What Exactly is a Zero Energy / Net Zero Home? [Podcast]
Listen and Learn!
This comes courtesy of our friends at Build Your House Yourself University hosted by Michelle Nelson, informal residential construction student. She shares information on home building practices as well as interviews with experienced contractors and industry experts to bring you tips, tricks, and trends in home building.
So, what exactly is a Zero Energy Home? To quote the folks at
ZeroEnergyProject.org, “Zero energy homes are just like any home—except better.”
They are air-tight, well-insulated, and extremely energy efficient homes that produce as much energy as they use, over the course of a year. That means that for heating and cooling, electricity, and water heating, your net payment to the power company would be zero, zilch, nothing! You’d have no net utility bills with a zero energy house. More about that later.
Zero energy houses also have very little negative impact on the environment. If all that sounds good to you, but you’re weary of looking into a zero energy house because you think that it has to be a super modern, minimalist white box of a house, think again.
These houses can be built in a variety of sizes and styles and for any climate. If you want a zero energy house that looks very unique and unconventional, that’s fine. But, you can also build a zero energy house that looks like any other home—like a traditional colonial or craftsman, or a Mediterranean or bungalow. You could build a large estate house, or a tiny house, or something in between, and you could make any one of those a zero energy house.
We’ll get more into the subject in just a moment. But now, let’s go over this week’s Pro Term:
Renewable energy is defined as energy that’s collected from a source that’s renewable or regenerated, and not depleted, when used. This is in contrast to
non-renewable energy that comes from sources that can eventually be used up, like coal, natural gas and oil. Renewable energy comes from natural sources that will continue to be around well into the future—energy from the sun, the wind, water and from the internal heat of the earth. The internal heat from the earth is called geothermal heat.
Ok, pop quiz. We talked about geothermal heating and cooling systems last week in episode 44. A geothermal heat pump system takes advantage of the earth’s constant temperature. Here’s the pop quiz question: What is the constant temperature of the earth several feet underground? Is it a constant 50 to 60 degrees Fahrenheit, or is it a constant 100 to 120 degrees Fahrenheit?
The answer is 50 to 60 degrees F. Geothermal systems use that constant temperature of the earth to heat and cool your house, making it a great example of renewable energy.
So, our pro term for this week is renewable energy which is energy that’s collected from sources that are naturally replenished and never depleted, such as the sun, the wind, and the internal heat of the earth.
Alright, on to the mini lesson.
Remember, zero energy houses use zero net energy because they produce as much energy as they use over the course of a year. Zero energy homes are also called net zero houses. Energy produced by a zero energy house is usually produced on-site, through technologies like solar panels and wind turbines. Wind turbines are those windmill-looking structures that have 3 large spokes. They convert wind energy into electricity.
Ok, now let’s talk about those net zero utility bills. If you build a zero energy house, it doesn’t mean that you’ll never, ever have to pay a utility bill again. Let me explain how this all works.
Most months of the year you’ll produce enough energy to off set all the energy that your family uses. But occasionally, you might have to pay a small utility bill. This is especially true in unusually hot or unusually cold months, when heating and cooling costs might be higher than expected. So sometimes, you will have to pay a small power bill. But, in other months of the year, your zero energy house with produce more energy than your family needs, so you can sell that extra energy to the power company. You’ll get paid by the power company for the extra energy that your zero energy house produces. So, by the end of the year, your net payment to the power company will be zero.
Zero energy homes are built not only to produce energy, but they are also built to minimize energy losses and decrease overall energy use. They’re airtight structures with a high level of insulation and high-performance windows, so not only are the houses energy efficient, but they’re comfortable and quiet too.
Zero energy houses are healthier than standard homes because fresh, filtered air circulates through the house, significantly reducing allergens and pollutants.
Most zero energy homes use solar panels to produce the energy that they need. There can be some challenges with the positioning of solar panels since the panels can’t be shaded by trees or adjacent structures. Positioning solar panels is much less of an issue in the suburbs. But in dense urban neighborhoods, where there are lots of tall buildings, it can be difficult for unobstructed sunlight to get to solar panels. For that reason, it can be easier for suburban homes to meet the zero energy criteria.
Perhaps the biggest challenge with building a zero energy house is coming up with a big enough budget to invest in the extra insulation, the high-performance windows and the solar panels that are required. Solar panels are one of the greatest expenses.
According to solar-power-now.com, in 2016, the average sized solar panel system cost $15,000. And that $15,000 is just an average amount for a 5000-watt system. Systems can cost more or less, mostly depending upon how much energy the home will need. A bigger system will cost more, because you’ll need to buy more solar panels and more labor will be needed to install them.
To offset some of that cost, check into tax incentives. Recently, there have been tax credits that reduce that price of solar panel systems by 30%. That credit may or may not be extended, so check online, with your CPA, or with sellers of solar panels to see what tax credits, if any, are available.
With tax incentives and cost-effective design and construction, a zero energy home may add only 5 to 10% over the cost of a similar-sized standard home. This is according to ZeroEnergyProject.org. But don’t forget, you can save thousands of dollars per year by not having to pay for utilities. And you’ll start saving the first day you move in.
