Green Home Builders Guidelines

Building Green requires a change in the mindset of builders and consumers alike. Builders build what consumers demand and are willing to pay for, but the public is not used to thinking in terms of long-term paybacks because the average family moves every 5-7 years. If the cost of a green product doesn’t return the investment in 5-7 years, the consumer is usually not willing to make the initial investment.Builders as a whole are not good at selling the value of green products, and are slow to investigate new products that may not increase the overall cost of construction. Some concepts that consumers will have to start embracing are: Smaller homes, fewer windows, greater energy efficiency, value engineering, awareness of which products are made of non-renewable materials or consume large amounts of non-renewable energy in manufacturing or transport. Other concepts such as building stiffness and choosing materials based on their longevity will enhance the life expectancy of the home, thereby affecting the long term impact on the environment.

The NAHB has published some Green Home Building Guidelines. They focus on 7 key areas.

1. Lot Design, Preparation, and Development

Resource-efficient site design and development practices help reduce the environmental impacts and improve the energy performance of new housing. For instance, site design principles such as saving trees, constructing on-site storm water retention/infiltration features, and orienting houses to maximize passive solar heating and cooling are basic processes used in the design and construction of green homes.

2. Resource Efficiency 

Most successful green homes started with the consideration of the environment at the design phase—the time at which material selection occurs. Creating resource efficient designs and using resource efficient materials can maximize function while optimizing the use of natural resources. For instance, engineered wood products can help optimize resources by using materials in which more than 50% more of the log is converted into structural lumber than conventional dimensional lumber. Resource efficiency is also about reducing job-site waste. Invariably, there are leftover materials from the construction process. Developing and implementing a construction waste management plan helps to reduce the quantity of landfill material. By creating an effective construction waste management plan and taking advantage of available recycling facilities and markets for recyclable materials, construction waste can be reduced by at least two-thirds, reducing the burden on landfill space. Lastly, basing the selection of building materials on their environmental impact can be tricky. For instance, a product might be renewable, but on the other hand it takes a relatively great amount of energy to transport the product to a project’s job site. So there are trade-offs that need to be taken into consideration that makes product choices somewhat unique for each project and each locale. Finding building products that are made locally will reduce transportation impacts as well as impart a local flavor to your home.

3. Energy Efficiency

Energy consumption has far-reaching environmental impacts: from the mining of fossil-fuel energy sources to the environmental emissions from burning non-renewable energy sources. Energy consumption occurs in the production of the materials that go into the home, during the construction of a home, as well as during the operation of a home. Each home consumes energy year after year, meaning that the environmental impacts accrue over time. Therefore, energy efficiency is weighted heavily in a green building program. No matter what the climate, energy efficiency is considered a priority in most existing green building guidelines/programs. Moreover, as the cost to heat and cool a home becomes more unpredictable, it is advantageous to every homeowner to be “insulated” from inevitable utility bill increases. As with all aspects of these guidelines, the greatest improvements result from a “whole systems” approach. Energy performance does not end with increased R-values, the use of renewable energy, and/or more efficient HVAC equipment. Rather, there needs to be a balance between these features and careful window selection, building envelope air sealing, duct sealing, and proper placement of air and vapor barriers from foundation to attic to create a truly high-performance, energy efficient home that is less expensive to operate and more comfortable to live in than a conventionally constructed home.

4. Water Efficiency 

The average indoor daily water use in today’s homes is slightly over 64 gal/person. Implementing water conservation measures can reduce usage to fewer than 45 gallons. For this reason, green homes are especially welcomed in dryer climates. The importance of water resources is becoming increasingly recognized in the western third of the country. Choices between sending water to urban areas and keeping water available for agricultural uses highlight the importance of this valuable resource. Green homes often conserve water both indoors and out. More efficient water delivery systems indoors and native and drought-resistant landscaping choices outdoors can help prevent unnecessary waste of valuable water resources. Communities can obtain additional benefits when home owners use native species in landscaping.

