Category Archives: passive solar

Passive Solar Design: Free Heat in Winter

Six years ago New Zealand experienced the coldest week in recorded history, but our recently finished passive solar villa performed perfectly during the cold snap. Even with single-glazing in much of our home, it stayed warm during the frigid week without using any heat source other than the sun. (Of course the curtains and blinds did their job at night.)

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Here is a blog post I wrote six years ago today that explains the great result:

http://ecothriftydoup.blogspot.co.nz/2011/08/power-of-sun.html

Here is a blog post written a month later that explains how and why the sun can be used to heat a home in winter for free.

http://ecothriftydoup.blogspot.co.nz/2011/10/sunrise-sunset.html

 

Peace, Estwing

Insulated Door: Easy as 1-2-3

Glass doors are common in New Zealand homes.

Glass doors are cold doors.

South-facing glass doors are especially cold.

Here is a cheap and easy way to retrofit a four panel rimu glass door into a warm and cosy door. First, find yourself a comfortable working area and lay out the door.

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Next, cut insulation to cover each glass panel on both sides.

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Finally, cover with thin ply, hardboard or other suitable material. I used the waterproof wallboards that we removed from the old laundry when we extended our kitchen. They were just sitting in the shed.

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Hang the insulated door and paint the lot.

(Note the second door handle is for our three year-old daughter.)

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Not 100% flash, but a very high performance door at a low price.

 

Peace, Estwing

Before ‘Villa Wars’

Before “Villa Wars” there was the Eco-Thrifty Renovation.

As newlyweds, Dani and I started renovating an abandoned Castlecliff villa in 2010. The roof leaked. It had no power or water. Half of the windows were smashed. The hot water cylinder and copper wiring had been stolen. It was our honeymoon.

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The four villas on this season’s The Block NZ look like luxury accommodation compared to what we shifted into five years ago. A reasonable person would have torched the structure. We decided to save it.

Despite it’s condition when we took possession, the old girl had potential – solar potential to be specific. I’ve said it before and I’ll say it again: I would never consider buying a home in New Zealand with the living spaces facing south. It just makes no sense.

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Far and away the best use of solar energy in the housing sector is passive heating. This is followed by solar hot water. Other forms of solar energy have yet to prove themselves as being cost effective in the residential sector.

While The Block NZ makes for entertaining television, from a Whanganui perspective it must be taken with a grain of salt. While house prices in Auckland have skyrocketed over the last five years, prices in our River City have fallen. Many people in our community have done up their homes only to see the valuations drop.

From what I have observed, renovation is less of a factor for increasing a home’s value compared with a thriving job market or foreign investment. Until we see one or the other locally, there won’t be significant increases in valuations.

In our community, renovation needs to be more of a labour of love than anything else, especially if you plan to invest in energy efficiency and/or solar. It appears that most valuers do not understand solar energy and are unable to place accurate figures on it. Unfortunately this holds back a cultural shift toward high performance housing in New Zealand.

This is not to say that we should not renovate our homes. We should. It’s just that our focus needs to be a return on health and comfort rather than on ‘climbing the property ladder.’ Additionally, smart investments in energy efficiency will reap ongoing financial rewards for homeowners and the local economy. Intelligent communities around the world have realised up to 20% savings in domestic power usage. Imagine all of those dollars circulating in local economies rather than being sent away to power companies.

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One final note on renovation that may come as a surprise to some: the building inspector is your best friend.

Blockaholics know that Peter Woflkamp is revered as the watchdog of the programme. Although he is the butt of many jokes, his role is indispensible. In the same way, our building inspectors play critical roles in overseeing works. They too are maligned, but at the end of the day they are the most important people on a job site.

The legacy of leaky homes – a period of time when building oversight was weakend in New Zealand – will end up costing the nation tens of billions of dollars. Watchdogs are important on TV and in real life.

No Depression in New Zealand…and no cold, damp homes either.

Editor’s note: Here is another weekly column in the Wanganui Chronicle.

John Maslin recently wrote an editorial for the Chronicle titled: ‘Get real’ on heritage protection. Given the number of heritage buildings in our city and the cost of strengthening them, a realistic approach is certainly in order for progress to be made.

After reading Maslin’s piece I was driving to work and heard that the song, “No Depression in New Zealand” was up for the missing Silver Scroll award from 1981. It seemed an appropriate ‘get real’ anthem:

There is no depression in New Zealand

There are no sheep on our farms

There is no depression in New Zealand

We can all keep perfectly calm

Blam Blam Blam did not win the Silver Scroll, but I am happy to honour the song for the rest of this column as it reminds us to be suspicious of spin doctors and their reluctance to recognize facts.

