Shaping and Resisting Climate (21) Flashcards
What is the purpose of the building envelope?
The building envelope separates the interior from the exterior and controls the passage of temperature, air (flow), solar radiation, liquid water, and water vapor.
What are “control layers” in a building envelope?
Control layers are materials in the envelope responsible for mitigating the passage of temperature, air (flow), solar radiation, liquid water, and water vapor.
How does conduction affect temperature control in buildings?
The mass of exterior air adds heat to or takes away from anything it is in direct contact with via conduction, including the building’s skin.
What is convection in the context of building temperature control?
Convection is the process where moving air of one temperature carries heat from a warm space to a cool one as it finds equilibrium.
What are R-values and U-values in building materials?
R-values indicate the conductivity of a specific material in its manufactured form or as a regularized thickness. U-values are used for whole assemblies, such as doors and glazing. High R-values and low U-values indicate low conductivity.
How can we control airflow in buildings?
By air-sealing the building and allowing air to enter through controlled means like windows and HVAC systems. Ensuring airtightness can be achieved by layering on a membrane.
What is the role of cladding in solar (UV) radiation exclusion?
Cladding shades building layers from UV rays, which can be damaging to building materials. Special glazing films and laminations can help control which wavelengths of light enter and how much.
What are the three strategies for liquid water control in building envelopes?
- Reservoir: Allows water to permeate, hold, and then release it.
- Perfect Exclusion: Prevents any water from entering beyond the exterior face.
- Layered Control: Stops most water at the face of cladding, with inner layers stopping some water and allowing it to exit via openings.
Why is it important to control water vapor in building assemblies?
Water vapor can condense into liquid water on cool surfaces, which can be damaging. A vapor barrier membrane is used to exclude vapor.
What is a “Building Envelope”?
The building envelope is the physical barrier that separates the interior of a building from the exterior environment, controlling the passage of temperature, air, solar radiation, liquid water, and water vapor.
What are “Control Layers”?
Control layers are materials within the building envelope that mitigate the passage of temperature, air, solar radiation, liquid water, and water vapor.
Define “Conduction” in the context of building temperature control.
Conduction is the process by which heat is transferred through direct contact between materials, such as the exterior air and the building’s skin.
What is “Convection”?
Convection is the transfer of heat by the movement of air, where warm air moves to cooler areas, carrying heat with it until equilibrium is reached.
What is an “R-value”?
An R-value measures the thermal resistance of a material, indicating its ability to resist heat flow. Higher R-values mean better insulation.
What is a “U-value”?
A U-value measures the overall heat transfer coefficient of an assembly, such as a window or door. Lower U-values indicate better insulating properties.
