Building Services Engineering 5th Edition Handbook

84 Heat loss calculations
27. Which of these calculated values of thermal resistance is not correct?
1. 110 mm of brickwork is 0.13.
2. 150 mm of fibreglass roof insulation is 3.75.
3. 100 mm concrete having a thermal conductivity of 2.0 W/mK is 0.05.
4. A metal window frame 20 mm thickness has a thermal conductivity of 50.0 W/mK and
has a thermal resistance of virtually zero.
5. A low-energy building wall has 1.0 m thickness of phenolic foam having a thermal
conductivity of 0.04 W/mK making a thermal resistance of 25.0 m 2 K/W.
28. Which of these is correct?
1. U value is the sum of all thermal resistivities in a structure.
2. R value is the sum of all thermal resistivities in a structure.
3. Y value is the sum of all thermal resistivities in a structure.
4. U value is the sum of all thermal resistances in a structure.
5. R value is the sum of all thermal resistances in a structure.
29. Which is the correct description of a thermal transmittance exposure location?
1. Sheltered is only for below-ground structures.
2. Normal exposure means the surface faces the prevailing wind direction.
3. Severe exposure applies to fifth floors anywhere.
4. Severe exposure applies to floors above fifth floor in suburban districts.
5. Sheltered exposure means the building is surrounded by trees.
30. Which is correct about an existing structure’s thermal transmittance?
1. Can only be calculated from design information.
2. Cannot be measured in situ.
3. Measurement requires a thermal imaging camera.
4. Measure structural temperatures to calculate U value.
5. Thermocouple temperature sensors have to be buried into drilled holes through the
structure.