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 21^st 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.

Architect:

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.

Do we really need a bathroom as big as a squash court? Small was beautiful in the ‘70s, and it still is today if you want to lighten your load on the planet. Every wasted square meter of your home will have to be heated and lit for decades to come, on top of the embodied energy of floor, roof and walls. Remember, your architect is probably getting paid a percentage of the whole building project. You aren’t.

Builder:

Which local bricks have lowest embodied energy? Capetonians may find that cement bricks from Cape Brick with recycled aggregate are the solution, while Gautengers may want Corobrik’s gas-fired clay bricks from their ultra-efficient, Midrand plant. The carbon footprint for these face bricks is about half that of a typical coal-fired clay brick. Local is most definitely lekker. Trucking a brick across the country could double its carbon footprint.

Can you work with alternative mortars and plasters? Cement is the bugaboo of green building. Worldwide, cement plants account for 5 percent of humanity’s carbon dioxide emissions. Lime, popular among green builders as a mortar and plaster, creates fewer emissions and then actually absorbs CO₂ for years. Your walls become carbon sinks. Where you cannot get away from cement—and it is inevitable—ask your builder to use one with a high fly-ash content.

What can we reuse? Building materials belong in houses, not in a landfill. Usually someone on your building crew will be happy to recycle your doors and windows, if they are carefully removed. You can also reuse bricks if your builder will assign the labour to knock them into shape. There’s no greener brick than a used one. And you may want to source vintage materials taken from other houses. The Yard in Johannesburg is a good starting point, especially for reclaimed Oregon-pine flooring.

What recycled ceiling insulation can you source? Whether you are perspiring in Phalaborwa or freezing in the Free State, ceiling insulation is the first step toward creating a comfortable, energy-efficient home. But some insulation is produced by toxic manufacturing processes. One environmentally friendly alternative is Isotherm insulating blankets made from recycled cool-drink bottles. For real comfort, install two layers, 100mm each, with the top layer overlapping the bottom and covering the joists. Cellulose insulation from recycled newspapers must be blown into your roof space by a professional, but is an efficient insulator and helps seal air leakages.

Will you use low-VOC paint? Wall coatings with volatile organic compounds not only cause city smog, they unleash carcinogens inside your home. Many South African paints would actually be illegal in California. Jutta Berns-Mumbi of Ecocentric consultants and developers trusts the low-VOC paints from Cape Town’s Harlequin Paints for her projects. “If it smells of paint, it’s probably not good for you,” she explains.

Plumber:

Can you flex your PEX? Copper pipe is starting to fall out of favour around the world, and many green builders are replacing it with flexible cross-linked polyethylene (PEX) pipe. Afripex (www.afripex.com) can help you find plumbers who are trained to install it. Though made from petroleum, PEX manufacturing is less polluting compared to making many other plastics, and certainly compared to mining and smelting copper. A further advantage is that hot water will reach your tap or shower slightly sooner due to the smaller inside diameter. If your bathroom is far from your geyser, you can save much more hot water by asking for small-diameter PEX lines running directly from the geyser to the tap or shower, instead of pushing all of that water through a main line to the bathroom. The savings on your utility bills should pay for the extra pipe within a couple of years. And your hands will thank you.

Can you identify water-saving fixtures that work? Low-flow showers and dual-flush 3/6 litre toilets belong in every environmentally conscious home, but your water consumption won’t fall if that trickling shower makes you opt for a bath or you regularly have to flush twice. A maintenance plumber should know what works and what doesn’t. A well-made low-flow shower rose will usually give a more satisfying, high-pressure shower than a flow restrictor added to an existing shower head. And it’s better to pay now for a good-quality dual-flush toilet, rather than pay the water company for extra flushes over the years to come.

Can my geyser stand tall? South African geysers tend to be mounted horizontally, even though this is known to be inefficient. Most heat losses come off the top of the geyser, a much larger surface area when your cylinder is lying prostrate. In addition, water stratifies better in a vertical tank, so that cold water entering the bottom is less likely to cool the hot water at the top before you draw it off for your shower. A renovation is the perfect opportunity to find a new home for the geyser, perhaps in a cozy spot inside the house near the taps, where you can access it to turn down the thermostat.

