Net zero homes are a new classification of buildings that have become increasingly popular over the past decade. In an era when increased environmental responsibility is necessary for sustainable living, net zero homes are being built to reduce the net energy consumption in people’s daily lives.
With global potential, net zero homes can be built practically anywhere in the world, while relying solely on the resources found in and around the property. In this sense, increased localization of energy from sustainable resources has the potential for positive environmental consequences around the globe.
In this detailed deep dive, we explore the definitions, intentions, and components of net zero homes. In doing so, we hope to bring a better understanding of what they are, how they work, and whether or not net zero homes are a trend or the future of sustainable housing development.
What is a Net Zero Home?
First and foremost, let’s define our hero of this story. Net Zero Homes can be called by many different names including:
- Zero-energy Buildings (ZE)
- Zero Net Energy Buildings (ZNE)
- Net-Zero Energy Buildings (NZEB)
- Zero Energy Ready Homes (ZERH)
- And more.
No matter what you call it a net zero home is simply a building that has zero net energy consumption. To achieve this, a home must produce the same amount of energy onsite through renewable resources that is equal to the amount it consumes over the length of a year.
Of course, energy is not the only resource that is used in a home. Whereas net zero homes generally refer to a building’s heating and electricity, additional systems can be installed to improve the home’s self-reliance and reduce its global impact.
Beyond net zero energy buildings, homes can install systems for the sustainable use of water, waste, and food. Whereas these are great features, net zero homes generally focus on energy use with the idea of limiting carbon and greenhouse gas emissions.
The Goal of a Net Zero Home
So clearly, the goal of a net zero home is to produce as much renewable energy as the home consumes each year. Most commonly, this is achieved by building renewable energy systems directly onsite to power the home’s electricity and heating systems.
As a result, more efficient systems often lead to reduced costs in building operations. Although maintenance and replacement are required for old systems, in general, renewable energy resources are free to use. So long as no taxes are ever imposed on the wind or heat and light from the sun, most renewable resources are virtually cost free after the initial installation. Depending on the price and efficiency, renewable energy systems usually pay for themselves when compared to traditional utility energy costs.
How Do Net Zero Homes Work?
Net zero homes are able to balance the “supply and demand” of a building’s energy with the proper components installed. As a sum of all its parts, net zero homes are built and operated intentionally so as to produce renewable energy and limit the amount of energy used within the building.
This is achieved by using the following:
- An Efficient Renewable Energy Resource
- PV Solar Power
- Wind Energy
- Microhydro electric systems, etc.
- A Well Insulated Building Envelope
- Energy Efficient Appliances and Lighting
- Smart Design and High Performance Windows & Doors
- Careful Home Energy Consumption
Net Zero Home Designs
Now more than ever, new construction projects are favoring designs that are environmentally friendly and designed to limit future resource use. In fact, now that we are beyond the year 2020, California’s Solar Mandate requires photovoltaic (PV) panels to be placed on all new roofs in the state. With that in mind, many modern residences can also be retrofit to lower or eliminate the need for traditional utility power.
Net zero home designs can come in all shapes and sizes, however here is a pretty good example of one net-zero living arrangement:
In this design found on 24hPlans.com, the deconstructed diagram notes some of the most important features of a net-zero home including efficient appliances, insulation, high-performance parts, and more.
Whereas the specific layout of the home is not as critical as you may think, the best net zero home designs consider all of the necessary components and build the design around them. Today, there are many pre-designed manufactured net zero homes that are made to work on almost any property. In other instances, net zero home design plans may have to be modified to suit a specific climate or parcel of land.
Challenges with Net Zero Homes
Although good intentions are never an issue, there are still many problems with net zero homes that people run into when designing, building, and maintaining one of these residences. On a case by case basis, here are some of the most common problems with net zero homes:
- Too much shade on the property for passive and PV solar
- No access to well or rainwater
- Too expensive for upfront high-quality materials and appliances
- Local mandates and preventative HOAs
- Continued reliance on grid power and services
Essentially, most of the problems associated with zero energy homes come from an adaptation standpoint. Here, the climate, property attributes, or cost to build fully-sustainable systems prevent many people from being able to operate a fully net zero home.
Accordingly, many environmentally-minded homeowners still try to achieve a zero net energy level, even if they fall short each year. For example, a modest grid-tied PV solar energy system will likely generate a home’s electricity demand (or more) every summer, while not quite netting zero during the darker months of the year.
How Much Does a Net Zero Home Cost to Build?
Because they are designed to reduce the long term running expenses of a home, net-zero buildings typically require a large upfront cost to build.
Of course, a net-zero home will cost only as much as the sum of its parts. Whereas new construction zero energy buildings are often marketed as a carefully engineered premium package, a net zero building can also be created as a result of the slow accumulation of high-quality appliances, technologies, and renovations.
