A Cooling System defines how a building's spaces are cooled. The system covers how cooling is generated and delivered to spaces. Following is a full list of the current systems options in cove.tool which cover all code baselines and more energy efficiency solutions. To see how each of these systems interact with specific air and cooling systems refer to the System Types article.

Water Cooled Chiller

Chillers are major pieces of cooling equipment found in central plants. Chillers utilize a refrigeration cycle to chill water for distribution around a building and reject heat to another medium. A water cooled chiller rejects heat from a building via a condenser water system and a Cooling Tower. The primary energy source for a water cooled chiller in cove.tool is electricity and electricity is also used by the distribution pumps. Water Cooled Chillers are supported on a wide array of air systems in cove.tool.

Gas Boiler

Furnace

Electric Boiler

Electric Resistance

Air Source Heat Pump

CAV with Reheat

X

X

X

X

VAV with Reheat

X

X

X

X

VAV with Radiant

X

X

DOAS with FCU

X

X

X

X

DOAS with Induction

X

X

X

X

DOAS with Radiant

X

X

X

X

Single Zone

X

X

X

X

Air Cooled Chiller

Air Cooled Chillers are central pieces of cooling equipment similar to the water cooled versions. The primary difference is that Air Cooled Chillers reject heat directly to the atmosphere and therefore do not require cooling towers. They do however need to be located outside, most typically on a buildings roof. Primary energy source is electricity and pumps are also used to distributed the chilled water through the building. Air Cooled Chillers are supported on a wide array of sir systems in cove.tool See this article for a more in depth comparison between Air and Water cooled chillers.

Gas Boiler

Furnace

Electric Boiler

Electric Resistance

Air Source Heat Pump

CAV with Reheat

X

X

X

X

VAV with Reheat

X

X

X

X

DOAS with FCU

X

X

X

X

DOAS with Induction

X

X

X

X

DOAS with Radiant

X

X

X

X

Single Zone

X

X

X

X

Ground Source Heat Pump

A Ground Source Heat Pump (GSHP) uses the constant temperature of the Earth's crust to exchange heat instead of the air, which temperature varies throughout a day and the year. By utilizing this constant temperature difference the heat pump is able to achieve a higher and more consistent COP than an air source equivalent. Typical GSHP access this constant temperature through boreholes which can range from 100 to 600 feet deep and must be spaced at least 20 feet apart. These boreholes lead to high construction costs that must be offset by the energy and cost savings. The heat pump itself can provide heating hot water, chilled water or both. Like a standard chiller the heat energy is distributed by water with electric pumps used for the circulation. More about GSHP on energy.gov

GSHP

CAV with Reheat

X

VAV with Reheat

X

DOAS with FCU

X

DOAS with VRF

X

DOAS with Induction

X

DOAS with Radiant

X

Packaged DX

A Packaged DX systems includes a direct expansion cooling unit attached to an air handling unit to provide cooling and ventilation via the same equipment. Typical applications include roof top units and single zone AHU. The advantages of a packaged system come from the single source and majority factory assembly of the equipment which can lead to cost and time savings. Packaged DX units do not require a central chiller which means that no pumping energy is required for cooling. As these units reject heat to the atmosphere they must always be located externally. Another disadvantage is the lower COP possible with direct expansion equipment verse a central chiller. Packaged DX can be used with several air and heating system combinations within cove.tool

Gas Boiler

Furnace

Electric Boiler

Electric Resistance

Air Source Heat Pump

CAV with Reheat

X

X

X

X

CAV with Radiant

X

X

VAV with Reheat

X

X

X

X

Single Zone

X

X

X

X

Variable Refrigerant Flow

Variable Refrigerant Flow (VRF) providing heating and cooling via room units. See this article for details about this unique HVAC solution.

Cooling Tower

A cooling tower is a heat rejection device that can be coupled with other equipment to provide cooling to a project. One approach, described above is to pair with a chiller, however another option is to connect the condenser water loop to heat pumps throughout the building which provide the conditioning to supply air and spaces. cove.tool enables the modeling of several of the typical approaches for a cooling tower system:

Gas Boiler

Electric Boiler

DOAS with VRF

X

X

DOAS with WSHP

X

X

Direct Expansion

Direct Expansion is the most fundamental form of cooling in a building. It utilizes a refrigeration cycle to cool zones within a building. Examples of Direct Expansion (DX) are window AC units you may see in older homes and mini split systems which local the condensing portion remotely. DX is most typically paired with natural vent or other min outdoor air systems. cove.tool supports DX with the following air and heating systems:

Gas Boiler

Electric Boiler

Electric Resistance

ASHP

Natural Vent

X

X

X

X

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