Heating and Cooling

Heating and Cooling19 Jun 2013 04:44 pm

Twin Draft Guard

The draught stops here

As a son of the American snowbelt, I have always been mystified by South Africans’ ideas about “fresh air.” I put these words in quotes because what a South African calls, “fresh air,” an American calls a “draught.” I see doors left wide open for minutes or even hours on frosty mornings. Friends sleep with their bedroom windows cracked open through the winter. When I first moved into my Johannesburg house, I was dumbfounded to discover that every room had a ventilation brick with holes to let in the breeze. My house was intentionally draughty.

I suspect that living in a house filled with fresh, bracing, 10 degree air is marvelously healthy for a family, as long as they are dressed warmly enough to prevent hypothermia. But this doesn’t seem to be how it works, because at the same time that people are letting all of this cold air into their homes, they are trying to keep warm with some sort of heating.

My nieces, who live in a home filled with north-facing windows and even underfloor heating in some rooms, say that they like my warm house. But the only advantage my home has over theirs is that I try to keep it sealed up like a submarine. I plastered over the ventilation bricks long ago. Windows are basically locked shut for the duration of the winter. Curtains are opened as soon as the sun strikes a window, but closed at sunset. Anyone who leaves a door open for more than five seconds knows they will hear me bellowing, “I can feel a cold draught!” from a room away. And I really do feel it. A door left open for just 30 seconds can drop the temperature of a house by several degrees.

I will acknowledge that at some point on a highvelt winter’s day, the outside air may be warmer than the inside. But this window of opportunity for open windows is shorter than you might think. Standing in the sun or driving in a car gives a deceptive impression of the outside temperature. This week, the temperature is predicted to reach 20° just once. On that day, the outside air may be warmer than the inside from about 1 pm to 3 pm. By 4 pm, the temperature chart falls off a cliff.

My latest victory as a draught resister was to purchase and install draught stoppers to plug the large gaps under my house’s front doors. I bought mine in America, but I have seen them sold by hawkers in Johannesburg at traffic lights. They consist of of two fabric channels, each filled with a long foam cylinder, one to block the two sides of a door. The foam can be cut to size to fit the door’s width.They have made a big difference in keeping my lounge warm through the night.

I’m not blind to the risks of carbon monoxide poisoning. If you heat your home with anthracite in an open fireplace, you need to ventilate. (Reasons not to heat this way can be found here and here. Likewise, inexpensive rollabout gas heaters should be used with a window cracked open. For the rest of us, if you need some fresh air in the winter, slip out the door quickly and take a walk.

Global Warming &Heating and Cooling04 Sep 2010 05:09 pm

The new view from my lounge

Regular GreenerHouse readers know that I believe a closed-combustion wood stove is one of the greenest ways to heat your home. (And that burning wood in an open fireplace is perhaps the worst.) Early this year, I finally decided to put my funds where my flue is. I kept quiet about this at first, because I thought I should experience a winter’s worth of cold weather before reporting on the results.

First, the numbers: I already had a fireplace with an inefficient Jetmaster in it, so rather than a stove that juts out into the room, I opted for a fireplace insert. The Danish-built Scan 3-5 insert I purchased from Cosy Heating cost a steep R27,000. There are less costly stoves and inserts out there, but these high-tech wood-burners are never cheap. Running costs are a different story. A cubic meter of wood cost me R600 and lasted the winter, though we did escape Gauteng for three of the coldest weeks. Since buying that first load of wood, however, I have suddenly become aware of all the free firewood suburban homeowners leave on the roadside. My kids tease me about this freeloading, but I’m only saving my neighbours the cost of hauling the wood to the dump. Long before the next heating season begins, I have at least a year’s worth of wood that didn’t cost a cent. Since we used our Rinnai LPG heater much less, mostly in the morning, our gas consumption fell from about 2½ 48kg bottles for a winter to less than one bottle, saving me about R2300. A rough calculation, ignoring the cost of capital, suggests that it will take me about 16 years to recoup the R27,000 outlay. If I had been relying primarily on the gas-guzzling Jetmaster to warm my lounge, I would be confident of a relatively quick payback.

