A welcome to our blog

Welcome to the Direct Exchange Geothermal weblog. Authored by members of the EarthSource Energy Solutions staff, this blog aims to illuminate new technology which can minimize the effects of civilization on the climate. We welcome any insight, questions, or general comments, either on a direct exchange heat pump installation at your home or any other topic relating to ecological sustainability.

We should be updating this blog fairly regularly with up-to-date information, so be sure to check frequently for new content.

To begin, I'll start with a brief discussion of direct exchange geothermal heat pumps while touching on the concept of a "green home" and a low-cost option to help decrease a home's impact on the environment.


Direct Exchange Geothermal Heat Pump Basics

Geothermal heat pumps are not what one might think of when the word "geothermal." Unlike the spectacular effects of geothermal energy in places like Yellowstone Park, DX heat pumps use the surprisingly stable year-round temperature of the Earth to heat and cool your home. Because the Earth is constantly collecting solar energy, the ground about 5 feet below the surface is usually around 50 degrees Fahrenheit. Any heat pump operates by extracting heat energy from one side of its operation and depositing it in the other. Unlike air-source heat pumps, which must extract heat from air which might be at a very low or very high temperature, DX heat pumps are always working with one side around 50 degrees. This makes them very efficient and very reliable, even in extreme weather.

The difference between direct exchange heat pumps and other geothermal heat pumps is that, with DX, copper loops are buried in the ground to provide direct heat transfer with the Earth using refrigerant. This requires very little digging (sometimes just a 10 foot diameter circle will do) because the heat transfer from refrigerant to copper pipe to soil is very efficient. So, any DX heat pump utilizes copper ground loops, a small heat pump unit which contains a compressor and a few other mechanical parts, and an air handler or other internal coil which is used to distribute conditioned air or water to the home.

Essentially, a direct exchange heat pump is a refrigerator. You know that hum coming from your fridge? Well, that's the compressor cycling refrigerant through two coils. One of those coils is the big coil on the back of the fridge. It gets hot while the refrigerator is in operation, while a second coil inside the refrigerator gets cold. When a direct exchange heat pump is in heating mode, the air handler inside the home functions as the warm coil. Heat energy is transferred from the ground and into the home through the refrigerant. In cooling mode, the cycle is reversed, and heat from the home is discharged to the ground through the refrigerant, making the indoor coil cold and cycling cool air through the house.

This entire process is very energy efficient. Instead of a large A/C unit and carbon-unfriendly heating oil, year-round heating and cooling needs are performed by a single unit drawing 30-70% less energy than typical HVAC units. With some other additions, heating and cooling your home can be a zero-carbon process, but we'll talk more about that later.


The Green Home

The concept of a green home has become particularly relevant as oil and energy costs rise. Although initial investment is usually much higher than the construction of a standard home, lower energy costs indicate reduced environmental impact while also reducing the load on the homeowner's wallet. As part of an ongoing series, I'll highlight some technologies and ideas which can be used both in new home construction as well as retrofits, with an emphasis on reducing energy use and carbon production.

One simple (and inexpensive) method to increase the efficiency of a home is to collect rainwater in large cisterns. Although rainwater is typically unsuitable for drinking, it can be used for tasks as simple as watering plants or as part of an advanced gray water system. A gray water system uses non-potable water, including rainwater, to operate toilets and water yards, among many other uses. Although the concept makes sense ecologically, it still poses legal questions, so be sure to check local laws and regulations. If you encounter obstacles, write your representatives!

-Marcus