Electrician:

Can you make my house LED-ready? LED lighting is the green future. The bulbs use about 80 percent less electricity than incandescents and will probably last longer than you will. Unlike the diffuse glow of fluorescents, they project a beam, more like the popular halogen downlights. Affordable, high luminosity LED bulbs are not quite ready for your house, but your house should be ready for them. By 2010 or 2011, major manufacturers like Philips and Osram will be selling downlight replacement LEDs that replicate the ubiquitous 50 watt halogen. So if you must install downlights now, skip the 75 buck transformer for low-voltage halogens, and use the savings to put toward future LED purchases. (The bulbs currently cost hundreds of rands.)  Many electronic transformers won’t work with LEDs and these modern globes will be happier with 220 volt fixtures. The brightest LEDs also tend to need the extra space of a high-voltage, GU-10 halogen. Yes, the 220 volt halogens do not last as long as their low-voltage cousins, but you only have hold on for a number of months.

Can you install a timer for my solar geyser? Now that you are spending R15 000 to put solar hot water panels on your roof—because no environmentally conscious South African would want a roof without them—you will want the sun to work hard for you. But solar panels will have little to do if the electric element in your tank reheats the water after your 8 a.m. shower. A timer can shut the element off, give the sun a chance, and cut the geyser’s consumption by perhaps a third. Let the element come back on at 3 p.m. for a few hours if the temperature needs a top-up. For the ultimate in control, you can spend a little more for Geyserwise, a timer which also allows remote control of the thermostat setting.

Can you fix the fluorescent flicker? Noisy fluorescent tubes that flicker aren’t just an irritation, they waste electricity. The culprit is the cheap magnetic ballasts that electrical contractors routinely supply with fluorescent fixtures. Electronic ballasts cost more, but they can cut your fixture’s wattage by a quarter.

Sidebar: Building from Scratch

Though building a house from scratch will likely use a lot more energy than a renovation, it does create an opportunity to take the environment into consideration from the ground up. Quite literally the ground.  Topsoil is a precious natural resource that is usually ruined by builders, mixed with rubble and hauled to a landfill. Insist from the start that any removed topsoil is stored separately and covered for reuse in the garden.

As far as placement of the house, the mantra for real estate may be “location, location, location,” but in green building it is “orientation, orientation, orientation.” Maximize northern exposure so that your house can perform daily salutations to the sun for you. Twenty degrees off north in either direction is no tragedy.  A little bit of northeastern exposure is welcome on a chilly winter morning.

Now you can put all of that north-facing space on your roof to work. Since the sun is weakest in the winter, help it out with a steeply pitched roof so that solar panels face it directly. Solar installers use latitude plus 10 degrees as a rule of thumb. That’s about a 35 degree pitch in Johannesburg and 45 degrees in Cape Town. You will want hot-water solar panels up there right away. Photovoltaic panels for electricity make some sense for the environment today, but not for your wallet. In a few years, when solar-cell prices have fallen, Eskom rates have risen, and the government has legislated a feed-in tariff that pays you for your excess electricity, you’ll be glad for that north-facing roof.

Of course moving into an energy-efficient home is of little benefit to the atmosphere if it increases your rush-hour driving. The greenest home is any house within walking distance of work, school or shops. For parents, a 10 km commute to school may add as much carbon dioxide to the atmosphere as your entire daily electricity consumption at home. Location + Orientation = Conservation.

Since the issue of Maverick containing my Solar Photovoltaics vs. Diesel Generators article is off the newsstands, I can now publish the article in full on Greenerhouse. Enjoy:

Bringing Back the Light:

Diesel vs. Photovoltaic

It began with an email. My brother-in-law asked me, the family’s resident green guru, to weigh up the relative merits of diesel generators vs. solar power.

Load shedding is clearly driving him to distraction. Computers are crashing in his home office, and he has scrambled to reschedule meetings of 30 and 40 people to stay out of the dark. He wants to know that the power will be there where he needs it, when he needs it. “I’m looking for a complete solution, and I don’t want hassles,” he told me, admitting that he was close to choosing the diesel route.