But my reasons for switching to wood were more psychological than financial, and I’m happy to report that the emotional payback was instantaneous. The romance, beauty and warmth of the fire drew my family out of their rooms to congregate in the lounge. The children repeatedly asked to eat supper in front of the fire. I usually found the 15 minute task of preparing and lighting the fire to be an earthy pleasure that carried me back to my childhood. Knowing that all of these benefits were fossil-fuel free heightened my enjoyment immensely. Since the burning wood is close to carbon neutral, my reduction in LPG consumption cut my household annual carbon dioxide emissions by approximately 300 kilograms. If I had been heating with electricity the figure would be even higher.

At times I was tempted to kick myself for not installing a wood stove years ago, but one blistery burn on my hand reminded me that little children and wood burning devices require careful thought on safety issues. My burn was a result of hastily ignoring the cardinal rule to have both hands gloved when restocking the stove. A small child could be burned just by touching the glass, which reaches hundreds of degrees. Still if I had to start from scratch, I would have a wood stove and a Rinnai gas heater, using the wood stove sporadically and only when I felt comfortable about safety while our children were young and relying on it more heavily as they became old enough to understand the risks.

Even as the heat of summer approaches, I take comfort every time I walk past my woodpile, knowing that I have evenings in front of the fire to look forward to when winter returns.

Global Warming &Heating and Cooling04 May 2010 09:58 am

Rinnai 323 Jetmaster

His                                          Hers

I received an email today from someone asking whether Jetmasters use a lot of gas. It’s a question that I answered best a few years ago when I wrote about heaters for Fairlady magazine. So I’m reprinting that article below.  Other GreenerHouse posts on heating can be found here and here.

Warm House, Cool Planet

The battle of the sexes erupted in our lounge one recent winter when our creaky Westpoint oil heater finally conked out. To replace it, my wife demanded something that flickered yellow, glowed orange and suggested romance. I insisted on something calculated to maximize efficiency, easy on my green conscience and not too hard on my wallet over the long-term, either. In the end, there was only one way to keep the peace: His and hers heaters.

Chilly consumers today are faced with a wider range of home heating options than ever before. You can plug in convection heaters, oil-filled radiators, or fan heaters. You can light anthracite in a fireplace, a convector, or an airtight stove. You can install electric heating wires underfloor, undertile or undercarpet. Gas heaters may be radiant or convective, flued or unflued, rollabout, built-in or freestanding, and any combination of the above. To add to the confusion, what looks cheap today may cost more down the line. And more importantly, what appears clean may force the environment to pay a price for generations to come.

South Africans have made electricity their first choice for home heating, encouraged by some of the cheapest kilowatts in the world. But Eskom derives 88 percent of its power from the dirtiest of fossil fuels: coal. Think of the electric main arriving at your house as a little pipeline of coal slurry. For every 100 rand on your electric bill, more than a quarter tonne of carbon dioxide has been pumped into the atmosphere on your behalf. The Australian Consumers’ Association has calculated that in equally coal-dependent Sydney, where winters are a little cooler than Cape Town’s, but considerably warmer than Johannesburg’s, warming a house with electric heaters can contribute 3.4 tonnes of CO2 toward global warming each year, far more than any other energy source they investigated.

In the resulting global greenhouse, the last of Mt. Kilimanjaro’s glacial ice will melt in 2015; South Africa’s drought-plagued maize crop will fall by a fifth in the next 50 years; and rising temperatures will trigger massive extinctions of sensitive fynbos flowers. It may be too late to stop some of these catastrophic projections from becoming reality, but I would rather not have them on my conscience. I moved down the list to other heating options.

Ironically, burning anthracite coal at home can produce far less carbon dioxide than heating with electricity. It depends on how you burn it, however. Throw the nuggets into a hole-in-the-wall fireplace, and up to 90 percent of your heat and coal-budget goes up the chimney. This black option makes electricity look positively green. Modern, tapered fireplaces and convectors improve the heat output, but the cleanest, most efficient option is an airtight heating stove. These pricey heaters—nearly R8 000 for Franco Belge’s popular Belfort stove—combine high-tech inner construction with an old-fashioned, cast-iron exterior to convert 65 to 85 percent of coal energy into heat for the room. In contrast, three-quarters of the coal energy that goes into electricity is lost in generation and transmission.


