An Introduction to Propane Cooling  

Using propane cooling to achieve grid independence, add resilience, and save money

Sponsored by Propane Education and Research Council | By Amanda C Voss, MPP

Photo courtesy of Robur Corporation

Alleviating strain on the grid while providing security during power outages—propane cooling combines a clean fuel source with unique sustainability attributes. 

 

The Climate and Power Use Conundrum 

Blackouts. Brownouts. Prohibitions against charging EVs. Exponential energy surcharges during peak hours. Businesses closed or facing lost revenue and product. 

These headlines inevitably dominate the news cycle as the weather heats up. Rising temperatures strain an already aging and overburdened electrical power grid: “Adequate energy supply can be impacted in several ways, primarily by high temperatures which causes increased air conditioning use and drives up electricity demand,” states the California Independent System Operator (ISO). “Other factors include unexpected power plant or transmission line outages caused by mechanical failure, wildfire, or constraint on transmission lines.” 

Beyond complete power outages, severe limits are often placed on power usage. “California Governor Gavin Newsom is asking all Californians to not charge their electric vehicles between the hours of 4 p.m. to 9 p.m. while California grapples with an energy shortage as a heat wave bears down on the state,” reported The New York Times. 

California, Texas, and Colorado are among the states that ask residents to turn up their thermostats and turn off their lights during heat waves. And while Western states grab headlines, the rest of the country is not immune to power loss. Brownouts in the Midwest can occur due to grid strain and extreme weather. Electricity brownouts and blackouts are occurring more often and in more places.

Photo courtesy of Robur Corporation

Propane cooling is a viable solution for commercial and industrial applications and is a proven technology that has been used for decades. 

 

Globally, the electric power system is increasingly stressed, witnessing higher demand and reduced capacity due to more frequent occurrences of extreme weather events. Since the majority of U.S. states experience their highest peak loads during the summer, characterizing the climate sensitivity of summer-time electricity demand has become an important pillar in energy adequacy planning. To complicate these calculations, soaring temperatures and increased occurrence of heat waves have drastically increased air-conditioning demand. 

Once considered a luxury, air conditioning is now an essential service, cooling homes, businesses, hospitals, data centers, laboratories, and other buildings vital to the economy and daily life. In fact, air temperature is so critical that 48 percent of all energy consumption in American homes is a result of cooling and heating, according to the Energy Information Administration. Because of rising temperatures, air conditioning is now a necessity in many commercial buildings and regions that didn’t typically have large cooling loads. 

The pressure is on to design and provide clean, resilient cooling that avoids the grid. A solution that is site-based technology adds further resilience. Propane cooling has the unique advantage of demonstrable environmental, economic, and equipment performance that can satisfy these demands today. 

 

Using Heat to Chill: Understanding System Basics 

A Brief History of Air Conditioning Technology 

The first commercial air conditioner was developed by Willis Carrier in 1902 in an effort to control humidity at Sackett-Wilhelms Lithographing and Publishing Company in Brooklyn, New York. By the 1970s, air conditioning technology had been refined and expanded, serving buildings from massive warehouses and theaters to single-family homes. The air conditioning technology powered by propane operates on the same principles as electricity-based models and has been used for decades. 

Propane cooling technology dates to the early days of refrigeration, with propane being used as a refrigerant alongside other natural options like ammonia and sulfur dioxide. The first commercially available propane refrigerators were introduced during the 1930s under the brand “Servel” and gained popularity due to their ability to function without electricity in areas lacking power access. Natural gas and propane-powered air conditioners arose during the 1960s, primarily powering commercial buildings, including a series of shopping malls in Kentucky, Ohio, and Florida, and the Los Angeles County Museum of Art.

American Gas Association magazine advertisement for a natural gas cooling system installed at the Los Angeles County Museum of Art.

 

For propane-fueled air conditioning, the cooling technology operates like a traditional, electric-powered system and simply substitutes propane as the energy source to power the compressor or ignite the gas burner. 

Propane cooling systems are readily available on the market today in sizes ranging from 5 to 400 tons. Cooling systems are measured in tonnage, versus a measurement in BTUs for heating systems. One ton is equal to 12,000 BTUs. The cooling tonnage required for a building is dependent on its geographical location. Cooling systems in regions with a hotter climate and longer cooling season require more tonnage. The building size will also play a significant factor. Today, propane-powered cooling systems have numerous end uses, from comfort cooling to process cooling to refrigeration, and operate well in a wide range of ambient conditions, providing the flexibility of gas cooling systems in various climates and environments. 

Modern Propane Cooling Systems 

There are two types of modern propane cooling methods: engine-driven and absorption. Question 2 To understand these methods, it is important to understand how a standard electric-powered air conditioner works. Air conditioners are designed to not only cool the air but also dehumidify it to improve comfort. Air conditioners operate similarly to refrigerators, transferring heat from a building’s interior to the outside environment. The essential components of an air conditioning unit are its Evaporator Coil, or Indoor Coil, which is the cold coil that absorbs heat from the indoor air. The Condenser Coil, or Outdoor Coil, is the hot coil that releases absorbed heat outside. The Compressor is the electric motor-driven pump that circulates refrigerant between the evaporator and condenser. This design is an engine-driven system. During operation, the refrigerant evaporates inside the evaporator coil, absorbing heat from the indoor air and cooling the building. The heated refrigerant gas is then pumped to the condenser, where it releases heat to the outside air and reverts to a liquid state. 

Photo courtesy of Robur Corporation

Propane cooling systems are readily available on the market today in sizes ranging from 5 to 400 tons. The equipment has numerous end uses, from comfort cooling to process cooling to refrigeration, and operates well in a wide range of ambient conditions. 

 

Propane Engine-Driven Cooling 

The typical electric air conditioning system uses an electric motor to engage the compressor to start the refrigeration process.  Propane equipment operates in the exact same manner, merely replacing the electric motor with a natural gas or propane engine.  This gas-driven engine engages the compressor to start the process. The remainder of the cooling process is identical to that of electric air conditioning equipment. Engine-driven systems typically have larger tonnages and are used in commercial buildings.

Image courtesy of The Propane Education & Research Council 

Engine-driven propane cooling is a mechanical process using the same technology, but with different fuel, as traditional electric-powered air conditioning units. 

 

Propane Absorption Cooling 

Absorption, on the other hand, is a thermal process. An absorption cooling system uses a gas burner to ignite and then heat a solution of water and ammonia. The ammonia has a lower boiling point, so it boils off and becomes high-pressure water vapor. In this method, chilled water is used for cooling rather than a refrigerant. 

Very little electricity is required for either of these processes. Choosing propane-powered air conditioning, whether engine-driven or absorption, provides grid relief, energy independence, and resiliency. 

Image courtesy of The Propane Education & Research Council 

Absorption cooling is a thermal process, versus the mechanical process used by engine-driven cooling. 

 

Codes and Standards 

CSA/ANSI Z21.40.4-23/CSA 2.94-2023, “Performance testing and rating of gas-fired air-conditioning and heat pump appliances,” is the most recent standards update governing propane-powered air conditioning, heat pumps, chillers, and other equipment. As propane cooling has both an established and demonstrable history, its performance is easily verified.

Additionally, all propane installations are governed by NFPA 54. NFPA 54/ANSI Z223.1, National Fuel Gas Code, offers the latest comprehensive provisions for the safe design, installation, operation, maintenance, purging, and inspection of gas piping, equipment, accessories, and appliances supplied with fuel gas. The code covers piping system design, materials, and components, pipe sizing and installing pipes underground, above ground, and inside concealed spaces, and piping inspection, 

testing, system leak check, and purging. NFPA also addresses requirements for process air and installation of appliances and minimum safe performance criteria, general requirements, and specifications for venting combustion products. NFPA provides the industry benchmark for safe storage, handling, transportation, and use. Adhering to the provisions mitigates risks and ensures safe installations that prevent failures, leaks, and tampering.

