Leveraging High-Efficiency Propane Systems in Zero Net Energy Homes  

Image courtesy of The Propane Energy & Research Council

A mix of energy sources, including solar and propane, provides energy security for this remote, high-efficient home.

There is a misconception that zero net energy (ZNE) means all-electric, but propane can provide a clean, efficient, and affordable energy solution for both builders and their customers. This course will discuss how ZNE fits into the country’s energy landscape and how mixed-fuel homes featuring propane can be leveraged to meet ZNE homeowners’ energy and lifestyle demands. The course explores design strategies architects can use to achieve zero net energy homes and case studies where propane’s versatility and low-carbon output helped achieve resiliency, sustainability, and performance in ZNE builds. 

The Global Push for Decarbonization and Various Strategies for Achieving this Goal 

Climate change and related extreme weather events are gaining in frequency and intensity, prompting more and more organizations, from private companies to federal governments, to take steps to minimize their impact on the environment and gain control of greenhouse gas emissions. Consumers are increasingly savvy about the environmental impact of their purchasing and lifestyle choices, with many prioritizing homes that utilize renewable energy sources, incorporate recycled materials, and otherwise minimize their environmental footprint. This shift in priorities matters because the structures in which we live, work, learn, and worship use a vast amount of the energy and water consumed on the planet for building operations and maintenance. Therefore, achieving carbon neutrality, among other sustainability goals, is vital to the AEC industry because of buildings’ significant impact on environmental and occupant health. 

Net Zero 

Net zero is a practice that seeks to balance the emission of greenhouse gases by removing carbon dioxide (CO2) from the atmosphere. Zero net energy (ZNE) buildings produce as much energy as they use over the course of a year via renewable energy sources such as photovoltaic (PV) arrays. An increasing number of homeowners are choosing to build ZNE (or ZNE-ready) homes, which is the topic of this course. Note that different regions refer to buildings as either net zero energy, zero energy, or zero net energy (ZNE), the designation we will use throughout this course unless a specific agency discussed uses a different term. Regardless of semantics, it’s becoming increasingly important for architects, engineers, and other building professionals to use these tools to design a sustainable built environment to further the global decarbonization effort. 

Path to Zero 

There are a multitude of programs that aim to help countries, municipalities, organizations, and consumers meet their decarbonization goals. In addition, architects can use numerous sustainable design frameworks to design buildings that reduce their environmental impact. Here are a few of the larger organizations and programs at work both globally and in the United States.

United Nations Race to Zero 

To further this global mission of carbon neutrality, the United Nations sponsors the Race to Zero campaign, which aims to achieve a 45 percent reduction of emissions by 2030 and net zero carbon emissions by 2050. The goal is to build momentum around the shift to a decarbonized economy. 

U.S. Department of Energy’s Zero Net World Initiative 

In the U.S., the Department of Energy (DOE) launched the Net Zero World Initiative in 2021 to accelerate global energy system decarbonization. Then-Secretary of Energy Jennifer M. Granholm said, “With Net Zero World, our partnering nations will harness the power and expertise of the National Laboratories, federal agencies, think tanks, businesses, and universities, to develop tangible clean energy projects that meet their energy needs.” These partners have helped a range of countries attract the billions of dollars in private capital needed for global clean energy transformation. The Net Zero World initiative signals the U.S.’s commitment to collaborating with partners to replicate successes, scale up clean energy deployment, and inspire a race to the top across countries. 

Zero Energy Ready Home Program 

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Designing a net zero home requires attention to myriad products, systems, and energy sources.

The DOE also administers the Zero Energy Ready Home (ZERH) program. Most types of new homes in the U.S. are eligible to participate in the program, including single-family, multifamily, and manufactured homes. To be certified under the ZERH program, a home must meet all requirements of the applicable version based on building type, the builder/developer/planner must be registered as a ZERH program partner, and the project must be approved by an official third-party verifier. We will discuss this program in more detail later in the course. 