Heating and Cooling &Lighting &Solar &Water Use/Greywater29 Jul 2009 01:43 pm

Real Simple 1 Real Simple 2

The July issue of Real Simple magazine is now off the newsstand. So in case you missed it, I am reprinting my article about green renovations. The editors asked that the information be presented  as a series of questions for the various contractors that might work on a home renovation. I couldn’t really do justice to any of the subjects covered in that format and the space allowed, so I will try to expand upon some of them in future posts.

Crumbling house prices and economic jitters have convinced many homeowners that it’s safer to adapt what they have to what they need, rather than jump into a shaky housing market. But can a renovation help your house adapt to the planet as well?

Throwing a few photovoltaic solar panels on the roof won’t make your home green. And environmentally sensitive architects have moved beyond the singular obsession with energy efficiency. The catchphrase of green building in the 21st century is “embodied energy.” How much fossil fuel went into the bricks, cement, steel and glass that make up your house? What quantity of greenhouse gases is your home responsible for even before you switch on the first light? For some houses, the embodied energy of day one will exceed the sum of a few decades worth of electricity and gas bills.

Building in harmony with nature means working with the local climate, local suppliers, and even local soil. There is no one-size-fits-all solution. Instead of waiting for easy answers, start with the right questions. And if a contractor stares blankly at the ceiling in response to your queries, you may want to look for someone with greener credentials.


How earthy can our house be? Green architects agree that adobe, cob and rammed earth are wall materials of first choice for low embodied energy. An architect who has worked with them will know whether they suit your project. The biggest concern: banks will not approve a bond for new structures supported by such raw materials. A home renovation, however, may be able to get financing.

Can we aggressively pursue passive solar? The right combination of windows, walls and floors can supply most of your heating needs in sunny South Africa. But a large roof overhang is vital to keep the high summer sun out. If your architect cannot calculate the ideal overhang based on your latitude, orientation, roof pitch and height, find another architect.

Can we build around a wood stove? If you have a local source of sustainable wood, such as suburban tree fellers, a closed-combustion wood stove is the greenest way to heat. But with all of your warmth concentrated in one spot, careful designing is needed to help the heat reach colder parts of the house. Keeping the stove central to an open plan but away from any double-volume ceilings is a good start.

How can our home use nature’s air conditioning? Your architect should know how to take advantage of prevailing winds. Low windows on the cooler, south side of the house can draw breezes to force out summer heat from high windows on the north side. Drain the pool of heat on your ceiling with small, high windows that you can leave open all night without worrying about cats or cat-burglars. Transom windows aid the flow between rooms. Trees or shutters can shield western surfaces from the afternoon sun. Don’t let some sweet-talking salesman convince you into electric air-conditioning until you’ve given nature a chance.


Global Warming &Heating and Cooling01 Dec 2008 08:11 pm

Polar Bears Don't Like AC

Polar Bears Don't Like AC

The December issue of Red: the Green Magazine is out in the Cape, and it features an article I wrote about alternatives to air conditioning, especially evaporative cooling.  Here’s what it has to say:

Craig Bransgrove has been installing air conditioning in Cape Town homes and offices for the last six years. So it may seem surprising that when he recently installed a cooling system for his own home, he did not choose traditional air conditioning at all. Bransgrove’s Blouberg home uses an evaporative cooling system that takes advantage of the same effect that makes a wet swimming costume feel so chilly on a windy day. “I looked at all the options,” says Bransgrove. “It’s a lot healthier and it’s cost effective.”

Evaporative cooling is gaining popularity as environmentally conscious South Africans increasingly look for ways to keep cool without resorting to air conditioning. In the driest parts of the country, the systems are actually more common than refrigeration air conditioning in residential installments. “I don’t think there’s a household in Upington that doesn’t have evap cooling in it,” says Philip Coreejes, owner of Hi Power Electric.


Global Warming &Heating and Cooling29 Apr 2008 11:15 am

This week, my favourite little Rinnai gas heater stopped working when load shedding began on a cold night. It may use gas, but it also has an electric fan so it isn’t Eskom-proof. I’ve been looking at alternatives.

