Top 5 Ways to Make Your ADU More Sustainable

Want to make your ADU more sustainable but don't know where to start? In this blog post, we share or our top five tips for designing and building greener ADUs.

Last updated 
February 21, 2023
Top 5 Ways to Make Your ADU More Sustainable

Top 5 Ways to Make Your ADU More Sustainable

As climate change continues to impact the planet, many people are trying to find ways to build and live with the lowest impact on the environment. Traditional development carries a large carbon footprint, but accessory dwelling units—particularly those converted from existing space—use fewer materials and therefore have a much lower impact. In fact, ADUs have a lot of potential for green living!

In the following blog post, we’ll discuss reasons for wanting a green granny flat and introduce the top five ways to make your ADU more sustainable and better for the environment. As a bonus, most of these tips will end up saving you money in the long run!

Why go green?

Some homeowners don’t have a preference about the ecological impact of their in-law unit, or are on a strict budget and can’t afford some of the sustainable building alternatives. However, others feel strongly that they want to pursue as many low-impact building options as they can. Here are some of the reasons why someone might prefer to build a “green” ADU:

Better for the environment

While ADUs naturally have a smaller environmental impact than larger homes, there are additional choices for building materials, appliances, and other aspects that can reduce the unit’s carbon footprint even further.

Lower energy costs

Many of the most environmentally friendly options for accessory dwelling units have the added bonus of lower operational costs. While extra insulation and gas heat pumps may be more expensive than traditional options initially, you will save money over time due to reduced energy costs.

High quality materials last longer

Another bonus: many of the “green” appliances and building materials are of a higher quality than the industry standard options. As a result, they usually last longer and perform better than their traditional, energy-consuming counterparts.

Best options for sustainable ADUs

In this section, we’ll go over some of our favorite options for making accessory dwelling units more sustainable. Keep in mind that you don’t need to adopt all of these approaches, and even choosing just one or two will have a more positive impact on the planet (and, over time, your wallet). Click on the links below for recommended vendors!

1. Electrify everything

This is a big one. Choosing to go fully electric with your ADU is the best way to reduce your day-to-day energy usage. And recent changes to California’s 2022 Energy Code (Title 24) have made going all-electric even easier for small units like ADUs. Here are some electric options and their benefits:


Forego gas appliances for electric. Natural gas has a bigger environmental impact, and electric appliances can run on green energy. Better yet, produce your own with solar panels (see more below)! And if all of your appliances run on electricity, you won’t have to run a gas line out to the ADU, which saves you money.

Electric induction cooktops use electromagnetic energy and are more efficient than gas. These aren’t your old electric burners, but vastly improved cooktops that are cool to the touch and boil water faster than gas. In fact, many chefs prefer electric induction cooktops over traditional gas ranges. Furthermore, their efficiency means that the heat your oven creates goes toward cooking your food rather than heating up your kitchen (a must-have in hot SoCal weather) or polluting the air.


Heating and cooling accounts for at least half of a home’s energy usage. Electric is already the industry standard for A/C, but the addition of electric heat pumps allows heating to be all-electric, too. Heat pumps are more efficient and cost-effective than other heating options (in addition to being better for the environment).

Hot water

Water heating accounts for about 20% of home energy usage. Heat-pump hot water heaters run on electricity and are much more efficient than gas tankless water heaters.

Electric heat-pump water heaters are admittedly more expensive than gas-tank water heaters, but this choice allows you to go all-electric and will pay for itself over time.

2. Solar energy

It always pays to add solar if you can! While solar panels can be expensive to install, you might qualify for a federal solar tax credit to help subsidize the cost. Solar panels enable the unit to create all of its own electricity, and if you can add enough panels, your ADU might be able to offset the energy use of the main house as well.

3. Limit water usage

Water usage is a big concern, especially in drought-prone Los Angeles and the surrounding areas. To reduce your water use indoors, install low-water appliances and plumbing fixtures (like low-flow shower heads and toilets) and motion controlled water faucets in the bathroom.

Outside, plant California native drought-tolerant landscaping with a smart drip irrigation system. You can even capture rainwater to use for irrigation!

Although it is not commonly done, you might be able to set up a greywater system to further reduce your water usage. A greywater system filters the water from your shower and sinks using a multi-stage filtration system to remove impurities, then diverts it way from the sewer and into your garden for irrigation purposes.

4. Recycled materials

You remember the old slogan: reduce, reuse, recycle. It applies to ADU construction as well as household items! Use recycled or secondhand materials whenever possible. It’s also best to look for local materials, as international shipping creates a significant amount of greenhouse gases.

To start, we recommend considering recycled/environmentally friendly insulation. Fiberglass is industry standard, but it’s not the only option! Mineral wool, cellulose, wood fiber, sheep's wool, cork, and even denim can all be used as insulation. Whatever type of insulation you choose, be sure to use plenty of it! Insulation helps reduce the thermal transmittance of a building, keeping it warm in the winter and cool in the summer while using less energy to do so.

There are great recycled material options for flooring, too. Reclaimed wood flooring diverts construction waste from the landfill and can be refinished for a beautiful new floor with built-in character.

5. LED fixtures

Last but not least, replace incandescent bulbs with LED lights. LED bulbs use 80% less energy than incandescent. Not only will they last longer and use less energy (which is better for the environment), their long life means that fewer bulbs are sent to the landfill. And it’s such an easy change to make! Although LED bulbs can be more expensive than their incandescent counterparts, the energy savings make up the difference.

Another great benefit of LEDs is that it is much easier to control the brightness and color temperature than incandescent lighting. Controlling light—whether from sunlight or from electric lighting—is key to creating ambiance in a small space, transforming a house into a home.

Do what you can

While the above list may seem a bit daunting, it’s perfectly fine to pick and choose what works best for you and your situation. Your ADU doesn’t have to be LEED Platinum certified or fully off-the-grid to be better for the environment. Every green choice you make when designing, building, and outfitting your unit helps the planet and all who inhabit it.

If you want to build a more sustainable ADU, contact Otto! We are happy to incorporate any and all of the above ideas to create your perfect unit.

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