• Passive Heating & Cooling

    Passive heating and cooling systems are designed to collect, store, distribute and control solar heat without the aid of mechanical or electrical devices. Passive techniques are effective in reducing energy use only if they are combined with energy conservation techniques. In most cases passive solar design is best addressed in the site planning and design phase of new home construction, however a number of strategies can be effectively employed in retrofit and remodeling situations as well. In retrofit situations the most available passive heating options include direct gain, sun spacing, thermal mass and wind breaking. The most available passive cooling options include shading and ventilation.

    Direct gain passive heating is simply the absorption of solar radiation directly entering the living space. The proper selection and placement of windows and the correct distribution of storage mass in the living space are critical elements of this technique. Window design should generally optimize window size and placement on south and southeast facing walls. Window selection should employ high performance, energy efficient windows.

    Sun spacing involves creating an attached south-facing sun room or other isolated area that becomes a more focused space to collect, store and distribute direct gain solar energy. The solar energy collected by the sun space is used to heat both the sun space and adjacent living areas. The proper design of a sun space is critical or the efficiency of the space can be severely compromised both in terms of temperature fluctuations and effectiveness in distributing the heat to other areas.

    Thermal mass involves the use of high mass materials (such as concrete, natural stone, brick and water) as a solar heat absorption and radiation medium. Thermal mass is employed in floors and walls in both direct gain and sun spacing to improve the effectiveness of these passive heating methods. Thermal mass can also be used in a standalone thermal storage wall, such as a Trombe wall – more commonly designed into new construction.

    Wind breaking is the tactical use of trees and shrubs, grading and hardscape elements (such as walls and fences) to deflect or lift wind over the home. Usually concentrated plantings of evergreen trees and shrubs on the north and northwest side of the home are used (direction of winter prevailing winds.)

    Shading is used to control the amount of solar energy entering the living space. Three shading methods are commonly used: sunscreens, louvers/roll shading and solar landscaping. Sunscreens include properly designed eve overhangs, wood slats, trellises and canvas awnings. Sunscreen design involves two elements – the size (depth) of the sunscreen and its aesthetics. The depth of the sunscreen must be sized to block the sun entirely in the summer and to allow winter sun to fully penetrate into the living space.