Mar

25

Components Of A “Green” Home

Posted by cameron

March 25, 2007 |

“Seek first to understand” – Steven Covey.

In a previous post I stated a need for my retirement house to be as “green” as practical. You can read that post here. That could mean a simple strategy to have the best possible insulation or it could mean having a home that runs entirely on renewable energy sources. My motivations are twofold: 1. To minimize my costs in retirement and 2. To make my own small contribution to resolving the environmental problems we now have.

The best way of coping with living on a fixed income is to be pro active in the choices you have on all aspects of your life, including housing. In this post I’m exploring the components to a self-sufficient home run entirely from renewable energy. It is broken into three parts: 1.Energy Generation 2. Energy Use. 3. Energy Sharing through Net Metering.

Energy Generation

The most likely scenario for me is a system based on Sunlight and Photovoltaic technology. There are four required pieces before you can unhook the power to a house:

  1. The Photovoltaic cell is simply a device that creates DC electricity when light shines on it. The technology has been around for decades; old cameras used them for light level sensing. If you wire enough of them together you can generate significant power. These cells are not cheap and only respond to certain wavelengths of light. Researchers recently demonstrated cells that can respond to those lost wavelengths thus making them more efficient. In other words, you will need less of them in the future and the cost of an installation should be lower.
  2. You need somewhere to store the energy created by those cells so there will be a bank of rechargeable batteries, typically lead-acid batteries. There are special considerations for the housing of battery banks because of gases emitted during charging.
  3. A battery charger goes between the photovoltaic cells and the batteries. Its job is to charge the batteries at the proper rate and at the time when they need charging.
  4. Now you have stored electrical energy what do you do with it? All the electrical equipment in your home runs off Alternating Current (A.C.) not Direct Current (DC) from the batteries. You need a device called an Inverter. These have been around a long time and it’s just a techno-jargon name for something that converts D.C. into A.C.

That’s all you need to generate electricity but the question really is “how much do you need and how much will that equipment cost?” which takes us to “how much will you use?”

Energy Use

It’s surprising how quickly I became sensitized to equipment and home efficiency as I was pondering the cost of generating the electricity. Normally I would just plug a new device into an outlet and expect it to work. Naturally I would only complain if it didn’t work or when I received my monthly bill. Not so in this scenario, I care about everything. In order to figure out the cost of electricity generation you must start with the electricity usage. Only then can you determine how large of an inverter, how many batteries, how many photocells etc.

When I look at my electricity bill it is obvious that heating and cooling are the largest components of my energy usage. I’m now looking for the most efficient way to heat and cool my home and retain it for as long as possible. That’s my next post. I am going to work through the following list until I can get an idea of the best ways to deal with each or leave them alone as is. Either way I will end up with an energy budget that my generation equipment must supply:

  1. Heating and cooling
  2. Hot water
  3. Appliances
  4. Lighting

Check back to see progress on these issues.

Energy Sharing

Lets pretend I now run my home from renewable sources. What if my equipment failed? What could I do with any excess capacity I generate out of that Inverter? Well, I could leave my house hooked up to the grid. With one move I can answer both questions. When I need power it just flows into my home from the grid, when I have excess capacity I could sell it back to the utility company. Can this be done? Yes, with something called Net Metering. In this scheme you have a meter that can run backwards as well as forwards. It down-counts when you supply the grid. This has another couple of benefits: it smoothes out your highs and lows of generation and it returns “green energy” to the utility company thus lowering their emissions. If enough people did that we could have a real impact. Of course the utility companies don’t really want to do that but political pressure is mounting. If you are wondering where to find your states policies and regulations on this issue then go to DSIRE and find out. For running my house it is not necessary for me to hook to the grid but it may well be desirable.

If you want to keep up with my research and results in this matter feel free to take a feed from this site.


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