 

The Benefits of Being “Chill”: Benefits of Propane 

Photo courtesy of Tecogen, Inc.

An air-cooled chiller unit powered by propane. 

 

The U.S. Energy Information Administration’s (EIA) Commercial Buildings Energy Consumption Survey (CBECS) provides data on energy sources and types of equipment used for cooling and energy consumption for cooling in U.S. commercial buildings, including electricity consumption. According to the most recent CBECS, in 2018, electricity consumption for cooling accounted for about 14 percent (170 billion kWh) of total electricity consumption in U.S. commercial buildings. An additional 18 percent (213 billion kWh) of electricity was consumed for ventilation, some of which involves moving the cooled air through commercial buildings.

EIA’s Manufacturing Energy Consumption Survey (MECS) provides data on how much energy is consumed across heating, ventilation, and air conditioning (HVAC) in U.S. manufacturing facilities from multiple energy sources, including electricity. According to the most recent MECS, in 2018, electricity consumption for facility HVAC accounted for about 8 percent (76 billion kWh) of total electricity use at U.S. manufacturing facilities.

The amount of energy consumed by air conditioning and cooling places a heavy economic and infrastructural burden on businesses and commercial buildings. When faced with today’s energy outlook of rising demands and prices and limited infrastructure investment, propane cooling creates a viable conditioning solution for many commercial applications. Because propane cooling systems significantly reduce electricity requirements, they are also ideal in areas faced with high electric rates and limited infrastructure.

Benefit: Grid Relief

The ever-increasing demands and inadequate supply of electricity make propane a perfect alternative energy solution. Propane cooling reduces a facility’s electricity use, freeing capacity for other loads, such as EV charging stations. The reliability of the electric grid is also improved, particularly during peak summer demand. 

Additionally, for buildings looking to revitalize older neighborhoods or those built in rural areas, choosing propane frees the property from connecting to the grid or stressing a limited local infrastructure. This provides clients with a more diverse choice of business location.

Benefit: Resiliency 

When paired with a backup generator, propane systems continue operating during electric power outages, ensuring resiliency in mission-critical applications. Many units feature built-in modularity and redundancy, maintaining performance even during service disruptions. 

In areas where natural disasters occur, many projects have discovered the value of marketing more durable structures. This is certainly true for net-zero or off-grid developments that may utilize multiple forms of power, including solar and wind. Propane offers a powerful, reliable way to protect workers, their products, and businesses from the damage a power outage can cause. 

Economic Benefits 

Propane is a domestic resource and in high supply, so pricing is consistent and competitive with other energy sources. Selecting propane-powered cooling equipment instead of electric-driven air conditioning provides a huge reduction in electrical power consumption; depending on the equipment manufacturer, this reduction can range from 80 percent to 90 percent. Picking propane also avoids costly electrical upgrades and expenditure of capital costs when faced with a lack of utility infrastructure. Choosing propane for cooling can also avoid the possible addition of substations or extension of pipelines to the site, which can be cost-prohibitive. Savings on electrical loads allow commercial building owners to consider adding other propane-powered loads, such as EV car charging stations and water heating, building heating systems, and standby power.

Many commercial building types are required by code to install and maintain backup generators. When a building’s cooling is propane-powered, the size of backup generators can be greatly reduced. Having propane cooling also offers the potential for a complete off-grid operation. Propane generators, coupled with propane cooling, offer grid independence. By eliminating excessive demand rates or surcharges during peak electric usage and through reducing backup generator expenses, propane cooling lowers operating costs. Its seamless integration with existing infrastructure also avoids costly upgrades.

Finally, propane equipment is about 30 percent more efficient than traditional electric-powered air conditioners. Designing a system to run on propane generates immediate savings on project air conditioning costs. For large commercial systems, multiple cooling units can operate independently, which provides redundancy if one unit goes down. This is especially vital for commercial businesses that will lose profit if operations are interrupted or equipment is damaged. There are also equipment options to incorporate the recovery of hot water from the cooling process and reuse it in process applications. Instead of having two pieces of equipment, such as a furnace or boiler and an air conditioner, buildings can have one system that does both.

 

It IS Easy Being Green: Environmental Benefits 

Photo courtesy of Robur Corporation

Propane cooling is scalable and redundant – if one unit goes offline, the rest will continue to function, offering protection to operations.

 

Because air conditioning can demand high amounts of energy consumption, the source of that energy is particularly important when calculating a building’s environmental profile. Propane is a high-performing, safe, and cost-effective energy source. Propane has lower carbon emissions than fuel oil, diesel, and even electricity. In fact, 60 percent of the U.S. electric grid is still powered by natural gas or by coal, sources that create high carbon emissions. Propane cooling reduces reliance on coal and natural gas to produce electricity. As a clean energy source with low carbon emissions, propane can provide substantial emissions reductions and environmental benefits.

All things electric, from vehicles to appliances, remain in the spotlight. However, it is important to understand that switching equipment to electricity does not automatically equal de-carbonization. Electricity must be generated by a primary energy source, and in the U.S., natural gas and coal are electricity’s largest primary energy sources. Because electricity is a secondary energy source generated using a primary energy source, labeling electricity as the most environmentally friendly energy available is far from accurate. Furthermore, once generated, electricity must be transmitted through power lines, where electrons encounter resistance and lose energy. This means that getting one unit of electricity to wherever the plug is located can consume up to three units of source energy. 

The U.S. Department of Energy’s (DOE) Office of Scientific and Technical Information recommends embracing a broad range of opportunities to reduce building emissions, including the use of low- or zero-carbon alternatives. Design teams, builders, and contractors are increasingly navigating energy source discussions with their clients. Decarbonization in commercial buildings will require more clean energy options. The DOE classifies propane as a clean alternative fuel. 

Propane is not mined like battery materials or extracted like oil. It is primarily manufactured from natural gas as a by-product of methane purification. Propane’s low carbon intensity is why it is an approved clean alternative fuel under the Clean Air Act of 1990. Throughout the 20th Century, propane’s adoption grew due to its efficiency, reliability, and environmental benefits. Legislative acts like the 1990 Clean Air Act and the 1992 Energy Policy Act further cemented propane’s status as a clean alternative fuel. Propane is a critical energy source, valued for its stability, clean-burning properties, and diverse applications. Propane is also methane-free, as opposed to natural gas. Over a 20-year period, one ton of methane has a global warming potential that is 84 to 87 times more than CO2 alone. Propane burns cleaner; propane combustion is cleaner than oil, resulting in lower CO2 emissions and 52 percent fewer greenhouse gas emissions for equipment when using propane, compared to an equivalent amount of electricity generated from the U.S. grid. 

Additionally, propane provides resilience, as it is stored on site and is not delivered on demand through the grid or other infrastructure sources. According to the Department of Energy’s Energy Star program, propane has a source-site ratio of 1.01. It is supplied on site rather than transmitted or piped, so virtually no energy is lost in the transfer. Plus, propane’s storage flexibility means sensitive habitats can remain undisturbed, eliminating the need for pipelines or high-voltage power line installations. Because it vaporizes when exposed to air, stored propane on site does not harm the soil and has negligible effects on the ozone. Similarly, propane poses no hazard to groundwater or sensitive ecosystems. Propane only ignites when in the presence of a specific air mixture and an ignition source above 920 degrees Fahrenheit, making it safer to store than other fuels. Using propane also prevents deforestation by replacing solid fuels such as wood and coal.

