Category Archives: solar hot water

Equinox: Honoring the Sun

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We’ve reached the autumnal equinox and there is probably not a person in the city that would not say what a glorious summer we have had. Plenty of sunshine, light winds, and, after an initial dry spell, enough rain to green up the pastures and the garden.

But, like it or not, summer will come to an end, and the equinox is a reminder that we are tipping toward winter with the hours of daylight becoming shorter than hours of darkness for the next six months. It is also a timely reminder of how valuable the sun is to life on earth, and what a difference its absence can make.

But like every great Achilles, Solar energy has its heal: it only works when the sun is shining on our side of the planet. I often use a solar cooker as a way to engage people in conversation about the potential for sunlight energy. Inevitably someone will ask, “What happens when the sun isn’t out.” Screen shot 2015-03-21 at 7.02.14 AM

Sadly, no one has yet to invent a lunar cooker, but there are many ways to store solar energy overnight and even for a number of cloudy days in a row. With solar cooking, the best place to store it is in your belly, but other solar storage systems include batteries, water and concrete.

Batteries are often used to store electricity generated by photovoltaic (PV) panels in places not served by mains power. Whether it is a yacht at sea or a bach in the wop wops, these situations are often called, “off-grid.” The “grid” refers to the network of power lines that serve the vast majority of us.

Obviously, off-grid housing is not vulnerable to mains power interruption, and is therefore valuable for emergency preparedness. Even though our rural home is served by mains power, I am designing a hybrid PV system that will heat our water most of the time but also have a small battery bank for emergency lighting, water pumping, radio and mobile phone charging.

Without meaning to offend anyone’s intelligence, a traditional solar hot water system stores sunlight energy in the form of heated water. The energy itself (heat) is stored inside of an insulated cylinder overnight. Depending on the amount of insulation around the cylinder and a household’s hot water use, the supply can last for three or four cloudy days. Solar hot water would also be a treat in the case of a prolonged mains power outage. Screen shot 2015-03-21 at 7.02.38 AM

Sunlight energy stored in an insulated concrete slab is called “thermal mass.” Like solar hot water, the heat is stored overnight and potentially for a number of cloudy days in a row. For any new home being built in New Zealand, passive solar design is an affordable approach to a high performance dwelling. Additionally – you guessed it – a passive solar home would serve its occupants very well during a mid-winter power failure if their only heating sources relied on electricity such as a heat pump or plug in heater.

Finally, don’t make the mistake of thinking that solar cooking is only a summertime endeavour. We have cooked through the last six New Zealand winters with great success. Memorably, during the week-long cold snap in August 2011 when we had snow flurries in Majestic Square, I managed to burn a pot of rice and a curry on the very same day. That is solar power. Screen shot 2015-03-21 at 7.02.46 AM

Peace, Estwing

Keep Calm and Think Different: It Takes Money to Save Money, Part 2

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Last week I introduced a new variation on an old adage: it takes money to save money. Of course this idea is not new to most people, nor is it new to this column, which has focused on the concept of ‘payback period’ since it was first published two and a half years ago.

But this concept is long overdue for the New Zealand housing sector that is known for high running costs and low performance. According to Nick Collins, the CEO of the housing performance research organization Beacon Pathway, “Much of New Zealand’s existing housing is cold, damp and unhealthy which leads to poor social and health outcomes. Poor quality, poorly performing housing affects residents’ health, education and quality to life, the resources we use, and general community wellbeing.”

I would suggest Collins’ words describe the situation in Wanganui to a tee, yet this issue does not seem to get significant traction in our community. As a self-described “struggling provincial economy” it astonishes me that, ‘zombie-like’, we voluntarily send millions of dollars to power companies in Auckland, Wellington and Christchurch every year when we could easily retain them in our community.

Maybe it comes from growing up alongside the dying city of Detroit, or maybe it comes from being an under-sized gridiron (American football) player, but I have always made it a point to stand up for the ‘little guy.’ I hate waste and I like supporting local businesses.

