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One of the most effective ways to lower our energy bills and reduce our carbon footprint is to incorporate passive solar design into any new home.  Passive solar design allows the house to be impressively warmer in winter and noticeably cooler in summer.  With this design you can easily harness the renewable aspects of nature, i.e. the sun, shade and moving air, to passively heat or cool the house depending on the season.  This in turn allows for less dependence on unrenewable fossil fuels to provide us with the same amount of heating or cooling, ideal for an energy efficient home. 

 

To help achieve the maximum potential for a passive solar home it is important to orientate the house to a northerly aspect, the reason for this is that during our winter, the sun sinks to its lowest point in the northern sky.  With the correct design the north-facing house gets flooded with this low winter sunshine and warmth during the coldest months providing you with a ‘free’ passive heating system.  To allow for the maximum northerly winter sun to enter and warm the home large windows must be placed at the very front/ northern part of the house.  Ensure that there are no trees to shade out this sun.  Also it is vital to choose a building material that provides good thermal mass.  Thermal mass is a measurement for the capacity of any building material to absorb and store heat from direct sunlight.  This stored heat is then released back into the house and with appropriate insulation, held within the home to provide you with effective passive heating.  Examples of good thermal mass are stone, brick and sawment.  Where the thermal mass is a darker colour it will heat up more readily.  So for the optimum passive solar winter design there needs to be large north facing windows for excellent solar access, whilst making sure the sun’s heat is being directly absorbed by good thermal mass.  In our house the thermal mass is sand, sawdust and cement (sawment).  Another important factor is to have appropriate curtains for the nighttimes so that all this captured heat doesn’t just dissipate through the large glass windows.

 

 

To achieve maximum potential for a passively cool house in summer, the house must have minimal access to the hot sun entering it and also allow any built up heat to easily escape.  One of the disadvantages of the modern pitch roof house is that when the house gets hot the heat rises to the ceiling and cannot escape, the house heats up and the environmentally expensive aircon needs to be switched on.  It is therefore important to allow this heat to escape, either through whirly gigs or effective passive solar design.   We built a simple skillion roof, which slopes upwards to the north with the lowest point being at the southern part of the house.  This allows easy access to the winter sun through the large north-facing windows and also provides a natural slope for the summer heat to rise up the ceiling and out open windows at the highest point of the house.  To take fullest advantage of this hot air rising it is necessary to strategically place doorways and hall ways to draw in cooler air that naturally replaces this rising hot air.   This passive cooling system in the hottest months can be referred to as ‘free aircon’.  For this cool air to be even cooler as it enters the house it is necessary to have verandas, awnings, trees etc to provide shade over these doorways.  We have purposely placed a hallway in our coolest, shadiest, southern part of the home to siphon this cooler air up the hall and into our open plan living area.    It is advantageous to have a light coloured roofing material for the hotter climate to reflect the sun’s heat and to have large shade trees on the western side for shady protection against the afternoon summer sun. 

 

So with correct passive solar design and the appropriate passive solar features incorporated into the home you can dramatically decrease your power bills and stay cool whilst others are sweltering and paying large electricity bills to burn fossil fuels to power dinosaur air-conditioners.   And you will feel comfortable vitalised and warm in your sun flooded passively warmed winter house.

 

 

You will love it and so will the Earth.

 

Booker & his partner Michelle designed and built an energy efficient, passive solar home in Northern NSW. Before they began they had absolutely no experience in building or using power tools.   For more information visit -  www.reducingthefootprint.com

 

 

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