How to Incorporate Sustainable Design in ADUs

We hear regularly from clients that they would like to incorporate elements of sustainable design in their accessory dwelling unit. If the client has a specific practice that they’re investigating, such as greywater systems, we evaluate on a case-by-case basis and according to budget. It of course takes extra time and budget to integrate specific systems, but we work with our clients to provide the specific services they are looking to achieve.

There are many different applications of “sustainable design,” so no list is really complete… but here is our list of main sustainable design considerations for ADUs:

  1. Site Optimization: Choosing the placement and orientation of a building – even a small ADU – is something to look at closely from the start of every project. Every case has a different scenario, and often clients have a specific area or size they’d like the ADU. In many cases with smaller lots, there are only a few layouts that work for the site. With more space, there is more opportunity for solar and wind oriented design.
  2. Reducing Energy Usage: Some strategies include:
    • Solar shading devices (designed window shading outside per climate/latitude, insulative curtains inside)
    • Thick walls/roofs with high insulation
    • Thermal mass (tile/concrete/stone to store and let off heat in cold months)
    • Light colored roofs/exterior materials to reflect sun rays
    • Efficient lighting and plumbing (standard for all projects in California, but you can always increase the efficiencies through product selection)
    • Photovoltaic (PV panels) systems (now required for California new construction projects)
    • Solar water heating
    • Cross-ventilation oriented to wind direction
    • Green walls/roofs (can get very pricey) or deciduous landscaping to reduce solar heat gain during summer and allow sunlight in during winter
  3. Environmentally Conscious Products: There are multiple agencies that evaluate the environmental quality of materials. In larger projects the main resource is “LEED accreditation,” which is a standard that provides guidance on how to design, build, and maintain energy efficient and sustainable structures. This has endless possibilities and can vary in cost greatly. It can be as simple as choosing a recycled glass countertop or recycled flooring, on up to various levels of LEED certification.
  4. Water Conservation: This varies in complication and cost and depends on the client’s preferred end result. Beyond the typical plumbing efficiency selection, conserving & protecting water can include:
    • Treating site runoff or Bioretention systems (required in some municipalities)
    • Greywater systems
    • Rainwater cisterns
    • Bioretention systems that treat water
  5. Indoor Environment: We typically provide consideration of indoor quality in all homes, especially daylight maximization, appropriate ventilation, walkway widths etc.
  6. Aging in Place Design: Otherwise worded as “accessibility” or “ADA guidelines,” designing for elderly and disabled persons is essentially accommodating extra space for wheelchair/walker accessibility. Design can go as far as grab bar installations, lower counters, etc. The cost of this kind of design is that it increases the required space significantly (example: 3’ doorways instead of typical 30”, wheelchair space in front of appliances, etc.) and some features are slightly inconvenient when not being used for accessibility (like low counters).
  7. Off-Grid Living: Some clients wish to build a fully off-grid ADU, which can be accomplished in some areas by using a septic system and an all-electric power source like solar. Read more about taking your home off-grid.

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