Passive architecture uses the natural processes of a site to reduce or replace the need for mechanical systems in buildings.

Many features of passive design were intuitively discovered and utilized by ancient world cultures, from the Greeks and Chinese to the Puebloan peoples of the American Southwest. Only since the advent of cheap fossil fuel, have buildings throughout the world had the luxury to neglect the importance of sun, wind, light and water in their forms.

Here is a very brief introduction to how these four natural processes can be utilized in Los Angeles's Mediterranean climate to create better performing, less wasteful buildings. Technical terms are in italics.

Sun: In the winter, south-facing windows allow the sun to heat an interior surface throughout the day and then release the heat throughout the night (reducing the need for a heater). This interior surface should have thermal mass - the ability to store heat or coolness. Materials such as adobe, tile, stone, concrete, brick and plaster all have thermal mass.

In the summer when the sun in higher in the sky, properly sized overhangs or shading devices reduce excess heat gain (reducing air conditioning loads).

Wind: Incorporating wind patterns and/or the stack effect, through which hot air rises and draws in cooler air, allows for effective natural ventilation (reducing air conditioning loads).

Further, because summer and fall evenings are consistently cooler than daytime temperatures, you can utilize simple cross ventilation to store coolness in the thermal mass, which will then radiate throughout the next day.

Light: Place windows deliberately to allow ample light, but prevent excess heat gain (avoiding unnecessary electrical lighting and reducing the need for air conditioning).

Greywater: Capture water from showers, laundry and sinks for landscaping or internal water reuse (for example, to flush toilets, which is unfortunately not yet permissible in Los Angeles).

Rainwater: Capture rainwater onsite for landscaping or internal water uses (this is also not yet permissible in LA). A 500 square foot roof drains over 300 gallons of water per inch of rain.

 

Further reading:

Passive Solar Architecture: Heating, Cooling, Ventilation, Daylighting and More Using Natural Flows 
by David Bainbridge, Ken Haggard

Climate Considerations in Building and Urban Design
by Baruch Givoni

Autodesk Sustainability Workshop: Passive Design Strategies

Architecture 2030 Design Palette