Dual-fuel heat pumps are perfect for retrofit applications where decarbonization and reducing greenhouse gas (GHG) emissions are a driving factor.

It is a challenge to retrofit existing facilities with new equipment to begin with, let alone having to change over the main heating energy source from fossil fuels (such as natural gas) to electric. The existing building’s infrastructure makes this difficult due to space constraints, lack of infrastructure, or impractical costs. 

Packaged dual-fuel units, which are now becoming quite popular, are the best option for replacing existing roof top units (RTUs) if fossil fuel consumption and reducing GHG emissions are a driving factor. On average, you can reduce your carbon emissions between 80-90% per RTU by simply replacing it with a dual-fuel unit.  

What Are Dual Fuel Units?

Dual fuel units are standard RTUs with the functionalities of a heat pump built into the box. By adding a reversing valve and some additional controls, the cooling process is reversed. Instead of rejecting heat outside (air conditioning), it can absorb heat from the outside and deliver it into the space (heating). With this process, the heat pump is able to provide heat more efficiently than an electric heater. 

However, there are limitations with this technology in cold Canadian winters: when you need the heat the most (when it’s coldest outside), there is less “heat energy” outside to draw from. That is why the heat pump technology truly shines in the shoulder seasons or when outdoor ambient is within a certain range. When it is too cold outside, the unit can then switch to natural gas burning to still deliver the required heat for the space. Hence the name: “dual fuel”. Also, if there ever is a failure where the heat pump cannot operate, then you still have the gas heat for backup.

It’s important to note that this technology is rapidly improving; there are some units on the market that can now operate at 0F (-17C) outdoor ambient; there are also units that can engage the heat pump and gas heating function simultaneously to provide the necessary heating while still reducing carbon emissions.

What Makes Dual Fuel Units Perfect for Retrofits?

When considering decarbonization solutions for retrofit applications, there are a number of things to consider. Ideally, you want a unit that has minimal changes to your building and is cost effective. If your facility is primarily served by RTUs, dual fuel units are the perfect plug and play solution. 

These units can oftentimes be installed on the existing roof curb of the unit it is replacing. Generally for the same tonnage of RTUs, its new dual fuel counterparts are the same size. Therefore, minimal roofing work is required.  

Furthermore, the weight of dual fuel units is very similar to a standard RTU of the same tonnage, so major roof reinforcement would not be necessary for the new installation. However, it is recommended that a structural engineer is engaged if the weight of the new unit is significantly higher than the previous. 

Lastly, there are minimal power upgrades required for the AC-units below 7.5 tons. For the tonnages 10 and above, the power service may need to be upgraded to service the new unit. Always consult an electrical engineer 

Of course, there is a cost premium for dual fuel units. On average, a 15% to 20% increase in cost is seen on RTUs between 3 and 20 tons. However, minimal disruption to the existing building and infrastructure make dual fuel units the most cost effective option. Therefore, based on the above considerations, dual fuel units are perfect for retrofit applications.

Benefits of Dual Fuel Units for Decarbonization

Dual fuel units are perfect for retrofit applications when considering the significant carbon emission reductions these units can deliver to your portfolio. 

In the chart below, the natural gas consumption of a standard Lennox RTU (yellow – averaged across the 3-20 ton unit range) is compared to its dual fuel counterpart (red). Both are modelled annually in the same Canadian climate. The dual fuel unit operation reduces the natural gas consumption by 96% as compared with the standard unit. This would equate to a carbon emissions savings of _________.

In comparing the actual utility costs of operating both types of equipment, the dual fuel units come out slightly higher. The amount of energy consumed by dual fuel units and standard RTUs in the same environment is the same, only the type of energy differs. Since electricity is still the more expensive energy compared to natural gas, the utility cost of the dual fuel units are higher. 

In summary, dual fuel heat pumps are perfect for retrofit applications. They are a plug-out-plug-in solution that require minimal structural and electrical infrastructure upgrades to the existing building. The unit cost premiums and slightly higher operating costs are a small trade-off to the significant impacts to GHG reduction. On average, replacing a standard RTU with a dual fuel unit can reduce your carbon emissions by up to 95%. This technology is rapidly evolving with efficiency improvements and additional features that make decarbonization possible for old buildings. 

Do you have an existing portfolio that needs to meet your company’s GHG reduction targets? Do you have equipment coming up for replacement and you are looking for a greener option? Reach out to discover how dual fuel heat pumps or our other solutions can help your organization move toward a greener future!