This excerpt was reproduced with permission from Green Building Guidelines. To purchase this book, please visit the Oikos Bookstore.

Checklist for Good Design

Building Orientation. A number of innovative techniques can be used to achieve good solar access. No matter what the house’s design, and no matter what the site, some options for orientation will be more energy efficient than others, and even a simple review of the site will probably help you choose the best option.

Upgraded levels of insulation. It is possible to achieve very high energy efficiency with a “superinsulated” design. But in many cases, an advantage of passive solar design is that energy efficiency can be achieved with more economical increases in insulation. On the other hand, if very high energy performance is a priority—for example, in areas where the cost of fuel is high—the most cost-effective way to achieve it is through a combination of high levels of insulation and passive solar features.

Reduced air infiltration. Air tightness is not only critical to energy performance but also makes the house more comfortable. Indoor air quality is too important and complex an issue for a complete discussion here, but in general, suntempered and passive solar houses built according to the Guidelines provide an alternative approach to achieving improved energy efficiency without requiring air quality controls such as air-to-air heat exchangers, which would be needed if the house were made extremely airtight.

Proper window sizing and location. Even if the total amount of glazing is not changed, rearranging the location alone can often lead to significant energy savings at little or no added cost. Some energy-conserving designs minimize window area on all sides of the house—but it’s a fact of human nature that people like windows, and windows can be energy producers if located correctly.

Selection of glazing. Low-emissivity (“low-e”) glazing types went from revolutionary to commonplace in a very short time, and they can be highly energy-efficient choices. But the range of glazing possibilities is broader than that, and the choice will have a significant impact on energy performance. Using different types of glazing for windows with different orientations is worth considering for maximum energy performance: for example, using heat-rejecting glazing on west windows, high R-value glazing for north and east windows, and clear double-glazing on solar glazing.

Proper shading of windows. If windows are not properly shaded in summer—either with shading devices, or by high-performance glazing with a low shading coefficient—the air conditioner will have to work overtime and the energy savings of winter may be canceled out. Even more important, unwanted solar gain is uncomfortable.

Addition of thermal mass. Adding thermal mass—tiled or paved concrete slab, masonry walls, brick fireplaces, tile floors, etc.—can greatly improve comfort in the house, holding heat better in winter and keeping rooms cooler in summer. In a passive solar system, properly sized and located thermal mass is essential.

Interior design for easy air distribution. If the rooms in a house are planned carefully, the flow of heat in winter will make the passive solar features more effective, and the air movement will also enhance ventilation and comfort during the summer. Often this means the kind of open floor plan that is highly marketable. Planning the rooms with attention to the use of patterns and energy needs can save energy in other ways, too—for instance, using less-lived-in areas like storage rooms as buffers on the north side.

Selection and proper sizing of mechanical systems and selection of energy-efficient appliances. High-performance heating, cooling, and hot water systems are extremely energy efficient, and almost always a good investment. Mechanical equipment should have at least a 0.80 Annual Fuel Utilization Efficiency (AFUE). Well-insulated passive solar homes will have much lower energy loads than conventional homes, and should be sized accordingly. Oversized systems will cost more and reduce performance.