– Source for quality information on efficiency, conservation, and clean energy

August 29, 2007

Homes without heat?

Category: Efficiency – Dan 2:12 pm

Efficiency is the ugly stepchild of solving our energy woes. While solar panels and windmills are high profile and focus on alternative sources of energy, efficiency focuses on needing less in the first place. How dull.

How do you spice this up? How about the idea that you don’t actually need any home heating. What, you say? Maybe in moderate climates, but that’s not going to cut it in Minnesota! But the hotbed (no pun intended) of this technology is in Germany, which is anything but warm in the winter.

Germany has several home heading standards in place[1].

  • A “Low Energy House” (Niedrigenergiehaus) cannot require more than the equivalent of 7 litres of heating oil for each square meter of room for space heating annually (in US terms, 15,850 Btu/ft²/yr)
  • The German Passivhaus ultra-low energy standard, is set to less than 1/3 this level, with a maximum space heating requirement of 4,755 Btu/ft²/yr. These homes are generally built with no central heating system, because it’s not needed.

Compared with buildings that follow the 2003 Model Energy Efficiency Code in the United States, these ultra-efficient homes use 75% to 95% less energy for heating or cooling.

Yes, you say, but what are the costs of building this way. Data on this varies widely, but seems to be in the 3% to 8% range. The challenge (as I saw in one article) is that the developer is generally not the owner.[2]

What to do in the near term? When buying new homes, demand higher energy efficiency! Be willing to pay the additional costs. But more important, we need to lobby for higher efficiency standards and incentives for developers to implement higher standards. The US has just come off a massive housing construction boom, and the sad truth is that a majority of those homes were not particularly energy efficient.

August 11, 2007

Clean energy – Reaching a tipping point?

Category: Alternative Power – Dan 9:31 am

I just finished reading an article on RenewableEnergyAccess by Ron Pernick that took a very positive viewpoint of the sea change with alternative and renewable energy.

[Clean energy sources] will they represent the highest growth and innovation opportunity in the energy sector and double-digit chunks of our energy infrastructure…

He quotes a number of statistics to back up this viewpoint:

  • PV – In 2003 the solar industry was valued <$5 billion globally with ~600 MW of solar manufactured worldwide. By 2006 that number had more than tripled to nearly $16 billion with more than 2 GW of solar manufactured globally.
  • Wind – In 2003 new isntalled generation was about 8,000 MW worldwide. THis nearly doubled to more than 15,000 MW in 2006, and last month T. Boones Pickens announced plans for a 4,000 MW wind power plant (equal to the total annual global install less than a decade ago) and FPL announced that it will develop 10,000 MW of new wind power projects between now and 2012.
  • China has a new renewable energy law is targeting 120 GW (that’s equivalent to 200 or more coal fired plants) of new renewable energy generation capacity by 2015.

Ron closes his story with this conclusion:

As I look out over the next 5-10 years I’m confident that the most important development in the clean-energy sector will be the scaling of manufacturing, systems integration, and equally important, technology deployment. Millions of jobs and billions of dollars will be generated in the process if policymakers, investors, corporations, and innovators get this right.

Let’s do what we can to get U.S. policy makers behind this, so that the U.S. can join the rest of the world in helping drive this innovation and adoption!

August 6, 2007

Why isn’t there more Solar Thermal?

Category: Solar Thermal – Dan 6:06 pm

In terms of what you can do at home to make a difference, one of the top items on the “more expensive but worth it” list is solar thermal — essentially hot water generated by rooftop collectors.

We like our hot water. We talk about taking a “long hot shower”, we rely on it to clean our clothes and dishes. A typical family of four uses an estimated 65 to 75 gallons of hot water per day[1]. According to an article by the Renewable Energy Resource Center in Vermont:

By installing a solar water heater, a family of four, who currently use an electric water heater and consume an average of 80 gallons of hot water per day, will prevent 3,400 pounds of greenhouse gas emissions each year. This represents a reduction in household greenhouse gas emissions of 20% or more for a typical household.

If the goal is to achieve 80% reduction in greenhouse gases by 2050, that requires a 2% reduction per year. So solar hot water can buy you the first 10 years down this path. The investment can range from $3,000 to perhaps $10,000, depending on if it’s for new construction or a retrofit, and depending on the size of the installation.

How does Solar Thermal work?

Solar thermal is one of the simplest green technologies. Basically, you pass water through a collector on the roof during the day. Whenever the sun is shining (and really whenever it’s relatively bright outside), the collector heats the water. This water is then stored in a tank for later use. Depending on the configuration, the solar portion of the system could be the only source of heat (if the tank is large and the collector is sufficiently large relative to the daily demands), or a traditional water heating system is provided to boost the heat from the solar system to acceptable levels.

Why is the US so far behind?

The US investment in solar thermal collectors is incredibly small. Look at this chart of data from the German Solar Energy Industry Association for 1999 installations (m2 of collectors):

Country Total Per Person
China 4,000,000 3.09
India 2,000,000 1.92
Japan 1,000,000 7.84
Europe 890,000 1.23
South Korea 500,000 10.55
Turkey 430,000 6.27
Israel 400,000 63.46
USA 25,000 0.09

How depressing. And while I fear China’s ongoing construction of coal fired facilities, you have to admit that their investment in solar thermal is impressive. But it’s not limited to developing countries like India and China, and it’s not limited to mid-latitude countries like Israel or Turkey.

I’d postulate three reasons why the US is so far behind here:

  • Cheap energy – Why worry about additional stuff in your house when gas and electricity is inexpensive.
  • Lack of policy – We don’t have any incentives to encourage developers, homeowners, or businesses to invest in solar thermal.
  • Lack of feedback – Those homeowners who do have solar thermal systems don’t get any sense of how well it’s working, or how much money they are saving by having it.

Installing Solar Thermal

If you can afford the investment ($3K to $10K, depending on your home and size), where do you go and what can you do? Here are several leads for systems:

  • Heliodyne Inc has been manufacturing solar thermal products for 30 years, primarily flat plate collectors and heat transfer appliances. They sell both components and off-the-shelf packaged systems ranging from smaller residential systems to large pool or commercial heating systems.
  • Alternate Energy Technologies, LLC manufactures flat plate solar thermal collectors and fully integrated solar hot water systems for medium and high-temperature commercial, industrial and residential applications. They have a nicely integrated system that reduces the number of overall components and therefore the installation costs.
  • Conergy is a supplier of flat panel collectors and systems for domestic hot water, space heating, and pool and spa heating. Their applications include use of solar powered water pumps to ensure reliability and eliminate dependence on grid power for their operation.

There are many more. You can find companies like this at, or by doing Google searches.