 

An Alternative Fuel with Endless Possibilities 

Application Diversity 

In the past, propane cooling was primarily used in greenhouses due to its efficient dehumidification or in high-demand businesses located in remote areas. But there are many other applications for process cooling. Large-scale gas cooling installations can include wineries, distilleries, breweries, and indoor agriculture projects. Other businesses have equipment that must be cooled, such as server rooms, commercial printing facilities, dry cleaning facilities, and MRI machines in hospitals, among others. Industrial and commercial applications such as these require a great deal of process cooling, and the resulting electric rates can be astronomical. Propane cooling, on the other hand, offers market-specific operational cost savings.

“Propane-powered technologies like cooling and CHP systems are transforming how businesses approach energy. This propane equipment offers unmatched reliability and efficiency, especially in today’s energy landscape,” said Bert Warner, director of commercial business development at the Propane Education & Research Council.

When building owners want to add cooling to schools, churches, offices, assisted living facilities, multifamily residences, healthcare, hospitality, or restaurants but don’t have the electric load to handle it, propane cooling steps in. In many regions, it is more economical to incorporate a propane tank and propane cooling system because it does not require large capital infrastructure upgrades to the electrical panel or substation. An added bonus is that in large commercial systems, multiple units can operate independently, which provides redundancy if one unit goes down. This is especially vital for commercial businesses that will lose profit if operations are interrupted or equipment is damaged. There are also options to recover hot water from the cooling process and reuse it in process applications. Instead of having two pieces of equipment, such as a furnace or boiler and an air conditioner, the building can have one system that does both.

Propane cooling offers complete connectivity to a building management system (BMS) control system or building automation system (BAS) that monitors and controls a building’s electrical and mechanical systems. This allows it to integrate within existing controls, if desired.

Propane cooling systems can meet various needs, such as comfort conditioning, process cooling, dehumidification, medium-temperature refrigeration, and extreme ambient operations. Target applications include areas with limited electric capacity/infrastructure, multifamily and custom residential applications, healthcare, education, hospitality and restaurants, indoor agriculture, data centers, and mission-critical centers. Propane cooling also provides a unique outlet for churches or historical buildings being retrofitted for air conditioning. These buildings often face 

limited wiring, panels, and infrastructure supply. Using propane creates an economic path to condition the space while preserving the structure.

New Technology 

Emerging equipment systems and applications will provide new ways to move efficiency forward. Propane makes new technologies, like ultra-efficient Combined Heat and Power (CHP) technology, possible. CHP refers to on-site generation capable of providing reliable electricity. Unlike centralized electrical generation plants that operate at only 33 percent efficiency, CHP systems capture heat and achieve total system efficiencies of 60-80 percent for producing electricity and useful thermal energy. Some systems can achieve efficiencies approaching 90 percent. Almost no energy is lost as it travels from tank to application. The DOE Energy Star program gives propane a source site ratio of 1.01, compared to 3.03 for electricity from the grid. This means it takes 3.03 units of electricity to produce and deliver one unit of energy to a building, compared to only 1.01 units to deliver one unit of energy for propane. This advanced technology can significantly reduce energy costs, lower greenhouse gas emissions, and provide reliable on-site power. The lower operational costs of this equipment provide an affordable option for business owners looking to increase efficiency and sustainability.

Advances in Renewability 

Using propane as an energy source means harnessing an available clean technology to reduce emissions while still meeting energy needs. Propane is clean and non-toxic. Propane is abundantly available, and the growth of renewable propane means it can be used for generations to come. 

Renewable propane provides a truly renewable energy source because it is made by converting plant and vegetable oils, waste greases, and animal fat into fuel. This not only circumvents disposal of waste grease and oil, but it also allows for a circular energy source. Renewable propane has the same great features as conventional propane—reliability, portability, power, and reduced carbon emissions—but with even lower carbon emissions when compared with other energy.

 

Case Study: Providing cool treats in the heat

The Barbados Ice Cream Company Ltd. (BICO LTD) is the leading Barbadian manufacturer of frozen desserts. The company, located near the Harbour Port Office park in Bridgetown, was started in December 1901 as the Barbados Ice Company Limited, which made ice, and started making ice cream in 1949.

BICO LTD, during retrofit works, decided to adopt propane-fueled chilling units, installing 6 chillers with heat recovery and 3 low-brine chiller models. These units provide comfort conditioning of the offices and for the warehouse, generate the cooling necessary for freezing ice cream mixes, and deliver cooling of the pasteurizing mixing tanks. Free heat recovery hot water is used for cleaning items inside the facility. The total cooling BTU/h range is more than 34 tonnes.

The business recognized multiple advantages from the new units, including operational cost savings; minimized electric demand charge; zoning flexibility and comfort; modular redundancy; and application process usage.

 

Case Study: Keeping cool on Martha’s Vineyard

A beautiful, contemporary summer home overlooks Chappaquiddick in Martha’s Vineyard. Designed as a family refuge, the home provides entertainment during any rainy days that the island may experience. The home’s lower level includes a full game room, complete with its own Photo Dark Room, and a Bowling Alley with a built-in scoreboard. 

The exceptional surroundings require exceptional cooling equipment to maintain comfort inside and harmony outside. A modular chiller unit with a capacity between 14 and 34 tons was the ideal choice to satisfy the designer and homeowner.

The new gas absorption cooling system makes it possible to additionally provide chilled water, enabling ease in design for modern residences featuring many amenities. The chiller installed outside produces chilled water for cooling the interior spaces. To provide cooling, small, insulated water lines are piped to strategically located air handlers inside the residence, avoiding the need for large and cumbersome duct runs. This conditioning strategy was picked as the best solution to maintain comfort, aesthetics, and the architectural integrity of the home’s interior. Scattering numerous electric air conditioning units was never an option for this residence.

The selected unit was chosen to provide chilled water to the 12 zoned air handlers located throughout the home’s expansive 15,000 square foot space. Each zone is controlled by its own thermostat. That specificity allows the chilled water to air condition that area of the home to the occupants’ personal preference. In the wintertime, these same zones are supplied with hot water from a boiler located in an equipment room in the lower level. The exterior chiller system is located more than 200 feet from the house, allowing the exterior quality and appearance of the home to be the focal point of the property. 

A direct digital control (DDC) was picked by the design team and installed, ensuring optimal performance of the cooling system. The DDC generates automatic staging of the modular chillers to match the indoor cooling load, equalizes run times of the chiller modules for longer life, provides an LCD readout display of the system’s operating parameters, and eases any future maintenance. The DDC keeps a complete log and record displaying any fault code history.

 

Case Study: Delivering Environmental and Economic Performance for Indoor Agriculture

Photo Photo courtesy of Tecogen, Inc

A water-cooled chiller unit. 

 

Indoor cannabis cultivation is surprisingly energy-intensive: about 10 times as much as an office building per square foot. It is not just the lighting used to help the plants grow, although that makes up 30 to 40 percent of the energy use. The largest energy use, often making up 50 to 60 percent of the demand, is for cooling and dehumidification. That is because cannabis plants are sensitive to moisture and can grow mildew if the air is too humid.

The high energy demand for dehumidification can send energy costs soaring for cannabis-growing facilities and can even require expensive and time-consuming electrical infrastructure upgrades. Therefore, some growers are turning to an innovative, cost-saving alternative technology: chillers driven by propane or gas.

