HEAT TRANSFER IN BUILDINGS

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• Q1: Define Heat.
  Ans: Heat is a form of energy that flows from a hotter object to a cooler one, causing temperature changes.
• Q2: Define Temperature.
  Ans: Temperature is a measure of the average kinetic energy of particles in a substance, indicating how hot or cold it is.
• Q3: Write different methods of heat transfer.
  Ans: The three methods of heat transfer are:

  • ➔ Conduction
  • ➔ Convection
  • ➔ Radiation
• Q4: How does heat transfer in solids?
  Ans: In solids, heat transfer occurs through conduction, where heat moves from high to low temperature areas via particle collisions.
• Q5: How does heat transfer in liquids?
  Ans: In liquids, heat transfer occurs through convection, where heated molecules rise and cooler molecules sink, creating a current.
• Q6: How does heat transfer in gases?
  Ans: In gases, heat transfer also occurs through convection, but the molecules are more spread out, allowing for faster movement and heat transfer.
• Q7: Define Conduction.
  Ans: Conduction is the transfer of heat through direct contact between particles in a substance.
• Q8: Define Convection.
  Ans: Convection is the transfer of heat through the movement of fluids (liquids or gases), where hot particles rise and cooler particles sink.
• Q9: Define Radiation.
  Ans: Radiation is the transfer of heat in the form of electromagnetic waves, such as infrared radiation, which can travel through a vacuum.
• Q10: What is Thermal Insulation?
  Ans: Thermal insulation is the process of reducing the transfer of heat between objects, typically using materials that resist heat flow.
• Q11: What are three general applications of temperature range?
  Ans: These are:

  • ➔ Home heating and cooling
  • ➔ Industrial processes (e.g., cooking, metalworking)
  • ➔ Electronics and machinery that require temperature control
• Q12: What is the selection criteria for insulating materials?
  Ans: Insulating materials are chosen based on their thermal conductivity, cost, durability, fire resistance, and ease of installation.
• Q13: Name some thermal insulating materials.
  Ans: Some of the thermal insulating materials are:

  • ➔ Fiberglass
  • ➔ Cellulose
  • ➔ Mineral wool
  • ➔ Polystyrene
  • ➔ Polyurethane
  • ➔ Aerogel
• Q14: Enlist the types of insulation.
  Ans: The types are:

  • ➔ Thermal insulation
  • ➔ Acoustic insulation
  • ➔ Electrical insulation
• Q15: Enlist the forms of insulation.
  Ans: The forms are:

  • ➔ Batts and rolls
  • ➔ Rigid boards
  • ➔ Loose-fill
  • ➔ Spray foam
• Q16: Define Thermal Conductivity.
  Ans: Thermal conductivity is the ability of a material to conduct heat, usually expressed in watts per meter per degree Celsius (W/m·K).
• Q17: Define Thermal Resistance.
  Ans: Thermal resistance is the property of a material to resist the flow of heat, and it is the inverse of thermal conductivity.
• Q18: Define Specific Heat Capacity.
  Ans: Specific heat capacity is the amount of heat required to raise the temperature of one unit of mass of a substance by one degree Celsius.
• Q19: Define Density.
  Ans: Density is the mass of a substance per unit volume, typically measured in kilograms per cubic meter (kg/m³).
• Q20: Define Thermal Diffusivity.
  Ans: Thermal diffusivity is a measure of how quickly a material responds to changes in temperature, combining both its thermal conductivity and specific heat.
• Q21: Define Vapour Permeability.
  Ans: Vapour permeability is the ability of a material to allow water vapor to pass through it.
• Q22: What is Cellular glass available in?
  Ans: Cellular glass is available in rigid boards or blocks, often used as a high-performance insulation material.
• Q23: What is Cellulose available in?
  Ans: Cellulose is available in the form of loose-fill insulation or batts, often made from recycled paper products.
• Q24: What is Rock Mineral Wool available in?
  Ans: Rock mineral wool is available in batts, boards, and loose-fill forms for thermal and acoustic insulation.
• Q25: What is Phenolic foam?
  Ans: Phenolic foam is a rigid, closed-cell insulation material with low thermal conductivity and high fire resistance.
• Q26: What is Polyurethane?
  Ans: Polyurethane is a versatile insulation material, available in rigid foam boards, spray foam, or flexible forms with good thermal resistance.
• Q27: Define Aerogel.
  Ans: Aerogel is a highly porous, lightweight material with excellent insulating properties, often used in high-performance applications.
• Q28: What are Shading Devices?
  Ans: Shading devices are architectural elements designed to block or control the amount of sunlight entering a building.
• Q29: Name some Shading Devices.
  Ans: Some of the shading devices are:

  • ➔ Blinds
  • ➔ Awnings
  • ➔ Shutters
  • ➔ Louvers
  • ➔ Overhangs
• Q30: Name some fixed exterior Shading Devices.
  Ans: Some of the exterior shading devices are:

  • ➔ Fixed louvers
  • ➔ Overhangs
  • ➔ Pergolas
  • ➔ Trellises
• Q31: Define Overhangs.
  Ans: Overhangs are horizontal extensions of a building's roof that provide shade to windows and reduce solar heat gain.
• Q32: What are Slanted louvers?
  Ans: Slanted louvers are angled slats that control the amount of light and air entering a space while blocking direct sunlight.
• Q33: Define Awnings.
  Ans: Awnings are fabric or metal coverings that extend over windows or doors to block sunlight and reduce heat gain.
• Q34: Define Canopy shade.
  Ans: A canopy is a roof-like structure that provides shade to outdoor areas, often made of fabric or metal.
• Q35: Define Groundcovers.
  Ans: Groundcovers are low-growing plants or materials used to cover soil, helping to control temperature and reduce heat absorption.
• Q36: Define Eggcrate shading.
  Ans: Eggcrate shading is a type of shading device with a grid-like structure that diffuses sunlight and reduces glare.
• Q37: Define Deciduous plants.
  Ans: Deciduous plants are trees or shrubs that lose their leaves in the fall and regrow them in the spring.
• Q38: Define Evergreen plants.
  Ans: Evergreen plants retain their leaves year-round, providing consistent shade and protection.
• Q39: Write the role of trees, bushes etc. to control a building’s temperature.
  Ans: Trees and bushes provide natural shade, reduce heat gain by blocking sunlight, and cool the air through transpiration, helping to lower indoor temperatures.
• Q40: Define Heat transfer.
  Ans: Heat transfer is the movement of thermal energy from a hotter object or area to a cooler one through conduction, convection, or radiation.