Last year at about this time, I wrote an overview of home heating options. In it, I ranked an open fireplace heated by gas 8th out of 11 options, well worse than average. This is because gas may burn cleanly, but any open fireplace loses most of its heat up the flue.

I failed to mention then that I own a Jetmaster open gas fireplace. In the past, I only used it a few times a year for ambience when we had guests, but I’ll have to use it a lot more during load shedding this winter since it’s my only heater that runs without electricity. That’s a problem, because LPG has risen in price from R367 for a 48 kg bottle when I installed the Jetmaster in 2001 to R820 now. And according to my own ranking, I’ll be using one of the least environmentally friendly options around.

When I first installed the Jetmaster, I briefly considered a wood stove, but I knew that wood burning was a source of carcinogenic particulates, and I didn’t see how wood made sense in a semi-arid country with so few trees.

I’ve learned two important things since then. First, I got a quick lesson in urban forestry a few years ago when I had to remove a giant dying oak from my garden. It broke my heart to see tons of potential firewood being carted away by a tree-feller who told me he was taking it to the dump. (The trunk and limbs were too large for me to split.) The logs would ultimately decompose, releasing greenhouse gasses without benefiting anyone. I called around and learned that some other tree-fellers cut and split the wood they retrieve to sell for firewood. In the future, I would only use a tree-feller who recycled this way.

Johannesburg is sometimes called the world’s largest urban forest. I suspect that this is hyperbole that could not be proven, but the fact is that the city creates enough firewood to heat many more local homes than it currently does. (Though not all of the homes, of course.)

The second education I received was when I began researching the latest wood stoves and fireplace inserts. They aren’t just better than open fireplaces, they are unrecognizably better. An open wood fireplace loses 90 percent or more of its heat up the chimney and releases about 50 grams of particulates per hour. Anyone who has read what I have writing about diesel emissions in the Mail & Guardian and on this website knows that particulates are a serious health risk.

But modern stoves typically emit 2 to 4 grams of particulates per hour, and some are closer to 1, that’s just 2% of the particulate pollution from a wood-burning open fireplace. And about a quarter of what a typical diesel car might produce. In addition, they retain 75 percent or more of the energy in the wood to heat the room, losing just a fraction to the flue. A free-standing stove unfortunately doesn’t suit my lounge, but the fireplace inserts are only a few percentage points less efficient and just as clean.

Perhaps most important, burning wood is widely considered to be almost carbon neutral, because a decaying dead tree would release carbon dioxide anyway, while a new tree growing in the place of the old one absorbs the greenhouse gas. Firewood from the urban forest is even closer to carbon neutral than most because it was going to be cut anyway and involves minimal transport.

Only two fireplace inserts fit my opening, but they seem like good units. I’m seriously considering the Scan DSA 3-5, which rates at 76 percent efficiency. I haven’t yet found particulate emissions data for this fireplace, but it seems similar to the DSA 4 which emits a very low 1.1 grams of particulates per hour. If I could choose among a wider range of wood stoves, I would look for one with the Swan eco-label. Among the brands in South Africa, Scan, Morsø, and Jötul all have stoves that meet the wide variety of environment criteria to earn the Swan logo. A list of Swan stoves can be found here.
These advanced, closed-combustion stoves are not cheap. Expect to pay at least R10 000, and up to R40 000 for a top-of-the-line wood burning stove. But the wood is cheap. Malcolm Sims of Cosy Heating has done calculations suggesting that gas now sells for R1.23 per kilowatt hour of energy, whereas wood is about 30 cents per kwh if burned in a 75 percent efficient stove-cheaper than electricity. (Cosy Heating sells both gas and wood heaters.) Comparing my inefficient Jetmaster with the Scan fireplace, I could heat with wood for one-tenth the price, though the Jetmaster offers greater control in adjusting the flame, which would mitigate that somewhat.

Sadly, Cosy Heating says that my Scan fireplace is out of stock because of the load-shedding rush. So for the next seven weeks we’ll be huddling next to the open gas fireplace when the lights go out, and thinking about how warm that chimney must be.