What is a Gas-Driven Chiller?: Gas chillers are really a form of combined heat and power, or CHP, says Steve Lafaille, vice president of business development for Tecogen. The system uses a propane- or gas-powered engine to drive the compressor in a chiller machine to create chilled water while the waste heat from the engine is recovered to create hot water.

Powering these energy-intensive chillers with more affordable propane or natural gas, instead of electricity, can reduce utility costs by 50 percent, Lafaille says. Perhaps just as importantly, these systems can help growers quickly and affordably retrofit industrial buildings for growing cannabis when the existing electrical infrastructure is insufficient.

That was the case for a cannabis grower in Douglas, Massachusetts, that converted an old factory building that made envelopes to more lucrative cannabis cultivation. Many existing old buildings are electrically constrained and at the mercy of the electrical utility to obtain an upgrade.

“These people have been told 18 months, 24 months, 36 months to upgrade the power,” Lafaille says. But growers don’t have time to wait. “If you look at what’s happening in cannabis, in three years, the price is going to be cut in half on the market. So, time is money in the business.”

Instead, the Douglas grower brought in a propane-powered unit that eliminates the need for additional power from the utility. With natural gas lines eight miles away, the facility used the existing 30,000-gallon propane tank onsite to fuel the unit.

Applications in Agriculture and Beyond: Cannabis cultivation is a smart application for gas-driven chilling because facilities use cooling year-round. The chilled water takes humidity out of the air before it is reheated with hot water created by the unit’s waste heat and a propane boiler, a process that is common in buildings such as hotels and hospitals.

Cannabis growers can even capture the CO2 from the engine exhaust and inject it back into the facility to provide enrichment for the plants. The captured CO2 both reduces emissions generated by the equipment and saves money otherwise needed to purchase CO2 in bulk.

The nature of the business also means that cannabis growers are willing to take risks and try new things, which is one reason Lafaille thinks the technology is quickly catching on in the industry. But gas-driven chilling has applications in other agriculture and commercial markets. Growers of lettuce, leafy greens, and herbs are also using these types of systems, although their plants are not quite as dependent on dehumidification as the cannabis plant.

Gas chillers have long played a role at buildings such as universities and hospitals for comfort cooling, Lafaille says. But he foresees the technology playing a larger role in facilities that use process cooling all the time, such as food and beverage manufacturers. “We’ve really proven that the product can run 24/7, 365 days a year and have a really high degree of uptime and reliability,” Lafaille says. “And that’s what those other process-cooling customers really want to see.”

Resilience and Carbon Footprint Reduction: For businesses seeking to enhance resilience, gas-driven chillers can help reduce not only the amount of electrical infrastructure they need but also the size of their backup power generation equipment. Given the intensive energy demand, many cannabis growers are installing 2-megawatt or 4-megawatt generators to protect the crops they are growing, which may be worth up to $10 million at any given time. By shifting some of the electrical demand to propane or gas, businesses can cut the size of the generators in half, saving millions of dollars by allowing the businesses to purchase more affordable units.

Powering the chilling with high-efficiency propane can also help to reduce greenhouse gas emissions in many parts of the country where the power grid comes from plants burning fossil fuels such as coal. Industry manufacturers aim to put even more control in the hands of building operators with the 2023 launch of a hybrid-drive chiller that can run on propane, gas, or grid power.

This hybrid chiller adds additional resilience by allowing the unit to run on electricity if there is a fault in the engine. Perhaps most importantly, it future-proofs the system by allowing the operator to choose whether the system runs on propane or electric, based on energy costs or carbon footprint considerations. “If the grid is 100 percent renewable in 10 years, great – you can run this thing on grid electric,” Lafaille says. “If all that stuff doesn’t happen in 10 years, you can have the option to still run it efficiently in CHP mode.”

By proving the real-world performance and efficiency of gas-driven chilling, cannabis growers may provide the innovative spark that spreads this cost-saving technology throughout the building industry.

 

 

END NOTES

  1. “Rotating power outages.” California Independent System Operator. 2023. https://www.caiso.com/documents/rotating-power-outages-fact-sheet.pdf. Accessed March 7, 2025.
  2. “Amid heatwave, California asks electric vehicle owners to limit charging.” The New York Times. September 1, 2022. https://www.nytimes.com/2022/09/01/us/california-heat-wave-flex-alert-ac-ev-charging.html. Accessed March 7, 2025.
  3. Vargas, Oscar. “Brownouts and blackouts now occur more often, in more places.” ecoPreserve. January 12, 2025. https://www.ecopreserve.net/brownouts/. Accessed March 7, 2025.
  4. Intergovernmental Panel on Climate Change. (2018).
  5. Maia-Silva, D., Kumar, R., & Nateghi, R. (2020). The critical role of humidity in modeling summer electricity demand across the United States. Nature Communications, 11(1), 1–8. https://doi.org/10.1038/s41467-020-15393-8. Accessed March 7, 2025.
  6. Obringer, R., Nateghi, R., Maia- Silva, D., Mukherjee, S., CR, V., McRoberts, D. B., & Kumar, R. (2022). Implications of increasing household air conditioning use across the United States under a warming climate. Earth’s Future, 10, e2021EF002434. https://doi.org/10.1029/2021EF002434. Accessed March 7, 2025. 
  7. “History of Air Conditioning.” The Department of Energy. July 20, 2015. https://www.energy.gov/articles/history-air-conditioning#:~:text=The %20idea%2of %20artificial %20cooling,of %20air %20in %20textile %20mills. Accessed March 7, 2025.
  8. Strader, Courtney. “The history of propane refrigeration.” Warehouse Appliances. March 31, 2019. https://www.warehouseappliance.com/blog/the-history-of-propane-refrigeration/#:~:text=Propane %20Refrigerator  %20History: %20Who %20Invented,SERVEL %20propane %20refrigerators %20were %20invented.. Accessed March 7, 2025.
  9. “Air Conditioning.” U.S. Department of Energy. https://www.energy.gov/energysaver/air-conditioning. Accessed March 10, 2025.
  10. Ibid.
  11. Frequently asked questions. Independent Statistics & Analysis. U.S. Energy Information Administration. March 15, 2024. https://www.eia.gov/tools/faqs/faq.php?id=1174&t=3. Accessed March 11, 2025.
  12. Ibid.
  13. “Ready to replace your AC? Learn why a heat pump is a win for homeowners using propane.” News & Case Studies. Air Source Heat Pump Collaborative. June 30, 2022. https://www.mnashp.org/ready-replace-your-ac-learn-why-heat-pump-win-homeowners-using-propane. Accessed March 28, 2025.
  14. (2020) IEA - Methane Tracker 2020. https://www.iea.org/ reports/methane-tracker-2020
  15. “Substituting LPG for Wood: Carbon and Deforestation Impacts.” Atlantic Consulting. World LPG Association. July 2018. https://www.worldliquidgas.org/wp-content/uploads/2018/10/Substituing-LPG-for-Wood-Carbon-and-Deforestation-Impacts-Updated.pdf. Accessed March 26, 2025.
  16. (2021) EPA - CHP Benefit. https://www.epa.gov/chp/chp- benefits
  17. (2021) Renewable Propane as a Sustainable Fuel Solution in California. https://www.gladstein.org/renewable-propane- sustainable-fuel-solution-california/.

 

 

Photo courtesy of Robur Corporation

Alleviating strain on the grid while providing security during power outages—propane cooling combines a clean fuel source with unique sustainability attributes. 

 

The Climate and Power Use Conundrum 

Blackouts. Brownouts. Prohibitions against charging EVs. Exponential energy surcharges during peak hours. Businesses closed or facing lost revenue and product. 

