What Makes a Home "Green"?

Multi-year drought, distressed forests and intense wildfires bring awareness of the local impacts of climate change. Efforts to address climate change have long focused on cutting greenhouse gas (GHG) emissions and more recently on sequestering carbon. But because the impacts of climate change are now upon us, we need to add to our efforts resilience planning. What is the focus of these efforts related to our buildings?

In reviewing many “green building” programs, the most common characteristics are: energy efficiency, water conservation and selecting materials that are sustainable and used in a resource-efficient way.

Because energy use is strongly linked to GHG emissions, reducing energy consumption in homes tends to decrease damage caused by burning fossil fuels. There are many ways to reduce energy use in homes: install more efficient appliances, select higher performance windows, or add thicker insulation.

Water conservation makes sense in most regions of the country, excluding only those where fresh water is abundant. In California, water is directly linked to energy, for close to 20 percent of our energy use statewide is consumed in transporting and treating water. Residential water conservation emphasizes careful selection of plumbing fixtures and appliances but also promotes rainwater collection.

Choosing materials for a green home involves selecting materials that are naturally renewable (for example, wood from sustainably harvested forests), have recycled content, or are harvested/manufactured regionally. These materials also need to be incorporated in structures as efficiently as possible.

Other green building criteria worth considering are:

·         Designing and building homes that last longer. Although rarely thought about, designing to make future changes easier helps save materials. Selecting materials that require less cleaning and less maintenance are also aspects of durability.

·         A green home is small. Scaling down is unpopular with Americans, but greatly reduces impact.

·         A green home provides superior indoor air quality and promotes human health. Avoiding materials and furnishings that involve toxins and outgassing is key. Good natural and mechanical ventilating is also important.

·         Because transportation involves our biggest consumption of fossil fuel, selecting a location that is close to work, shopping, schools and public transportation could be the most impactful of all criteria, but is rarely addressed.

Resilience focuses on livable conditions in buildings after a disaster; on backup power; and on access to potable water. These strategies are being woven into “green building” programs but expanded to community scale. Photovoltaics with on-site storage can provide basic services and information during power outages. We know how to build tight buildings out of non-combustible materials to resist wildfires. Mechanical ventilation with HEPA (high efficiency particulate air) filters can handle smoke and ash from wildfires. Rainwater collection, composting toilets and recycled water are other resilient strategies.

Resilience in our Houses

Resilience in our Houses

Between 1955 and 1965 about 18 natural disasters occurred in the US annually. This decade, starting in 2010, we are averaging about 110 nationally declared disasters a year- roughly 2 per week. In the past, building codes were developed from historical data, but now State and Federal agencies are pushing communities to use predictive climate models to address more appropriately what’s coming.

Resilience is defined as “the intentional design of buildings, landscapes, communities and regions in response to vulnerabilities to disasters and disruptions to normal life.”

The local environment always plays a critical role in determining what makes a building resilient, or not. In other words, resilient design is always locally specific. Tapping into historic vernacular architecture, as well as local wisdom, knowledge and experience, often prompts strategies enabling buildings and occupants to better survive disasters. The big natural challenges we face in our region are droughts, wildfires, landslides, debris flows, intense precipitation, flooding, earthquakes and maybe even tsunamis. Resilience planning “is not about keeping people comfortable; it’s about keeping them alive” says Alex Wilson, President of the Resilient Design Institute. Preparedness includes planning for potable water, food, first aid, news and communication, toilet needs and getting around, probably without a car.

The 3 most important areas to focus on are:

Creating livable conditions for post-disaster. That means making your house (and surrounding space) wildfire resistant, constructing it to be seismically strong but flexible, and incorporating passive solar heating, cooling and natural ventilation. It is also important to provide protection from heavy rains with suitable roof overhangs, drainable planes behind siding, break-away panels, if in a flood plain, and infiltration swales and catch basins near the house.

Providing for back-up power. Evolve your home to be all electric with photovoltaic panels. Provide back-up power/storage for key electrical circuits in your home: refrigerator, cooking (if electric-magnetic induction), media, phone charging, electric car/bicycle, and a few lights. Avoid diesel generators. Battery back-up is increasingly affordable and reliable.

Accessing potable water. Develop a water supply, perhaps using rainwater collection, which can be filtered/purified with hand equipment to make it drinkable-safe. There are good filters pumps and ultraviolet portable treatment equipment available that were developed for wilderness trekking.

Doing all one can to stop, and even reverse, the climate crisis needs to be our top priority, but we also need to prepare for the disasters already arriving.

Fire Resistant Homes - New & Remodeled

No home is entirely protected against wildfire. Most have at least a few weaknesses, a few materials or openings that make them vulnerable to flying embers or to the intense heat of wildland firestorms.

Reducing this risk channels attention to a few fronts. Creating a 30’-50’ “fuel free” zone around a dwelling is mandatory: key steps to implementing this strategy are pruning up and thinning out trees; changing decks, trellises, fences, patio furniture and other flammable outbuildings to non-combustible materials; and removing all plant dead wood, wood piles and other easily ignitable materials. Stone, tile or concrete patios, metal or masonry fences, tube steel trellises and cementitious sheds near the house are worthy choices.

Shifting attention to the house, avoid wood or vinyl siding (susceptible to melting in high heat). Fiber-cement siding is a good choice, preferably with tongue-and-groove rather than shiplap joints. Stucco is also an excellent non-combustible covering option. Both materials have the added advantages of being rot and rodent proof, low maintenance, requiring infrequent or no painting.

Roofs need to be constructed with non-flammable underlayment on top of plywood sheeting, which is better than oriented strand board, a composite material commonly used. Superior roofing materials are tile, metal, cementitious composites and slate. Stay away from wood shingles or shakes, even when treated with fire retardant. Don’t forget to clean gutters regularly to maintain fire safety.

Double pane windows perform far better than single pane in resisting sudden spikes in temperature during wildfires and impact from wind-driven flying firebrands. Such spikes often cause window blowout. Smaller panes survive better than bigger ones. Wood, wood clad with aluminum, metal and fiberglass frames all perform well—certainly better than vinyl frames. All exterior doors should have a one hour fire rating.

Selecting high performance foundation, eave and attic vents is critical for creating a fire-resistant dwelling shell. Soffit and attic vents can be eliminated by using icynene insulation (an open cell foam) on the underside of the roof, the only code-approved way to do so. In homes with crawl spaces, foundation venting is required by code for moisture control. Baffle vents, auto-closing vents and 1/8” screened vents are recent developments specifically designed to protect vent openings from heat and embers. In wildfires, there are hundreds of thousands of flying embers driven far ahead of the fire front by strong winds. Most are small and go out immediately. The larger ones can get pushed into any opening in the house shell, where they can smolder for hours, until possibly igniting nearby combustible materials and burning the house down. 

Wildfires are important to the health and beauty of natural landscapes. Their periodic pattern reduces fuels, recycles nutrients, regenerates plants and stimulates biodiversity. We cannot “fireproof” forests, grasslands or shrub lands that depend on fire, but we can design, build and remodel homes to be more fire resistant.