Global Warming &Heating and Cooling07 May 2007 02:56 pm

Rinnai 323 Gas heater

My Rinnai

I saw frost for the first time in 2007 today. My wife has started to grumble about the cold. And the stores are full of heaters for sale, all of them claiming to be energy efficient. It’s time to review which heating options will warm your home without heating up the planet too much.

First, the worst: electric underfloor heating and open fireplaces. Talk to any underfloor heating salesperson, and they will tell you that underfloor heating is incredibly efficient. Talk to any homeowner who has had it installed, and they will tell you that their toes are very warm on the tiles (don’t these people own slippers?) and that their electricity bill shot up the day they turned on the underfloor heating.

The issue is not so much whether underfloor heating is efficient or not. It’s a form of central heating, and most South African suburban houses are not built for central heating. They have big, draughty, single-glazed windows, and uninsulated walls and ceilings. When I moved into my house, each room had a brick with big holes in it to let in outside air, for heaven’s sake. To centrally heat such a house with coal-derived electricity is an environmental abomination.

Open fireplaces have lots of charm, but two big drawbacks. The first is that most of their heat goes up the chimney, and in doing so, draws cold air into the house through any leaky door or window it can find. Nature abhors a vacuum. The second drawback is that, whether burning wood or coal, they emit lots of pollution up the chimney.

According to The Consumer’s Guide to Effective Environmental Choices, by Michael Brower and Warren Leon:

On a per-household basis, the most polluting option is wood heat. The main reason is the very high emissions of particulate matter from uncontrolled fireplaces and wood stoves. Particulates are given a heavy weight in our air pollution index because of strong evidence that they cause serious health problems.

I hate to diss wood heat, because it is carbon neutral, presuming that a new tree is growing in the place of the one you are burning. A good compromise is a modern, super-efficient wood stove, such as the ones sold by Franco-Belge or Morso. The best wood stoves produce one-twelfth the emissions of a typical fireplace.

Electric heat in all forms is relatively efficient, but that isn’t a great help because generating the electricity from coal is very inefficient, and releases far too much pollution and carbon dioxide. If you are heating a relatively small space for a couple of hours in the morning and few hours in the evening, however, it is an affordable, environmentally tolerable option.

Research at the University of Pretoria found that the quickest, most efficient electric heater for warming a space is a fan-assisted heater with a thermostat. Fin radiator heaters—often called oil heaters because of the liquid circulating inside them—and other heaters without fans are slower to heat a room and let much of that heat drift to the ceiling.

Radiant bar heaters, which glow red, do not heat a space, but can efficiently heat any person who stays close to them. If you are staying put, reading or working, they may be your best option, particularly if you buy one with a low wattage setting. (1000 W or less) Leaving one of these heaters on when no one is in the room, however, is a complete waste. An electric blanket is another good option for anyone who isn’t moving.

If you are lucky enough to live in a Johannesburg suburb with piped gas, this is an excellent option, particularly now that South Africa is importing natural gas from Mozambique. Gas is the cleanest-burning fossil fuel and releases the least carbon dioxide, too. Bottled propane gas also burns cleanly, but its global-warming credentials are tainted by the fact that in South Africa much of it is produced from coal. Gas is also more efficient than coal-derived electricity because the heat from burning the gas goes straight into your house, bypassing the inefficiencies of generating electricity.

Burning gas in an open fireplace takes us right back to where we started, however, with heat escaping out of the chimney. My favourite gas heaters are the pricey, but super efficient ones made by Rinnai. My Rinnai has given me three years of faultless service. I keep large, 48 kg bottles of LPG outside my house, piped to a wall outlet where I connect the Rinnai. It produces heat in seconds and uses very little gas. (To find a local dealer, phone the distributor Jay MacDonald and Sons, 021 696 7930.) The only problem is that my children fight over who gets to sit closest to it when they turn it on in the mornings.

I’ll take a risk and produce an unscientific ranking of heaters from best to worst:

1. Gas heater with piped natural gas
2. Gas heater with LPG
3. Modern, efficient stove burning wood
4. Modern, efficient stove burning anthracite
5. Electric bar heater for warming people who are staying in one place
6. Electric fan heater with thermostat
7. Other Electric heaters
8. Gas fireplace
9. Wood fireplace
10. Anthracite fireplace
11. Electric underfloor