Learn Why Geothermal Works So Well
Frequently Asked Questions About Geothermal Systems
The exact cost of a geothermal heating and cooling system depends on many variables. Geothermal typically costs more to install than traditional HVAC systems, but the difference in upfront installation cost is often returned to the owner within 3-7 years due to drastically lower operating costs. In new construction, any increase in mortgage payment due to installing a properly sized, designed and installed geothermal system is immediately offset by lower energy costs, creating a cash flow positive investment from day one.
Many government agencies and electric utility companies offer valuable incentives to encourage private property owners to install geothermal systems. Most of these incentives are offered in the form of tax credits, tax deductions, cash rebates and preferred financing. The exact incentives available typically depend on property location, property type and utility service provider. Federal tax credits for geothermal systems of 30% for residential properties and 10% for commercial properties are in place through 2016. Contact us today for the most current information.
The pipe buried underground to exchange heat with the Earth is made of high-density polyethylene (HDPE) plastic. HDPE geothermal pipe is ultra-durable and is typically guaranteed for 50 years or longer. HDPE is the same material often used for underground natural gas and water lines, with the main difference being pipe diameter and color – geothermal HDPE is black, while natural gas lines are colored yellow, and water lines are blue.
Water is the primary fluid circulated in the ground loop to exchange heat with the Earth. In cold climates, appropriate amounts of an antifreeze solution are added to the water to keep the fluid from freezing as the pipes come near the surface to enter the building. Where Steady State™ works, non-toxic, environmentally friendly food grade glycol is sometimes used as an antifreeze agent if needed. In warm climates, ground loops usually do not need any antifreeze at all with the water.
According to the International Ground Source Heat Pump Association (IGSHPA), geothermal systems are 50-70% more energy efficient than competing heating systems, and 20-40% more energy efficient than available air conditioning systems. The exact dollar amount that can be saved depends on many variables including the heat loss and heat gain of the building itself, the efficiency of existing or other proposed HVAC equipment, other heating fuel types available (i.e. natural gas, propane, fuel oil, electric, etc.), and the current and projected costs of these alternative fuels and electric rates in your location. Steady State offers comprehensive analysis of all available alternatives to determine how the economics of geothermal systems should work out for your project.
Geothermal ground loops can be designed and constructed in several configurations. When land is plentiful (i.e. 1-2 acres for a single family home), and horizontal trenching or boring is not too difficult due to extremely rocky or sandy soils, a horizontal system is often a good alternative to vertical drilling. When land area is limited, vertically-bored ground loop systems are usually required. If a property has a large pond that holds a significant mass of water year-round, and the building to be heated and cooled is sited within several hundred feet or so, a pond loop may be an attractive option.
Yes. It is possible to use an existing or new water well to transfer heat between the ground source heat pump unit and the Earth. This type of “open loop” or “standing column” system can be an initially more affordable alternative to horizontal trenching or vertical boring. However, the effectiveness of this type of system is highly dependent on the quality and quantity of the water provided. Minerals and other impurities in the groundwater supply can build up within the heat pump unit over time, reducing operating efficiency and causing premature equipment failures and maintenance issues. In addition, a second “injection well” may be required to dump the used water back into the ground if a nearby stream or pond is not available, adding to the cost of an open loop geothermal system. Steady State only works with “closed loop” systems to ensure long-term operating efficiency, thermal comfort and equipment life.
Yes. Properly designed and constructed horizontally trenched or bored ground loops can deliver identical operating efficiencies. However, since horizontal loops are buried at much shallower depths (4-8 feet) than vertical loops, horizontal loops may be more exposed to changes in ground temperature and moisture, which can affect system operating efficiency. Most experienced geothermal designers and installers will often compensate for these variables by making the pipe lengths slightly longer than for vertical piping, which may add to the cost of a horizontal system. It is important to note that horizontal systems must be VERY carefully back filled to ensure that the pipe is not damaged by rocks, and to allow for proper contact between the pipe and ground to ensure adequate heat transfer.
Under the right conditions, horizontally trenched or bored geothermal ground loops may cost less to install than a vertically bored system. If a person has sufficient land area to work with, and the land is not so rocky or sandy that horizontal trenching or boring becomes cost prohibitive, then a horizontal system may be cost-effective. A horizontal system can also be very affordable for the property owner who owns, or has access to, a backhoe, trackhoe, chain trencher or road boring rig, and has plenty of extra time on their hands. Coordinating the installation of a horizontal geothermal loop with road, utility or other excavation is another great way to reduce the cost of horizontal systems.
Geothermal HDPE pipe is typically offered in diameters ranging from 3/4 inch to 2 inches. Residential ground loops are typically constructed with 3/4″ pipe, while commercial projects are often designed to use 1″ or 1 1/4″ pipe.
The required depth of the ground loop depends on many variables, including the configuration of the ground loop (i.e. vertical vs. horizontal), the size and heating loads of the building being served by the geothermal system, the available land area, and the diameter of the pipe, among other considerations. On average, the geothermal boreholes for a vertical system are drilled to depths of 200-400 feet, but may go down as far as 600-1000 feet for large commercial projects with limited land area for drilling. Horizontal piping is often buried at depths of 8 feet, 6 feet and 4 feet, depending on a number of variables.
Due to the invasive nature of underground construction, it is impossible to install a geothermal system without leaving at least a small impact on a lawn or landscape. However, today’s innovative geothermal installers can minimize damage to existing turf, landscapes, hardscapes and trees by utilizing lightweight, compact and powerful drilling equipment. Both horizontal and vertical ground loops can be affordably installed with minimal impact on the environment using state-of-the-art drilling technology.