A very old idea, "It's free energy. "
Thousands of years and all manner of construction experiments have made one thing clear: ancient homes inspired some of the best modern technology.
Passive solar can easily and affordably be tied into any new home budget. The key is to start considering it early in the design process. Whether you're building in Alaska or Arizona, the basic principles of passive heating and cooling are universal.
When it comes to passive heating and cooling, what a new house needs is a few really old tricks. Using sun, wind and thoughtful design from the start, mechanized heating and air conditioning are a lot less necessary these days.
"We attempt to use all the free energy we can get - free solar gain, free light without the heat; Passive heating and cooling concepts are the foundation of Spherical Design Engineers sustainable home designs. "This is how indigenous' cultures lived. This is absolutely nothing new. It worked for eons."
Skyrocketing energy costs and more appealing design are a winning combination that increasingly draws homeowners to passive solar: Fifteen years ago we had to do a lot of convincing to get clients to embrace passive solar in their home design.
Climate is a determining factor in how the home takes shape, but assessing the specific building site is critical. The basic rule of thumb for passive solar is "Look South." Design your home on an east-west axis with lots of windows on the southern side. The sun gets so low on the east and west sides that you'll get it whether you want it or not, but it's the steady sunlight from the south that works best for passive solar. By maximizing south facing windows with well engineered overhangs, your home will capture heat when the winter sun sits low on the horizon and remain shaded and cool when the summer sun rises high.
The trick is getting just the right amount of windows. Building computer models to help home owners economize construction and optimize passive solar opportunities can help. We try getting involved as soon as you can in the design and engineering process. We have three different energy rating software programs to maximize solar potential.
Design Engineers recommend starting with a design that puts seven percent of a home's total square footage in south facing windows. For a 2,000 square foot home, that's 140 square feet of south-facing glass. The other three sides would get only 50 to 60 square feet of windows apiece. This ratio is the optimum place to start a design, although plans often change to accommodate everything from egresses to aesthetic concerns. Generally speaking, no more than 10 percent of the floor area should be in south-facing glass, or the home will probably overheat.
Planting trees is the easiest way to take care of shading on the east and west sides of a house, but placing critical overhangs on the southern eaves is a more exact science. Overhangs should be precisely calculated based on a home's location and how high the summer sun is. Latitude is a big factor. For instance, homes in the southwest and southeast generally need more shade than a home in the northern states. Make sure your eaves are designed to maximize the quantity and intensity of your site-specific sunlight.
The rows of windows above the kitchen and living room, often called a lantern, bring in air flow and light. The solar spine of a house: Terrazo concrete floors and plastered concrete block in the hall are solar heaters that gather up solar gain from south windows and skylights. South facing windows and a thermally massive floor provide passive solar heat for this home.
.eere.energy.gov/RE/solar_passive.htm I
This illustration shows winter and summer sun angles, and a diagram of passive cooling
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