Arlington Designer Homes is committed to green building for the health benefits, energy savings, and reduced environmental footprint it provides for our buyers and our community. With constantly changing regulations, technologies and products, buidling a new green home from the ground up isn't always easy - but it's always interesting!

Welcome to our behind-the-scenes blog about green building and remodeling, where you can watch a green home go up step-by-step and learn about using green building techniques for your own home. And visit our website at to learn even more about green building and remodeling.

November 5, 2010

Geo-Thermal Heating and Cooling

I am currently working on a home where we have  installed a Geo-thermal heating and cooling system. This is not the first Geo-thermal system we have installed and it won't be the last. Installing the systems can be 2-3 times more expensive than a typical HVAC system, but the payback can be huge.

Currently the federal government is offering a 30% tax credit (stay tuned for my next blog to learn more about tax credits) on any sustainable energy system that is installed. This means that with the tax breaks, you are paying a lot less in initial costs and the payback period is much shorter. The way that I have calculated it for the house that I am currently working on, is that if energy costs stay constant, the geo-thermal system will start paying itself off in 7 years. So the geo-systems that we install can then actually make money for you for up to 43 years!

Installing geo-thermal HVAC is a big project,
but across the board, our customers have
been thrilled with how well it works!
Installing Geo-thermal systems on a tight lot like the one that we are currently working on can be tricky. It is a sequencing challenge. I had to excavate the house and coordinate the foundation work with the Geo-thermal drilling work. In this house, we installed 2 ground loops that go 300' into the ground. These loops happen to be installed beneath the garage floor, although they could have just as easily been installed under the basement slab or in the yard.

The idea behind Geo-thermal systems is that you are using the earth's constant temperature to heat or to cool your home, depending on the needs. The system operates like a heat pump exchanging hot or cold energy with the coolant that runs down and then back up two 300' loops. Once this energy has been exchanged, it enters the unit and is dispersed like a typical forced air unit is, throughout the house.

So, for example, when you are heating your house, your unit will exchange the energy from the cool air that is brought into the unit with the air that is heated to a baseline of 55 degrees from the earth. The earth's temperature is a constant 55 degrees. Once this air is in the unit it will be heated to the temperature on the thermostat by using natural gas or electricity to bring it up the extra few degrees. So in essence, this system helps create a constant 55 degree air intake that can be heated as necessary.

The entire unit takes up a little more space in your utility room, but has the distinct advantage of eliminating noisy outdoor AC units. Overall it is a very interesting and unique system that works great for our customers.

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