But he also knows that his green credentials need some buffing since he traded in his Honda Jazz for a Land Rover Discovery last year. Is solar electricity an affordable alternative?

Until the beginning of this year, the answer to his question would have been simple: In South Africa, solar cells may be virtuous, but they don’t pay for themselves. (Solar hot-water panels do pay for themselves, but you can’t run your PC on hot water.) Even the national sales manager for Sanyo photovoltaic panels in South Africa, Win Kurzyca, says, “it doesn’t pay me to put 10 of these on my roof—even at staff price—instead of paying 32 cents a kilowatt hour for electricity.”

But suddenly everything has changed. In fact, the question has changed. My swaer is not asking whether photovoltaic panels pay for themselves; he wants to know whether solar electricity is competitive with diesel-generated electricity.

Diesel gensets have become the latest accessory for the manor homes of South Africa’s best suburbs. On one block in Houghton, Johannesburg, three homes in a row glow brightly during each load-shedding event, automatically powered by Cummins engines installed for a cool R200 000 each. Forget the jet set; in 2008 we ogle the genset.

Such outlandish figures are as thrilling for solar cell manufacturers as they are for the diesel makers. The price of a solar roof no longer seems quite so ridiculous, especially once a generator begins slurping fuel. When Sanyo ran a full-page advertisement promoting its panels in The Star and Sunday Times, just before the latest round of load-shedding began, the response jammed the company’s switchboard. “What has changed the picture is the diesel generator,” says Kurzyca, “the longer the running period for a diesel generator, the quicker the payback for solar.”

My task was to determine exactly how long that payback period would be. I started by inviting Deutz, the respected German engine manufacturer, to send a representative, Craig Potts of CDDG Electrical Contractors, to my brother-in-law’s house to size up his needs. The following day, J.P. de Villiers, director of Eco Zone, performed the same exercise on behalf of the sun.

The difference between the mentality of a generator installer and a solar-cell contractor quickly becomes obvious. The genset man’s motto is: “Go big or go home.” Tumble driers, underfloor heating, pool pumps, ovens—put them all on the system. Bulking up from a 15 kVA generator to a 21 kVA model bumps the price up by less than 5 percent. Says Potts: “Rather go larger than smaller, that’s what I say.”

The meaning of life for a solar man, however, can be summed up as: “Every watt is sacred.” These panels are made from the same precious silicon crystals used for computer chips. Double the watts and you’ll have to double the price. De Villiers wanted to replace 59 halogen bulbs with 9-watt mini fluorescents. Such a conversion would cost nearly R10 000. He instantly ruled out using solar to power the pool pump, the oven, and the entire suite of appliances in the scullery. “The tumble drier takes 3 kilowatts, the dishwasher another 3 kilowatts, and the washing machine will use 500 watts on cold up to 3 kilowatts on hot,” he notes, “if you ran more than one of those at the same time, the system would come crashing down.”

Electric geysers, heaters and stoves are also beyond the might of photovoltaic panels. In most homes, de Villiers would like to see electric heat replaced by gas or wood, solar hot water panels mounted on the roof (R20 000 to R40 000 after Eskom’s rebate), and a gas stove installed in the kitchen (R5 000 and up), before adding sun power.

Since my brother-in-law powers his geysers, heaters and hob with town gas, he would be spared those up-front expenses. Still, he was becoming skeptical about the solar hassle factor. “I don’t want to have to know what is working and what is not working,” he moaned.

One conversation with the Deutz workshop convinced me that the diesel hassle factor is just as onerous, however. In addition to checking oil and coolant levels once a month, the engine would need a R2 000 service every 250 hours, more than once a year at current load-shedding levels. “And you must supply the oil; we don’t ride around with oil in our bakkies,” the foreman told me. Fuel deliveries would have to be organized several times a year.

In contrast, de Villiers said that his solar system could be left untouched for five years, at which time the batteries should be checked. With no moving parts, the Japanese-made panels’ power output is guaranteed for 20 years; the Deutz generator set’s warranty lasts for 24 months.

