SOLAR EXPOSURE
By Fred C. Hutchinson, BA, NSLS, CLS

 

The cost of heating a home during the cold winter months is an expense that faces every Canadian homeowner.  Whether you use wood, oil, gas or electric as a heating source, the price is on the rise.  Given the climate of our region along with its northern latitude, we are faced with having to heat our homes for at least two thirds of the year.  More, if you count some of our cool summer nights.

SoÖthe trick is to use the heat that you generate as wisely as possible.  This includes efficiency of the heating source, proper insulation of the home, big woolly sweaters and sitting close to a sunny window.  The sun is the source of all life on earth but can also provide some additional heat to the home with a little planning.  Your options for passive solar heat may be limited if you have an existing house with limited exposure, but with new construction the options increase.  

Many of the new urban building lots really only allow a traditional orientation with the front facing the street for maximum use and access to the property.  Taking advantage of solar heat must then be incorporated into the house design.  But before you can design anything, you need to understand a few things about the relationship between the sun and the earth as well possible obstructions.

The earth orbits the sun in a counter-clockwise direction, causing the sun to appear to rise in the east and set in the west and rotates on its polar axis as it revolves around the sun on its elliptical orbit.  The earthís axis is 23.5į from perpendicular, causing the sunís rays to hit the earth at an angle as it revolves around the sun.  This tilt of the axis is also the reason why the sun appears to climb above the equator in the summer months and below it in the winter. The whole process results in day and night and gives us our four seasons with spring and fall being the transition periods.

See http://www.physicalgeography.net/fundamentals/6h.html for a much more detailed explanation.

   The main thing that you need to know about solar heat is that you want it in your home in the winter and that it is always from a southerly direction.  You therefore need to be able to determine solar south in order to maximize the sunís energy.

The easiest way is to simply look towards the sun at noon and mark the direction.  If you observe this direction in Nova Scotia with a compass you will note that the sun lies about 22 degrees west of south.  Magnetic south and solar south are not the same.  If you decide to position your home with an exposure to magnetic south you will be about 22 degrees east of south, which will result in more of the early morning sun but with less than 10% loss of energy.  Now, if you happen to want a late evening sun then you should face more to the west of south in orientation.  Just remember that more windows will allow more heat but only when the sun is visible.  Cold cloudy days will have a negative effect on your solar design

The horizontal view south is important but so is the vertical view.  The sun is much higher in the summer sky as compared to the winter and the winter is when you want the sun streaming in through those large panes of glass.  This means that sunlight is more easily blocked in the winter by obstructions such as buildings or vegetation due to the sunís low vertical angle.  The sun is at its lowest point in the sky on December 21 so it is always suggested to observe the shadows created over your building or site to determine possible problems.  You may wish to remove some trees in order to take greater advantage of the exposure. It is always wise to think of obstacles that may present themselves in the future such as: the neighborís new fence, love of large spruce trees or a building addition.  Just remember that a winter shadow is nearly three times as long as the object is high.

If you happen to own a home that has few or no windows on the solar face then you may wish get out the old sledgehammer and create some openings for windows.  Just keep in mind that you need to preserve the structural integrity of the building.  The creation of a window near a corner can add greatly to the collection of solar heat as well as increase the architectural attractiveness.  The addition of a sunroom can also act as a solar collector and add to the value of your home if done correctly.  The sunroom is unlikely to pay for itself in the reduction of your heating bill so it should be a room that also adds to the function and enjoyment of the dwelling.

It is wise to be observant and take notes if you are serious about taking advantage of the sunís energy.  For new construction, the long term savings and comfort can be significant with just a little planning. The savings and comfort can also be yours if you own an older home but it will usually require some renovations as well as possible landscaping alterations.  You should check books and the Internet for information on passive solar heating or with companies that supply mechanical solar equipment since the same natural concepts apply.

 

Fred Hutchinson has been the Executive Director of the Association of Nova Scotia Land Surveyors since 1999 and also is a Past President of the Association.  Mr. Hutchinson was licensed in 1971, employed by municipal government for nearly six years and spent over twenty-two years in private practice.