I was recently browsing one of my favourite sites looking for inspiration for an article. I like to write about the kind of things people are wondering about.

Devyn posed an interesting question by asking: “What are some limits of passive solar energy homes?”

I'm presuming, Devyn already knows the benefits of such a home and was wondering amid all that wonderful news if there was anything less wonderful that needed to be considered. And of course, there is.

So, to begin with I'll list many of the benefits just in case someone out there has yet to be exposed to the concept of solar passive design in homes, apartments, offices and shopping centres.

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  I watched a recent television program where a builder suggested that merely changing the orientation of your home (almost any design) to make maximum use of the sun's energy would give you around 80% of the benefits of solar passive design.

  
  
  

  I know this from personal experience of some dear friends who built their dream home.

  
  


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  They bought a traditional home plan but made certain that the main living areas faced the northern sun (in Australia), they installed electric in-slab heating and a small wood combustion heater for the winter.

  
  


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  However, they soon discovered that they really didn't need their slab to be heated by electricity because the sun just poured in through their large windows and sliding doors – they had to open their windows on some days because it became too warm inside!

  
  


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  They now use just a tiny portion of their infloor heating (bathroom floors being particularly favoured) and if there is a longish period without sunshine they have two backup systems they can rely on.

  
  
  

  Solar passive homes work because they allow sun into the home in the winter and stop it entering in the summer. They have "heat banks" inside the home to store that winter warmth and re-radiate that back into the rooms of an evening - this can be brick walls, concrete floors or any other innovative method of storing the heat. In the summer, these same things help keep the home cooler (if you stop the sun entering the home) and ensure you have good ventilation.

  
  


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  Understanding the differences in the location and strength of the sun in relation to your house and designing to suit that will ensure you gain all that free, healthy energy available to you from the sun.

  
  

So the design of your home is very important but equally important is the design of your garden in terms of shade and light, structures to offer shade in summer and allow sun to filter through in winter.

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  Removable or retractable blinds and awnings, deciduous trees and vines, pergolas and verandah's are all things you can consider and reconsider as you make your home more solar passive, more eco-friendly and more comfortable to live in.

  
  

Once you have made your initial investment to either design and build a passive solar home or to re-think and retrofit your existing home, the benefits are free, forever.

Having said all of that, solar passive design is not the total solution to our energy needs for heating and cooling our homes. No matter how good the design, there will be times when supplimentary measures are nessessary.

So this would be the first limitation one should consider:

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  Passive Solar Design in homes reduces the need for extra energy needed to heat and cool the home. It does not negate that need entirely.

  
  


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  It is possible and even desireable to have an additional mechanical heating source for days or weeks when the sun just doesn't shine. Wood, gas, electrical, geo-geothermal are all suitable systems to have on hand for those seasons of the year when an additional boost of warmth or coolness is needed.

  
  

Just a few years ago my family and I moved from living in a 1870's stone cottage to living in a standard 1980's cream brick veneer home.

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  We didn't give it much thought when we chose the new house (we were renting at the time and didn't have a lot of options to choose from), but as luck would have it, this house faced it's main living areas to the north and collected all that delicious sun.

  
  


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  The difference to our lives was immense. The rooms were filled with light and warmth, the amount of energy we needed to buy to heat it to a comfortable level was significantly reduced and it was a delight to live in.

  
  

I'm sharing this with you because this was just a very ordinary four bedroom 1980's family home. Ordinary construction, insulation and all the rest, but it faced exactly the right was to be snug on a winters day and reasonably comfortable (without airconditioning) during our hot, hot summers.

As the builder I quoted earlier said – 80% of the benefits can be derived by correct orientation to the sun. Imagine how nice it would be if there were floors to catch and store the heat to be released during the evening!!

In climates colder than those I have experienced it will be necessary to consider including a conservatory or greenhouse to catch the winter sun and then radiate that through the home, it will also act as an air-lock to keep freezing air from entering each time the door is open.



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  These can be incredibly efficient and lovely to look at and if you are in the market to refit your home then this would be an excellent thing to consider.

  
  

Of course cost is also a potentially limiting factor but the imporant thing to remember is that it is a once only cost. Once it's done, the rest - the benefits, comfort, energy savings and pleasure you get – are all free. Forever.

On the question of some blocks/lots not being suitable for solar passive design - that is true but in my mind that makes then unsuitable for any home.

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  If you can't build a home that is more sustainable then perhaps you should reconsider the place you are looking at building.

  
  


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  I would suggest also that you never, ever buy a home that faces the wrong way, doesn't have solar access to help you live comfortably, or that has the sun blocked out by trees (in the winter) or a building. It will be uncomfortable and very expensive to live in and this is only going to get worse as we go on.

  
  

After 10 or more years of planning my family and I are self-building our own eco-friendly home from recycled materials and straw bales. We have attempted to incorporate as many of these designs features as possible given our ability and budget. We expect our home to be beautiful, comfortable and energy efficient. Time will tell.

Cate Ferguson