USGBC and ILFI 

In addition to these global and federal programs, certifications to recognize high-performing net-zero projects—such as those offered by the U.S. Green Building Council (USGBC)—could give these projects a competitive edge in the marketplace. For example, LEED Zero (administered by USGBC) complements LEED (Leadership in Energy and Environmental Design) and offers a framework for designing high-performance buildings and spaces, as well as reducing greenhouse gas emissions. 

It includes strategies impacting land, energy, transportation, water, waste, and materials. It recognizes projects that have reached net zero or net positive status in carbon, energy, water, or waste categories. As of December 2024, more than 460 projects were registered and certified under various categories of LEED Zero. 

The Energy & Environmental Building Alliance (EEBA) 

Many private organizations educate and advocate for decarbonization, building science knowledge, and sustainable business practices in residential construction. EEBA (the Energy & Environmental Building Alliance) helps the industry understand rapidly changing codes, rating systems, and homeowner expectations. This is important as healthy, resilient, zero-energy, and zero-carbon homes are now required in some places and increasingly expected by consumers. The EEBA community offers education, support, and resources on leading-edge building science knowledge and sustainable business practices. 

The Role of Zero Net Energy (ZNE) Homes in Achieving Decarbonization Goals 

Image courtesy of U.S. Dept. of Energy

The U.S. Dept. of Energy administers the Zero Energy Ready Home program.

In her article “Navigating Net-Zero Energy and Net-Zero Carbon Building Certifications,” author Kate Zeile notes: “In recent years, there has been significant growth in the number of zero net energy projects due to increasingly stringent energy policies and greater awareness. From long-term cost savings to market differentiation to climate change mitigation, there are myriad reasons to pursue a zero net energy project.” ZNE is an energy-neutral approach that many architects, builders, and designers use. In the simplest terms, a ZNE home produces as much energy as it uses. Builders achieve this by increasing a home’s energy efficiency and then adding renewable energy sources such as solar or wind. 

A ZNE-ready home, on the other hand, might not necessarily be seeking ZNE now, but it’s constructed with a building envelope and systems that can achieve this goal if the current or future homeowner desires. A ZNE-ready home is incredibly energy-efficient and can reach ZNE status by using propane appliances and adding renewable energy in the future. Zero-energy building types can include both multifamily and single-family. Energy performance levels that these buildings can meet include zero energy ready, zero energy, net producer, and retrofit program. 

U.S. Zero Net Energy Home Market 

While still in its infancy, the market for net zero homes is rapidly expanding. According to the New Buildings Institute (NBI), the count of verified and emerging net zero buildings across the United States and Canada has increased tenfold in the past 15 years and encompasses more than 62 million square feet of commercial and multifamily building space. This growth will only expand as more cities and states pursue climate action plans and focus on net zero building performance as a standard for homes and commercial buildings. The NBI states: “This new vision is capturing the attention of building owners, designers, policymakers, civic leaders, operators, and others who see its potential to help rethink how we approach building design and operation into a future that uses clean energy resources efficiently and eliminates the carbon footprint of buildings.” 

New Buildings Institute’s Getting to Zero Buildings Database 

As of March 2025, NBI was tracking 172 certified or verified and 593 emerging zero energy projects across North America in its Getting to Zero Buildings Database. These are various building types, not just residential. ZE projects span all climate zones and almost every state and province in North America. Still, they are concentrated in California and the Northeastern U.S. NBI maintains a comprehensive list of ZE commercial and multifamily buildings across North America. This interactive tool allows the generation of customized maps, lists, and charts and can be found at https://newbuildings.org/resource/getting-to-zero-database. 

