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.)

Screen Shot 2017-08-16 at 7.17.46 am

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.

Screen Shot 2016-05-12 at 6.30.39 am

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

Screen Shot 2016-05-12 at 6.31.02 am

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.

Screen Shot 2016-05-12 at 6.31.17 am

Hang the insulated door and paint the lot.

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

Screen Shot 2016-05-12 at 6.29.50 am

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.

Screen Shot 2015-10-09 at 9.56.54 am

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.

Screen Shot 2015-10-09 at 9.57.32 am

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.

Screen Shot 2015-10-09 at 9.51.02 am

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