A Complete Guide: Wine Cooling 101

Before deciding on the best wine cooling system for your application it is important to first understand wine cooling 101. Having this knowledge will empower clients to better work with architectural designers and contractors to build their dream wine storage spaces. In order to select the best temperature and humidity control solution, it is beneficial for wine lovers to understand how the technology operates and to consider the options when the room is still being planned.

Constructing a Wine Storage & Aging Space

Whether you are envisioning a wine display or cellar, the goal is to create an air-tight space. Since the insulation of the room is critical in calculating the heat load, there are several factors that should be considered before construction begins.

Vapor Barrier

The vapor barrier is a thin layer of plastic installed on top of the wooden frame enclosing most wine cellar applications. The barrier serves to keep moisture out of the room and helps to control humidity levels.


Wine cellar insulation goes on top of the vapor barrier and is not unlike what is used in residential spaces (in most cases). Insulation can vary in thickness and is meant to control both temperature and humidity. The floor of a wine room should also be insulated if space is available. In general, the quality of insulation impacts the heat load, which dictates the size of a cooling unit.


Double-paned glass, exterior-grade doors, and tightly sealed thresholds are a few of the finishing touches needed to ensure a closed wine cellar environment.

Environmental Considerations

There are several key factors to consider before selecting the appropriate cooling unit for your application.

Size of Space

The size of the wine storage space determines the size of the cooling capacity. Wine Guardian, and many general climate control experts, offer heat-load calculators that provide guidelines based on your specifications. Do not select a cooling unit based exclusively on the volume of the wine room, since that will omit other critical considerations.

Volume and Type of Glass

An application with more glass may be more challenging to keep cool than one with only a glass door. Moreover, the type of glass will also determine the unit. Plate glass will require a cooling system that is able to work harder than a display made of insulated glass.

Ambient Temperature

Outside air temperature is also referred to as ambient temperature and it plays an important role in determining the size of a system. The optimal temperature for long-term storage and aging of wine is 55-58°F (12-14°C). If your home or business is in a hot climate you will require more cooling capacity than if the location is in a cold climate. Cooling units that are “too small” (lower capacity than the wine cellar requires) may run excessively and lower the relative humidity too much, while systems that are “too large” (much more capacity than the wine display requires) may cool the space very quickly but keep it from being dehumidified properly.


Humidity is a factor in the long-term storage of wine. Too much of it can cause mold and glue on labels to break down. Too little humidity can result in cracked corks, which leads to evaporation and degraded wine. Standard HVAC systems (including wine cellar cooling units) can remove humidity during their normal function but they cannot add humidity back. While effective door seals help ward off humidity issues, a cooling unit with built-in humidity control is necessary to increase humidity levels—especially in drier geographic areas and during certain times of the year.


Lighting is a key factor in determining the correct size of a cooling system. Lights generate heat, which means a wine display may need a cooling unit with more capacity to compensate for the added heat.

Climate Control Technology

At a high level, climate control technology essentially functions in a closed loop. One half of the system absorbs heat from the wine cellar, while the other half rejects heat out of the system. To make this happen coolant (also known as refrigerant) flows through the unit and undergoes changes in pressure that enable it to absorb and reject the heat.

Basic Terminology

There are four key components in any wine cooling solution that play vital roles in this process: compressor, condenser, metering device, and evaporator.


The compressor utilizes pressure to transform low temperature, low-pressure vapor refrigerant into a high temperature, high-pressure gas. This process produces extra heat and serves to also keep the coolant moving.


As this hot, high-pressure gas passes through the condenser two things typically happen. First, warm hair generated by the compressor is passed over the condenser coils via a fan and is vented out of the system through a duct or grill. Then, as the coolant continues through the condenser with the heat being vented out, the vapor cools and turns back into a liquid. The condenser may be located adjacent to the wine room, in a separate space, or even outdoors.

Metering Device

The metering device decreases the pressure of the coolant once again. As the pressure drops so does the temperature. Along with the compressor, the change in pressure the coolant experiences in the metering device is what keeps it flowing through the system.


At this stage, the lower pressure, lower temperature coolant enters the evaporator and is primed to absorb heat that is blown in from the wine cellar. Once the evaporator has extracted the heat a fan supplies cool air back into the cellar and the coolant increases in temperature. By the time the coolant has passed through the evaporator coils, it has returned to low pressure, low-temperature vapor, and the cycle is repeated.

Wine Cooling Solutions

There are a variety of solutions that meet the needs of the vast majority of a wine cellar, room, or display applications, both residential and commercial grade.


Through-the-wall (TTW) solutions are self-contained units, which simply means that the condensate evaporation systems are integrated. These solutions are easily mounted directly into a wall through a metal sleeve, feature a plug-and-play design, and have the added bonus of being do-it-yourself (DIY) friendly. TTW systems are ideally suited to smaller applications since their cooling capacity is limited.


Ducted systems are self-contained cooling units designed for maximum installation flexibility. The evaporator and condenser functions are housed completely outside of the wine cellar in an adjacent, or even more remote, space. A grille within the cellar or wine room is connected to the mechanicals via insulated flexible ductwork. Ducted systems have the most powerful cooling capacity, which makes them perfect for large cellars or commercial use.

Ductless Split

Ductless split systems indicate that the condenser and evaporator functions are not integrated. Similar to the ducted split, the mechanicals is separate. What is unique to the ductless split is that the evaporator portion of the system has a small footprint and can be surface, ceiling or through-the-wall mounted. These systems are perfect for smaller wine cellars with limited space available for mechanical equipment or if ductwork cannot be accommodated. Unlike ducted or through-the-wall applications, all split systems must be installed by a certified HVAC or licensed electrician.

Water-Cooled Systems

While most cooling solutions utilize air as the medium to absorb heat, certain applications are ideal for water-cooled units. These systems remove the need to exhaust heat but require a year-round supply with inlet water temperatures between 45°F to 85°F (7° to 30°C). For wine applications near a lake, cooling tower, or geothermal source, a water-cooled system offers flexibility in where to mount the unit as well as a more energy-efficient option for air-cooled solutions. Moreover, water-cooled options are ideal when space to vent warm condenser air is limited.

Now that you have the basic components of wine cooling technology under your belt, you can make the foray into building a wine storage space and selecting a complementary cooling system with more confidence. We are here for you every step of the way.

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