Ask a Solar Question

Ahh, solar bacon. 

Almost everything we think of as ‘energy’ on our planet can trace its power to the sun. These include petrol, diesel, coal, methane, propane, LPG, as well as wood, wind, and hydroelectric. The first six on this list are sometimes called ‘ancient sunlight’, because, as fossil fuels, they are the result of organisms (mostly plants) that lived and died millions of years ago. As we learned in school, the amazing process called photosynthesis converted that ancient sunlight into living matter (biomass).

The last three on the list are sometimes called ‘current sunlight’ because they are powered by solar energy that reaches the earth on more of a human time scale – from days in terms of wind to decades in terms of wood. While wood is considered a form of biomass, wind energy and hydroelectricity are not the result of photosynthesis, but rather the result of the sun heating the earth’s continents and oceans. High and low pressure systems cause winds, and water falling back to earth in the mountains can drive hydro dams as it travels down rivers back to the sea.

All of this demonstrates how important the sun is to life as we know it, but does not include a number of ways in which the sun is used directly by humans as an energy source. These different forms of ‘solar power’ can be roughly classified into two categories: heat and electricity.

Forms of solar heating include passive solar building design, solar hot water, and solar cooking. We use all of these at our home in Castlecliff. Together, these have helped us live comfortably with a power bill that ranges between $20 and $30 per month.

 Later afternoon winter sun.

Forms of solar electricity include photovoltaic (pv) panels and solar thermal power. Most of us are familiar with pv panels because we have seen them on houses or calculators. There is some very cool science that goes on in these ‘solar cells’ where sunlight forces electrons across a boundary, which then causes a flow of electrons (electricity) through a wire. We do not have pv panels on our home, but we do have an emergency solar radio and flashlight tucked away somewhere.

Solar thermal electricity may be the least familiar to New Zealanders because it is a younger technology than pv and no such power plants have been built here. It is, however, catching on in a big way elsewhere. California, for example, has just built the world’s largest solar thermal plant in the Mojave Desert, which consists of 170,000 mirrors and three 130-metre concrete towers. The mirrors track the sun throughout the day and reflect light onto the towers. This intense heat boils water over 500 degrees Celsius, which creates steam that turns a turbine connected to an electric generator. It is estimated that the plant will power 140,000 homes at a construction cost of $2.2 billion (US).

Don’t have that kind of cash on hand but still want to learn more about using solar energy in your home?

Ask a Solar Question.

Thursday, 5^th September, 7-9 pm.

256 Wicksteed St. Wanganui

$20. Registration essential. Ring CES – 345 4717

This workshop presents the basics on three common forms of harnessing the sun’s energy: solar electricity, solar hot water, and passive solar design. Bring your questions and get unbiased advice. 

Adult Learning for Sustainability and Resilience

Dani, Verti and I have been in North America visiting family. We flew over primarily to celebrate my parents’ 50^th wedding anniversary, but in the week before the big day we were able to briefly stop in to my old farm, named Trollbakken by a previous owner. Although the farm has been in the hands of a Springboks supporter for the last five years (a South African immigrant to the U.S.) it has remained in relatively good nick.

Verti has curbed her enthusiasm. 

The sights, sounds and smells of the place reminded me of the days, weeks, months and years I spent building soil fertility, growing organic veges, and renovating the farmhouse. When I bought the farm in 2000, I had no formal training in agriculture or building. I had been an environmental studies teacher for the previous ten years, and so I knew about crop rotation and solar energy on a textbook level, but had never done them.

The next eight years could be described as learning-by-doing. Although I acquired a large collection of books on organics and eco-building, the real learning took place through trial and error. There is no substitute for experience.

The kitchen at Trollbakken mixes the new with the old (see below). 

A number of unique features of the farm made for an unusual learning experience. First, it was the last property on a dead end road, a kilometre beyond the nearest neighbour. It was quiet, and days could pass without my seeing anyone.

Second, the house was wired for low voltage DC electricity powered by two small solar panels. Aside from a chainsaw, I rarely used power tools for building and renovation.

