Energy Efficiency

Insulation and other energy efficient improvements should always be the first steps in passive solar design.

1.  Insulation:  Every dollar you spend on insulation is like money in the bank. Build walls as thick as you can, and then fill them with insulation. Especially put as much insulation as is practical in the ceiling, it will pay you back in energy savings as well as comfort and livability.

2.  Clerestory windows:  Clerestory windows are high, overhead windows that get light to the back portion of a house that doesn't have windows. When you open clerestories, they'll cool the house by creating natural convection currents that circulate cooler air drawn from shady areas.

3.  Interior windows:  Windows can be used inside the home to better illuminate dark rooms and to add a sense of spaciousness.  Even small windows let in a lot of light.  Windows can be placed high in the walls to protect privacy.

4.  Window coverings:  Regardless of the type of windows you choose, they will still lose and collect a lot of heat.  Cover the windows with curtains, shades, or movable insulation.  There are many choices available to keep the heat in and for summer shading.

5.  Heat and cool wisely: Heat and cool only the areas of the house you are using. Use interior doors to close off areas that are not being used.

6.  Double entry:  Add a double entry to the entrance used most often.  A double entry room has two doors: one opening to the outside, and the second opening to the house. This enables people to come or go without having the cold or hot outdoor air blow directly into the house.

7.  Berm:  "Berming" or "earth-sheltering" entails mounding dirt up against the outside of the house or building to reduce heat loss. Below ground is always about 56 degrees Fahrenheit, and it will often be warmer than the winter air and cooler than summer air.  With a berm the house will naturally stay cooler in summer, and warmer in winter. Berming requires careful design and construction, most importantly do not pile dirt against any wooden or degradable substances.

Proper Orientation

Orienting your home correctly is a major element in solar design. The shape of the house and placement of the windows are what allow a solar home to collect sunlight.

1.  Orient the home east to west. The sun moves east to west, but it always in the southern sky here in the Northern Hemisphere. To take advantage of this, the long side of the house should run east-west. This creates a lot of surface area on the south side of the home, facing the sun. Try to berm the north side of the house, since it receives little sunlight and much of the cold winder wind.

2.  Have many south-facing windows. Place as many windows as possible on the south side, few on the east and west sides, and as few as possible on the north side. This opens the home to direct sunlight, and provides more insulation on the colder, northern side.

3.  Include operable clerestory windows. Clerestory windows are high, overhead windows that get light to the back portion of a house that doesn't have windows. When you open clerestories, they'll cool the house by creating natural convection currents that circulate cooler air drawn from shady areas.

4.  Install interior windows. Windows can be used inside the home to better illuminate dark rooms and to add a sense of spaciousness. Even small windows let in a lot of light. Windows can be placed high in the walls to protect privacy.

Summer shading

South-facing windows let in a lot of sunshine. Unfortunately, it is not always welcome. Here are some ways you can shade your home in the summer, but allow warm winter sunshine in.

1.  Use large window overhangs. These block the sunlight during the summer when the sun is high overhead, but don't block it in the winter when it is low in the sky. For best shading in most Oregon locations, these overhangs should be about 24" deep.

2.  Install movable awnings.

3.  Build a trellis on above the south-facing windows and plant a deciduous vine such as grapes, kiwis or trumpet vine that will shade the south side of the home in summer, but allow winter sunlight in.

4.  Plant deciduous trees or annual plants on the east, south and west of the house. These provide shade in summer, and allow the sun to shine through in winter. Be careful with trees on the south side, though. Many will block one-third of the light even without leaves. Try to plant coniferous trees and shrubs on the north, northeast and northwest sides of your home, so they can block cold winds.

Thermal Mass

Say "mass" often to your builder! Assuming modern wood-frame construction, the more you mass you can add, the better. What is mass? Why is it so great? Mass is heavy material like concrete, bricks, and rock. It is valuable in building design because it absorbs heat slowly and releases it slowly. On cold winter days, the mass absorbs the solar energy coming through the south-facing windows. At night, the mass slowly releases the heat back to the room as the outside temperature drops. This moderates the inside temperature, and keeps the room more comfortable.

A house with mass does take a little longer to heat up if it has gotten very cold. The benefit is that once the mass is warm, the home stays warm longer. The minute you turn off the heat, the room doesn't suddenly get cold. Instead, the mass stabilizes the inside environment.

There are many different ways to incorporate thermal mass into your home. The simplest uses "direct gain". This involves letting the sunlight in and then storing the sun-generated heat in the floor or other massive objects. In this case, the floor is usually rock or concrete, perhaps covered with tile. Another thermal storage method uses a "Trombe wall". This is a massive wall that is placed directly behind a windows or other glazing material. The wall absorbs energy directly, and then radiates it into the living space on the other side. Some Trombe walls also have vents, which pull cool air from the floor into contact with the warm mass wall, thereby creating natural convection currents that warm the room.