Introduction to Building Physics

Introduction to Building Physics

• Building physics involves studying thermal, moisture, air, acoustic and air properties of building materials
• Building physics concerns itself with the health and well-being of building occupants
• Building physics addresses energy-resilient buildings
• The first energy crisis occurred in 1973

Building Physics Scope

• Became known in the 19th century
• Focuses on understanding occupant comfort and interactions with internal and external environments
• Determines air quality, moisture levels, and heating/cooling demands
• Building physics considers the relationship between the environment, energy consumption(E.C), the materials(M) used to construct and human health and energy requirements (H&E.R)

Importance of Building Physics

• Protects interiors from unexpected outdoor environmental changes to maintain thermal comfort
• Aids in designing and selecting suitable materials and building envelopes like windows, walls, doors, and floors for sustainable building designs
• Takes into account loads like wind, rain, and water which might affect the building's performance
• Helps in understanding heating and cooling demands to prevent overheating and cold conditions
• Aims for resilient building designs that withstand environmental stress, aging, and natural elements.

Categorization of Building Physics

Thermal Energy

• Thermal energy or heat plays an important role in the building industry
• Thermal energy exists as a form of energy required to maintain indoor comfort
• Measures heat transfer between bodies via air, materials, and envelopes
• Represents the overall kinetic energy present in an object due to atomic and molecular movements
• Essential for studying the energy loss and gain within a building

Moisture

• Is water present in air, solid objects, or surfaces.
• Includes external, internal, and surface types
• High moisture levels inside buildings can lead to health problems and material disintegration
• It involves absorption and discharge of water at different temperatures that cause condensation
• Understanding moisture is essential to maintain indoor humidity and provide thermal comfort

Air Tightness

• Reduces heat loss or gain
• Helps control heat transfer and maintain indoor comfort
• Is important for energy efficiency
• Prevents or reduces infiltration and exfiltration
• Airflow is an important factor in the buildings and building physics
• Airflow and air change maintains contaminated free air and comfort in the building for occupants (ventilation)
• CO2 level should be below 0.1-0.15% indoor
• Airflow of minimum 3m3/h is vital to maintain the oxygen flow indoor

Acoustics and Light

• Acoustics relate to sound propagation in buildings
• It is one of the aspect to provide comfort from sound
• Aims to prevent or weaken sound transmission
• Sound travels through waves and is measured in decibels/
• Sound exists as airborne, liquid-borne, and solid-borne
• Sound waves travel through molecules within materials
• Acoustics act as noise barriers in various types of housing
• It is essential for occupants therefore maintaining comfort
• Natural light reduces the need for artificial lighting

Thermal Energy Transfer

• Thermal/Heat energy is forms of energy that play important roles in the building industry
• Energy transfer typically occurs in three modes:
  • Conduction
  • Convection
  • Radiation
• Insulation controls the release or absorption of energy

Moisture

• Moisture is present in air, solid objects, or surfaces
• Moisture is typically of three types: external, internal, and surface
• Higher moisture levels inside can cause health problems and disintegration of materials

Air Tightness

• Airflow is a key factor
• Airflow and circulation ensures contaminated free air and comfort for occupants through ventilation
• CO2 levels should stay below 0.1-0.15% indoors
• Airflow of at least 3m3/h necessary for oxygen flow