These headlines inevitably dominate the news cycle as the weather heats up. Rising temperatures strain an already aging and overburdened electrical power grid: “Adequate energy supply can be impacted in several ways, primarily by high temperatures which causes increased air conditioning use and drives up electricity demand,” states the California Independent System Operator (ISO). “Other factors include unexpected power plant or transmission line outages caused by mechanical failure, wildfire, or constraint on transmission lines.” 

Beyond complete power outages, severe limits are often placed on power usage. “California Governor Gavin Newsom is asking all Californians to not charge their electric vehicles between the hours of 4 p.m. to 9 p.m. while California grapples with an energy shortage as a heat wave bears down on the state,” reported The New York Times. 

California, Texas, and Colorado are among the states that ask residents to turn up their thermostats and turn off their lights during heat waves. And while Western states grab headlines, the rest of the country is not immune to power loss. Brownouts in the Midwest can occur due to grid strain and extreme weather. Electricity brownouts and blackouts are occurring more often and in more places.

Photo courtesy of Robur Corporation

Propane cooling is a viable solution for commercial and industrial applications and is a proven technology that has been used for decades. 

 

Globally, the electric power system is increasingly stressed, witnessing higher demand and reduced capacity due to more frequent occurrences of extreme weather events. Since the majority of U.S. states experience their highest peak loads during the summer, characterizing the climate sensitivity of summer-time electricity demand has become an important pillar in energy adequacy planning. To complicate these calculations, soaring temperatures and increased occurrence of heat waves have drastically increased air-conditioning demand. 

Once considered a luxury, air conditioning is now an essential service, cooling homes, businesses, hospitals, data centers, laboratories, and other buildings vital to the economy and daily life. In fact, air temperature is so critical that 48 percent of all energy consumption in American homes is a result of cooling and heating, according to the Energy Information Administration. Because of rising temperatures, air conditioning is now a necessity in many commercial buildings and regions that didn’t typically have large cooling loads. 

The pressure is on to design and provide clean, resilient cooling that avoids the grid. A solution that is site-based technology adds further resilience. Propane cooling has the unique advantage of demonstrable environmental, economic, and equipment performance that can satisfy these demands today. 

 

Using Heat to Chill: Understanding System Basics 

A Brief History of Air Conditioning Technology 

The first commercial air conditioner was developed by Willis Carrier in 1902 in an effort to control humidity at Sackett-Wilhelms Lithographing and Publishing Company in Brooklyn, New York. By the 1970s, air conditioning technology had been refined and expanded, serving buildings from massive warehouses and theaters to single-family homes. The air conditioning technology powered by propane operates on the same principles as electricity-based models and has been used for decades. 

Propane cooling technology dates to the early days of refrigeration, with propane being used as a refrigerant alongside other natural options like ammonia and sulfur dioxide. The first commercially available propane refrigerators were introduced during the 1930s under the brand “Servel” and gained popularity due to their ability to function without electricity in areas lacking power access. Natural gas and propane-powered air conditioners arose during the 1960s, primarily powering commercial buildings, including a series of shopping malls in Kentucky, Ohio, and Florida, and the Los Angeles County Museum of Art.

American Gas Association magazine advertisement for a natural gas cooling system installed at the Los Angeles County Museum of Art.

 

For propane-fueled air conditioning, the cooling technology operates like a traditional, electric-powered system and simply substitutes propane as the energy source to power the compressor or ignite the gas burner. 

Propane cooling systems are readily available on the market today in sizes ranging from 5 to 400 tons. Cooling systems are measured in tonnage, versus a measurement in BTUs for heating systems. One ton is equal to 12,000 BTUs. The cooling tonnage required for a building is dependent on its geographical location. Cooling systems in regions with a hotter climate and longer cooling season require more tonnage. The building size will also play a significant factor. Today, propane-powered cooling systems have numerous end uses, from comfort cooling to process cooling to refrigeration, and operate well in a wide range of ambient conditions, providing the flexibility of gas cooling systems in various climates and environments. 

Modern Propane Cooling Systems 

There are two types of modern propane cooling methods: engine-driven and absorption. Question 2 To understand these methods, it is important to understand how a standard electric-powered air conditioner works. Air conditioners are designed to not only cool the air but also dehumidify it to improve comfort. Air conditioners operate similarly to refrigerators, transferring heat from a building’s interior to the outside environment. The essential components of an air conditioning unit are its Evaporator Coil, or Indoor Coil, which is the cold coil that absorbs heat from the indoor air. The Condenser Coil, or Outdoor Coil, is the hot coil that releases absorbed heat outside. The Compressor is the electric motor-driven pump that circulates refrigerant between the evaporator and condenser. This design is an engine-driven system. During operation, the refrigerant evaporates inside the evaporator coil, absorbing heat from the indoor air and cooling the building. The heated refrigerant gas is then pumped to the condenser, where it releases heat to the outside air and reverts to a liquid state. 

Photo courtesy of Robur Corporation

Propane cooling systems are readily available on the market today in sizes ranging from 5 to 400 tons. The equipment has numerous end uses, from comfort cooling to process cooling to refrigeration, and operates well in a wide range of ambient conditions. 

 

Propane Engine-Driven Cooling 

The typical electric air conditioning system uses an electric motor to engage the compressor to start the refrigeration process.  Propane equipment operates in the exact same manner, merely replacing the electric motor with a natural gas or propane engine.  This gas-driven engine engages the compressor to start the process. The remainder of the cooling process is identical to that of electric air conditioning equipment. Engine-driven systems typically have larger tonnages and are used in commercial buildings.

Image courtesy of The Propane Education & Research Council 

Engine-driven propane cooling is a mechanical process using the same technology, but with different fuel, as traditional electric-powered air conditioning units. 

 

Propane Absorption Cooling 

Absorption, on the other hand, is a thermal process. An absorption cooling system uses a gas burner to ignite and then heat a solution of water and ammonia. The ammonia has a lower boiling point, so it boils off and becomes high-pressure water vapor. In this method, chilled water is used for cooling rather than a refrigerant. 

Very little electricity is required for either of these processes. Choosing propane-powered air conditioning, whether engine-driven or absorption, provides grid relief, energy independence, and resiliency. 

Image courtesy of The Propane Education & Research Council 

Absorption cooling is a thermal process, versus the mechanical process used by engine-driven cooling. 

 

Codes and Standards 

CSA/ANSI Z21.40.4-23/CSA 2.94-2023, “Performance testing and rating of gas-fired air-conditioning and heat pump appliances,” is the most recent standards update governing propane-powered air conditioning, heat pumps, chillers, and other equipment. As propane cooling has both an established and demonstrable history, its performance is easily verified.

Additionally, all propane installations are governed by NFPA 54. NFPA 54/ANSI Z223.1, National Fuel Gas Code, offers the latest comprehensive provisions for the safe design, installation, operation, maintenance, purging, and inspection of gas piping, equipment, accessories, and appliances supplied with fuel gas. The code covers piping system design, materials, and components, pipe sizing and installing pipes underground, above ground, and inside concealed spaces, and piping inspection, 

testing, system leak check, and purging. NFPA also addresses requirements for process air and installation of appliances and minimum safe performance criteria, general requirements, and specifications for venting combustion products. NFPA provides the industry benchmark for safe storage, handling, transportation, and use. Adhering to the provisions mitigates risks and ensures safe installations that prevent failures, leaks, and tampering.

 

The Benefits of Being “Chill”: Benefits of Propane 

Photo courtesy of Tecogen, Inc.

An air-cooled chiller unit powered by propane. 