The process of renovating our villa in Castlecliff ‘stimulated’ the local economy to the tune of $35,000. This total sum will be ‘paid back’ through energy savings and low maintenance costs over the course of about 12 years. The exceptional level of sustainability of this property can be explained through exemplary levels of energy efficiency, long-term durability of products, and the high productivity of fruits, veges and fowl. The entire property has been designed and managed to be low-input and high performance, ie, it takes money to save moneyScreen shot 2014-10-10 at 8.09.50 PM

As regular readers are aware, the villa was redesigned and renovated as a passive solar home. Between April and August, morning sunlight reaches deep into the structure, bringing warmth inside early in the day when the temperature is lowest. An abundance of glazing on the northeast and northwest sides ensure that free sunlight energy heats the northern parts of the home on most winter days to 20 – 25 degrees.

Throughout the day some of the sunlight energy is absorbed within thermal mass, ensuring that the interior does not overheat while storing the excess warmth overnight when it is released into the home. This extra thermal mass takes the form of a second layer of Gib on the walls, a cast iron claw foot bathtub, and a multi-fuel cooker with brick surround. When the sun is not shining, the multi-fuel stove easily heats the northern part of the home to 20 degrees or above on a few sticks of wood, with the added benefits of cooking and baking.

Two-thirds of the home is easily heated by this combination of sunshine and a small amount of firewood. (The southern bedrooms are kept cooler as is common in most Kiwi homes.) A super-insulated building envelope ensures that much of the heat remains in the structure overnight. Temperature in the lounge, kitchen and bathroom rarely drops below 14 degrees overnight with no heaters running. Some of this energy performance can be attributed to a combination of double-glazing, pelmets, and floor-length lined curtains, Roman blinds and window blankets. This combination of window treatments performs to a level of triple-glazing or better.

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Other energy-efficiency measures we used in the home were Energy Star appliances, compact fluorescent light bulbs, and solar hot water. This combination meant that our power bills over the last year ranged from $17 to $35 per month. Contrary to what some of our critics claim, we do not sacrifice comfort or convenience. Solar hot water allows us to take long showers even in winter, while our appliances include the following: refrigerator, freezer, oven, toaster, electric kettle, cake mixer, wizzy stick, wifi, alarm system, clocks, radios, power tools, etc.

How’d we do it? By thinking different: it takes money to save money.

Peace, Estwing

Would You Buy This House? Part 1: Energy

Sustainability at 10 Arawa Place

The exceptional level of sustainability of this property can be explained through exemplary levels of energy efficiency, long-term durability of products, and the high productivity of fruits, veges and fowl. The entire property has been designed and managed to be low-input and high performance.

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Part 1: Energy Efficiency

10 Arawa Place has been redesigned and renovated as a passive solar home. Between April and August, morning sunlight reaches deep into the structure, bringing warmth inside early in the day when the temperature is lowest.

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An abundance of glazing on the northeast and northwest sides ensure that free sunlight energy heats the northern parts of the home on most winter days to 20 – 25 degrees. Screen shot 2014-09-06 at 8.01.59 AM

Throughout the day some of the sunlight energy is absorbed within thermal mass, ensuring that the interior does not overheat while storing the excess warmth for overnight when it is released into the home. Beyond the mass already in the structure, we added approximately one thousand kilograms of thermal mass that receives direct winter sunlight from sunrise to sunset through three large windows and the French doors. Screen shot 2014-09-06 at 8.00.21 AM

This extra thermal mass is essentially invisible because it takes the form of an extra layer of Gib on the walls, a cast iron claw foot bathtub, and a multi-fuel cooker with brick surround. When the sun is not shining, the multi-fuel stove easily heats the northern part of the home to 20 degrees or above on a few sticks of wood, with the added benefit of cooking and baking.

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Two-thirds of the home is easily heated by this combination of sunshine and a small amount of firewood. (The southern bedrooms are kept cooler as is common in most Kiwi homes.) A super-insulated building envelope ensures that much of the heat remains in the structure overnight.

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The walls in the northern parts of the villa are insulated to R-2.8 and the ceilings are insulated to R-3.6 above the kitchen and bathroom and to approximately R-5 above the lounge and all three bedrooms. These all far exceed the building code. (The underfloor insulation is incomplete at the moment.)

