Vampire energy

Standby power (a.k.a. "vampire energy") is the power consumed by devices that are simply plugged in but not really turned on. For example, a device with a remote control, uses a trickle of power to listen for the signal from the remote control in order to fully turn on. The amount of standby power is typically small. For example, a modern TV will consume 0.5W in standby, but can consume over 200W when fully turned on.


So why care about vampire energy? The reason is that when you add it all up over all electrical devices in your household, it turns out to be a really big number. In the UK, for example, in 2006, estimates are that 8% of all electrical energy consumed goes to standby power. In the US, this would amount to almost 20 average-size power-plants!

I was curious to see how much standby power we use at home. The public utility recently upgraded our power-meter to a digital smart-meter, so it's easy to just read out the wattage consumed at any point in time. I waited until everyone was asleep and everything in the house was turned off (but still in standby). I also made sure that the fridge did not have its compressor running at the time.

The number? 85W.

Wow. This is surprisingly high! At 24h/day, 30days/month, this works out to 61kWh (around $8/month at today's energy prices). Given that we consume 300-400kWh average total per month, this is between 15-20% of our total consumption! For an average US household, which consumes closer to 1000kWh/month, this would be around 5%, which is about what the British study revealed.

How could we possibly consume 85W in standby mode? I broke it down by circuit, by switching the circuit breakers on and off and studying the devices connected to each circuit:

• 29W for the DSL modem + wireless router.
• 11W for the gas heater
• 8W for various stuff in the bedrooms (alarm clock, cell phone chargers, night-light, etc.)
• 5W for the garage door remote
• 4W for the PC
• 4W for the microwave oven
• 3W for the washing machine
• 3W for the electric oven
  
• 18W for other stuff I couldn't track down precisely

The modem + wireless router are an interesting case: while I could turn them off at night (from, say, midnight to 6am), they do need to be on during the day given the level of internet use at our place. So the 29W really needs to be pro-rated down to 7W to indicate it's standby power for only about 6 hours. Another option is to get a combination router + modem that consumes less power by itself, but that's harder since I'm picky about the routers I like. :)

The astonishing one is the gas heater, at 11W. I suspect this is because the heater uses an electric element to fire up the gas burner, and this electric element has to be always on. There isn't much I can do about that, and I don't really feel like messing with the heater since it a large, expensive, and scary device.

The remaining ones are relatively small. For things like the microwave oven and washer, I could get power strip with an external switch that fully turns off the appliance, but the cost of the power strip will easily outweigh the savings from the electricity for a few years at least.

I should also probably track down the remaining 18W and see where it's wasted, but I have a feeling it's going to be small amounts here and there, not one significant consumer.

The conclusion? The best way to eliminate standby power is to do it at the source (that is design the device to not consume standby energy as much as possible). The second best way is to use timers or switched power strips and force devices off. This only makes sense if the device is of a certain kind (indoor device, that doesn't suffer problems when turned off, like the gas heater). For the remaining devices, the ideal situation is to combine them all on one (or a few) power strips and force them off with a switch. If the devices are spread throughout the house (like the microwave oven in the kitchen and the washing machine in the garage), this is not really possible.

In the end there's little I can do about this. How frustrating. :(

Lead paint

Lead is a heavy metal with lots of industrial and commercial uses, ranging anywhere from batteries used in cars, to protecting nuclear physicists from radiation. One particularly colorful and sad chapter in the history of this otherwise boring metal is the use of lead in gasoline (tetraethyl lead) to prevent engine knock. Bill Bryson writes about it eloquently in his book A short history of nearly everything.

Another common use of lead is in household paint. The reason? It looks good: paint with lead in it is shiny and pleasing to the eye. It's also quite dangerous and poisonous. Lead also happens to be a neurotoxin, it likes to bind with neurons and prevents the normal formation of synapses, which is particularly bad for young children, who apparently can retain up to 100% of the lead that enters their system (adults, as it turns out, are better at eliminating the bad stuff, only about 20% of the lead that enters an adult body stays, the rest is eliminated).

