Our first two blog posts of 2023 shared how climate change affects our homes and how homes have been designed to respond to climate differences (vernacular architecture) in the past. How do we utilize this knowledge to address climate change in our residential work? In this month’s post, we’ll explain how we study existing conditions; assess sustainable options; and analyze the cost versus benefit between building anew and renovating.
Regardless of the project type, one key concept of sustainability is carbon neutrality. Carbon neutral buildings produce enough carbon-free renewable energy on-site to operate the building.
Existing Conditions & Needs
Sustainability and carbon neutrality can be achieved when we pay close attention to the existing conditions and environs of a property – also referred to as the site’s micro-climate. With this knowledge in hand, we develop a plan that enhances a site, versus trying to control it.
The site’s micro-climate can be evaluated in multiple ways:
A topographic and vegetation survey is taken before we ever put a pen to paper. Alongside our in-person exploration of the site, this allows us to pinpoint any existing trees, plantings, outcroppings and natural drainage that we want to protect. Saving such flora can enhance the history and beauty of the property, provide shade or preserve existing wildlife habitats.
A sun study can be performed in both analog and digital ways. Following a site walk and survey, we input the exact coordinates of a property into our 3-D rendering and drafting software – allowing us to see where the sun will rise and set on the property during each season. We utilize that information to understand our daylighting opportunities, shade and shadow, and general sun path. We can even perform a heat index analysis to learn where the sun might damage our exterior materials and, therefore, the home.
A soils report is also a vital design tool for our homes. By checking the stability and strength of the Earth on a property, especially on a hillside, we can determine where and how we build. The direction a tree is leaning on a hillside gives an indication of the “strong” or “weak” side of a slope. For example, in hillside areas, when the surface is nearly parallel to the tilted strata, the trees tend to lean and the slope tends to slide. Buildings are more stable when the strata are perpendicular to the top slope. The soils report and survey can also help us to determine the rain water collection opportunities. We even explore percolation rates, as rain retention is often required in many jurisdictions.
An evaluation of our clients’ needs and behaviors is also imperative to a successful and carbon neutral home. Understanding how our homeowners live and thrive in their homes allows us to determine any unique requirements that may impact the sustainability of a project. In particular: Do our homeowners have a pet? Do they play any sports? Do they desire a pool? Will they recycle? Compost? Garden? Providing carbon-friendly solutions to everyday problems is much easier while planning a project versus after move-in. One simple example of this is the integration of a retractable swimming pool cover to control evaporation, conserve heat and reduce cleaning effort and chemicals.
Assessing Sustainable Options
Assessing sustainable options for a project is also dependent upon the project type. Designing a new home, a renovation/restoration or addition to an existing house will determine different paths forward as we assess the sustainable opportunities. Most often, homeowners have already made this decision when contacting our studio, but sometimes, the answer is more complicated.
The decision to tear down a home is never an easy one, and is often based on finances. We make this decision together after reviewing the homeowners’ wishlist (program) and determining the extent to which the improvements will affect an existing home. If the early design process reveals that almost the entirety of the home must be altered or replaced, it can oftentimes be less expensive to start anew. In that case, we encourage our clients to sustainably deconstruct and recycle the existing home to reduce the overall environmental impact of the demolition. See more about that here.
In each project type, we consider strategies to reduce both the embodied and operational carbon.
Embodied carbon refers to emissions made as we build a home: the manufacturing, transportation, installation and disposal of building materials. How can we reduce these? We choose renewable, Earth-friendly materials wherever possible. We spec local materials, minimizing embodied carbon in the transportation and procurement of the product. We research existing products to verify that they are safely fabricated with no undesirable off-products. And, for those products that we cannot obtain locally, we look to the cleanest options for shipping.
Operational carbon, on the other hand, are the emissions released from energy due to the ongoing operation and use of a home, such as lighting, heating/cooling and power. This is often part of the “lifecycle cost” of a home. A well-designed and well-built home in Southern California can often remain comfortable without air-conditioning, greatly reducing operational carbon. California now also requires low-flow plumbing fixtures, smart thermostats, timers and motion-sensors on lighting and exhaust fans. Yet we can do more: We create space in our laundries to air-dry clothing. We write maintenance almanacs for our homes to remind homeowners when to flush the tankless water heaters, to change air and water filters, vacuum the dryer vents and clean the gutters. These are examples of small steps we take to cut down on the operational carbon footprint of our homes and our homeowners.
New Homes vs. Renovations
Is a new home more carbon-neutral than a home to be renovated? On the plus side, a new home built today will have better insulation, more efficient furnaces and water heaters, a reflective roof and windows that don’t lose heat. The pipes, paint and tiles will be lead-free and the flooring and insulation won’t hold asbestos. Those features must be retrofitted in a home we are renovating.
However, a new home will likely have more and larger spaces to heat, more bathrooms, and more (and larger) windows and doors. New homes often have more electricity and fixture requirements. Those appliances and fixtures currently are designed for 30-year life at best. Built-in sound, integral audio, video and data systems are also more extensive in new homes.
In some ways, renovation has a green advantage: The wood used in older homes is less prone to termites and rot. Plaster is less susceptible to mold and mildew than drywall. Walls are often thicker in older homes and can retain heat better than new homes. Crawl spaces are usually better-ventilated. Older windows might be single-glazed, but are often designed with better shading.
How do we offset embodied and operational carbon in our home? Put simply, by making informed choices. We consider our choices like a budget. For each negative impact we attempt to make an equally or more valuable positive impact.
For instance, we may debit our “sustainability/carbon neutrality” bank with:
- Construction material that ends up in a landfill
- The use of steel for structural needs
- Adding plumbing fixtures to an existing home
- Large unshaded glazing
- The removal mature trees
- Installation of a pool
- Imported marble or other materials
- Using inefficient electricity guzzling appliances
But, we attempt to offset those debits with a greater number of credits:
- Utilizing recycled house parts or existing items
- Utilizing FSC-certified, kiln-dried lumber
- Implementing water reclamation and recycling
- Providing triple-glazed low-E windows
- Planting mature trees
- Providing a pool cover
- Utilizing local sources for stone and materials
- Installing solar (PV) collectors
- Providing large roof overhangs for shading
- Using closed-cell foam insulation
- Installing a cool roof or green roof
For each negative choice, we provide an equally or more effective positive choice. The end result is a carbon neutral, Earth positive, sustainable home.
A useful exercise, or merely a game? We believe that any tool that raises our awareness and our response is useful. There are countless other ways to address climate change in residential architecture, but we must address it now. When construction and materials transportation account for more than a third of today’s newly embodied carbon, the opportunity and the obligation is in our care.