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We spent two winters in the small bedroom and never used a heater. Our body warmth alone kept the room above 15 degrees all night long. Temperatures in the lounge, kitchen and bathroom could drop to 14 or maybe 13 on the rare morning with a frost. Some of this strong energy performance can be attributed to a combination of double-glazing, pelmets, and floor length lined curtains, Roman blinds and window blankets. This combination of window treatments performs to a level of triple-glazing or better. Screen shot 2014-09-06 at 8.02.07 AM

Other energy-efficiency measures we used in the home were Energy Star appliances, compact fluorescent light bulbs, and solar hot water. This combination meant that our power bills over the last three years ranged from $17 to $31 per month including the daily line charge. The appliances we operated were: refrigerator, freezer, oven, toaster, electric kettle, cake mixer, wizzy stick, wifi, alarm system, clocks, radios, power tools, etc. Screen shot 2014-09-06 at 8.02.16 AM

The solar hot water system is set to a winter sun angle to maximize performance when hours of sunlight are shortest. The 240-litre tank allows ample storage to bridge three winter days without sun. We placed the temperature monitor in the hall next to the bathroom so it can be easily referenced. Over three winters, we only turned on the electric boost for the hot water a handful of times for 20 to 30 minutes each.

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To be continued…

 

Part 2: Durability

Coloursteel Maxx roof, November, 2011.

New, low-maintenance exterior cladding, 2012.

High quality exterior paint.

Walls braced against earthquake and wind.

Sistered bearers and joists fro added strength under floor

All floors treated for borer

All new wiring, November, 2011

Capping on fences to protect end grain from rain

Wind-hardy trees to protect netting from long-term UV damage

Earthen pizza oven protected from rain and wind

Brick patio instead of wooden deck

Driftwood – durable native hardwood timber for landscaping

 

Part 3: Productivity

Topsoil: 6 cubic metres for garden beds, trees and top-dressing lawns.

Wind protection: double-layer of wind cloth with new treated posts.

Rainwater collection

Compost: 8-10 cubic metres.

Native plantings for privacy and wind protection.

52+ Fruit trees: 7 feijoas; 11 olives; 13 apples; 5 peaches; 3 plums; 1 apricot; 2 guavas; 4 grapevines; 2 figs; 1 banana; 1 tamarillo; 1 orange; 1 loquat; plus rhubarb, cape gooseberry, strawberries, summer and autumn raspberries,

Vegetable gardens:

Rotational grazing of ducks and chooks:

 

 

 

Complimentary Design

Here we are in the middle of winter and it’s music trivia time again. If you are under 30, you may want to skip the next paragraph.

Released in 1972, this song was the first and only number one on both the soul singles and Billboard Hot 100 charts for singer songwriter Bill Withers. In 1987, Club Nouveau covered the song and took it back to number one for two weeks on the Billboard charts. That version reached number one in New Zealand in 1987, and earned Withers a belated Grammy award, as a writer, for Best R&B Song. It is ranked number 205 on the Rolling Stone list of 500 Greatest Songs of All Time.

This music trivia question was brought to you by Wikipedia. Any guesses?

The song: Lean on Me.

The moral: We all have our good days and bad days.

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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 organizations 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. For example, 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 both of 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 24 degrees, it heats our water, and cooks our dinner on the solar cooker outside on the patio.

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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 complimentary 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 like the All Blacks design their game plans to take into account the complimentary 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 present home there are days – one or two each month during May, June and July, that we run our 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 around 6 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.

Peace, Estwing

 

p.s. How many TV satellite dishes do you see in the title image and how many solar water heaters?

Passive Solar Renovation

The other day we were driving home at about 5:30 – just after sunset – and could barely make out plumes of wood smoke exiting cowls on Heads Road and Cornfoot Street. The day had been sunny, but cool, as would be expected in July. Our curtains were still open, so we hurried along while remaining under 50 km/hr.
We parked, grabbed the bubs and groceries, and walked inside. Upon entering our old villa on Arawa Place, we were pleased to feel the warmth gifted us by the sun. The thermometer in the kitchen read 23 degrees Celsius.
By now, my wife is tired of hearing me say, “Wow, it’s so warm in here. I can’t believe all those houses had wood burners going.”
I chalk the difference up to legacy and sunlight.
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 After
Unfortunately, Whanganui has been left with a legacy of thousands of homes built with seemingly no regard to the sun or even thermal comfort for that matter. Many of the dwellings I’ve audited during the last three months through Project HEAT share these characteristics: cold in winter and hot in summer.
Our home would have been the same before its passive solar renovation. As a matter of fact, we met a woman shortly after we bought the villa who told us, “I’ve been in that house before. I babysat there once. That’s the coldest house in New Zealand.”
While no longer the coldest home in the country, it is still far from the warmest. But on a sunny winter day, we find ourselves toasty warm inside long after dark, and with plenty of solar heated water – all free energy with no daily line charge!
The primary way we tapped into this free, abundant energy source required no specialist equipment and no specialist skills. As a matter of fact, the ‘solar collectors’ we used already exist in every home in the country: windows. The problem with most homes is that the windows are evenly distributed between the north, south, east and west.
On sunny winter days, only the northerly-facing windows have a positive energy balance. In other words, they gain more heat through sunlight energy during the day than they lose through radiation at night (if properly curtained, as you would). All of the other windows have negative energy balances even on the sunniest of winter days.
For us, the obvious solution was to ‘shift’ windows from southern exposure to northern exposure. While retaining roughly the same amount of total glazing, we were able to dramatically improve the solar gain of this old villa where – once upon a time – someone decided to put the toilet in the north corner.
 Before

