Other Factors that are Measurable
Maintenance Cost Factors are discussed in section 9 and show savings in the 30% to 50% range. These savings have been measured and quantified and are not "simulated estimates".
Full System Cost Factors often are difficult to compare. Note the Geother-mal heat pump ratings both the old ARI and the recently adopted ISO efficiency rating all included the full system level operational costs. Coefficient of Performance (COP) represents these factors. COP being the ratio of the purchased energy to the energy delivered or removed by the heat pump system. These costs include the efficiency of the heat pump but also penalties for water or loop pumping rates and penalties for pressure head in various applications.
When comparing a geothermal heat pump against a chiller system other factors as water pumping, water purchase and chemical purchase must be added to the chiller costs. When comparing a geothermal heat pump against a fossil burning system, remember to include the cost electricity to operate that fossil system.
Geothermal heat pumps are a single source of heating or cooling and in some cases heaters of domestic water. The reduction in operational costs by have a single piece of equipment for these functions should be considered in the evaluation of operational costs.
Life Factors are discussed in section 9.5. Field quantified historical data has evaluated compressors on small heat pumps and have measured a Mean Time Between Failure (MTBF) of 46 years. This is further discussed below.
Adaptation to Restricted Sites - Landmarks Districts in New York City restrict the use of exterior and roof top equipment (no external air conditioning condensers on the building). Often first cost of rigging roof top condensers or cooling towers provide the GeoExchange system with a lower first cost.
The negative Aesthetics of a myriad window air conditioners or a noisy air conditioning condenser on a roof or in a garden is alleviated. Historic buildings or buildings in historic districts where external equipment is not allowed have been provided with air conditioning with no external condensers to mar a building outline.
The personal Comfort Geothermal Heat Pumps provided by a geothermal heat pump system can be tied to superior year around humidity control. Lower winter temperature delivery systems do not dry the air in a conditioned space.
El In the summer, the colder condensers permit substantially colder evaporators with more efficient dehumidification, when compared with conventional air or water-cooled equipment. With better dehumidification, occupants are often more comfortable at higher temperatures which are less costly to maintain.
Safety for buildings and occupants can be traced to the lack of flame heating and the on-site use and storage of flammable gas or fuel oil. Building owners should inquire whether their insurance carrier will offer a reduced fire insurance premium for "no flame heating". In New York City annual boiler inspections and permit fees are saved. Without cooling towers and a condenser water loop, there is no need for algicides or other microbiological control programs, and possibility for the growth of Legionella bacteria.
Component and over all design durability is required from geothermal heat pumps. These heat pumps are designed for wide temperature variations and are fabricated with components that have wider dynamic controls ranges and of alloys and other components that are not found in normal range heat pumps used with circulating loops having a boiler and cooling tower controlling the loop temperature. The additional costs of these enhancements are accounted for above in the geothermal heat pump quantitative cost evaluations. Equipment located indoors is not subject to deterioration caused by the extremes of weather.
Vandalism has no opportunity when there is no component above ground that can be accessed to damage or remove. The vandalism factor is often quantified when considering GeoExchange systems in schools and other public venues.
1 Term for a complete geothermal heat pump system including, earth coupling method, the geothermal heat pump(s) and the terminals in the conditioned space.
2 See www.ghpc.org, the Geothermal Heat Pump Consortium, Washing DC. A consortium of Federal and industrial agencies speaking for the GeoExchange market.
3 M. L'Ecuyer et al, Space Conditioning the Next Frontier, EPA 430-R-93-004, April 1993
4 "Wright Suite" is an integrated software package with components that are the property of ACCA . The package has cost estimating and heat loss and gain and domestic water heating analysis. The package also has integrated earth coupling and radiant floor design software (Wright Soft, Lexington MA). Primarily used for residential and light commercial. The ACCA manual-N (Wright-N), is a literal interpretation of ASHRAE standard xxx.
5 These must be considered only a summary of some of the more popular New York area evaluation programs, is list is not exhaustive.
Definitions and Descriptions of Ground Source Heat Pump Equipment
Ground source heat pumps are space conditioning units that use the refrigeration cycle to heat or cool a medium (air or water), using the earth as a heat source or sink. The refrigeration cycle is reversible, so these units can be used to heat or cool.
The configurations manufactured are:
Water-to-air: water from a ground source is circulated through the unit, and air ducted to and from the space to be conditioned is either heated or cooled.
Water-to-water: water from a ground source is circulated through the unit, and chilled or hot water is circulated to fan coil units for cooling, and to heating elements, radiant floor systems, or fan coils for heating.
Was this article helpful?