Not long after Maslin’s editorial we were treated to David Scoullar’s insightful piece on managing decline: Accepting decline best way for cities to plan for future. Scoullar points out examples of “cutting-edge” urban policy overseas and that they are “not on the radar of Wanganui District Council.”

WDC policy appeared on the front page of the Chronicle last month: “No Decline here, Duncan.”

And there is no depression in New Zealand.

Another ‘interesting’ narrative that has come under scrutiny lately has to do with the cost of building homes in New Zealand. A recent 3D investigation on TV3 asked the question, “Are we paying too much to build our homes?”

While the popular narrative points the finger at land prices and council fees, the ‘get real’ answer points to exorbitant prices paid for building materials. From the 3D investigation:

Tony Sewall , head of Ngai Tahu, the biggest developer in the South Island, has sent teams around the world to investigate building materials prices.

“We’d be paying around 30 percent more than in Australia, probably 60 percent more than the United States,” he says. “And the United States’ product is better.”

Quotable Value statistics indicate that identical medium-sized homes built in New Zealand and Australia cost Kiwis $20,000 to $32,000 more than Aussies. This is not because Australia has higher regulatory costs. Screen Shot 2015-09-25 at 9.16.56 am

Cheaper Option: On and off the shelves just like that. 

The programme revealed exclusive arrangements between building materials manufacturers and certain retailers and builders. One example used was wallboard, and how one dominant brand controls 94% of the domestic market. A rival product briefly made an appearance in shops at a much lower price, but then suddenly disappeared. Meanwhile, all parties deny a “special arrangement.”

And there is no depression in New Zealand.

One final issue on the ‘get real’ front for this week. The Whanganui Regional Health Network (WRHN) recently flooded all three local papers with the same article asking for money from philanthropic organisations to support an insulation programme that has been under-funded by the current government. At the same time, we have a local MP who never hesitates to point out how many homes in the District have been insulated under his watch.

To be clear, here is a government agency asking for private donations because The Government has not provided enough funding for a government programme. Meanwhile, a representative of The Government is taking credit for the grand success of the programme.

And there is no depression in New Zealand.

Additionally, it appears that the WRHN has misidentified insulating floors and ceilings as “Healthy Homes.” A famous case recently linked the death of a toddler to the home where she was living that was insulated. As Labour housing spokesperson Phil Twyford stated, “When you insulate a cold, damp home it is still a cold, damp home.”

But on the other hand, this could all just be hype. After all, there are no cold, damp homes in New Zealand.

Side bar: Want to ‘get real’ about healthy homes in our community? A group has formed to look into the possibility of forming a trust that will address the issue of housing performance while creating jobs for local youth. Please contact me if you are interested.

Around the World in Eight Designs: Part 12

At the end of the last column I promised to include some more examples of thermal mass this week along with a photograph. As a reminder, thermal mass is part of the trilogy for passive solar design, which also includes solar gain and insulation.

Thermal mass absorbs heat from sunshine slowly during the day and then releases it at night. In this way it is a bit like the opposite of a night store heater, which stores cheap electric heat at night and releases it throughout the morning.

In modern houses, thermal mass can take the form of an insulated concrete foundation slab, but retrofitting a 100 year-old villa is a different story. Because an old villa has a raised floor (ie, built on piles) adding thermal mass inside of the thermal envelope is more of a challenge. During the renovation of our villa we added mass in three ways.

The first and easiest way we added thermal mass was to add a layer of plasterboard (aka “Gib”) to a number of north-facing internal walls that receive direct sunlight during the winter months. If you have ever lifted a sheet of plasterboard you would know it contains lots of mass. In other words, it’s heavy.

The next way we added mass was to install an iron claw foot bathtub in our northwest-facing bathroom. Like the extra layer of plasterboard, the iron slowly absorbs the sun’s warmth during the day and releases it at night.

Finally, and most dramatically, we installed an old Shacklock 501 cooker in the kitchen. The placement of the Shacklock ensures that it receives direct sunlight three times a day through three different windows during winter. The cooker weighs 300 kg, and is surrounded by another 300 kg of bricks. The insulated hearth accounts for another 100 kg. Screen Shot 2015-09-07 at 12.07.04 pm

All in, the 700 kg heater/cooker works great as thermal mass during sunny winter days. It moderates the kitchen from overheating during the afternoon and helps ensure the morning temperature is a little higher than it would otherwise be.

Oh, and on cloudy days we stoke the Shacklock with wood and cosy up with a big pot of soup on top and a loaf of bread in the oven.

