Category Archives: The Little House That Could

It’s Academic

As part of our education programme, we have developed a curriculum  on passive solar design for upper primary and lower intermediate/middle schoolers. It is included in the current edition of Green Teacher, and viewable on our website: http://www.theecoschool.net/The_Eco_School/Research_and_Publications.html

Screen shot 2014-02-17 at 3.56.24 PM

Here is a story that sets the scene:

Once upon a time, in a small country at the edge of the world, a couple bought a run-down house and renovated it into an eco-home using passive solar design. They shared the project with the local community through open homes, workshops, school visits, and presentations. And they shared the project with the world with their blog. Word of the project traveled far and wide, up the Whanganui River and out across the Parapara Range to number of rural schools that formed a cooperative network called a “cluster.” Teachers from three schools in the cluster decided they wanted the theme of their final term (Term 4) to be sustainable energy use. They contacted the couple and arranged a hui – Maori for gathering or assembly – to talk about working together.

Screen shot 2014-02-17 at 4.04.41 PM

At the hui they decided together to take a cross-curricular approach, integrating science, maths, English and the arts. The isolated locations of the schools across the rugged New Zealand countryside offered both challenges and opportunities. On the one hand, the couple would not be able to visit the schools during the term. But on the other hand, they could use the Internet as part of an innovative unit plan that could be shared not only across the Parapara, but also across the world. Additionally, the rural schools had roles of five to 25 students, so mixed-age classrooms were the norm. Therefore, the lessons would need to be adaptable for different ages and abilities. The couple returned home and developed a series of multi-disciplinary lessons on energy that became The Little House That Could (TLHTC). What follows is an overview of the unit and then a number of individual lessons.

Also check out TLHTC on Facebook: https://www.facebook.com/pages/The-Little-House-That-Could/205750306163061

Warm and Fuzzy



This post is part of The Little House That Could series, designed for upper primary school and lower intermediate school children. The academic curriculum that accompanies these posts was developed by the ECO School with partial funding from Wanganui District Council and administrative support from the Sustainable Whanganui Trust.

So far we have learned about how the sun can warm a home and how “thermal mass” can store heat during the day and let it out at night. The third thing to include in a passive solar home is insulation.
Remember, things that sink in water are better as thermal mass and things that float are better as insulation. The higher they float in water means they are probably better insulators.
When it’s cold, most heat escapes from a house through the roof, then the walls and then the floor.
So we put heaps of insulation above the ceiling, some in the walls, and a bit under the floor. We also removed the window in the yellow part of the house on the left because it faced southwest. That means it let lots of heat out in the winter and let lots of heat in during the summer. That’s no good!
This is the way it looks now. Warm as!
Thermal curtains also act as insulation to keep heat from going through windows. You probably already use them at home. We use thermal curtains, but also put an extra layer of wool on some windows for extra insulation.
And another way to insulate windows in double glazing. The two layers of glass hold an air space between them that acts as an insulator. We don’t have double glazed glass windows, but we are using plastic to double glaze our windows. Can you see it?
It’s practically invisible! For about $100 you can do every window in your house. That much money won’t even buy one double glazed glass window. If your family does not have very much money to spend but wants a warmer home and lower power bills, this might be a good idea for them. All of these things together – plus solar hot water and energy efficient fridge, washing machine, etc. – help us have a warm house and low power bills.
During August we used 68 units of electricity. The average home in NZ probably used about 800. If each unit of power costs 25 cents, how much money did we save in just one month compared to the average NZ home?
(800 x 0.25) – (68 x 0.25) = ?
Post your questions and comments. I look forward to seeing you on a field trip to our Little House That Did!
Peace, Estwing

Keep it Comfortable



This post is part of The Little House That Could series, designed for upper primary school and lower intermediate school children. The academic curriculum that accompanies these posts was developed by the ECO School with partial funding from Wanganui District Council and administrative support from the Sustainable Whanganui Trust.

One problem that happens sometimes with passive solar houses is that they can get too hot even in the middle of winter. For instance, once when we were house sitting in Raglan, the temperature inside the house could reach almost 30 degrees in the late afternoon just from sunlight. This happened because it had lots of windows facing north that let the sun inside, but most of the energy from the sun heated the air. But overnight the heat would escape and by the next morning it would be 12 degrees inside. A graph of the temperature would look like this.


This graph shows that it’s hot during the day and cold at night. You might as well live outdoors! The reason for this is because the house had lots of windows in the right places, but not enough “thermal mass” inside to absorb the heat during the day and let it out slowly at night. An example of thermal mass is our brick patio. Even an hour after sunset the bricks still feel warm. In a way, the bricks are like rechargeable batteries because they can store the sun’s energy like a battery stores electricity. But when the energy runs out they need to be recharged.

But of course the patio is outside. We want more thermal mass inside. To get an idea of what might be a good example of thermal mass, think of water and anything that sinks in water. We might call these things “heavy.” Anything that floats in water is not so good as thermal mass, but is better as insulation. That’s what the next post will be about.

So how do we get thermal mass inside our house that is up on piles? Here are a few ways.

Our iron bath.

Our Multi-fuel Stove

Extra layer of GIB on some walls.

We put the bath, the stove and the extra GIB all along the northwest-facing interior wall as shown in the picture below.


The winter afternoon sun shines directly on them, and instead of our house overheating, it gets up to 22 or 23 degrees. Then as the house cools down at night, the heat stored in the bath, stove and GIB goes into the air space of the house. A graph of the temperature in a house that gets lots of sunlight but also has enough thermal mass and insulation would look like this.


This graph shows that it gets warm during the day but not too hot, and it cools down at night but doesn’t get cold. Goldilocks might say that this is “Just right!”

Any questions or comments?



Peace, Estwing

Sunrise, Sunset

This post is part of The Little House That Could series, designed for upper primary school and lower intermediate school children. The academic curriculum that accompanies these posts was developed by the ECO School with partial funding from Wanganui District Council and administrative support from the Sustainable Whanganui Trust.

It was August, 2011, and the little blue house on Arawa Place in Wanganui had almost been renovated.

Before and After
And then it happened…

… the coldest week in recorded New Zealand history. Times were tense.
And the plumber had not come to install the wood burner. What to do? We could just turn on the electric heaters, but that would cost a lot of money. Luckily, we had a plan. We renovated our home to be heated by the sun in winter. This is how it works.
The sun rises and sets in different places at different times of year. In the winter, it rises in the northeast and sets in the northwest. During our renovation, we added windows on the northeast and northwest and removed windows on the southeast and southwest.
The winter morning sun comes into our lounge and our kitchen at a low angle.
The midday sun comes in our French doors on a low angle.
And the afternoon sun, well look at all that we do with it!
In the winter, the sun appears low in the sky, so the sunlight reaches deep into a home.

We put the lounge, kitchen, bathroom and dining room on the north side of the house because those are the places we like to be when we are awake. The bedrooms are on the south side. We use hot water bottles in bed.
Even though that was a cold week, with snow in Auckland and Wellington and even Wanganui, it was also a very sunny week. Cold and sunny are perfect conditions for Passive Solar Design. That is the name for what we’ve done. And how did it work?
Celsius – Top is indoors & bottom is outdoors – Farenheit
These are the indoor and outdoor temperatures when we closed our thermal curtains at 5:30 pm. Good one, eh?

Peace, Estwing