The moral: We all have our good days and bad days.
The same goes for passive solar homes, especially on cloudy winter days. But there is a silver lining when eco-design is involved.
Here is what I mean.
Central to eco-design is working with nature instead of against it. Aside from those people and organisations who prefer wasting money and increasing pollution, we all understand this.
Part of working with nature is understanding the patterns in nature. With regards to a passive solar home, this means sun angles: morning, noon and night, summer, autumn, winter, spring.
It also includes an understanding of winter weather patterns. Most sunny winter days are followed by clear, cold nights. On the other hand, most cloudy winter days are followed by warmer nights because the cloud cover holds the warmer daytime air against the Earth.
The passive solar design of our home takes into account these two conditions in order to keep our power bill as low as possible.
On fine winter days, the sun warms our home to a comfortable 24C, it heats our water, and cooks our dinner on the solar cooker outside on the patio.
On overcast winter days, we can light a fire in the cookstove if needed, which then heats our home and cooks our meals. Wood, after all, is just sunshine one step removed.
In both cases, the result is a warm home and a hot meal without the need to use any electrical power. This can be considered a complementary design strategy: when one element of the system is lacking, another element in the system steps in to help out.
Lean on me when you're not strong
I'll be your friend, I'll help you carry on
For it won't be long
'Till I'm gonna need somebody to lean on
It will not come as a surprise that most great teams design their game plans to take into account the complementary skills of each player, and to adjust the game plan to take advantage of those players who are performing at their best during any particular contest while others may turn in sub-par performances.
But then again, every Achilles has his heel. In our home, there are days - one or two each during May, June and July - that we run out of solar hot water and have to turn on the electric element for 20 or 30 minutes in order to take showers. This boosts our monthly power bill from its usual $22 all the way up to $25.
This minor expense of about $10 per year does not justify the cost of connecting a wetback to our wood burner, which would run into the thousands of dollars.
In other words, the payback period for a wetback would be many decades while the payback for our solar hot water will be somewhere about six years.
However, when we shift homes next week, we will be facing a different set of circumstances where the installation of a wetback may be justified.
Time, and eco-design, will tell.
If you have questions, come along to one of our events.
Nelson Lebo is an eco design professional specialising in new residential building, renovation, and healthy homes - 022 635 0868; 06 344 5013; theecoschool@gmail.com