 

The U.S. Energy Information Administration’s (EIA) Commercial Buildings Energy Consumption Survey (CBECS) provides data on energy sources and types of equipment used for cooling and energy consumption for cooling in U.S. commercial buildings, including electricity consumption. According to the most recent CBECS, in 2018, electricity consumption for cooling accounted for about 14 percent (170 billion kWh) of total electricity consumption in U.S. commercial buildings. An additional 18 percent (213 billion kWh) of electricity was consumed for ventilation, some of which involves moving the cooled air through commercial buildings.

EIA’s Manufacturing Energy Consumption Survey (MECS) provides data on how much energy is consumed across heating, ventilation, and air conditioning (HVAC) in U.S. manufacturing facilities from multiple energy sources, including electricity. According to the most recent MECS, in 2018, electricity consumption for facility HVAC accounted for about 8 percent (76 billion kWh) of total electricity use at U.S. manufacturing facilities.

The amount of energy consumed by air conditioning and cooling places a heavy economic and infrastructural burden on businesses and commercial buildings. When faced with today’s energy outlook of rising demands and prices and limited infrastructure investment, propane cooling creates a viable conditioning solution for many commercial applications. Because propane cooling systems significantly reduce electricity requirements, they are also ideal in areas faced with high electric rates and limited infrastructure.

Benefit: Grid Relief

The ever-increasing demands and inadequate supply of electricity make propane a perfect alternative energy solution. Propane cooling reduces a facility’s electricity use, freeing capacity for other loads, such as EV charging stations. The reliability of the electric grid is also improved, particularly during peak summer demand. 

Additionally, for buildings looking to revitalize older neighborhoods or those built in rural areas, choosing propane frees the property from connecting to the grid or stressing a limited local infrastructure. This provides clients with a more diverse choice of business location.

Benefit: Resiliency 

When paired with a backup generator, propane systems continue operating during electric power outages, ensuring resiliency in mission-critical applications. Many units feature built-in modularity and redundancy, maintaining performance even during service disruptions. 

In areas where natural disasters occur, many projects have discovered the value of marketing more durable structures. This is certainly true for net-zero or off-grid developments that may utilize multiple forms of power, including solar and wind. Propane offers a powerful, reliable way to protect workers, their products, and businesses from the damage a power outage can cause. 

Economic Benefits 

Propane is a domestic resource and in high supply, so pricing is consistent and competitive with other energy sources. Selecting propane-powered cooling equipment instead of electric-driven air conditioning provides a huge reduction in electrical power consumption; depending on the equipment manufacturer, this reduction can range from 80 percent to 90 percent. Picking propane also avoids costly electrical upgrades and expenditure of capital costs when faced with a lack of utility infrastructure. Choosing propane for cooling can also avoid the possible addition of substations or extension of pipelines to the site, which can be cost-prohibitive. Savings on electrical loads allow commercial building owners to consider adding other propane-powered loads, such as EV car charging stations and water heating, building heating systems, and standby power.

Many commercial building types are required by code to install and maintain backup generators. When a building’s cooling is propane-powered, the size of backup generators can be greatly reduced. Having propane cooling also offers the potential for a complete off-grid operation. Propane generators, coupled with propane cooling, offer grid independence. By eliminating excessive demand rates or surcharges during peak electric usage and through reducing backup generator expenses, propane cooling lowers operating costs. Its seamless integration with existing infrastructure also avoids costly upgrades.

Finally, propane equipment is about 30 percent more efficient than traditional electric-powered air conditioners. Designing a system to run on propane generates immediate savings on project air conditioning costs. For large commercial systems, multiple cooling units can operate independently, which provides redundancy if one unit goes down. This is especially vital for commercial businesses that will lose profit if operations are interrupted or equipment is damaged. There are also equipment options to incorporate the recovery of hot water from the cooling process and reuse it in process applications. Instead of having two pieces of equipment, such as a furnace or boiler and an air conditioner, buildings can have one system that does both.

 

It IS Easy Being Green: Environmental Benefits 

Photo courtesy of Robur Corporation

Propane cooling is scalable and redundant – if one unit goes offline, the rest will continue to function, offering protection to operations.

 

Because air conditioning can demand high amounts of energy consumption, the source of that energy is particularly important when calculating a building’s environmental profile. Propane is a high-performing, safe, and cost-effective energy source. Propane has lower carbon emissions than fuel oil, diesel, and even electricity. In fact, 60 percent of the U.S. electric grid is still powered by natural gas or by coal, sources that create high carbon emissions. Propane cooling reduces reliance on coal and natural gas to produce electricity. As a clean energy source with low carbon emissions, propane can provide substantial emissions reductions and environmental benefits.

All things electric, from vehicles to appliances, remain in the spotlight. However, it is important to understand that switching equipment to electricity does not automatically equal de-carbonization. Electricity must be generated by a primary energy source, and in the U.S., natural gas and coal are electricity’s largest primary energy sources. Because electricity is a secondary energy source generated using a primary energy source, labeling electricity as the most environmentally friendly energy available is far from accurate. Furthermore, once generated, electricity must be transmitted through power lines, where electrons encounter resistance and lose energy. This means that getting one unit of electricity to wherever the plug is located can consume up to three units of source energy. 

The U.S. Department of Energy’s (DOE) Office of Scientific and Technical Information recommends embracing a broad range of opportunities to reduce building emissions, including the use of low- or zero-carbon alternatives. Design teams, builders, and contractors are increasingly navigating energy source discussions with their clients. Decarbonization in commercial buildings will require more clean energy options. The DOE classifies propane as a clean alternative fuel. 

Propane is not mined like battery materials or extracted like oil. It is primarily manufactured from natural gas as a by-product of methane purification. Propane’s low carbon intensity is why it is an approved clean alternative fuel under the Clean Air Act of 1990. Throughout the 20th Century, propane’s adoption grew due to its efficiency, reliability, and environmental benefits. Legislative acts like the 1990 Clean Air Act and the 1992 Energy Policy Act further cemented propane’s status as a clean alternative fuel. Propane is a critical energy source, valued for its stability, clean-burning properties, and diverse applications. Propane is also methane-free, as opposed to natural gas. Over a 20-year period, one ton of methane has a global warming potential that is 84 to 87 times more than CO2 alone. Propane burns cleaner; propane combustion is cleaner than oil, resulting in lower CO2 emissions and 52 percent fewer greenhouse gas emissions for equipment when using propane, compared to an equivalent amount of electricity generated from the U.S. grid. 

Additionally, propane provides resilience, as it is stored on site and is not delivered on demand through the grid or other infrastructure sources. According to the Department of Energy’s Energy Star program, propane has a source-site ratio of 1.01. It is supplied on site rather than transmitted or piped, so virtually no energy is lost in the transfer. Plus, propane’s storage flexibility means sensitive habitats can remain undisturbed, eliminating the need for pipelines or high-voltage power line installations. Because it vaporizes when exposed to air, stored propane on site does not harm the soil and has negligible effects on the ozone. Similarly, propane poses no hazard to groundwater or sensitive ecosystems. Propane only ignites when in the presence of a specific air mixture and an ignition source above 920 degrees Fahrenheit, making it safer to store than other fuels. Using propane also prevents deforestation by replacing solid fuels such as wood and coal.

 

An Alternative Fuel with Endless Possibilities 

Application Diversity 

In the past, propane cooling was primarily used in greenhouses due to its efficient dehumidification or in high-demand businesses located in remote areas. But there are many other applications for process cooling. Large-scale gas cooling installations can include wineries, distilleries, breweries, and indoor agriculture projects. Other businesses have equipment that must be cooled, such as server rooms, commercial printing facilities, dry cleaning facilities, and MRI machines in hospitals, among others. Industrial and commercial applications such as these require a great deal of process cooling, and the resulting electric rates can be astronomical. Propane cooling, on the other hand, offers market-specific operational cost savings.