EEBA Inventory of Zero Energy Homes Report 

The EEBA also tracks zero-energy homes and explains how quickly this market is expanding. This report is the most comprehensive list of single and multifamily, net positive, net zero, and zero energy ready units in the U.S. and Canada. All projects are zero energy ready/capable (ZER/C) and above, with most projects now listed in the inventory as net zero or net positive. The EEBA says of its 2022 inventory (the most recent report): “This latest report shows 190 percent growth in total projects as well as 440 percent growth in single-family houses. It appears we have reached the inflection point in market adoption.” EEBA Team Zero started tracking the number of U.S. and Canadian ZE homes in 2015, with its yearly report showing a consistent upward trend since then. And 2022 was the first year that single-family homes made up the majority of projects, outpacing the multifamily sector. 

Some underlying factors behind this growth are the cost-effectiveness of high-performance technologies, a steady increase in energy codes over time that has made “standard” homes ever more efficient, and increased awareness that many projects can readily achieve zero energy ready or net zero performance levels. 

Design Strategies Designers Can Use to Achieve ZNE Homes 

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Homes play a large role in the quest for a carbon-neutral economy.

The program a builder uses to receive ZNE certification will define “zero” and how it’s measured. For example, suppose a builder participates in a third-party program like the DOE Zero Energy Ready Home or utility program. In that case, the program establishes how zero is defined and measured and clarifies any particular requirements. There are two different ways to measure the energy use of a ZNE home: site energy and source energy. 

Site Energy 

Site energy measures energy use by the energy flow into the home. In the case of electricity, this means measuring the input to the home at the house’s electric meter. The same logic would apply to the use of natural gas measured with the home’s gas meter or the use of propane as measured by deliveries to the home’s storage tank. One issue with using site energy to define zero energy is that it only measures the energy used at the house and is, therefore, less accurate. Site energy doesn’t account for the energy production, upstream losses, or inefficiencies of different energy systems. Also, in some cases, a home might not be well suited for a PV system due to shading, limited roof area, or other factors. Such dwellings can technically still obtain zero net energy if the owners purchase renewable energy for their energy usage. So, some projects could benefit from a ZNE definition that accommodates off-site renewable energy, such as the renewable energy sources offered by some utilities. 

Source Energy 

Source energy is more accurate, as it measures energy use starting at the source, further “upstream” from the house, including the energy required to extract and process fuel. A benefit of considering a home’s energy use from the source energy perspective is that it can capture the overall resource efficiency of the house more completely and recognize more efficient energy systems. Target energy levels and how a program defines zero will subsequently affect the systems specified in a home. The economics of getting to zero energy are essential in projects, and the costs for increasing levels of efficiency tend to get higher as a project gets closer and closer to zero energy. 

Measuring ZNE progress with the Home Energy Rating System (HERS) Index 

To measure the progress toward a zero net energy home or even a zero-energy ready home, many builders use the Home Energy Rating System (HERS) Index. The HERS Index offers a scale for measuring and comparing the energy efficiency of houses. The lower the HERS score, the better. A typical home built to 2006 energy code levels has a HERS Index of 100, while more efficient homes have lower HERS scores. A HERS of 0 means a zero-energy home. 

Zero Energy Ready Homes 

Image courtesy of iStock; by armckw

There are two different ways to measure the energy use of a ZNE home: site energy and source energy.

Another option is to design and build a zero energy ready home, typically a less aggressive energy target. This threshold is also less costly to achieve and can be a stepping stone as builders and designers become more experienced. The price of adding photovoltaics, utility net metering policies, and other factors will also affect the decision to aim for zero net energy in a project. A zero energy ready home can be positioned using renewable energy on-site or procured from off-site renewable sources. Builders, designers, or homeowners can use the HERS Index to demonstrate how close a home is to achieving zero energy. 

It’s possible to lower a HERS score using several methods: 

• Reducing energy loads via the building envelope 
• Having higher-efficiency mechanical systems 
• Trimming other energy use 
• Using renewables 

Building Envelope 

Superior insulation is essential to reduce energy loads via the foundation, the walls, and the roof system, also referred to as the building envelope. Reference the International Energy Conservation Code (IECC) to verify recommended insulation levels for specific climate zones, but remember that these are the minimum levels of insulation to consider and that most ZNE projects will add higher insulation levels to the envelope. How much more will depend on the types of construction they are using and the economics of adding more insulation versus other efficiency investments. Energy modeling of different design options helps to inform these decisions. 

