Question
Hi, Mark,

1. I would like to know if there are formula to calculate how far deceduous trees need to be planted on the south (controversial....??), east, or north side away from a house in order to gain the sunlight in winter and cool down the house in summer.  I knew that the height of a tree is a factor which determines the shade it casts and the height of a house, in combination of the latitude.  However, the science I cannot figure out is the angle of the sun position between summer and winter.  How do I figure the different angles, and how do I use the angle in combination of the height of a tree and the height of the house, assuming the land being flat at his point?

2. The lot I am obtaining is surrounded by woods.  The only clear land is the lot.  How is this condition be advantages or disadvantage to the windbreaks or even more seriously tornado strikes (I am in GA; we just had some houses completely blown away), if nothing is done to the woods?

3. I am very much interested in green/sustainable design and would love to build a house and create a landscape as sustainable as possible.  What would be a typical rate for a landscape architect to charge for a sustainable landscape design on a 0.4 acre land?

Any answers will be much appreciated

Answer
As you have stated, how far to plant a tree for a home depends on the type of tree (deciduous for sun/shade, and evergreen for winter storm-blocking), your global latitude, and other impediments such  as adjacent objects such as utility poles & wires, views to be preserved, 1-story versus 2-, are there solar panels on the roof that cannot be blocked, etc.  
As far as tree placement orientation in relation to the home, the primary orientation is the house抯 southeast, south, and southwest exposures for maximum benefit of summer shade and winter heat gain.

For shading in the summer is the critical component.  Winter twigs are not that important.

My apologies in advance for all of the math, but you asked for a formula*.  Its trigonometry.  We have to assemble some bits of information first.  Here goes...

Georgia is between 30 degrees (Valdesta) and 35 degrees (Dalton) north latitude.  Atlanta is at approximately 33 1/2 degrees north.  

The University of Oregon has a REALLY cool site that can generate a custom solar azimuth chart for anywhere on the globe:  http://solardat.uoregon.edu/SunChartProgram.html

As an example, I did Atlanta, GA (33.755 N Lat, -84.39 W Long); Your location will be slightly different.  Using our U of O solar azimuth chart, we can read off the chart that the summer solstice (Noon, June 21st) sun position for Atlanta will be 80 degrees in the sky.  

Now, imagine a 20-foot tree.  Add to that a triangle where the base of the tree is a right triangle, with a label point C.  At the top of the 20-foot tree, is a point B, and off to the north is our final point of the right triangle, A.  According to geometry抯 triangle postulate, all the inside angles of every right triangle must total 180?  So 80?sun +angle B+ 90?triangle = 180?  The top angle B has got to be 10 degrees.  

We need to use trigonometry functions and the Law of Sines that says that sin A/length a=sin B/length b=sin C/length c.  Where 80?is angle A, 10?is angle B, and the 90?right angle is angle C.  In our case, (sin 80)/20 = (sin 10)/b.  Solve for length b.
Here is the math:  0.9848/20=0.1736/b.  We cross multiply, and you get 3.473 = (0.9458) x b, or a shadow length of b = 3.53 feet from the trunk of the 20-foot tall tree.

For a 40-foot tree, you抣l get twice the shadow, or 7.05 feet, 60-foot tree will be 10.6 feet, etc.

Now a tree is NOT a single stick pointing up 20 or 40 feet.  A canopy will be about 2/3rds of the height.  If the average height of the canopy is about 20 to 30 feet, you抣l get a shadow cast of about 4 to 6 feet beyond the canopy, best case, and only when the sun is highest in the summer sky.

As the sun rises and sets, the shadows will cast farther in either direction, so it would be better to plant several trees along the length of the southern exposure, catching as much of their shadows as possible.

In the dead of winter (Dec. 21st,) the sun will only be up 32 degrees, and the tree抯 shadow really doesn抰 matter all that much without its leaves.

Here is a more basic primer on solar design using trees:
http://oikos.com/library/solar_site_design/index.html

Regarding WIND BREAKS ?The damage has already been done, as a forest is more than just a collection of trees, but a system that is knit together to resist nature抯 fury, as a whole.  If an area has been cleared, the sharp edge of forest/not forest may actually have created a weak spot in the canopy that a storm event can take advantage of.  I remember the few hurricanes I experienced living in the east, and the pine smell after all the needles were ripped off of the fallen trees.  What a mess!   

With a tornado, luck is the biggest part of it. Solid construction will do more for you than a windbreak.  Windbreaks are more for channeling snow away in the winter or gaining a few fickle breezes in the summer.

Regarding GREEN/SUSTAINABLE design ?br> There are several whole books that you can read online explaining the subject (Google Books).  Here is one by Duncan Erley & Martin Jaffe that is free to read on-line, that goes into great depth:

http://tinyurl.com/3p9xg9t

A landscape architect should already be thinking of these elements as he/she is designing.  I have been asked the 揾ow much?question before, and it is tricky in this economy.  If I tell you too low a figure, there will be responses that I am giving away the store, and if I tell you to expect a big fee, I抣l be accused of not giving you a realistic answer.  Suffice to say it is worth shopping around.  

In this economy, prices vary widely.  It is a service, and some offer it cheaper than others.  Each area is unique in its supply & demand for talent. Expect to pay a licensed landscape architect at least $120/hour, if not more, for a full LEED certified sustainable green design.  Depends on the depth to which you wish to take the plans.   I have had projects built off of napkin sketches, and others from expensive, thick, multi-sheet construction drawings and details that required permits & inspections.

There are very good designers (in the $50-$75/hour range) that may have less-than LEED certification, that can still offer a good, and  valuable design (and even installation) for a lot less.  You also get what you pay for ?if you solicit off of Craig抯 List, you might get a lucky deal or you might get a college kid trying to work his way through next semester.

Typical rate?  Site-unseen, I抎 hazard a guess of $2,000 ?$5,000, depending on how elaborate.  Maybe a lot less if you shop around.  Solicit several proposals for work from firms and individuals that know the area and have done successful sustainable design projects.  If you are incorporating the architecture, too, then all bets are off.   You抣l want to solicit a seasoned residential designer or architect抯 proposal.  Their fees (also called 揷ommissions?-- like works of art) are based on square footages or sometimes % of cost.

If you take a look at the links, you抣l notice it isn抰 just about the trees and landscape 揻ur? it is also about placing the building in the right spot, and taking advantage of any opportunity to modify it or the surroundings to gain that 揼reen?edge.

Best of luck!  ~Marc

For more detailed information:

Georgia Green*A*System: Environmental Checklist for Landscape Professionals, from University of GA Ag Extension  (http://extension.uga.edu/):

http://www.caes.uga.edu/Publications/pubDetail.cfm?pk_id=7879&pg=np&ct=&kt=&kid=
http://www.greenstone.org/greenstone3/nzdl%3Bjsessionid=B248D7E01284DE1608DF129C

*Math CHEAT site -- http://easycalculation.com/trigonometry/triangle-angles.php