, ventilation and air conditioning equipment.
What makes up a cooling load?
Heat through the envelope, solar gains through windows, internal heat from people and equipment, and ventilation or infiltration air.
Why is over-sizing a problem?
Oversized equipment cycles on and off, which reduces humidity control and wastes energy.
How is Building thermal analysis used in practice?
Typical applications include sizing the air conditioner for a small office with large windows, estimating the heating demand of a house in winter and checking how solar gain through glazing affects summer cooling loads.
What should I learn before Building thermal analysis?
Study "Electronics cooling" first (topic 97 of 105 in Thermodynamics & Fluids). It covers the groundwork this topic builds on.
What are the key points of Building thermal analysis?
U-values. Psychrometrics for latent loads. Passive house standards.
Can you give an example of Building thermal analysis?
Upgrading windows from U=5 to U=1.2 cuts glazing heat loss by 76%.
What comes after Building thermal analysis?
The next topic is "Mass transfer basics", which builds directly on this one.
How difficult is Building thermal analysis?
It is classed as Advanced in Thermodynamics & Fluids (topic 98 of 105). It is an advanced topic. It assumes you are comfortable with the intermediate topics in Thermodynamics & Fluids.