Sealing the building envelope is one of the most cost-effective ways to increase a home’s efficiency, as it dramatically reduces heating and cooling loads, makes the home more comfortable for occupants, and helps move a building design toward zero energy. It is crucial to measure air leakage with a blower-door test, which pulls air out of the residence with a fan and measures how tightly sealed the envelope is. The test results in a metric called ACH50, which means how many air changes the home undergoes when it is pressurized up to 50 pascals with the fan. 

Windows are often the weakest thermal link in a building envelope, so many zero-energy or near-zero-energy homes use high-quality dual-glazed windows. An increasing number of projects include triple-glazed windows, especially in mixed and colder climates. The amount of fenestration should be carefully evaluated, as homes with a significant amount of glazing can experience higher heating and cooling loads. 

Home Orientation 

Finally, the home’s orientation can affect summer heat gain and the amount of roof area suitable for solar panels. A house can sometimes be designed for passive solar heating in the winter based on its orientation. Modeling allows designers to assess the impacts of different orientations on heating and cooling loads. 

Higher-Efficiency Mechanical Systems 

Image courtesy of The Propane Energy & Research Council

On-site renewable energy positions a home to be zero energy ready.

The mechanical systems for a home provide heating, cooling, and hot water. Modern homes must include a well-designed mechanical ventilation system because air sealing is a core element of the minimum energy code. Balanced ventilation systems such as a heat recovery ventilator (HRV) provide ventilation air and help temper the fresh air coming into the home through a heat exchanger, which extracts energy from the outgoing air.

Heating system options include high-efficiency furnaces, heat pumps, and hybrid heat pump-furnace combination systems. High-efficiency propane or natural gas furnaces offer Annual Fuel Utilization Efficiency (AFUE) ratings as high as 98 percent. AFUE is a standard measurement of how efficiently a furnace converts energy from the fuel it uses into warm air for a building. Hybrid heat pump-furnace systems, also called “dual fuel” systems, can optimize the performance of both systems. 

High-efficiency cooling systems reduce energy consumption as well. The dehumidification performance is also critical because the reduced cooling load on the home means that the central cooling system will run less and provide dehumidification less frequently. Variable-speed cooling systems that operate based on temperature or humidity are one option. Another option is the use of a supplemental dehumidification system. 

As the envelope improves and heating and cooling loads are diminished by 50 percent or more, water heating becomes a more significant part of the home’s energy budget. High-performance options include propane tankless water heaters, heat pump water heaters, high-efficiency tank systems, and hybrid systems. 

Further Trimming Energy Use 

Like hot-water energy, as high-performance homes’ heating and cooling loads become smaller, a home’s lighting and appliance energy becomes proportionately larger. Lighting strategies to reduce energy use most often involve LED lighting. On the controls side, auto-off vacancy-sensing switches can help limit lighting energy use, especially in out-of-sight spaces like a finished basement or closets. 

For appliances such as dishwashers, refrigerators, clothes washers, and even ceiling and bathroom fans, ENERGY STAR-labeled units help ensure efficient operation to further trim the home’s energy use. Energy monitoring and feedback devices are other tools to consider in a zero-energy project. Seeing the real-time and historical energy use can help attune residents to how the home uses energy and can encourage energy-saving habits. 

Renewables 

Once the home’s loads are reduced and efficient equipment is used across the board, renewable energy such as wind, hydropower, and renewable propane can be added to the mix to partially or completely offset the home’s energy use. Renewable propane is made primarily from plant and vegetable oils, animal fats, or used cooking oil. Another renewable energy source is roof-mounted photovoltaics (PV). Among the many factors to consider when adding PV to a home’s roof are the utility’s net metering policy and the resulting value of the energy that the home might sell back to the grid. Another option 

is to couple on-site battery storage with a home’s PV system so the energy produced can be used as needed by the house. Control systems can set up the use of battery-stored energy to maximize the value to the homeowner. If a home isn’t a good candidate for solar, other options include renewable energy purchased from the utility or community-scale PV systems, where available. 

