Seven Steps to a ZEH

 

Construction of a ZEH involves many of the same materials and technologies familiar to the building trades and homeowners. Opportunities to reduce energy use exist in all areas of the home. The first opportunity to save energy is to reduce space heating and cooling and water heating loads. This often means that more insulation is required, along with attention to other important features such as air infiltration moisture barriers, and ventilation. Major equipment in the home should also be of the highest efficiency that is affordable, and be sized and installed correctly. That includes the furnace, air-conditioner, and water heater as well as the duct and piping systems that deliver air and water to the outlets. The next opportunity to reduce energy loads is to use higher efficiency lighting and appliances. The final opportunity is to be aware of energy use on a daily basis and turn off lights and appliances when not in use. Once the home's energy use requirements are reduced, a photovoltaic (PV) system is installed to provide the electricity used in the home and offset electricity supplied by the utility when averaged over the course of one year.

The means to achieving a successful ZEH are not the same for all homes. There are new building systems that can be used to increase the insulation of the walls and the roof, including Structural Insulated Panels (SIPS), Insulated Concrete Forms (ICF), and typical frame wall systems which can be used with new types of insulation. Research into energy-efficient construction techniques will prove fruitful in designing and constructing the most energy efficient home for the least amount of money. The NAHB Research Center's technical resource for building products can be found at toolbase.org.

As a quick summary of the process to construct a ZEH, consider the following steps.

Seven Important Steps to a Successful ZEH

  1. Decrease the energy requirements for space heating, cooling and water heating:
    1. Orient the home with smaller walls facing west and include overhangs and porches (See Passive Solar Design Fact Sheet)
    2. Increase foundation, wall and ceiling insulation (See Oak Ridge National Laboratory's Insulation Fact Sheet and ENERGY STAR's Recommended Levels of Insulation)
    3. Use low U-value, low-E windows in all climates and low solar heat gain (low SHGC) windows in cooling climates (See Efficient Windows Collaborative)
    4. Seal all holes, cracks, and penetrations through the floor, walls, and ceiling to unconditioned spaces (See Department of Energy's Air Sealing Fact Sheet)
    5. Install adequate ventilation, especially from kitchens and baths (See Ventilation Control Systems and Whole House Mechanical Ventilation Strategies)
  2. Increase the efficiency of the furnace (or heat pump), and the air-conditioner:
    1. Buy as high-efficiency equipment as affordable for the climate
    2. Design the supply and return duct system appropriately and seal tightly using approved tapes or mastic
    3. Consider ground-source heat pump technology where space and cost conditions permit
    4. Where climate-appropriate consider alternative cooling systems such as ventilation only or evaporative coolers
    5. Find addtional information at:
  3. Install a solar hot water pre-heat system, an efficient backup water heater, and an efficient distribution system:
    1. Consider a parallel, small diameter piping system for the hot water outlets
    2. Install low-flow fixtures
    3. Choose water heating equipment with a high Energy Factor
    4. Look for a knowledgeable solar hot water installation company
    5. Evaluate solar systems using the Solar Rating and Certification Corporation (SRCC)
    6. Find addtional information at:
  4. Install efficient lighting fixtures:
    1. Consider permanent fluorescent fixtures in as many locations as possible
    2. Look for the ENERGY STAR® label
  5. Install efficient appliances:
    1. Include the refrigerator, dishwasher, and laundry appliances
    2. Look for the ENERGY STAR label
    3. Compare appliance efficiencies (See American Council for an Energy-Efficient Economy - Consumer Resources)
  6. Install a properly sized photovoltaic (PV) system:
    1. Look for a knowledgeable solar PV installation company
    2. Evaluate tax and other incentives (See Database of State Incentives for Renewable Energy)
    3. Use PVWATTS for a quick estimate of PV output
    4. Find a Certified Solar PV Installer from the North American Board of Certified Energy Practitioners
  7. Turn off lights, computers, and appliances when not in use
    The successful Zero Energy Home doesn’t end with the designer and builder. The homeowner plays an extremely important role as they do with any well-maintained home. Throughout the life of the home, the homeowner has the most significant impact on the actual performance of the ZEH. Therefore, the ZEH homebuyer must be conscious of daily habits and patterns that affect energy use in the home as well as proper maintenance of equipment and appliances. For instance, understanding the way certain energy efficiency features of the home work such as programmable thermostats or photo-sensitive outdoor light fixtures is essential. Simple things such as turning off lights when leaving a room or closing doors when performing even quick tasks outdoors can eliminate "wasted" energy. Paying careful attention to actual energy needs and avoiding unnecessary energy use are the first steps in ensuring that the ZEH performs as it was designed and built. Secondly, as with any valued property, equipment in the home and the structure itself must be carefully maintained. Changing furnace filters, having heating and cooling systems cleaned regularly, periodically checking the operation of solar systems, and maintaining exterior caulking and painting are only a few examples of ways in which a homeowner can assure a long-lived, high-performance, and zero energy home.