Building Envelope

Building Envelope

• Physical separator between interior and exterior spaces– Walls– Floors– Roofs– Fenestrations (any opening in the structure)– Doors

Envelope for Climates

• Respond to the local climate• 4 common extremes– Arid Climate– Tropical Climate – Cold Climate– Mixed Cold/Hot Climate

Arid Climate

• Dry and hot but have large swings of temp. from the day to night

• Thermal mass on the outside is most crucial design strategy to even out temp swings

• Consistently hot locations it helps to have high ceilings and shaded breezeways, light colors, daylighting via reflected light (not direct sun)

• Courtyards with natural ventilation, pools or fountains can provide evaporative cooling

Arid Climate

Tropical Climate

• Hot and humid areas• Keep the heat of the sun off and maximize ventilation,reflective insulated roof with walls that pass breeze but not rain• Light colored

Cold Climate

• Maximize insulation, use windows for solar gain on thermal mass inside the envelope

• Air tight envelope, avoid infiltration

Mixed Cold/Hot Climate

• Flexibility is key to design for this climate• Deep overhangs, allows low winter sun in

through windows to heat up high-mass concrete slab inside, while blocking summer sun

• Light roof/darker walls to repel summer sun but absorb winter sun

• Extra insulation, operable windows

Mixed Cold/Hot Climate

Envelope Energy Flow

• Envelope is a composition of layers with varying thermal and permeability properties

• Composed of membranes, sheets, blocks and preassembled components

• Choice is governed by climate• 2 opposite design concepts– Open frame– Closed shell

Closed shell

• Harsh climates• Closed shell design with carefully placed

openings to make limited contact with the outdoors

• Also useful when there are unwanted external influences (noise, visual clutter)

Open Frame

• When external conditions are close to desired internal conditions

• Open frame with parts of the envelope added to modify outside forces

Envelope Energy Flows

• Flow of heat varies by season and path of heat– Flows from a building in winter and to a building in

summer– Through the building’s skin or outdoor air entering