Pangea BiotectureOff-grid systems · ComfortPassive solar · Thermal mass · Earth coolingSheet M-500

Warm in winter, cool in summer, no fuel.

Passive solar design heats with the sun and stores it in thermal mass. Cooling tubes and operable windows ventilate it, with little or no electricity. Utility bills fall toward zero, and the building is more comfortable to live in.

Section M-500. One year at 36.4° N, heating and cooling only. In December the noon sun sits 30° above the horizon, shines under the overhang and charges the thermal mass, which gives the heat back at night. By June it climbs to 77° and the overhang shades the glass. In summer the earth cooling tube draws outside air through the cool earth of the berm; in winter its doors stay closed.

01Direct gain

The building is the collector.

Every south-facing window is a direct-gain system; windows facing east, west and north lose more heat than they gain in winter. The glass acts as a one-way heat valve: short-wave sunlight comes in, and the heat cannot get back out.

Thermal mass inside the building (earth, stone, concrete, water) absorbs that heat, which prevents overheating by day and stores warmth for the night. Furniture and drywall help, but they are rarely enough; the mass goes into the walls, floors or water containers. Getting the ratio of mass to south glass right is what makes it work.

Clerestory windows facing south carry sunlight deeper into the building than convection can, and give excellent daylight, because light from above is best. Straight walls facing due south, or as close as possible, collect the most energy for the least cost.

“All design projects should engage the environment in a way that dramatically reduces or eliminates the need for fossil fuel.”
The 2010 Imperative · Edward Mazria, AIA, founder of Architecture 2030

Building codes set a minimum indoor temperature but no maximum. Good passive design covers both: warm enough in January, cool enough in July.

02Passive building

More comfort, not less.

Passive building is a construction concept, not a brand, and anyone can apply it. It has stood the test of practice for thousands of years.

Heating + cooling energyup to 90%less than typical existing buildings

Versus new construction75%+less than average new builds

AirFreshcontinuous ventilation without drafts, which also keeps radon low

Well-insulated windows and a shell of insulated exterior thermal-mass walls, roof and floor slab keep winter heat in and summer heat out. Heat from inside the building, such as the oven, people and the sun through the glass, does much of the rest. The same savings hold in hot climates, where the mass keeps buildings cool.

Passive house design and construction →

03FAQ

Heating and cooling, answered.

What is a passive building?

A building designed to hold a comfortable indoor climate mainly through passive heating and cooling (insulation, airtight construction, window placement and thermal mass) so it needs little or no mechanical heating and cooling.

How does climate shape the design?

Sun angle, prevailing winds, temperature swings and humidity decide the materials, orientation, window placement and shading. In hot, dry climates, thick high-mass walls moderate indoor temperatures; in humid climates, cross-ventilation matters most.

What is thermal mass?

A material’s ability to absorb and store heat. Concrete, stone, earth and water act as thermal batteries, soaking up heat by day and releasing it slowly at night, which evens out temperature swings.

What is a Trombe wall?

A south-facing wall of dark, heat-absorbing material such as concrete or stone, with glazing a few inches in front of it. Sun heats the wall, and the warmed air between glass and wall circulates heat into the building; vents at the top and bottom control the airflow.

How does the greenhouse effect heat a building?

South glass lets short-wave sunlight in but traps the longer-wave heat given off by warmed surfaces inside. The building warms by day, and the thermal mass stores that heat for later.

R-value or U-value?

R-value measures resistance to heat flow: higher is better. U-value measures heat transfer: lower is better. Both describe how well an assembly insulates.

What are earth tubes?

Buried pipes that use the earth’s stable, cooler temperature to cool and dehumidify air drawn through them before it enters the building.

Why natural materials like adobe or rammed earth?

They are often local, which cuts transport cost and impact; their mass helps passive heating and cooling; they make beautiful, healthy buildings.

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