Components of a Net Zero Home
As many great MC’s have said over the years, “It’s time to break it down.” Let’s take a look at the ins and outs of all of the parts that make up a zero energy home:
Passive Solar Design
The earth is solar powered, just as your home should be. Passive solar design is perhaps the most important aspect of maintaining a livable ambient temperature with the walls of your home.
Not only is passive solar heating easy to design and install, but it also is “passive.” This means that it requires minimal effort and attention to operate and maintain.
Passive solar design uses high quality glass in windows and skylights to let in direct sunlight into the home during the winter. As the sun hangs lower in the sky, the direct light is able to heat the interior of the home. Ideally, the sun’s rays are directed to a heat-capturing material on the illuminated surface, such as masonry.
Critically, a well designed passive solar home is able to also keep a home cool in the summer. Here, direct sunlight is blocked by an overhanging roof in order to prevent the home from overheating from constant direct overhead sunlight. Beyond this, retractable awnings and manual or automatic blinds can be installed to further control passive solar heating.
Proper Insulation & Building Envelope
Of course, keeping a stable interior temperature is only possible if a home is properly insulated. In a controlled environment, the physical separation of heat, air, light, and noise is what is known as the “Building Envelope.” With this in mind, the building envelope is one of the most important elements of maintaining comfort in an efficient zero energy building.
A properly insulated building envelope is ideally made up of the following:
- Concrete Foundation
- Insulation Throughout the Walls, Floors, and Ceilings
- Advanced Framing TEchniques
- Over-the-Top Sealant
- High-Quality Roofing Materials
- And High-Performance Doors and Windows
Here, it is important to note the insulation volume in your home is going to be affected by your local climate conditions. Insulation is measured by its “R-value,” which can be aligned to coincide with the various North American climates on this resource from Energy.gov.
There are many insulation materials to help maintain steady home temperatures. Most commonly zero energy homes use:
- Rigid Foam Boards
- Blow Insulation
- Cotton Batts
- And more
In many cases, multiple materials can be used to fully insulate the continuous barriers of a zero energy home. Here, it is most common to use whatever can be locally sourced for the least amount of capital.
Of course, if you strive to limit carbon emissions, it is important to remember that many types of insulation are made up of synthetic materials. With this in mind, it is best practice to limit the Global Warming Potential (GWP) of each of the materials that you use.
Energy Efficient Appliances
Modern living requires modern appliances, and the creature comforts of today’s world do not have to be limited in a Zero Energy home. Increased efficiency in today’s consumer products has made it possible to run modern appliances on less power than ever before. With this in mind, consumers can now use less energy and save money on a home’s operating electricity costs.
Nearly every electrical component in your house is currently being researched and developed to become more energy efficient. Net zero energy homes take advantage of the following products to reduce their power demand:
- LED Lighting
- High Efficiency Washing Machines
- High Efficiency Clothes Dryers (or a Simple Drying Rack!)
- Energy Efficient Dishwashers
- Air Conditioning Units
- And more.
Whereas it is a bit more difficult to locate energy efficient drills or video game consoles, most of the essential living appliances in today’s homes can be upgraded to a more energy efficient model. If you are striving for net zero, energy efficiency appliances can lower your electricity consumption, and therefore your electric bills and carbon footprint.
Renewable Energy Sources
Of course, the crux behind using any appliance in a net zero home is obtaining the necessary electricity from a renewable resource. As technologies have advanced and prices have dropped rapidly over the last 20 years, renewable energy sources are becoming increasingly easy to adopt.
In the United States, the most common off grid renewable energy sources are:
- Photovoltaic (PV) Solar Panels
- Wind Turbines
- Biomass (Wood Burning Fireplaces)
- Hydroelectricity (micro hydropower)
Today, photovoltaic solar panels are becoming the most rapidly adopted renewable energy technology on homes across the world. Systems can be incorporated into the existing utility grid and/or utilize an off-grid solar battery.
In many regions throughout the world, local utilities allow for “net metering” which enables homes to only pay for the surplus of electricity they consume against the amount of electricity they produce. For solar and wind systems, the grid essentially acts as a “back-up,” which powers the home when the renewable energy is unavailable. If a home produces more energy than it uses, in many cases utilities will end up paying homeowners for the excess electricity produced by their renewable energy system.
Renewable Energy Heat Pumps
Anyone who has ever paid a utility bill probably knows that it takes more than just electricity to properly run a home. In fact, gas energy accounts for the majority of water heating in the United States. For increased self reliance and reduced operating costs, zero energy homes can adopt several kinds of heat pumps in order to sustainably heat the building’s water.
- Thermal Solar Panels (also known simply as “solar hot water“)
- Geothermal (or Ground Sourced) Heat Pumps
- Solar Hot Air Heat Pumps
- And Hybrid Systems
Here, choosing the right type of system is again largely dependent on your local climate and resource availability. Thermal solar panels and hot water heat pumps transfer the heat from the sun to the hot water tank in a home. Clearly, these are better suited for climates where the temperature remains above freezing all year round.