Around the World in Eight Designs: Part 11

Editor’s Note: This is part of the continuing series on good home design from around the world.

 

In the last column I wrote about adding glazing to the northern side of an old, run down villa to increase the amount of free solar heating during the winter. Specifically, we made three of the windows larger and added French doors. At the same time, we reduced the amount of south-facing glazing by removing two windows and replacing them with insulated walls.

These steps were part of the process of creating a passive solar home while drawing on many of the examples of good home design that I have seen all around the world.

However, one of the main problems with passive solar design over the last four decades has been homes that overheat during winter because of too much north-facing glazing and not enough thermal mass. Thermal mass is the least understood aspect of passive solar design. I’ll do my best to explain it by comparing it to a rechargeable battery, but first some background.

During the 1970s some very well meaning hippies started building homes with heaps of glazing but overlooked the inclusion of thermal mass. The homes overheated during sunny winter days and the occupants had to open windows to let out some of that heat.

Here is where the battery analogy comes in. Thermal mass absorbs the extra heat (energy) during the day and stores it like charging a battery. Think of a curb or concrete stairs that have been in the sun all day long and retain some of that heat after sunset. If you touch them they are warm after the sun has disappeared.

To get an idea of what thermal mass is, think of water and anything that sinks in water. These things are “massive,” or in other words dense. In a home, common forms of thermal mass are concrete, bricks and tiles.

But don’t be confused by a home with brick cladding or stucco. The thermal mass must be inside of the home, not outside. Specifically, it must be inside of the building envelope, which includes the stud walls, windows and doors.

Another key aspect of thermal mass is that it should be struck directly by sunlight to be most effective. In the same way, rechargeable batteries work best when the charger is plugged into the power point!

With plenty of north-facing glazing and ample thermal mass, instead of overheating during a sunny winter day, the excess sunlight energy is stored in thermal mass during the day (charging the battery) and then slowly released at night as the home cools (discharging the battery). I am partial to thermal mass as a design element because there are no moving parts, and it effortlessly takes excess heat energy at one part of the day and tucks it away for another part of the day, or rather the “middle of the night.”

I hope that helps explain how thermal mass works. In the next column I will give some more examples.

 

Peace, Estwing

Dodgy Tradesmen

The Irish builders have been copping it lately for substandard work during the Christchurch rebuild, but I reckon there is enough dodgy building work to go around. Here are a few things to keep in mind.

Lesson Number One: Never trust a property inspector who says, “Yeah, the ceiling is insulated.”

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It wouldn’t take more than an inch of 40-year-old ‘insul-fluff’ for the average pre-purchase home inspector to tick the box for ceiling insulation. The average homebuyer would trust the property inspection report, buy the home, and then spend the next decade or more shivering in a cold home.

Don’t trust these guys on the topic of insulation. Here’s why: For the most part, they are the same people that built much of the low quality housing stock that New Zealand suffers from.

Think about it. A property inspector is a retired house builder. Most houses built in the last 50 years are under-insulated and cold. These are the guys we are trusting to assure us the large investment we’re about to make is fit for purpose. It’s a bit like allowing the Wall Street tycoons who crashed the world economy to be the guys to help ‘reform’ the financial system.

If you are looking to buy a home, make sure you bring a ladder and a torch. Pop your head above the ceiling. If you can see the ceiling joists then the ceiling is under-insulated. It does not mean you shouldn’t buy the home, but it might mean you can negotiate on price.

Lesson Number Two: Never trust a plumber or electrician to put insulation back in place after they have removed it to do work. Screen Shot 2015-08-21 at 7.18.03 pm

Many of you reading this column right now are living in homes with small and large sections of the ceilings completely uninsulated. If you have had a sparky or a plumber in your ceiling cavity anytime during the last two decades, I strongly advise you to get a ladder and a torch, and to have a thorough look.

Recently I was shocked by the actions of a very experienced and very pricey plumber who did some work at our home. About three weeks after he left I had reason to visit the ceiling cavity to reload bait stations for mice, rats and possums. I was shocked to see a large amount – and I mean LARGE amount – of recently installed insulation piled up against the flue for our wood burner.

Aside from the portion of our ceiling that went three weeks without insulation, stacking batts against a flue is obviously a fire hazard. Negligent is the kindest word I would use to describe this particular plumber. Screen Shot 2015-08-21 at 7.18.13 pm

Lesson Number Three: Don’t trust the New Zealand Building Code minimum levels of insulation. Note the key word is “minimum.”

Many houses built today are destined to be cold homes due to poor design and under-insulation even though they “pass inspection” according to the letter of the law.

