From Residential Safety Frameworks to Commercial HVAC Deployment: Challenges and Opportunities for R290 (Propane)

Keywords: R290, Propane, refrigerants, GWP, HVAC

Introduction

R290 is already gaining traction as a natural, environmentally friendly refrigerant, and this article discusses what is needed to support its wider deployment across commercial HVAC systems.

The HVAC sector is rapidly shifting towards natural refrigerants to align with energy efficiency and climate objectives. This transition is driven globally by the Kigali Amendment and, in Europe, by the European Union’s tighter F-gas framework, which is phasing out higher-GWP refrigerants over the coming years. Within the ventilation community, this transition is taken seriously as more integrated solutions enter the market and refrigerant-based technologies become increasingly embedded in building systems.

Regulatory frameworks are also evolving to support this transition. Alongside the F-gas framework, the European Commission is updating EU Ecodesign requirements to reflect the latest market and technological advancements, ensuring high standards for the HVAC sector throughout the EU. As these discussions continue, it is important for R290 to be fully recognised as a viable and environmentally responsible refrigerant for HVAC applications where appropriate safety concepts are built into product design and installation.

Environmental and system performance advantages

R290 offers significant environmental and operational benefits. As a natural refrigerant with an extremely low Global Warming Potential (GWP), it represents a substantial improvement compared with most synthetic refrigerants.

Natural refrigerants typically have a GWP that is far lower than synthetic alternatives. In addition to reducing direct emissions, R290 systems can achieve high thermodynamic efficiency and improve the overall performance of heating and cooling equipment, offering a critical step in reducing overall HVAC CO₂ emissions.

Effective and cost-competitive natural refrigerants, such as R290, extend the operating range of heat pumps (HPs), allowing them to serve as standalone heating and cooling solutions in more geographical areas. Additionally, HPs are already designed to integrate with electricity smart grids, able to reduce electricity demand during peak hours and store energy as heat during off-peak hours, providing a double benefit. This will be a major differentiator and advantage as the sector progresses with the Green Transition to environmentally friendly energy sources.

These capabilities make R290-based systems a valuable component of the wider transition toward low-carbon energy systems.

Why R290 should be fully endorsed

One of the primary advantages of R290 is that, while it is flammable, its risks can be effectively managed and reduced. This is achieved through thoughtful product design, application-specific risk controls, and adherence to relevant standards and engineering best practices. As such, R290 is not a "drop-in" refrigerant; it should only be used in equipment explicitly designed and certified for its application.

Furthermore, proper procedures must be followed during its installation, commissioning, operation, and servicing to ensure safety and performance. Hydrocarbon refrigerants, including R290, have a proven history in refrigeration applications. Today, R290 is recognised as a well-established, low-GWP solution in a wide range of commercial refrigeration, heat pump, and other HVAC systems.

The appropriate position is not that R290 is without risk, but that it can be a technically viable and responsible option when supported by proper system design, leak prevention and mitigation, ventilation, ignition-source control, appropriate detection and protective functions, and competent handling throughout the equipment life cycle.

European and international standards, such as EN 378 and IEC 60335-2-40, provide an important framework for the safe implementation of flammable refrigerants. These frameworks define and give guidance on mitigation measures depending on installation conditions and the type of space in which equipment operates.

Engineered safety solutions further reduce risks through mechanisms, such as refrigerant leak detection, dilution through airflow, and the removal of potential ignition sources from the air stream. Refrigerant circuits are typically factory-assembled, pressure-tested, and enclosed within sealed casings, reducing the likelihood of leaks compared with systems assembled on site.

For air handling units (AHUs) and other ducted HVAC equipment, internal airflow may assist refrigerant dilution after a leak, but its effectiveness depends on the specific equipment layout, leak scenario, and operating conditions. It should therefore be understood as one risk-reduction measure within a broader safety concept that also includes leak detection, ignition-source control, and appropriate protective responses.

The benefits of smart design

Modern HVAC systems further incorporate multiple design features to minimise leakage risks. Small refrigerant leaks are expected to dilute rapidly under designed airflow conditions, while larger leaks can be addressed through fan-assisted mixing, leak detection, and protective shutdown or evacuation logic. This way, safety is ensured in both product design and the mitigation measures.

Computational fluid dynamics (CFD) simulations and real-unit testing have also demonstrated that potential leak scenarios can be managed effectively. With proper design, refrigerant releases are diluted to concentrations well below flammability limits before entering the duct system leading to occupied spaces.

In standby mode, any accumulated refrigerant must also be addressed by the system’s safety concept, with detection and response functions designed to dilute and evacuate the gas safely.

Where further research can support deployment

While the safety framework for R290 is increasingly well developed, its wider application in indoor and ducted HVAC systems still raises additional engineering questions, particularly in relation to how charge-limit approaches established for room air conditioners should be translated to other equipment types.

Recent review literature shows that current standards and the surrounding technical literature already incorporate a range of safety measures, including refrigerant charge limits, ventilation or airflow criteria, leak detection, gas sensors, and ignition-source control. The same literature also indicates that allowable charge depends on factors like refrigerant class, occupancy category, system type and location, conditioned space size, and refrigerant flammability properties. At the same time, refrigerant charge remains one of the main practical constraints on the broader deployment of systems using flammable refrigerants.

Much of the published evidence base behind these approaches is still weighted toward wall-mounted residential split systems, where refrigerant dispersion behaviour has been studied under relatively simple room airflow conditions. In those systems, airflow and ventilation can materially improve refrigerant mixing and reduce the probability of flammable concentrations forming. However, airflow should still be understood as a risk reduction measure rather than an absolute guarantee, since the literature also makes clear that zero risk cannot be claimed.

An important part of the existing evidence base is the empirical leak-hole dataset reported by Colbourne et al. (2021), who analysed more than 1,000 field leak holes from refrigeration, air conditioning, and heat pump systems and showed that realistic leak sizes are generally far smaller than many of the conservative assumptions historically used in safety treatment. This is a useful contribution because it strengthens the case for more realistic charge-limit methods based on empirical leakage behaviour, rather than purely hypothetical worst-case assumptions.

However, that still does not remove the need for equipment-specific validation in indoor, ducted, and other commercial HVAC configurations. Review literature on leakage and diffusion shows that refrigerant behaviour depends strongly on system type, leak location, airflow pattern, installation height, ventilation conditions, and the detailed characteristics of the release scenario. For that reason, the remaining issue is better understood as an evidence and standardisation gap rather than a reason to question current R290 solutions.

For manufacturers whose commercial product range includes ducted equipment, this is better understood as an evidence and standardisation gap rather than a reason to question current R290 solutions. Until comparable empirical data exists for commercial HVAC components, applying current charge-limit approaches to these systems still benefits from further validation specific to commercial equipment.

A study that characterises leak behaviour in commercial HVAC components would therefore provide the equipment-specific evidence needed to support future standards development, reduce uncertainty for indoor and ducted commercial applications, and help extend proven R290 safety concepts to a wider range of system designs. Larger R290 application, particularly in outdoor configurations, are already being developed, and broader empirical evidence would support more confident, harmonised, and scalable deployment across the full commercial HVAC market.