The most common way for children to be exposed through lead is, you guessed it, household paint. Specifically, in older homes, the lead paint can naturally chip and fall on the floor, where a child can ingest it. One easy solution to this is to paint over the areas with lead paint therefore "trapping" the bad stuff and preventing it from flaking or otherwise getting off the walls. In general, good house keeping (cleaning, vacuuming, and in general maintaining the surfaces whether through washing or painting over) does a lot of good and cheaply.

San Francisco's housing stock is old, some of it built before 1900, and a lot of it built after the earthquake of 1906. There are few modern houses, and even fewer built after lead paint was made illegal. Ironically, the more expensive and "fancy" a house, the more likely it is to have lead paint in it; some of the highest concentration of lead paint in San Francisco is apparently in the fancy mansions of Pacific Heights. Besides paint, which is by far the most common place for lead, another relatively common place is glazing on tiles, for example shower tiles. A good rule of thumb is that -- if the paint or the tiles look nice and shiny, they're probably leaded.

It may be tempting to get very worried about lead paint and decide to "strip" it out. This is not only costly -- it involves sanding most surfaces that can contain lead paint -- but it also frees the stuff in the air and it can become a true nightmare to get it all out.

How would you know if you have lead paint in your house? You can hire someone to test it, or you can even do some of it yourself.

One kind of test involves taking flakes of paint and send them to a lab where they are analyzed. To cover the house, the technician has to take a sample from each wall, or at least each room, since some rooms may have been painted with lead paint, while some weren't. If this sounds like a pain, it is. You can also use a home lead-test kit in area where the paint is exposed. The lead-test kit is basically a "brush" that contains a reactant in it, you brush over the paint, and if there is lead present, it turns red. The test is controversial, and has a false-positive rate, but it can give you some idea.

Another kind of test is using an XRF gun. This gun fires off a stream of high-speed particles which only bounce back when they hit something dense ... like a lead atom. The gun approach is far easier to use since you can just take "readings" from all surfaces you care about and the results are instant.

As a side note, it is remarkable to what extent people have ignored common sense or made bad choices in the name of "looking good".

Quake busting

California is earthquake country. From the iconic 1906 earthquake, to the daily reminders that we live on top of 3 major tectonic faults, earthquakes are a big part of the local consciousness. You would imagine that, after San Francisco was almost leveled in 1906, the building codes would change to take into account such large tremors and build stronger houses. Unfortunately, that's not the case. It's true that a majority of buildings in San Francisco are wood-frame houses with at most 3 floors, which tend to be pretty flexible and withstand earthquakes reasonably well (although they can easily succumb to fire). Still, lots of older houses are vulnerable: they can shift and fall off the foundation, or the lowe stories can crumble under the weight above them. This is especially true of soft-story homes, which are prevalent in the Sunset and Richmond districts. To reduce earthquake risk, it is possible to retrofit an older home to better resist a large earthquake. There is a lot of good evidence that such retrofitting can make a big difference. So what goes into a retrofit?

1. Foundation work. Many older houses literally "sit" on the foundation with no additional reinforcement. When the ground shakes, it can "push" the house off the foundation. Even a small push, say a few inches, can have disastrous consequences, it can sever water, sewer, and gas pipes, start a fire or worse. To mitigate this, the house can be bolted to the foundation, so that the ground and the house move as one.
2. Cripple wall work. Most houses don't sit directly on the foundation, to prevent the wood from getting damaged or weakened by natural ground moisture and the like. Houses are either built on top of a narrow "crawl space", or, in the case of soft-story houses, the living quarters are built above the garage. In an earthquake, the heavy part of the house above carries a lot of inertia, and if the underside is bolted to the ground, the house above can shatter the walls underneath and fall. To mitigate this, the lower walls can be reinforced with plywood shear walls that strengthen them and essentially stiffen the house, preventing the upstairs from swinging wildly in a quake.
3. Garage opening reinforcement. Even with bolts and shear walls, the garage door opening remains a major weak point, as it weakens one of the key structural walls of the house. This can be reinforced with a steel frame or a steel beam to give it the same strength as the other 3 walls.