“Propane-powered technologies like cooling and CHP systems are transforming how businesses approach energy. This propane equipment offers unmatched reliability and efficiency, especially in today’s energy landscape,” said Bert Warner, director of commercial business development at the Propane Education & Research Council.

When building owners want to add cooling to schools, churches, offices, assisted living facilities, multifamily residences, healthcare, hospitality, or restaurants but don’t have the electric load to handle it, propane cooling steps in. In many regions, it is more economical to incorporate a propane tank and propane cooling system because it does not require large capital infrastructure upgrades to the electrical panel or substation. An added bonus is that in large commercial systems, multiple units can operate independently, which provides redundancy if one unit goes down. This is especially vital for commercial businesses that will lose profit if operations are interrupted or equipment is damaged. There are also options to recover hot water from the cooling process and reuse it in process applications. Instead of having two pieces of equipment, such as a furnace or boiler and an air conditioner, the building can have one system that does both.

Propane cooling offers complete connectivity to a building management system (BMS) control system or building automation system (BAS) that monitors and controls a building’s electrical and mechanical systems. This allows it to integrate within existing controls, if desired.

Propane cooling systems can meet various needs, such as comfort conditioning, process cooling, dehumidification, medium-temperature refrigeration, and extreme ambient operations. Target applications include areas with limited electric capacity/infrastructure, multifamily and custom residential applications, healthcare, education, hospitality and restaurants, indoor agriculture, data centers, and mission-critical centers. Propane cooling also provides a unique outlet for churches or historical buildings being retrofitted for air conditioning. These buildings often face 

limited wiring, panels, and infrastructure supply. Using propane creates an economic path to condition the space while preserving the structure.

New Technology 

Emerging equipment systems and applications will provide new ways to move efficiency forward. Propane makes new technologies, like ultra-efficient Combined Heat and Power (CHP) technology, possible. CHP refers to on-site generation capable of providing reliable electricity. Unlike centralized electrical generation plants that operate at only 33 percent efficiency, CHP systems capture heat and achieve total system efficiencies of 60-80 percent for producing electricity and useful thermal energy. Some systems can achieve efficiencies approaching 90 percent. Almost no energy is lost as it travels from tank to application. The DOE Energy Star program gives propane a source site ratio of 1.01, compared to 3.03 for electricity from the grid. This means it takes 3.03 units of electricity to produce and deliver one unit of energy to a building, compared to only 1.01 units to deliver one unit of energy for propane. This advanced technology can significantly reduce energy costs, lower greenhouse gas emissions, and provide reliable on-site power. The lower operational costs of this equipment provide an affordable option for business owners looking to increase efficiency and sustainability.

Advances in Renewability 

Using propane as an energy source means harnessing an available clean technology to reduce emissions while still meeting energy needs. Propane is clean and non-toxic. Propane is abundantly available, and the growth of renewable propane means it can be used for generations to come. 

Renewable propane provides a truly renewable energy source because it is made by converting plant and vegetable oils, waste greases, and animal fat into fuel. This not only circumvents disposal of waste grease and oil, but it also allows for a circular energy source. Renewable propane has the same great features as conventional propane—reliability, portability, power, and reduced carbon emissions—but with even lower carbon emissions when compared with other energy.

 

Case Study: Providing cool treats in the heat

The Barbados Ice Cream Company Ltd. (BICO LTD) is the leading Barbadian manufacturer of frozen desserts. The company, located near the Harbour Port Office park in Bridgetown, was started in December 1901 as the Barbados Ice Company Limited, which made ice, and started making ice cream in 1949.

BICO LTD, during retrofit works, decided to adopt propane-fueled chilling units, installing 6 chillers with heat recovery and 3 low-brine chiller models. These units provide comfort conditioning of the offices and for the warehouse, generate the cooling necessary for freezing ice cream mixes, and deliver cooling of the pasteurizing mixing tanks. Free heat recovery hot water is used for cleaning items inside the facility. The total cooling BTU/h range is more than 34 tonnes.

The business recognized multiple advantages from the new units, including operational cost savings; minimized electric demand charge; zoning flexibility and comfort; modular redundancy; and application process usage.

 

Case Study: Keeping cool on Martha’s Vineyard

A beautiful, contemporary summer home overlooks Chappaquiddick in Martha’s Vineyard. Designed as a family refuge, the home provides entertainment during any rainy days that the island may experience. The home’s lower level includes a full game room, complete with its own Photo Dark Room, and a Bowling Alley with a built-in scoreboard. 

The exceptional surroundings require exceptional cooling equipment to maintain comfort inside and harmony outside. A modular chiller unit with a capacity between 14 and 34 tons was the ideal choice to satisfy the designer and homeowner.

The new gas absorption cooling system makes it possible to additionally provide chilled water, enabling ease in design for modern residences featuring many amenities. The chiller installed outside produces chilled water for cooling the interior spaces. To provide cooling, small, insulated water lines are piped to strategically located air handlers inside the residence, avoiding the need for large and cumbersome duct runs. This conditioning strategy was picked as the best solution to maintain comfort, aesthetics, and the architectural integrity of the home’s interior. Scattering numerous electric air conditioning units was never an option for this residence.

The selected unit was chosen to provide chilled water to the 12 zoned air handlers located throughout the home’s expansive 15,000 square foot space. Each zone is controlled by its own thermostat. That specificity allows the chilled water to air condition that area of the home to the occupants’ personal preference. In the wintertime, these same zones are supplied with hot water from a boiler located in an equipment room in the lower level. The exterior chiller system is located more than 200 feet from the house, allowing the exterior quality and appearance of the home to be the focal point of the property. 

A direct digital control (DDC) was picked by the design team and installed, ensuring optimal performance of the cooling system. The DDC generates automatic staging of the modular chillers to match the indoor cooling load, equalizes run times of the chiller modules for longer life, provides an LCD readout display of the system’s operating parameters, and eases any future maintenance. The DDC keeps a complete log and record displaying any fault code history.

 

Case Study: Delivering Environmental and Economic Performance for Indoor Agriculture

Photo Photo courtesy of Tecogen, Inc

A water-cooled chiller unit. 

 

Indoor cannabis cultivation is surprisingly energy-intensive: about 10 times as much as an office building per square foot. It is not just the lighting used to help the plants grow, although that makes up 30 to 40 percent of the energy use. The largest energy use, often making up 50 to 60 percent of the demand, is for cooling and dehumidification. That is because cannabis plants are sensitive to moisture and can grow mildew if the air is too humid.

The high energy demand for dehumidification can send energy costs soaring for cannabis-growing facilities and can even require expensive and time-consuming electrical infrastructure upgrades. Therefore, some growers are turning to an innovative, cost-saving alternative technology: chillers driven by propane or gas.

What is a Gas-Driven Chiller?: Gas chillers are really a form of combined heat and power, or CHP, says Steve Lafaille, vice president of business development for Tecogen. The system uses a propane- or gas-powered engine to drive the compressor in a chiller machine to create chilled water while the waste heat from the engine is recovered to create hot water.

Powering these energy-intensive chillers with more affordable propane or natural gas, instead of electricity, can reduce utility costs by 50 percent, Lafaille says. Perhaps just as importantly, these systems can help growers quickly and affordably retrofit industrial buildings for growing cannabis when the existing electrical infrastructure is insufficient.

That was the case for a cannabis grower in Douglas, Massachusetts, that converted an old factory building that made envelopes to more lucrative cannabis cultivation. Many existing old buildings are electrically constrained and at the mercy of the electrical utility to obtain an upgrade.

