Jargon: Ground Source Heat Pump

According to the International Ground Source Heat Pump Association a

"ground source heat pump (GSHP) is an electrically powered system that taps the stored energy of the greatest solar collector in existence: the earth. These systems use the earth's relatively constant temperature to provide heating, cooling, and hot water for homes and commercial buildings."

In Las Vegas for example, to cool a space a standard heat pump must take heat from the interior spaces and move it to a heat sink. The heat sink is typically the air outside, and the higher the temperature of the heat sink the more energy is required to operate the heat pump. With ground source heat pumps the heat sink is the cool earth starting about 5'-8' below grade. Other sources of heat sinks include domestic water, ground water, ponds or lakes, and even sewer systems. I can imagine a system that uses a pool as a heat sink thereby saving heating costs for the pool.

More often this would be achieved by drilling an array of dry wells into the site and installing closed loop piping (often copper) packed in a heat conductive slurry (often bentonite) connected back to the heat pump by a system of valves and pumps. In Geothermal Heat Pumps Provide Sustainable Alternative for Architects, Russell Boniface explains energy costs for heating and cooling can be reduced by 40-70% with a properly design GSHP system. While this provides significant savings to an owner it may still be difficult to justify added up front costs of the system. Lenders and commercial leases are just beginning to take into account these energy and operational savings when evaluating the cost of these systems.

(Image at right from DavidDarling.info)

In their book Geothermal Heat Pumps, Oschner and Curtis provide an overview of design and installation of GSHPs. They demonstrate that GSHPs generate 20-25% of the CO2 of standard heat pumps and obtain their energy saving from a truly renewable and secure source. A properly designed GSHP system may actually provide construction cost savings by down sizing emergency power requirements of projects like data centers and medical facilities. So you can save costs by going green!

Keep in mind that the phrase used to identify this technology varies in different markets; Wikipedia redirects you to geothermal heat pump, some builders use geoexchange, and others geothermal exchange or simply gx. Also, as this technology is often new to many designers and contractors, so you should seek out experienced professionals for advice.

Additional resources: US Department of Energy, US EPA Energy Star, and Natural Resources Canada
Normally, you can find additional information at the Geothermal Heat Pump Consortium but as of this writing their website is down.

This article has also published in the June 2008 issue of the AIA Las Vegas Forum Newsletter.

Paul Cline, AIA is an architect and builder in Las Vegas, Nevada. He is a member of the Young Architects Forum Advisory Committee and writes on issues of community, sustainability, and innovation in design and construction.

Jargon: Frost Line

Frost line and frost line (Wikipedia)

I was listening to the radio program Living on Earth and heard about The Home Ground Project which collects evocative definitions in their series The Language of Landscape. I heard Eva Saulitis of Homer, Alaska define frostline in a wonderful way, new to me. [Listen here.] It prompted me to give you my definition as well.

In architecture and construction foundations are critical to the success of any project. In this context the frost line is the depth below the surface that the ground freezes. I understand that the term originates from visual inspection of groundwater wells. You could actually see frost down the walls of the well.

Knowing the depth of the frost line is important in foundation design because soils increase in volume when they freeze (just like that soda that exploded in the freezer). If the primary foundation elements are above the frost line your whole house will move with the freeze and thaw cycle. If it is too expensive to dig below the frost line your structural engineer can look into shallow foundations intended to work with the freeze thaw cycle. For practical purposes the local building code may set an official frost line based on the worst freeze in the past 99 years.

If you are interested in more definitions from Home Ground: Language for an American Landscape check out their website The Home Ground Project or listen to previous entries from Living on Earth.

Jargon: Punch List

Punch List and Punch List (at Wikipedia)
In construction the punch list comes before the owner accepts the building. The building is ready for the owner to occupy but may have some details that need to be corrected, repaired, or replaced. The Punch List lists these items for the contractor to correct. Generally the item does not meet the quality standard of the inspectors which can be the architect, the owners, or both.
Sometimes the item may not constructed according to the design but the owner can live with it. In this case it is appropriate for the contractor to offer a fair credit for the work installed incorrectly as a condition of acceptance by the owner.

Jargon: Scope of Work

Scope of Work
The Scope of Work is the part of the contract that explains what work is to be completed in agreements with architects, designers, contractors, and subcontractors.
You should understand what it says. It is what you are agreeing to pay for (and nothing else).

These descriptions might be an exhibit or ammendment to a contract or in the body of the contract. They can be very detailed or general in their language. It might be called Scope of Work or Work Scope but it can be called anything or nothing. This description is the first place you will go to when you disagree about what is included in the price you've agree to pay.

Developing the General Scope of Work on the AIA Kansas Website

Jargon: Programming

Architectural Programming
Architectural Programming is an essential step in the design process. It includes developing an understanding of what uses a building will encompass and how they are related and it results in an objective outline that describes the scope of the design project. During the programming phase of building design you define the problem which the design is meant to solve.