Opportunities to Use Mixed-Fuel Design Strategies in ZNE Homes 

There is a misconception that ZNE means all-electric. There are opportunities to leverage propane systems in these designs. Builders and designers nationwide are achieving zero net energy performance with propane. It’s an excellent way to reduce emissions while meeting energy needs because it’s a clean, nontoxic, efficient, and affordable energy source. Its versatility and low-carbon output make it an ideal energy source for achieving resiliency, sustainability, and performance in ZNE builds. Propane-powered appliances can significantly lower a home’s energy consumption, making it easier to achieve ZNE goals. Plus, propane can work hand in hand with renewable energy sources like wind and solar. Mixed-fuel solutions are popular in ZNE projects because homeowners can lower their monthly utility bills while still enjoying the benefits of gas appliances. Propane also helps make families and businesses more secure, as the more diverse the country’s energy mix is, the more reliable it is.

In high-performance projects, the building’s heating and cooling loads are significantly reduced through the highly insulated envelope and extensive air sealing. Hence, it makes sense to use high-efficiency heating equipment. However, overinvesting in heating system efficiency may not be optimal and could divert dollars that could have a greater impact elsewhere in the home’s design. If a highly efficient but very high-cost heating system is selected, it may not operate enough to generate a quick payback. Whereas, in a more typical home with a greater heating load, the payback period for this type of system would be shorter. 

For example, installing a ground-source heat pump (GSHP) system in a high-performance home is a very efficient but high-first-cost option. Based on a detailed cost-estimating analysis by the Propane Education & Research Council (PERC), a GSHP for a typically sized home would cost just over $30,000. A 95 percent-efficient propane furnace would carry a much lower first cost at roughly $13,000. While the GSHP realized energy cost savings over time, the magnitude of these savings in a high-performance home with much lower loads would be smaller and extend the payback period significantly. 

Mixed-Fuel Options: Energy Cost Savings 

Image courtesy of The Propane Energy & Research Council

Higher-efficiency mechanical systems are crucial for a zero energy ready home.

Energy cost savings are an essential goal in all zero net energy or zero energy-ready homes. In mixed-fuel home designs, water heaters powered by propane can offer significant energy cost savings. As the heating and cooling loads diminish in a zero net energy home, finding cost-effective solutions to reduce water-heating costs becomes even more critical. In addition to providing annual energy cost savings compared with other water heaters, the propane condensing tankless system is also widely available, offers substantial space savings in a floor plan due to its compact size, and is cost-effective to purchase. 

Information provided by The Propane Energy & Research Council

Cost comparison of water heater type and fuel type.

Mixed-Fuel Options: Source Energy Savings 

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Source energy factor for storage water heaters.

Besides energy cost savings, propane water heating can also offer significant source energy savings. As described earlier in the presentation, source energy captures the “upstream” energy required to extract, process, generate, and transport energy to the house. 

As the first graph shows, the source energy factors connect the energy needed upstream of the home to get the energy to the house plus the water heater’s efficiency. Lower values are better, meaning less overall energy. A standard-efficiency propane storage water heater (shown on the left side in the first graph) is set at the baseline value of 1, with the other systems benchmarked to this value.

We can see that the standard-efficiency electric storage water heater has a source energy factor of 2.07. This means it takes more than twice the energy to supply hot water to the home compared with the propane water heater when the water heater efficiency and upstream losses are considered. The heat pump water heater has a lower value than the standard electric unit (source energy factor of 1.23) due to its high efficiency. This is still 23 percent higher than the standard propane tank. 