“These people have been told 18 months, 24 months, 36 months to upgrade the power,” Lafaille says. But growers don’t have time to wait. “If you look at what’s happening in cannabis, in three years, the price is going to be cut in half on the market. So, time is money in the business.”

Instead, the Douglas grower brought in a propane-powered unit that eliminates the need for additional power from the utility. With natural gas lines eight miles away, the facility used the existing 30,000-gallon propane tank onsite to fuel the unit.

Applications in Agriculture and Beyond: Cannabis cultivation is a smart application for gas-driven chilling because facilities use cooling year-round. The chilled water takes humidity out of the air before it is reheated with hot water created by the unit’s waste heat and a propane boiler, a process that is common in buildings such as hotels and hospitals.

Cannabis growers can even capture the CO2 from the engine exhaust and inject it back into the facility to provide enrichment for the plants. The captured CO2 both reduces emissions generated by the equipment and saves money otherwise needed to purchase CO2 in bulk.

The nature of the business also means that cannabis growers are willing to take risks and try new things, which is one reason Lafaille thinks the technology is quickly catching on in the industry. But gas-driven chilling has applications in other agriculture and commercial markets. Growers of lettuce, leafy greens, and herbs are also using these types of systems, although their plants are not quite as dependent on dehumidification as the cannabis plant.

Gas chillers have long played a role at buildings such as universities and hospitals for comfort cooling, Lafaille says. But he foresees the technology playing a larger role in facilities that use process cooling all the time, such as food and beverage manufacturers. “We’ve really proven that the product can run 24/7, 365 days a year and have a really high degree of uptime and reliability,” Lafaille says. “And that’s what those other process-cooling customers really want to see.”

Resilience and Carbon Footprint Reduction: For businesses seeking to enhance resilience, gas-driven chillers can help reduce not only the amount of electrical infrastructure they need but also the size of their backup power generation equipment. Given the intensive energy demand, many cannabis growers are installing 2-megawatt or 4-megawatt generators to protect the crops they are growing, which may be worth up to $10 million at any given time. By shifting some of the electrical demand to propane or gas, businesses can cut the size of the generators in half, saving millions of dollars by allowing the businesses to purchase more affordable units.

Powering the chilling with high-efficiency propane can also help to reduce greenhouse gas emissions in many parts of the country where the power grid comes from plants burning fossil fuels such as coal. Industry manufacturers aim to put even more control in the hands of building operators with the 2023 launch of a hybrid-drive chiller that can run on propane, gas, or grid power.

This hybrid chiller adds additional resilience by allowing the unit to run on electricity if there is a fault in the engine. Perhaps most importantly, it future-proofs the system by allowing the operator to choose whether the system runs on propane or electric, based on energy costs or carbon footprint considerations. “If the grid is 100 percent renewable in 10 years, great – you can run this thing on grid electric,” Lafaille says. “If all that stuff doesn’t happen in 10 years, you can have the option to still run it efficiently in CHP mode.”

By proving the real-world performance and efficiency of gas-driven chilling, cannabis growers may provide the innovative spark that spreads this cost-saving technology throughout the building industry.

 

 

END NOTES

  1. “Rotating power outages.” California Independent System Operator. 2023. https://www.caiso.com/documents/rotating-power-outages-fact-sheet.pdf. Accessed March 7, 2025.
  2. “Amid heatwave, California asks electric vehicle owners to limit charging.” The New York Times. September 1, 2022. https://www.nytimes.com/2022/09/01/us/california-heat-wave-flex-alert-ac-ev-charging.html. Accessed March 7, 2025.
  3. Vargas, Oscar. “Brownouts and blackouts now occur more often, in more places.” ecoPreserve. January 12, 2025. https://www.ecopreserve.net/brownouts/. Accessed March 7, 2025.
  4. Intergovernmental Panel on Climate Change. (2018).
  5. Maia-Silva, D., Kumar, R., & Nateghi, R. (2020). The critical role of humidity in modeling summer electricity demand across the United States. Nature Communications, 11(1), 1–8. https://doi.org/10.1038/s41467-020-15393-8. Accessed March 7, 2025.
  6. Obringer, R., Nateghi, R., Maia- Silva, D., Mukherjee, S., CR, V., McRoberts, D. B., & Kumar, R. (2022). Implications of increasing household air conditioning use across the United States under a warming climate. Earth’s Future, 10, e2021EF002434. https://doi.org/10.1029/2021EF002434. Accessed March 7, 2025. 
  7. “History of Air Conditioning.” The Department of Energy. July 20, 2015. https://www.energy.gov/articles/history-air-conditioning#:~:text=The %20idea%2of %20artificial %20cooling,of %20air %20in %20textile %20mills. Accessed March 7, 2025.
  8. Strader, Courtney. “The history of propane refrigeration.” Warehouse Appliances. March 31, 2019. https://www.warehouseappliance.com/blog/the-history-of-propane-refrigeration/#:~:text=Propane %20Refrigerator  %20History: %20Who %20Invented,SERVEL %20propane %20refrigerators %20were %20invented.. Accessed March 7, 2025.
  9. “Air Conditioning.” U.S. Department of Energy. https://www.energy.gov/energysaver/air-conditioning. Accessed March 10, 2025.
  10. Ibid.
  11. Frequently asked questions. Independent Statistics & Analysis. U.S. Energy Information Administration. March 15, 2024. https://www.eia.gov/tools/faqs/faq.php?id=1174&t=3. Accessed March 11, 2025.
  12. Ibid.
  13. “Ready to replace your AC? Learn why a heat pump is a win for homeowners using propane.” News & Case Studies. Air Source Heat Pump Collaborative. June 30, 2022. https://www.mnashp.org/ready-replace-your-ac-learn-why-heat-pump-win-homeowners-using-propane. Accessed March 28, 2025.
  14. (2020) IEA - Methane Tracker 2020. https://www.iea.org/ reports/methane-tracker-2020
  15. “Substituting LPG for Wood: Carbon and Deforestation Impacts.” Atlantic Consulting. World LPG Association. July 2018. https://www.worldliquidgas.org/wp-content/uploads/2018/10/Substituing-LPG-for-Wood-Carbon-and-Deforestation-Impacts-Updated.pdf. Accessed March 26, 2025.
  16. (2021) EPA - CHP Benefit. https://www.epa.gov/chp/chp- benefits
  17. (2021) Renewable Propane as a Sustainable Fuel Solution in California. https://www.gladstein.org/renewable-propane- sustainable-fuel-solution-california/.

 

 

Originally published in Architectural Record

Originally published in May 2025

LEARNING OBJECTIVES
  1. Examine available proven propane cooling technologies that utilize clean, dependable, and efficient site-based energy.
  2. Conduct a comprehensive and comparative analysis of propane-fueled cooling systems through the lens of resilience, energy usage, and economics.
  3. Explain the environmental benefits inherent in propane cooling technology, including grid avoidance, redundancy, and site-based advantages.
  4. Deliberate the potential for environmental and cost advantages when choosing propane as an energy source for cooling.

1 AIA LU/HSW

1 GBCI CE Hour

0.1 ICC CEU

1 AIBD P-CE
ALL CREDITS

Privacy Policy

Terms and Conditions

Do Not Sell My Personal Information

Privacy Request

Contact Us

FAQ

Site Map

Accreditations
Architectural Record Logo Floor Trends Logo Walls and Ceilings Logo Building Enclosure Logo Engineering News Record Logo Plumbing & Mechanical Logo Supply House Times Logo

BNP Media, All Rights Reserved

Powered by Building Media Inc (7.4.33)