Here's what it looks like (courtesy of seismicsafety.com): For most houses, the retrofit work can be done just with the help of a skilled contractor, who's qualified to install bolts and shear walls. For some houses, notably those on a steep hill, or soft-story designs, the help of an engineer is needed to design the retrofit and compute the appropriate material strengths, after which the contractor can install it. ABAG has a wealth of information to help people decide the risk of an earthquake and the impact in their specific area. In particular, the maps of shake intensity and liquefaction risk are extremely useful. In San Francisco, having your house on top of a hill can dramatically reduce both shaking and liquefaction, though it does increase the changes of a landslide. Sadly, the Marina with its gorgeous houses and amazing views, is built on top of landfill from the 1906 earthquake, so it's very vulnerable to an earthquake; it's no accident that in the relatively minor 1989 Loma Prieta earthquake, the Marina suffered the most damage (map courtesy of thefrontsteps.com). Another way to mitigate against earthquake risk is to get earthquake insurance. In California, this is of questionable utility: if a major earthquake were to hit, the CEA would probably run out of money, at which point people say that FEMA would have to step in and help the reconstruction. During that time, people would probably have to live in temporary houses, like the ready-made earthquake shacks of yesteryear. Still, having some earthquake insurance can provide a good cushion in the case of a major natural disaster. I personally found that learning about earthquakes made me worry about them less and take the necessary steps to increase our safety. I realize there are no guarantees, but doing even little things can go a long way towards helping deal with this reality. And I certainly wouldn't trade living in San Francisco for anywhere else, earthquakes and all.

Here comes the Sun

Renewable energy is becoming increasingly more visible in our society. The recent oil and food price spikes, the impending opening of the Northwest Passage, the coral bleaching in the ocean all point to the fact that we consume fossil fuels at unsustainable rates, and are changing our environment for the worse. Changing to renewable energy makes both economic and moral sense.

Of the many ways to produce renewable energy, solar is a big focus these days. In the US, the federal government has a generous subsidy, which looks to be extended in the following years. In California, there is an important state subsidy, and a generous San Francisco subsidy. (Lest you wonder, even foggy San Francisco gets plenty of sun.) In California, grid electricity is produced by PG&E, mostly using natural gas. The solar incentives aim to encourage private individuals and businesses to install solar panels and feed electricity back into the grid, thereby offsetting some of their consumption. If the solar installation produces more than the individual consumes, their PG&E bill can be negative (they get a check each month). In most cases, the solar panels would offset some fraction of the consumption, typically the expensive kWh's, more on this below. Here's what this looks like (video credit Solar City): One natural question at this point is: why feed the electricity back into the grid, instead of running your house directly on it? For one, the solar panels only work during the day. To have electricity at night, you would need to install a fairly large set of batteries to store excess energy. Batteries are very costly and often an environmental nightmare (containing acid or rare metals that are expensive to synthesize or extract). Second, solar panels energy output varies considerably between seasons (in the northern hemisphere, the sun's efficiency is very different in the winter vs. the summer), or even between days (on a cold, stormy day with cloudy skies, the output is quite different than on a warm, sunny day). Third, most electrical appliances expect a steady electrical output (110v, with small error margins), which are difficult to maintain even from a good battery bank. The goal of solar is not to necessarily replace the grid entirely, but rather to offset enough to substantially reduce our pollution and dependence on fossil fuels. Solar cells convert sunlight into electrical current. The conversion is pretty inefficient, around 20% of sunlight gets transformed to electricity. However, given that direct sunlight on average produces 120 W/square meter, on an 8 hour sunny summer day we can recover almost 200 kWh of electricity using a modest 1 square meter solar cell array. Solar panels produce DC current, but the grid operates on AC, so the output from solar panels has to be converted to AC using an inverter. This exacts another small efficiency penalty (around 20%), and has to be tuned to the size of the solar array. Solar panels are expensive (largely because they're not yet mass produced, so they can't leverage economies of scale). Absent generous subsidies, in order for them to make financial sense, they have to be sized as a function of household consumption. As of the time of this posting, PG&E uses a tiered price structure for electricity: the first 256 kWh are the cheapest, at 11c. If you consume more than 256 kWh, the price increases quickly, up to more than triple:

• 11c/kWh - 0 -100% baseline (256 kWh)
• 13c/kWh - 100-130% baseline
• 22c/kWh - 130-200% baseline
• 31c/kWh - 200-300% baseline
• 35c/kWh - over 300% baseline

For a residence, it makes sense to look at a year's worth of electricity bills and figure out what is the consumption pattern. In a warm area like California, odds are you'll use lots of electricity in the summer (A/C) and less in the winter when it's cooler, but not cold enough to require heating. One solar strategy is to get a solar array big enough to offset only the expensive kWh in the summer (those at 30c or more). There is no magic formula here, each house is different, although in very broad terms a 2.5-3.5 kW solar array should do the trick for a lot of average-size homes. Before embarking on a solar project, it makes sense to first optimize your consumption using the cheapest tools: replace all incandescent bulbs with CFLs, configure computers and TVs to go into standby when not used, increase the temperature of the fridge and freezer, insulate the attic to keep cold air in, and so on. This can have a dramatic effect on your electrical consumption, as much as 30% reduction! At this point, take stock of your usage and size the solar array as a function of the new energy consumption numbers. Go solar!

Gas vs. Electric

The two major sources of energy used in California homes are gas and electricity. In our home, for example, the stove uses gas, the water heater uses gas, the washer/dryer use electricity to spin and gas to heat, and the house heater uses an electric motor to push air over a metal tube heated with gas. It's no accident that the California's major utility company is called PG&E: Pacific Gas & Electric. I recently stumbled upon an interesting article about energy efficiency in home appliances. Among others, the article recommends using an electric room heater instead of running the home gas heater. I was generally under the impression that "gas is better" because it's cheaper and pollutes less (gas burns cleaner, whereas electricity is generally produced in coal burning power-plants that are far dirtier). So I decided to do some some research into the matter. For the baseline, I looked at the January bill from 2008 and 2007 (January is the coldest month around here, when one would expect the bill to be the highest, and this past January was especially cold):

• January 2007
• Gas: 53 therms @ $1.13
• Electric: 133 KWh @ $0.11
• Total: $74
• January 2008
• Gas: 49 therms @ $1.14
• Electric: 136 KWh @ $0.11
• Total: $71

Based on our usage patterns, I would estimate that roughly half the gas we consume is for heating the air in the home. So what would it look like if we used an electric Vornado heater instead? Based on the Vornado's specifications, it uses between 750 and 1500 Watts, depending on the temperature setting. I measured the wattage, and we're between 600 and 1200 Watts, since we never set it at the max (it gets too hot). For the purposes of this simple calculation, I'll assume the average consumption is 1000 Watts = 1 KW. We use the heater for a maximum of 5 hours per night (5pm - 10pm), so in one month, that's 30 * 5h * 1KW = 150 KWh. With this in mind, our January 2008 bill would have looked like:

• Gas: 25 therms @ $1.14
• Electric: 286 KWh @ $0.11
• Total: $56

That's a 22% reduction in cost! The heater would pay for itself in 3 months. In terms of quality of life, we've started spending more time in one room, with the door closed, in order to keep the heat inside. The Vornado works best in such a closed environment, and it often heats up the room far more than the gas heater. It takes a bit longer to get the room warm, but once it's warm, it consumes very little electricity to keep it that. I spoke to some colleagues at work about this, and the general consensus is that if you can thermally insulate individual rooms in the house, it makes sense to individually heat them using electricity, otherwise a gas heater is more efficient and economical for the entire house. What about the environmental impact? It turns out that in California, most electricity is also produced using natural gas, which is a reasonably clean way to do it. Some electric energy is lost in transmission, but it appears to be reasonably small (average 10%). The big upside, however, is that California is aggressively pursuing electricity generation using renewable energy: solar, wind, and so on, in which case electricity is definitely the way to go. You also have the option to offset the carbon used by your consumption, which is a nice bonus. In typical maverick fashion, San Francisco wants to become fully energy independent, and there are projects underway for that. In my case, it seems that electricity makes more sense than gas. At the end of the day, however, the most important thing is to be aware, measure the impact, and think about what makes sense. More on that, however, in another post.