So neither side scored a technical knockout, and I had no doubt that the match between diesel and solar would ultimately be decided on points, or, more precisely, rands. And when the quotes came in, the opening round left solar slumping in the corner. Deutz was asking a fairly steep R162 000 for a 22 kVA generator set that would power the entire house, including installation and an automatic changeover panel that would start the motor whenever the electricity was cut. Sixteen roof-mounted Sanyo solar panels connected to a bank of batteries and an inverter, however, begged a whopping R322 000. This would provide continuous, clean power for lights, fans, security system, microwave, televisions, hi-fi, computers and peripherals, every day of the year—for free. Well, for R322 000, but for free.

The diesel quote was not entirely complete, however. Even with automatic changeover, the generator would take a minute or so to respond each time Eskom pulled the plug. Without uninterruptible power supply (UPS) battery backup on each computer, television decoder and clock, the house would still need a reboot.

And every home with a generator should have two layers of protection against voltage spikes according to Seamus Finnegan of Northern Technologies SA, which provides surge protection for generators to Vodacom and other telecoms operators. “If you don’t, you will have problems,” he warns. Steven Moss of Deutz says that the voltage regulators on his generators are adequate for most houses, unless they have “really sensitive or expensive equipment.” Playing it safe means adding another R23 000 to the diesel total.

The solar quote had room to move in the other direction. Replacing an aging refrigerator with a new, energy-efficient model could save two kilowatt hours a day. It might cost R10 000, but the payback would be instantaneous—knocking two R10 000-panels off the roof and six batteries out of the storeroom. Diesel still had the edge, R185 000 to R300 000, but solar was starting to find its feet.

The final rounds would be fought on a spreadsheet calculating operating costs and savings over the next 20 years. Of course I had to make some assumptions. Is load shedding going to get better or worse? I opted for slightly worse: 10 hours a week. If summer was unmanageable for Eskom, what happens when the underfloor heating is switched on? For diesel prices, I optimistically assumed 13 percent inflation, half the rate South Africans have endured for the last four years. And I allowed Eskom its 61 and 51 percent rate hikes for the first two years before applying the brakes and marking up annual increases of 15 percent.

The spreadsheet shows the solar panels gaining ground as the genset runs out of gas. By the end of the fifth year, cumulative fuel costs and maintenance bills have just about made up the R115 000 difference in the original price. Meanwhile, the solar panels would have saved my brother-in-law a running total of R34 000 on his municipal bill.

Starting out by opting for diesel and investing the R115 000 difference in an interest-bearing account instead of spending it on, say, plasma televisions, puts off the day of reckoning for the genset by a few years. But its defeat is inevitable.

From there, two scenarios confront his generator. Either load shedding continues to push the diesel engine deeper into deficit, or Eskom pulls out of its crisis and lands my brother-in-law with a rusting white elephant. Either way, the solar panels continue to save, finally paying for themselves about when the warranty expires.

Allow greenhouse gasses on the balance sheet and the generator sinks deep into the red. Over five years, one diesel generator operating just 10 hours a week to power a house will coat the atmosphere with more than 15 tons of carbon dioxide. That’s enough to blanket a one-acre property in a 2-metre-deep layer of the greenhouse gas. Over the same period, the solar panels would have reduced the home’s C02 contribution by double that amount.

Carbon dioxide suffocates the planet, not your children, but diesel particulates are one of the most dangerous air pollutants for human health. A report last year in the South African Medical Journal estimated that particulates in outdoor air pollution lead to 4,637 premature deaths in South Africa each year, largely from cancer, strokes and heart attacks. Measurements of particulate matter in major South African cities are on average more than triple the levels deemed safe to breathe.

While tightening emissions regulations are gradually cleaning up diesel cars in South Africa, the sky’s the limit for stationary engines belching particulates and smog-forming nitrogen oxides. Deutz engines, cleaner than most, do at least meet the European pollution standards of 12 years ago. Still, they can emit up to 5 times the levels of particulates allowed by the EU today. Had any regulator imagined that these engines would be running on a weekly basis in the gardens of family homes—in this case 8 metres away from my nieces’ treehouse—particulate filters would have been mandatory.

For now, winter is approaching and my brother-in-law still has not made his decision. Both quotes came in well above what he had anticipated, and the spreadsheet seems full of uncertainties. Besides, it’s hard to read all those figures in the dark.