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Passive Solar Design

Are you in the market for a new building or home?  Are you considering the option of building a green or energy efficient structure?  Our recent article on building Net Zero homes will give you information on building the ultimate green home if you have a larger budget.  However, this could add significant expense to a project if you add all of the energy efficient systems at once.  Here are some simple, inexpensive design/build considerations that will help you save energy now and reduce the cost of future upgrades to your energy efficient design.

1. Choosing an Optimal Building Site

Think ahead and take into consideration the following when selecting a building site.  Pick a site that has great solar exposure. Having the Sun as both an active and passive energy source can work to your advantage.  Make sure there aren't any large solar obstructions such as billboards or power lines/towers.  You won't be able to remove these obstacles if you decide to add solar as an active energy source in the future.

If your region has good wind resources, look for a site with a steady wind.  This will help with passive heating and cooling through ventilation and allow for a future addiiton of a wind turbine as a power source.  If you can pick a site on a river or stream with significant volume and flow, it will serve both as a water source and allow for future micro-hydro power generation.

Understand the composition of the soil and ground on the building site.  Are you on shallow soil with hard rock below?  Pick a site where you have the option to drill a deep well both as a water source and for future ground-source heating and cooling with Geothermal.

2. Choosing Building Orientation is Important

Make sure that the building is aligned along an east-west axis so windows face either north or south.   In southern or hot climates, design large north windows to take in cool, diffuse northern light.  Minimize window height on the south side (strip windows work well), and shade the window from direct sunlight.  This can be accomplished either with an extended overhang, canopy or a deciduous tree.   When the sun is high in the south sky, an overhang, canopy or a tree makes an excellent sunshade.  Since deciduous trees lose their leaves in the fall through the winter, they will not shade the sun during the winter months when you desire radiant heat from the Sun for warmth.

In northern or cooler climates, placing small windows on the north side and large windows on the south side will minimize heat loss and maximize solar gain during the winter.  It is still important to shade south-facing windows during the warmer summer months to minimize solar gain during the cooling season.  Canopies, overhangs or other types of sunshades positioned correctly can admit the low winter sun while blocking the higher summer sun.  Deciduous trees are alse excellent for this purpose in northern climates, admitting light in winter and providing dense shade in the summer.

3. Pick an Optimal Roof Design and Material

Choose a roof design that will allow for future installation of a solar PV array and/or solar thermal collectors.  Choosing a design with a long, rectangular surface will optimize the size of the array that can be installed.  Make sure that skylights, vents or chimneys won't interfere with a future solar array.  If possible, put together a plan for a solar array on the roof as if you were going to install it today.  Plan for the position of PV modules and solar hot water collectors to make conduit runs and plumbing chases easy to reach your meter and the utility room where the hot water tank will be located.  Save the plans for later when you are ready to upgrade.  Pick a roof material that will reflect radiant heat and allow for rainwater collection.  A light-colored standing seam, metal roof is a great choice.  Asphalt shingles are not a good choice if you want to collect rainwater for drinking or watering vegetation.

4. Pay Attention to Size and Square Footage

Stick with the absolute minimum square footage required for the project.   Keep corridors at their minimum width.   If space can be shared by two purposes, suggest that to the architect.  This keeps construction cost, conditioned space, lighting, material/resource consumption, and site disturbance to a minimum.

5. Use an Open Design Layout

In addition to reducing construction cost, open planning improves daylight and natural ventilation, reduces duct runs, minimizes material use, and eases reconfiguration of the space.  Consider making a space that might normally be indoors, into an outdoor space for al fresco dining or gathering around a heat source to extend usage to multiple seasons.

6. Choose Water Conserving Fixtures and Appliances

There is rarely an additional cost for these types of fixtures.  On commercial projects, use electronic sensors or even push-rod faucets in lavatories.  Consider waterless urinals. They are clean and don't require a water source.  They are also very low maintenance and are less expensive due to the lack of flushing mechanisms and limited plumbing.

These tips are just a few of the many options homeowners have to choose from when planning for a new home.  Visit our community and share your ideas for Money Saving Tips for Energy Efficiency and Resource Conservation!

For more information on building green, visit the Department of Energy's site on Energy Efficiency and Renewable Energy.  You may also want to browse case studies on energy efficient building design from the Australian Building Energy Council.

Some of the information for this article was adapted from tips and resources from the American Institute of Architects.