5. Indoor Environmental Quality  

Healthy indoor environments attract many people to green building. After energy efficiency, the quality of a home’s indoor air is often cited as the most important feature of green homes. Many people interested in green homes have indicated that indoor air quality was their top issue of interest. An increase in reported allergies and respiratory ailments and the use of chemicals that can off-gas from building materials have contributed to a heightened awareness of the air we breathe inside our homes. Even though there is no authoritative definition of healthy indoor air, there are measures that can mitigate the effects of potential contaminants including controlling the source, diluting the source, and capturing the source through filtration.

6. Operation, Maintenance, and Homeowner Education 

Improper or inadequate maintenance can defeat the designer’s and builders best efforts to create a resource efficient home. For example, homeowners often fail to change air filters regularly or neglect to operate bath and kitchen exhaust fans to remove moist air. Many homeowners are unaware of the indoor environmental quality impact of using common substances in and around the house such as pesticides, fertilizers, and common cleaning agents. Home owners should seek out alternatives to toxic cleaning substances and lawn and garden chemicals, and utilize water-saving practices to help ensure that the green home that was so carefully built will also be operated in an environmentally responsible manner.

7. Global Impact 

There are some issues related to home building that do not fit neatly into any of the above guidelines. These items are placed into another section called global impact. One example of an issue having global impact is the selection of paints that contain relatively low or no volatile organic compounds (VOCs). Although the VOC content of paint is often considered for indoor environmental reasons, the vast majority of VOCs are released by the time the paint is dry. However, the release of VOCs from wet paint helps form ground–level ozone pollution. Therefore, the use of low or no-VOC paints falls under the global impact section because the use of paints with high VOC levels impacts exterior environmental quality perhaps even on a global scale.Many of the guidelines are difficult to measure and quantify. In addition, a particular guideline may contain trade–offs and carry with it contradictory characteristics. For example, a recirculating hot water system can help conserve water but may use a relatively large amount of energy in its operation.

Some specific ideas to incorporate into your new home might include some of the following: 

• High efficiency heating and cooling systems. This feature significantly lowers your monthly utility bills.
• Heat recovery ventilation system with a HEPA filter provides fresh air exchanges while maintaining interior air temperatures and filtering out smoke, allergens, and pollutants.
• Gas fireplace with exterior combustion air intake.
• R-23 BIBS insulation on all exterior walls (most homes have R-19 or R-21 fiberglass batts) and R-50 in the attic. The BIBS is far better insulation, reducing heating and cooling costs in addition to great sound-dampening qualities.
• R-19 insulation on foundation walls with 6 mil poly on crawlspace floor to prevent moisture infiltration, and a passive radon ventilation system.
• Energy heel trusses allow full attic insulation at all edges and corners of the attic, preventing “cold spots” and heat from escaping and stops ice dams on the roof.
• Energy Seal Package – expanding foam insulation that seals rim joists, wall and ceiling penetrations, reducing utility bills by preventing uncontrolled air movement.
• Programmable thermostats allow your home temperatures to automatically change several times daily to maximize your comfort level, and again help reduce utility bills.
• Energy efficient windows have Low E and Argon gas with a U-value of 0.35 or lower. A lower U-value allows less heat to move in or out, again reducing utility bills. The Low E reflects UV rays, reducing fading of furniture and carpets.
• Wide roof overhangs reduce summer solar gain, reducing air conditioning bills.
• Optimize north/south orientation with respect to day-lighting and passive solar gain.
• Figure load calculations and properly size the furnace, A/C, return air, and ductwork.
• Placement of the garage to provide a buffer against extreme weather.
• Insulate hot water pipes and the water heater or install an on-demand water heater.
• Choose engineered lumber for framing and sheathing materials.
• Framing exterior walls on 24″ centers rather than 16″ centers is more than adequate structurally and allows for much better insulation.
• Fiber cement exterior siding is fireproof and won’t absorb moisture which causes paint to crack and peel, thus reducing exterior maintenance.
• Strategic placement of windows allows for lots of natural light throughout the home.
• Open floor plans to enhance controlled air movement and give a more open, spacious feeling to the home.
• Built-in recycling centers.
• Energy Star Appliances (especially the refrigerator, dishwasher, washer, dryer).
• Low VOC paints, adhesives, and sealants.
• Choose an advanced waste–water system (such as NORWECO) instead of a conventional septic system to reduce the amount of nitrites released into the soil and ultimately the aquifer from which we get our drinking water.