Source energy factors for tankless systems are shown on this second graph and are still benchmarked against a value of 1 for the standard-efficiency propane tank unit. The standard-efficiency propane tankless and the “best available” propane tankless show much lower source energy usage. This is driven by the tankless system’s efficiency and propane’s relatively high source energy efficiency. The electric tankless options shown above have significantly higher source energy factors, driven by upstream system losses. 

Mixed-Fuel Options: Reduced GHG Emissions 

Image courtesy of The Propane Energy & Research Council

Source energy factors for tankless water heaters.

Considering zero net energy homes from the perspective of greenhouse gas (GHG) emissions, this graph shows GHG ratios from a source energy basis—meaning that the emissions from upstream operations are also included along with the energy use of the water heater at the site. The graph uses a baseline index of 1 for a standard-efficiency propane storage water heater, with the other systems referenced against this value. When accounting for source energy and the water heater’s efficiency, a system like the best available electric storage unit has GHG emissions 67 percent higher than the standard efficiency propane storage tank. The best available propane tankless system has the lowest greenhouse gas ratio, lower than the standard and high-efficiency water heater. 

Mixed-Fuel Options: Optimized Hybrid Systems 

Image courtesy of The Propane Energy & Research Council

Greenhouse gas ratios for water heaters.

Image courtesy of The Propane Energy & Research Council

Source energy ratio, hybrid sources.

Image courtesy of The Propane Energy & Research Council

Greenhouse gas ratio, hybrid sources. 

Mixed-fuel home designs can also incorporate hybrid systems combining propane systems with complementary technology, 

optimizing both components’ performance. For example, solar water heating is highly efficient from a source energy basis because the energy source is solar energy. However, these systems require a backup water heater in most cases, which can be served by an energy-efficient propane storage tank water heater. The first graph shows that combining an ENERGY STAR propane storage tank water heater with a solar water heating system creates a highly source-energy-efficient system. The source ratio is nearly 70 percent lower than the baseline system, a standard-efficiency propane storage tank. Recall that lower source energy ratios mean less energy is used to generate hot water. All the systems shown in these graphs are compared relative to a baseline propane tank system with a source energy ratio of 1. Ratios less than 1 are more efficient than the baseline, and those higher than 1 are less efficient. 

The hybrid solar/propane storage water heater is far more efficient on a source energy basis than the standard-efficiency electric tank, with a value six times higher. The hybrid system is also much more efficient than the standard heat pump water heater. In terms of GHG emissions, the hybrid solar with propane storage tank backup is also much lower. The same relative differences are seen in the second graph, with the hybrid system with a GHG ratio of 0.3 more efficient than the other options, especially compared with the standard electric water heater. 

Another example is a hybrid system combining a high-efficiency air-source heat pump with a high-efficiency propane furnace. This type of system is called a “dual fuel” system or a “hybrid heat pump” system and can reduce energy costs for heating and cooling. The heat pump-furnace hybrid system’s main advantage over the heat-pump-only system is allowing the high-efficiency propane furnace to handle the heating load at colder outdoor temperatures. This system replaces the inefficient electric resistance backup heating used in many heat pumps, resulting in energy cost savings worth several hundred dollars per year. Dual-fuel systems may add to the upfront cost for a system, but these operational savings will pay back that extra cost within a few years. Dual systems can also be adjusted to set the “switchover temperature”—the outdoor temperature at which the propane furnace takes over—to different levels based on homeowner preference or the cost of electricity and propane. 

Conclusion 

As we have seen, there is a global push for decarbonization, and various strategies are being developed to achieve this goal. One such strategy is zero net energy, but there is a widespread misconception that ZNE means all-electric. As the course and case studies we just discussed have demonstrated, propane can provide a clean, efficient, and affordable energy solution for both builders of ZNE homes and their customers. Mixed-fuel homes featuring propane can be leveraged to meet ZNE homeowners’ energy and lifestyle demands, thanks to propane’s versatility and low carbon output, which helps projects achieve resiliency, sustainability, and performance in ZNE builds.

