Sustainable Building Defined
The term “green building” or “sustainable building” is used by many and in diverse ways. We define it here as providing housing for people with methods, products, and processes that lessen its detrimental impacts on the health of the human and ecological environment.
Why Sustainable Building?
Faith and Stewardship
Because Habitat for Humanity’s Christian “theology of the hammer” forms the basis for its core work, we explore other critical scriptural passages. The two greatest commandments of Jesus were “love your neighbor as yourself” and “Love God with your whole heart, mind, and self.” Psalm 24 tells us that “The Earth is the Lord’s…” It follows that to honor the greatest commandments – to love God and your neighbors created by God – is to care for God’s manifestations in the visible world, God’s creation. William Penn in 1693 wrote, “It would go a great way to caution and direct people in their use of the world, that they were better studied and known in the creation of it. For how could [they] find the confidence to abuse it, while they should see the great creator stare them in the face, in all and every part thereof?”
Health and Economics
According to the Architecture 2030 Challenge “unknowingly, the architecture and building community is responsible for almost half of all U.S. greenhouse gas emissions annually.” According to the U.S. Energy Information Administration, buildings consume 48 percent of the energy in the U.S. The residential slice of the building sector consumes 21 percent, just behind the transportation sector (27 percent). In addition, the construction and maintenance of buildings are responsible for 30 percent of wood and raw material use. Sediments from unchecked construction site run-off damages fish and wildlife habitat in streams and lakes. The list goes on concerning negative impacts of construction and buildings on the health of our environment. Therefore, how and where we construct housing are critical issues to consider as our health, economy, and culture will feel the long-term impacts of our actions taken today. Economically, cost-benefit analyses show tremendous long-term savings to homeowners and society when we design housing that is energy—and resource—efficient.
The Core Elements of Green Building
Building affordable housing in a more sustainable, or green, manner means addressing certain core elements during the stages of planning, design, development, and construction. While many local, state and regional green building programs exist across the United States, only a few provide a national template and checklist.
For this discussion, we will use one such program, the Leadership in Energy and Environmental Design (LEED) Green Building Rating System™. Administered by the U.S. Green Building Council and a network of LEED Providers, LEED for Homes is a voluntary rating system that promotes the design and construction of high performance "green" homes. LEED can be applied to new, rehabbed or multi-unit housing and also to neighborhood developments (called LEED-ND). Under LEED, green building has been outlined under five categories: (1) Site, (2) Energy/Atmosphere, (3) Water Efficiency, (4) Materials/Resources, and (5) Indoor Environmental Quality. Highlighted under each section below is a critical, short list of issues that should be addressed. Consult the LEED checklist to view ALL issues under each category. Green Communities™ is also an excellent green building program with a checklist and similar programs. It is the first of its kind to focus entirely on affordable housing. For further information: http://www.greencommunitiesonline.org/
1 – SITE
(includes site selection and planning, reduction of construction waste stream, building orientation, landscaping, stormwater management)
- Locate housing in close proximity to public and private services that homeowners use often, in order to reduce the wasteful burning of dirty fossil fuels.
- Consider multi-units, clustered housing and rehabbing over more wasteful single, detached, new housing units.
- Build up, instead of out. Consider un-built land for green community spaces.
- Reduce waste stream through planning, advanced framing design, tracking and creative reuse and recycling.
- Orient housing on site to capture the benefits of passive solar strategies according to climate zone.
- Take advantage of the local USDA extension office or garden club to identify, save and plant vegetation that is both native and drought-tolerant (called xeriscaping). Make an intentional effort to save green space and trees on site. Practice proper fencing of tree root zones to lessen construction damage.
- Follow Low Impact Development (LID) practices (toolbase.org). Create and follow a site management plan that outlines proper erosion control, conservation, and stormwater management procedures. Following such a plan is critical for good neighbor relations, reducing silt into water bodies (streams, creeks, lakes, rivers, bays) and for replenishing groundwater in a safer and more efficient manner.
2 – ENERGY/ATMOSPHERE
(Includes Energy Star® or higher, energy-efficient envelope, energy-efficient systems and products, lighting and appliances)
- As stated in HFHI’s U.S. Construction Standards Guidance and U.S. Policy Handbook, building to the Energy Star® standards should be a minimum step along the continuum of energy-efficient building. Several regional and utility programs have their own similar standards. These are acceptable IF they meet or exceed Energy Star®.
- In the cooler climates especially, a super-insulated and super-efficient envelope reduces the size of the heating systems needed in the conditioned space of a home. Aspects of an efficient envelope include quality Energy Star windows, tightly-sealed construction with little air leakage and correctly installed insulation that provides a high R-Value.
- Unless you are in a tropical climate where seasonal conditions very little, building an energy-efficient building envelope is a traditional and smart technique in warm climates as well.
- In warmer regions techniques such as solar shading with wide roof overhangs, radiant barriers, cool roofs (material type and color) and slab cooling can significantly reduce utility costs, in addition to the proper solar orientation of housing on the site.
- In addition to an efficient envelope, mechanical HVAC systems in all climates should be properly installed and sized (J-Manual for heating and cooling). If using ducts, they should be air-sealed at all seams and joints with mastic. Raised heel or energy trusses provide better insulation coverage in the attic. Passive solar design elements benefit housing in all climates. If possible, the long side of housing should face south, with the short ends facing east and west. Trees provide cooling in summer and can provide a windbreak and warmer insulating air in winter.
- Certain systems and products are especially energy-efficient and are too numerous to address here for all climates. A few examples are the tankless and solar hot water heaters, radiant floor heating, SIPS, Insulated Concrete Forms and traditional adobe (refer to www.toolbase.org for these and other examples).
3 – WATER EFFICIENCY
(Includes efficient toilets and fixtures, smart landscaping)
- After global warming and greenhouse gas production, the scarcity of clean water is the second greatest environmental issue globally. Provide dual-flush or low-flow flapper-less toilets in the housing to reduce water consumption. In addition, low-flow faucet heads on all fixtures will conserve water.
- When landscaping be conscious of the fact that turf lawns need much water (and fertilizer). Reducing the size of lawns to little or no yard coverage will greatly reduce water consumption. The planting of native and drought-tolerant shrubs and trees over ornamentals and invasives (not native to the local area) is especially important for the health of the yard, neighborhood, birds and other wildlife.
4 – INDOOR ENVIRONMENTAL (AIR) QUALITY
(Includes proper ventilation, healthy indoor air quality, and mold and moisture reduction)
- HFHI’s U.S. Construction Standards Guidance includes the new Healthy Indoor Air Quality Standard. Following this new standard helps to ensure homeowner health and the durability of the housing structure over time. The issues of ventilation, mold and moisture, combustion safety, radon risk reduction and healthier interior products that reduce asthmatic conditions are all addressed in this document.
5 – MATERIALS/RESOURCES
(Includes systems and products that are more efficient, durable and environmentally friendly, that may be independently certified (such as the Forest Stewardship Council – http://fscus.org), and may have post-recycled or reclaimed content.
- Choose more durable, longer-lasting and environmentally friendly products and systems that make more efficient use of resources. Some examples of these are engineered framing systems, sustainably harvested lumber, long-lasting interior flooring, recycled-content and reclaimed materials, formaldehyde and fiberglass-free insulation, and PIN foundations.
- As always, when you make a choice between two different products serving the same function, consider the one that lasts longer, is healthier, and is manufactured with less negative impact on the health of our environment.