Exploring Energy Efficiency: Mini-Splits, Duct Systems, and Building Envelope

Introduction: The Importance of Efficient Heating and Cooling Systems

Heating and cooling your home is essential for comfort and maintaining a healthy living environment. Traditional split systems and ducted heating systems are common options for managing temperature in your home, but their efficiency may not always be optimal. In this article, we will discuss how to overcome common inefficiencies in heating and cooling systems and explore some alternative options.

Using Split Systems

Split systems are a popular choice for heating and cooling your home. They consist of an indoor unit and an outdoor unit connected by refrigerant pipes. This setup allows the system to heat or cool a specific area of your home. However, the efficiency of a split system can be impacted by the quality of your building envelope.

Building Envelope Performance

A high-performing building envelope is crucial to the efficiency of your split system. This refers to the overall thermal performance of your home, which needs to be considered when sizing a unit for the space you want to heat or cool.

Many calculators used to size up units do not take this into consideration, leading to inefficient heating and cooling systems being installed. To improve your building envelope performance, focus on sealing up your home, retrofitting insulation, and ensuring all air barrier surfaces are properly insulated.

Humidity Control

Humidity control is an essential aspect of maintaining comfort in your home. The ideal humidity range for human health and comfort is approximately 40 to 60%. Many split systems can control humidity, such as the Daikin US7. Having a system that can regulate humidity will help keep your home comfortable and reduce the likelihood of mold growth.

Comparing Split Systems to Gas Ducted Heating

Gas ducted heating systems are another common option for heating your home. However, they have several drawbacks when compared to split systems. One major issue is the energy loss from the ducted distribution system, which can aggravate air leakage and reduce efficiency.

Additionally, ducted systems complicate the building envelope by requiring large openings for the return air cavity. In contrast, split systems do not require such modifications, making them a more energy-efficient option.

Reducing Your Heating and Cooling Footprint

To maximize the efficiency of your heating and cooling systems, consider the following guidelines:

– Instead of installing multiple split systems, invest in one or two high-quality, efficient models that control humidity and provide fresh air.
– Focus on improving air tightness, insulation consistency, and shading in your home to reduce the overall need for heating and cooling systems.
– Ensure that any holes in your walls where the refrigerant pipes pass through are sealed to prevent air leakage and improve efficiency.

Alternative Heating and Cooling Solutions

Besides traditional split systems and ducted heating, there are other options available for more energy-efficient heating and cooling in your home.

Eliminating Box Air Conditioners

Box air conditioners are extremely inefficient and should be removed from your home. They are leaky, conductive, and require large holes in your building envelope to function. By eliminating these systems and repairing your building envelope, you can significantly improve your home’s overall energy efficiency.

Solar DC Split Systems

Solar DC split systems are a relatively new development in the heating and cooling market. These systems directly connect to a solar array and can provide “free” cooling. While this might sound appealing, the efficiency benefits of converting DC power into a split system are not significant enough to warrant relying on solar power exclusively for air conditioning.

Instead, use your solar panels to power other appliances or even store energy in a home battery system for greater overall efficiency.


Heating and cooling your home is essential for maintaining comfort and health, but it’s crucial to do so in an energy-efficient manner. By focusing on improving your building envelope performance, choosing efficient split systems that control humidity, and considering alternative solutions like solar DC systems, you can reduce your heating and cooling footprint while still keeping your home comfortable.

To learn more about optimizing your home’s heating and cooling system for efficiency, subscribe to our channel and visit our website at officience matters.com, where you’ll find many articles on building performance and energy-saving tips.

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