Third, I chose to manage my market gardens entirely by hand. Aside from transporting hay and compost in the back of a ute, I grew all of my veges without fossil fuels.

New white walnut (butternut) floor milled from a tree on the farm.  

To some readers this may seem like a Siberian work camp, but to me it was a postgraduate education in eco-thrifty design/build. Similar to the PhD I just completed through the University of Waikato, my ‘studies’ at Trollbakken required independence, determination and self-discipline. As I have come to understand, these are some of the key characteristics of adult learners.

Some vintage wallpaper was preserved during the kitchen renovation. 

When we are no longer in compulsory schooling, it is up to us to get off our bums and take ownership for our learning. I would argue that this is the best type of learning because adult learners usually undertake education – be it informal or formal – that is relevant and meaningful to their lives. This could include job training and career advancement programmes, or, as I’ve been involved with, sustainability workshops based on saving power and money while protecting the environment.

Any adult that lives in a home, pays a power bill, or eats vegetables may see some relevance in one or more of these upcoming free and low-cost presentations scheduled to mark Adult Learners' Week/He Tangata Mātauranga, 2^nd – 8^th September. The programme is a partnership between the ECO School, Adult and Community Education Aotearoato, and Community Education Service Wanganui.

Monday, 2^nd September – Warm, Dry, Healthy Homes

5:30-6:30 pm. Gonville Café Library, Abbot St. - Free

Tuesday, 3^rd September – Understanding Your Power Bill

5:30-6:30 pm. Gonville Café Library, Abbot St. - Free

Wednesday, 4^th September – Organic Vege Gardening

5:30-6:30 pm. 10 Arawa Place, Castlecliff - Koha

Thursday, 5^th September - Ask a Solar Question

7-9 pm. $20. Registration essential. Ring CES – 345 4717

Friday, 6^th September – Composting

5:30-6:30 pm. 10 Arawa Place, Castlecliff - Koha

Saturday, 7^th September – Fruit Tree Care: TBD (Ring 344 5013) - Free

Sunday, 8^th September – Eco-Literacy Day.

3-5 pm. 10 Arawa Place, Castlecliff - Koha

Eco-Thrifty Baby at One Year

Our daughter, Verti, is closing in on her first birthday. Here are a series of images of how we are able to integrate her into our sustainable, permaculture lifestyle.

Peace, Estwing

Insulation and Thermal Bridging

Look closely at this picture. Do you know what caused the 'stripes'? 

The building trade is full of exciting experiences such as watching paint dry, reading the Building Code, and talking about insulation. Flash new bathrooms and kitchens are much more exciting to consider when planning a renovation, but the choice to add insulation could serve you after the latest trends in cooking and bathing areas have passed. Fashions come and go, but human comfort is constant.

For most of the last half century, New Zealanders have looked at renovation as a way to improve the look of their homes rather than to enhance energy performance. While that perspective is slowly changing, there has been a renewed push for warmer, dryer homes from various health agencies. When compared against the costs of health care and lost productivity, the price of insulation is often considered low. This is why Sharon Duff at the WRPHO is doing great work acquiring funds for insulating ceilings and floors across our region.

Yet in many Kiwi’s minds, it’s still hard to justify spending part of a renovation budget on something stuffed in walls and ceilings that is rarely, if ever, seen. That notion of invisibility, however, is only skin deep. Let me explain.

Take our insulated walls. Well, please don’t actually take them, we’re using them at the moment. I’ll rephrase that: Take a look at the picture of one of our insulated walls. Notice anything that slightly resembles a wonky gridiron field?

Dry areas are where the studs are. 

If I have done my job as an amateur photographer, you’ll see a series of alternating vertical wet and dry ‘stripes’. No, the photo is not altered, nor did I take a rag to the wall. The pattern is the result of a phenomenon called “thermal bridging.” Where the wall is dry, heat from our home is conducting through the timber studs, and where the wall is wet, insulation between the studs has slowed the flow of heat. The studs act as “bridges” because they convey heat across the wall faster than the insulation. What seemed invisible becomes visible on a cool, winter morning.