Geothermal heat pumps are very popular for purposefully designed net zero homes. Although they can be expensive to dig and install, geothermal heat pumps are built entirely underground which saves space and allows for year round efficient operation.
Smart Water Systems
Often overlooked or taken for granted, water is one of the most critical resources in a modern home. After all, water is used to cook, clean, and hydrate everything in and around the house.
In truly net zero homes, an onsite or local water source is used to facilitate all of the operating demands for the home. Typically, this is sourced from:
- A Well
- Water on the Property
- Rainwater Harvesting
- or some combination
With today’s existing systems and freshwater availability, most defined “Zero Energy” homes do not actually factor water into the equation. Instead, the net zero homes that are connected to existing water and sewage systems try to focus on efficiency using every drop of water that enters the residence. Whereas the water may not be self-sufficient like in that of a “Net Zero Water Building”, conservation is still the goal when installing:
- Low Flow Toilets
- Water Efficient Showers
- Reclaimed Water & Gray Water Systems
- Multiple Use Water Systems
- And more
After the initial installation, the area around net zero homes can be taken even further to increase self-reliance, energy efficiency, and environmental impact. In some people’s eyes, the way that the property around a home is used is even more important than the inner workings of an energy-consuming home.
To start, trees and bushes can be purposefully placed on a property to shade areas of the home and property during periods of extended sunlight. Although you will not want to block your solar panels or windows, trees can provide a natural barrier to sunlight, wind, and corrosive airborne elements. Plus, plant life improves local air quality by consuming carbon dioxide and emitting oxygen into the atmosphere.
Beyond this, purposeful landscape architecture can also dramatically increase a net zero home’s water efficiency, while helping to maintain and improve the area’s ecological health and diversity. Smart sloping water systems along low impact terrains can help grow both native species as well as fruit and vegetable plants.
With sustainability as the ultimate goal, growing and harvesting edible plants of any kind are a great way to responsibly increase your property’s self-reliance. A word of caution though–gardening can be addicting! What begins as simply growing a few herbs or vegetables for many homeowners, often quickly morphs into full-fledged backyard farming.
Active Energy Monitoring & User Diligence
Last but not least, actively monitoring energy usage and staying diligent to low consumption is perhaps the most critical aspect of maintaining a net zero home. That’s right, no matter how well your home is designed, net zero energy use can truly only be obtained as a full lifestyle adaptation.
Thankfully, there are many smart home automation systems that can be installed to monitor and record all of the energy production and consumption in a home’s daily operation. Whereas many PV solar energy systems solely track kWh generation and use, full home systems can incorporate a building’s electricity, gas, water, battery reserve levels, Canadain and more.
Smart thermostats can be designed to automatically maintain home temperature levels by monitoring and deploying energy efficient heating systems. In the most advanced cases, automatic shades and other ordinarily manual devices can be automatically triggered by a home’s smart energy system.
Of course, over consumption is still likely to limit the possibility of net zero energy if electrical appliances are still used in high demand. For those who tend to let things slide more often than they should, the following can be done to limit energy consumption in your home:
- Turn off all of the appliances and lights when not in use
- Take shorter showers (less hot water)
- Unplug everything unnecessary (including computers and phones that are “off”)
- Limit continuous water use while brushing your teeth or doing the dishes
- Hang laundry rather than using a dryer
Net Zero Home Examples from Around the World
Want to see some real life examples for some net zero inspiration? Thankfully there are lots of case studies across the web showcasing zero energy residences all around the world.
First, here’s an image of Peter Amerongen in front of a Net Zero home. He is a Canadian designer who has been building zero energy homes since 2007. Peter runs Habitat Studio, which is based in Edmonton, Alberta.
Of course, you don’t have to be in Canada to enjoy a net zero home. In fact, many new manufactured homes like in the image above, come with all of the materials and systems necessary for maintaining a zero net energy level. With this in mind, prefab homes can be purchased, shipped, and lived in practically anywhere the dealer will deliver.
No man is an island and even the most remote homes can be considered the part of some sort of community. In this image from Colorado’s first Zero-Energy Community, a series of residences has been intentionally designed to supply a net zero energy consumption annually across the whole neighborhood. If this trend continues, sustainable housing developments may be more common across the country.
Lastly, it is hard not to think of bigger and better things when considering the scalability of a net zero home. In this mock-up of a commercial office space, rows upon rows of PV solar panels are installed to offset the building’s high electricity demands.
As data centers require an incredible amount of energy to power computer systems and maintain cool temperatures, installations like this have enormous potential in commercial buildings.
Conclusion: Are Net Zero Homes Worth It?
At the end of the day, net zero homes are a long term play. They generally require careful planning and a substantial upfront investment in order to live both cheaper and more sustainable for the next several decades. For the sake of the earth and your long term financial health however, net zero homes are definitely worth it when trying to reduce energy usage and lower your carbon footprint.