After
Shifting the toilet to a more appropriate location was accompanied by opening up the north corner to create a bright, warm, cosy kitchen with French door access to abundant backyard vege gardens and an outdoor pizza oven. All of the work was done in accordance with the New Zealand Building Code, with special attention paid to weather-tightness and bracing.
At the same time, we insulated the ceilings as well as those walls that were opened up during the renovation. And finally, we added thermal mass inside of the building envelope to moderate and store solar thermal energy, but that, my friends, is a story for another day.

Sun Angles: Winter and Summer

Mid-way between the autumnal equinox and winter solstice we find ourselves in the unenviable position of short days and long nights, and looking forward to even shorter days and longer nights for some weeks to come. Despite this, our renovated, passive solar villa has been performing well – the indoor temperature has not dropped below 18 degrees in 2013. (More on this in subsequent columns.)
The scientific explanation for the change in day length is that the Earth’s axis is ‘leaning’ the Southern Hemisphere away from the sun slightly more each day until June 21st. The way we perceive the sun in relationship to ourselves is that it rises a little further northeast and sets a little further northwest each day, as well as hanging lower in the sky at noon. Mind you, this is gradual. It takes 6 months for the ‘tilt’ to change from the sun’s highest point in the sky – and longest day of the year – and its lowest point in the sky.
A good eco-designer takes his of her lessons from nature. And nature takes his or her lessons largely from the sun. Using the transitive property, you can get the rest.
In the space below, I’ll explain two examples of good eco-design that take full advantage of the predictable behaviour of the sun: one biological and one physical.
 WBG, sold out quick-as.
If you were at Whanganui’s Saturday market for its last session before Christmas 2012, you may have been among the lucky few to have purchased The World’s Best Garlic. There is a lot that goes into growing The World’s Best Garlic besides humility. One important ingredient is timing. When I arrived in New Zealand five years ago I was told: “Plant garlic on the shortest day of the year and harvest it on the longest.” Generally speaking, this translates into June 21st to December 21st.
Please be aware, however, that this has nothing to due with full moons, cow poo vortexes, or Grecian Formula 44. It does have to due with soil temperature and gradually increasing sunlight day by day for half a year.
Also be aware that growing The World’s Best Garlic involves the right kind and amount of compost, mulch, and watering regimen, all of which are highly protected trade secrets.
The other example of good eco-design involves two examples of solar hot water that are dramatically different from one another but each serves its own users most appropriately. One system is set on an acute angle and one on an obtuse angle to the sky. In other words, one system is set up for maximum efficiency in the winter and one for maximum efficiency in the summer.
Solar hot water set for a winter sun. 
The solar hot water system on our home is set for a winter sun angle because we know that there are fewer total hours of daylight in winter, and that our insulated tank loses more heat each night in July than in January. There also tends to be more rain and clouds in winter, so we need to take advantage of every clear patch and fine day.
Even set at this high angle, our system can boil over any given day of the summer if we don’t use enough hot water. This ‘boiling’ water shoots down the gully trap as a safety feature to the system.
Solar hot water set for a summer sun. 
So who, you may ask, would set their solar hot water system for a summer angle when there are plenty of long, fine days. Answer: YMCA Central’s Raukawa Falls Adventure Camp. They get heaps of visitors all summer long, many of whom want a warm shower at the end of each day. But for much of the winter, the camp lays more or less dormant, and a back-up wood-fired hot water system can easily fill in when needed.
As spring follows winter, so form follows function…if the design is good.