Thermal bridging also occurs when insulation is placed between ceiling joists, as is normally done. As an alternative, we installed our ceiling batts across (perpendicular to) the joists. We also chose a thicker batt (higher R-value) than required by code. The combination of a thicker batt installed across the joists has resulted in a high performance ceiling at little additional cost.

Rafter to rafter insulation prevents thermal bridging. 

This strategy runs to the core of eco-thrifty design thinking: spend a little and save a lot. Regular readers of this column will know I emphasize the concept of payback period: the amount of time it takes energy savings to pay for the additional installation costs. We embrace payback periods of one to ten years, which represent 7% to 100% annual return. What bank is offering those terms at the moment?

Our money is, quite literally, earning us more stuffed in the walls and ceiling than in any bank in the country.

Want to learn more?

• Warm, Dry, Healthy Homes. Monday, 2^nd September, 5:30-6:30 pm. Gonville Café Library, Abbot St. Wanganui. Free

• Understanding Your Power Bill. Tuesday, 3^rd September, 5:30-6:30 pm. Gonville Café Library, Abbot St. Wanganui. Free

• Ask a Solar Question. Thursday, 5^th September, 7-9 pm. Quaker Meeting House. 256 Wicksteed St. Wanganui. $20. Registration essential. Ring CES – 345 4717

ETR @ 300

We are celebrating 300 blog posts with photos of some of our helpers over the last three years.

Our first intern, John. 

Our second intern, Amy.  

Graham the sparky. 

La Bandita 

Manuel Labour 

Tommy the third intern

Ji Qiao, the fourth intern  

Renovation interrupted by a home birth.  

Midwives, Syd and Jemma 

Verti does our online banking 

Cousins Molly and Jessea help out 

Xander, our fifth intern. 

Thanks for all the help.

Peace, Estwing

Thermal Mass and Multiple Functions

The concept of multi-tasking is familiar to most of us, but the concept of multiple functions less so, although we encounter many examples of it every day. For instance, with a modern mobile phone you can: ring your mate, text your partner, take a photo, tell the time, store your friends’ contact details, light up a dark night, and in some cases check your email or tweet. There are probably another 326 functions that I cannot figure out because I’m over 40.

Eco-thrifty design embraces the concept of multiple functions. A prime example involves the vintage Shacklock 501 multi-fuel cooker we installed during our renovation. The most obvious functions it serves are cooking and heating, but these only scratch the surface. (We did not hook up the wetback because we have so much solar hot water already.)

A naked Shacklock. 

 Jonah the Magnificent. 

More significantly, the Shacklock plays a key role in our passive solar home, which could be easily overlooked by those not familiar with eco-design. That role is ‘thermal mass’, or something very heavy (mass) that absorbs and releases heat (thermal).

Traditionally, thermal mass has been the neglected member of the passive solar trio: solar gain, thermal mass, and insulation. The term ‘passive’ indicates that the design harnesses solar energy effortlessly. (Active solar is another story.) Like a car parked on a sunny day, a passive solar home absorbs the sun’s energy by being in the right place at the right time. But a car on a sunny day gets too hot during the day and then cold at night. This was the case with many solar structures built in the late 1960s and early 1970s – too much glazing and not enough mass and insulation.

 Tiling the 70 mm thick concrete hearth.

Tiled hearth with beveled oak frame to match the oak floor.

Similarly, in late July I was invited by a homeowner to look at a TV room that had been added to an older home. The addition was recent, but before the present family bought the property. At 2 pm on that sunny winter afternoon the temperature was 27 degrees C. But she also complained of the room being uncomfortably cold at night.

This is a classic case of poor design I see over and over in Wanganui. It represents a lost opportunity, and detracts from the comfort and health of the human beings occupying the space. Not eco and not thrifty.

My suggestion for the volatile TV room was this: cut out the middle 2/3 of the timber floor and replace it with an insulated concrete slab. This would decrease the high daytime temperature and increase the low nighttime temperature. Problems solved.