If you are considering a zero energy house, here are the 12 steps that zero energy project.org recommends taking to build a more affordable zero energy home.
#1 Use smart design principles.
Build a simple house that takes advantage of the orientation of the sun. A solar energy contractor can perform a site analysis to be sure that sufficient sunlight is available for solar panels. The simpler the house design, the more affordable the house will be. Classic rectangular or square shapes are easier and less expensive to build, air seal, and insulate.
#2 Use energy modeling.
Energy modeling uses computer-based software to estimate the energy usage of a house. Energy modeling software is an important design tool that helps contractors identify the least expensive measures required to create a zero energy ho
#3 Air-seal the house envelope.
This is the single most cost-effective measure that you can take to improve the energy efficiency of a zero energy home. It’s also a smart idea for a standard home. High-performance homes have a continuous air barrier. The secret to a continuous air barrier is to use large sheets of wall and roof sheathing and to completely seal the seams of that structural sheathing. The ZIP system is one of the systems suggested by ZeroEnergyProject.org. I’ll do a product review on the zip system in an upcoming episode.
#4 Install lots of insulation.
In other words, your a zero energy house should be super insulated. It is important to insulate the walls, floors and ceilings with types and thicknesses of insulating materials that are appropriate for your climate.
#5 Heat your water efficiently and minimize hot water use.
After heating and cooling, water heating is often the largest single energy expense in a zero energy home. So selecting efficient water heating technology is important, along with implementing measures to minimize hot water use. You can install water saving faucets, shower heads, and appliances.
#6 Select high-performance windows and doors.
Control window and door heat loss and gain by selecting high-quality window and door products. For more information on selecting energy efficient windows, take a listen to episode 42 called Windows 102.
#7 Make the majority of your windows south facing to take advantage of the sun’s position.
Using the sun for heating through south-facing windows during the winter lowers heating costs. Shading those same windows in summer lowers cooling costs.
#8 Have a ventilation system installed.
This is especially important in an air tight zero energy home. Highly energy efficient ventilation systems, known as heat recovery ventilation (HRV) systems or energy recovery ventilation (ERV) systems remove stale air and return fresh air to the house. This makes the air quality in zero energy homes much healthier than the air quality in standard homes.
#9 Select highly-efficient heating and cooling systems.
Heat pumps are a good choice. Mini-split heat pumps are one of the more economical heat pump options. You can learn more about heat pumps in last week’s mini lesson in episode 44.
#10 Choose smart lighting.
LED lights are probably the best choice for zero energy homes since they produce lots of light, but minimize energy use.
#11 Choose super efficient appliances like Energy Star appliances.
Electricity from appliances and wasted energy from plugged in electronics can account for up to 60% of energy use in zero energy homes. Therefore, selecting energy efficient appliances is really important. You’ll also need to manage potential wasted electricity from electronics that are plugged in, but not in use. Almost all electronics use a large amount of energy when they’re plugged in, even when they’re turned off. That wastes energy everyday, all day. To alleviate this problem, install wall switches that are connected to all the electronics in a room, so when you turn the switch off, all the electronics are turned completely off too.
#12 Have solar panels installed.
This is the last step in achieving a zero energy home. Solar panels are the most cost-effective form of renewable energy for a zero energy house. They can provide all the power you’ll need for heating and cooling, lighting, running your appliances and heating your water. But they’re one of the most expensive components of a zero energy home. So, your goal is to minimize the number of solar panels as much as possible. To do that, you must maximize the efficiency of the home in the ways that we just talked about.
To ensure that your zero energy house they are the real deal, it should be certified by an independent organization, or individual not associated with your contractors. The most common certifications are:
- Department of Energy’s Zero Energy Ready Certification
- Living Building Challenge Zero Energy Certification
- Passive House Certification
- Earth Advantage’s Zero Energy
- Zero Energy Ready Certification.
Independent energy consultants like home energy raters can also provide third party verification of zero energy homes.
If you like the idea of a zero energy home, but don’t have the budget to invest in solar panels or other technologies required to generate energy, you could build a zero energy ready home. Zero energy ready homes are designed and built to the same high standards as zero energy homes. The only difference is that zero energy ready homes are designed and wired for solar panels, but solar panels are not added. Solar panels can be added in the future when your budget allows.
Well, that’s all I have for this week. Before you go, Let’s do a couple of quiz questions.
Which one is an example of renewable energy.
- natural gas
The answer is D, the sun. Renewable energy is energy that’s collected from sources that are naturally replenished and never depleted, such as the sun, the wind and the internal heat of the earth.
True or false. A zero energy house produces as much energy as it uses.
That’s true. That’s the definition of a zero energy house. They are super insulated, airtight and use high-performance windows and doors, LED lighting and energy star appliances to save energy and they use solar panels to produce energy.
Please remember that the purpose of this podcast is simply to educate and inform. It is not a substitute for professional advice. The information that you hear is based the only on the opinions, research, and experiences of my guests and myself. That information might be incomplete, it’s subject to change and it may not apply to your project. In addition, Building codes and requirements vary from region to region, so always consult a professional about specific recommendations for your home.
Thanks for stopping by. I hope you learned as much as I did. Let’s do it again next week. I’ll talk you in the next episode of BYHYU.