Zero Energy Ready Mountain Chalet Remodel, Flagstaff, Arizona 

Image courtesy of The Propane Energy & Research Council

Zero energy ready mountain chalet remodel in Flagstaff, Arizona.

 

Bill Owens has been closely involved with the green building movement for more than two decades. 

As a highly respected remodeler and active National Association of Home Builders leadership member, Owens has kept himself on the leading edge of energy-efficient construction technologies. So, it was only natural that when he remodeled his own “forever home,” Owens designed the home to be zero energy ready, with a predicted HERS Index rating under 30. 

Owens is president of Owens Construction, a design-build remodeling firm in Worthington, Ohio, but his new home is a renovation of a 1970s mountain chalet outside of Flagstaff, Arizona. Contrary to the common perception of Arizona, the home is in a dry, high mountain desert environment at an altitude of 7,000 feet, so it experiences extreme temperatures and an average of 100 inches of precipitation each year, mainly in snow. That climate and the home’s remote, semi-rural location led Owens to bust another common perception—that zero energy homes must be all-electric. Going dual-fuel with propane created an ideal energy solution to achieve the comfort, resilience, and efficiency Owens had in mind for his dream home. 

The project includes many of the technology and building material hallmarks of modern, ultra- efficient homes. Owens used continuous 2-inch foam insulation on the outside of the house, along with a reflective barrier that reduces heat flow. In remodeling the existing 2-by-4 construction, the team used a combination of open-cell and closed-cell spray foam insulation. That included 4 to 5 inches of closed-cell spray foam around the existing crawl space and about 8 inches in the attic to achieve close to an R-50 insulation value. He returned to pay special attention to reducing air infiltration around windows and used energy-recovery ventilators to provide efficient ventilation with about 1 ½ air changes per hour.

Image courtesy of The Propane Energy & Research Council

Propane keeps the family warm in a snowy climate. The area averages more than 100 inches of precipitation a year, mainly in snow.

 

With a home that well-insulated, a high-efficiency mini-split heat pump system can handle the heating load in moderately cold conditions. Still, temperatures on the mountain can drop as low as minus-30 degrees Fahrenheit. Plus, Owens didn’t want his standby generator to be huge enough to run all the heat pumps during an outage. A hybrid heating solution using propane furnaces for the first floor and crawl space was ideal. With backup propane heating in place, Owens could install a right-sized propane standby generator to handle the electrical needs of the furnaces, water pumps, refrigerator, and smart home features such as the smart water valve protecting against leaks. “We’re literally at the end of the grid,” Owens says. “I am the last house on about two miles of electric overhead running through a national forest.” 

Another feature that lends to the low HERS rating and the lower load on the generator is the propane tankless water heater, which provides a robust National Green Building Standard rating. The tankless unit includes a programmable recirculation loop to minimize wasted cold water dumped down the drain in a state where water is precious. 

Image courtesy of Adobe; by Buakung

Using a propane backup furnace and tankless water heater allowed Owens to specify an affordable standby generator, since it didn’t have to be sized to operate the home’s mini-split heat pumps.

 

In addition to energy-efficient features, propane fuels several of the home’s most appealing lifestyle amenities. Owens plans to install a propane fire feature on the enclosed porch, a safer approach than open wood fires. The home will also have propane cooking, both on an outdoor grill and on the kitchen cooktop. “I’ve checked with our energy rater, and he basically said that you get such a clean-burning fuel with propane that it’s not considered a detriment if you have an exhaust hood. It doesn’t work against you on the points for the green rating,” Owens says. 

Building to zero-energy standards comes with a higher cost, but the payback comes in long-term energy cost savings and immediate comfort improvements. “This house is so tight that we don’t notice when the wind’s just howling or when we’re getting huge temperature swings out there,” he says. The experience has also bolstered Owens’ support for dual-fuel homes. Trying to run his home purely on solar and battery backup, in a state with disincentives for solar installations, would have been cost-prohibitive. “In a fairly severe environment or environments that are enough away from the grid, there is no perfect panacea with just one energy source,” he says.