We insulated our stove foundation with pumice.  

Due to expense, it is unlikely the family will take this advice. Sadly, it is equally unlikely that the architect or builder considered passive solar design ten or so years ago when the addition was built.

Morning winter sun enters through a northeast window. 

For the passive solar renovation of our old villa, we didn’t need an insulated slab because of the strategic placement of our Shacklock 501. The 700 kilogram beast is centrally located between our kitchen, dining room and lounge, and receives direct winter sunlight three times a day: morning, midday, and afternoon. 

Midday winter sun enters through French doors.

The range, brick and hearth absorb the sun’s heat during the day and release it at night. The process is passive because it simply does it. There are no moving parts. As mentioned earlier, it would be overlooked as a ‘massive element’ in our design by the casual observer because it simply looks like an old coal range. It is that, but so much more. Other functions served by the Shacklock are: focal point of the kitchen, conversation piece, and, most notably, wedding present from me to my wife. BTW, Happy Anniversary, Dani.

Learn more: “Ask a Solar Question”

Thursday, 5^th September, 7-9 pm.

Quaker Meeting House, 256 Wicksteed St.

Registration essential. Ring CES – 345 4717

Dealing to Damp

Moisture has never been a problem in our home…until last week. We had three loads of washing on the line as the sun set and the rain began. We brought it all inside and discovered the next morning why it is recommended never to dry laundry indoors. On that morning we had more than twice as much water on our windows than I’ve ever seen before.

Any amount of moisture in a home will seek the coldest surface on which to condense. Let the science lesson commence!

Dew point is the temperature at which di-hydrogen oxide (water) turns from vapor to liquid. The good news is that this process releases energy. The bad news is that it makes your windows wet.

In most homes, a single-paned window on a long winter’s night is the coldest surface. It is colder than, for example, a wall, a ceiling, a floor, a cat, or your forehead, but not colder than a bottle of beer fresh from the fridge. Yeah, right.

No actually, I’m serious. A cold bottle of beer “sweats” because the warm, moist air around it condenses (dew point reached) on the cold exterior glass surface. Ever notice that once you’ve consumed the top half of beer that only the bottom half of the bottle continues to sweat? If not, tell your spouse you urgently need to conduct a scientific experiment. Find a friend and peer review your results. (Hurray for science!)

Dew point depends on two components: humidity and temperature. In our home, the humidity is usually so low that no matter the temperature of our single-glazed windows, we won’t get much condensation. You can’t get blood from a stone and you can’t get weeping windows from low relative humidity.

High humidity in a cold home is bad for human health. Additionally, our bodies feel more comfortable at low humidity than high humidity at any given temperature. So naturally, the aim is to reduce the total amount of indoor water vapor. There are a handful of ways that moist air can enter a home: showering, cooking, breathing, airing laundry, houseplants, and rising damp.

Most of us will agree that we won’t cut back on breathing, but we can avoid drying washing indoors. There are also ways to cut down on moisture while cooking and showering, which I’ll describe another day. I rarely ponder houseplants because we have none, but if you do, just be aware that they, too, “breath” out water. Preventing rising damp, however, can be inexpensive and highly effective for certain homes in certain suburbs.

Because Whanganui has a variety of soil types, some areas suffer more from rising damp than others. For example, we are on sand in Castlecliff and experience no rising damp. On the other hand, we have a number of friends on Durie Hill clay that used to complain about cold, damp homes. I used the past tense in that last sentence because all three of those families have installed polythene on the ground below their homes.

If properly installed, polythene can make a major difference in the “feel” of a home because of reduced relative humidity. It acts as a physical barrier to water vapor that wants to arise from the earth like an army of zombies waking from their graves to wander about your home causing mild discomfort, if not chaos and disarray. As seen in the photograph, proper installation includes: 1) cutting the polythene around the piles; and, 2) taping the seams.

At about $1 per square metre, polythene is one of the cheapest and most effective investments householders can make if they know their home suffers from rising damp. Ours doesn’t but yours might.