Zero Net Energy Basics for Home Builders

Buildings of all kinds — including homes — are a significant source of greenhouse gas emissions. According to the U.S. Green Building Council, buildings account for nearly 40 percent of carbon pollution in the United States. Zero Net Energy (ZNE) homes, on the other hand, generate as much clean, renewable energy as they consume, thus having a “net zero” annual energy impact.

As ZNE homes become increasingly popular, home builders are faced with a wide variety of construction decisions as they meet their customers’ demands for green home designs, technologies, and energy-efficient appliances that contribute to a ZNE home.

Incorporating propane appliances into a ZNE build significantly lowers a home’s energy consumption, making it easy to achieve sustainability goals and deliver premium performance to homeowners.

But before a builder determines how to best provide ZNE home solutions, it’s important to know the basics — and how propane can be incorporated to make reaching ZNE more attainable.

What is a ZNE home?

Simply put, a ZNE home produces as much energy as it uses. Builders achieve ZNE status by increasing a home’s energy efficiency and adding a renewable energy source such as solar to offset the home’s remaining energy consumption.

How do you measure energy usage?

It’s important for builders to ensure their customers understand the difference between site and source energy when working toward an energy-efficient home strategy. Site energy measures only the energy used at the house and doesn’t account for upstream losses or energy production — which is why it’s known to be less accurate.

Source energy — a more accurate measurement — measures energy use starting at the source, including the energy required to extract and process fuel.

When analyzing source energy ratios, propane wins hands down. Data based on national averages shows that it takes 3.03 units of energy to produce and deliver one unit of energy in the form of electricity to a home, versus just 1.15 for propane.

What’s a HERS score?

When it comes to the Home Energy Rating Systems (HERS) Index — used to measure efficiency — the lower the score, the better. ZNE homes have a score of zero and typical homes have a significantly higher score of 100.

For builders interested in maximizing a ZNE home’s energy efficiency and lowering its HERS score, here are three things you can do:

1. Focus on the building’s envelope. Achieving ZNE goals begins with reducing the loads on the building and focusing on building envelope priorities such as insulation quantity, insulation quality, air sealing, window performance, and house orientation.
2. Include high-efficiency propane appliances. Larger home systems — generally significant energy consumers — such as water heaters, space heaters, and generators should be the first to transition to high-efficiency propane appliances. Furthermore, propane can power several other high-efficiency appliances throughout a home including ovens, fireplaces, and clothes dryers.
3. Trim other energy use. Energy Star appliances, LED lighting, and energy monitoring devices can help further cut into a home’s energy consumption.

How can propane help?

Propane is a clean alternative fuel and can be used nearly anywhere, including beyond the natural gas grid. Often used in ZNE projects to power back-up generators, water heaters, fireplaces, and cooktops, high-efficiency propane appliances are helping builders and homeowners achieve energy-efficient living.

In addition to increasing a home’s energy efficiency, propane appliances produce much fewer emissions, which is important to any builder concerned with their property’s carbon footprint. For instance, a propane tankless water heater reduces emissions by 67 percent compared to an electric storage tank model.

For builders interested in learning more about how they can reduce energy consumption and lower a home’s HERS score with propane appliances as a part of their strategy, visit propane.com.

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