The current building code “minimum” for ceiling insulation is R 2.9 for this region. That is not enough. Don’t settle for a minimally insulated home. By international standards R 2.9 is meager. Throw in a couple dozen down lights and you may as well be living in a 1950s state house.

The take away for all three lessons above is this: If you can see your ceiling joists at all then your ceiling is more than likely under-insulated. You’ll need to put the insulation back in place from the tradesmen’s visits and then top up with blanket insulation over the joists and existing insulation. We have topped up with R 3.6 and except for a negligent plumber we have a fairly cosy home.

Got the message? Get the ladder!

Don’t say you’ll do it next week because you won’t. Put down your paper right now. Put down your coffee. Get that ladder and go!

 

Peace, Estwing

Around the World in Eight Designs: Part 10

For the last two and a half months I’ve shared examples of good home design from around the world. In a nutshell, good design includes using natural energy flows to heat and cool a structure. Natural energy flows include sunlight for winter warmth and wind for summer cooling.

A common term used for this approach to building homes is ‘passive design’. This approach to housing allows a well designed home to ‘just sit there’ and achieve comfortable temperatures year round with low power bills.

From desert to mountain, and from the tropics to cool temperate regions, I have included seven styles of homes so far in this column. For the eighth example I am offering a twist, because who in their right mind would include a 100 year-old New Zealand villa as an example of good home design?

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However, the process of transforming a cold, draughty villa into a cosy, warm home is only a matter of following the basic design principles from other high performance homes that we can see around the world. Just as a reminder, the basic design elements are these: solar gain, thermal mass, insulation, cross ventilation, and a centrally located fixed heating source.

The first challenge of turning a century-old villa into a passive solar home is increasing glazing to the north and decreasing glazing to the south. In other words, this means adding windows and/or glass doors to capture more winter sunlight and removing windows or glass doors that receive no direct winter sun.

This type of work is more than likely to require building consent, so make sure you do your homework. Special care must be taken to not compromise the bracing of the home or its weather tightness.

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Any northerly facing window is likely to provide an ample supply of free winter heating as long as the sun is not blocked by trees or neighbouring buildings. Once you have checked on potential winter shading, decisions can be made on increasing the amount of north facing glazing.

At the same time, southerly facing windows simply lose heat from a home almost continually from May through August. Replacing some of these cold windows with insulated walls will hold more warmth within a home, but remember all work needs to comply with the building code.

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Next week I’ll tackle the misunderstood issue of thermal mass.

 

Peace, Estwing

Around the World in Eight Designs: Part 8

Last week I wrote about a centuries-old style of home that ticks most of the boxes for good house design. The New England Saltbox can be said to be an early example of passive solar design, which takes advantage free heating by sunlight during winter months.

The obvious first requirement of passive solar design is to have more windows facing the equator than facing the poles (depending on which hemisphere the structure happens to be located in). Windows are both an asset and a liability to a warm home. When winter sun shines directly through glazing a house is warmed, but when it does not, windows release warmth to the outdoors.

In our region, south-facing windows lose heat more or less all the time between May and October. Even north-facing windows lose heat during winter nights, which happen to last 14 to 16 hours. From this perspective, window placement is key to passive solar design.

Taken to the extreme, a passive dwelling could have glazing on the entire north side and none to the south. This is exactly the type of structure I encountered a decade ago in Ladakh, India, although the orientation was reversed for the northern hemisphere.

The region of Ladakh lays mostly between the Himalaya and Karakoram Mountain ranges. The Ladakhi people live between 3,000 and 4,000 metres elevation. I spent five months working with a remarkable organisation called the Students Educational and Cultural Movement of Ladakh (SECMOL). Among the excellent work done by SECMOL is passive solar design/build using rammed earth.

Ladakh is a desert in the sky. Its primary resources are earth and sun. Trees are scarce. Wood is costly. Homes have been made using rammed earth for centuries, but better design has improved their performance during the last two decades. It is now possible to build homes, schools, and offices that are completely heated by sunshine. I spent a winter there in a room that was much warmer than most homes in the Manawatu.

Passive solar design is not only about sunshine. It also relies on thermal mass and insulation in proper proportions. Getting the balance right can result in warm, comfortable homes with very low running costs. And here is the best part: building a high performance passive solar home is cost comparable with building a typical New Zealand home.

Maybe rammed earth or a Saltbox is not your cup of tea. No worries. These are just examples of good passive solar design. There can be variations on the theme, but the theme does not change:

A-B-C, easy as 1-2-3, simple as solar gain, thermal mass and insulation. That’s how easy a cosy home can be.

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