The past few weeks (usually on Mondays) this blog has been highlight success stories of homeowners implemented changes to make their existing home a Net Zero Home (ZEH).

While retrofitting a home for renewable energy is a good idea, today we focus on what it takes to build a new Net Zero Home from the ground up.

What’s different about building a Net Zero Home?

Here’s the story:

Jeff Christian looks over the construction of ZEH5

When you build a Zero Energy House from scratch you have more options for economical energy saving.  As we have seen by looking at the first two options, reducing the need for energy reduces the cost of the PV.

Here are some general things you want to do when building a ZEH.  The importance of each item will depend on your climate.  Some of the items may not be applicable under all circumstances

Reduce cooling loads:

1. Increase the reflectivity of the roof (metal roofs with high reflectivity in the infrared spectrum work well)
2. Use low e-windows
3. Use double pane windows
4. Prevent southfacing windows from being in direct sun during summer (using adequate overhangs is one way)
5. Use deciduous trees on east and west to shade windows during summer
6. Plan for stack ventilation
7. Open windows at night and close them during the day
8. Use efficient cooling (geothermal is one option)

Reduce heating loads:

1. Use deciduous trees on east and west sides of the home to allow sun in during winter
2. Southfacing windows should allow sun in during the winter
3. Have thermal mass to absorb winter sun
4. Use an efficient heating unit such as geothermal

Reduce heating and cooling loads:

1. Install ducts in conditioned space
2. Tighten ducts (check by testing: 3%-6% leak is ok)
3. Minimize air infiltration (SIPS, blower door test)
4. Use adequate insulation for your area
5. Use ventilator recovery
6. Use thermal mass

Reduce hot water loads:

1. Install a solar hot water system
2. Minimize the distance from hot water to the point of use
3. Use a circulating pump for long runs

Minimize other loads:

1. Use energy star appliances, (compare Kwh consumption of different models and sizes, not just low or high energy on tag)
2. Use compact fluorescent (CF) light bulbs
3. Eliminate phantom loads

Generate energy with photovoltaic panels:

1. Install a 1-5kw system
2. Ensure that the panels face south
3. Ensure that the panels are not shaded
4. If panels are fix-mounted, tilt panels at latitude

Monitor energy consumption:

1. Use a whole-house monitoring meter such as the TED meter
2. Monitor individual appliances using a plug meter
3. Review your electric bill

Information provided by Sustainable Future, LLC.
For most current information refer to http://SustainableFuture.biz.

Those of us on the road to solar home energy get discouraged from time to time. It is hearting to see how others successfully incorporate solar energy as well as other renewable practices.

Would you like to see how others are successfully using solar home energy? Me too! Here’s one.

Home in Concord, Tennessee

This home is approximately 3400 square feet, and was built in the early 1990s.  It currently uses two old, inefficient, 10-SEER heat pumps for heating and cooling.  The clothes dryer and all kitchen appliances are electric.  Before the conversion to a solar hot water system, the home had two 50-gallon electric hot water heaters.

In October 2006, we began to improve the energy efficiency of the house.  Our strategies included finding out where our electrical loads were, doing as much of the work ourselves as possible, and replacing inefficient appliances with Energy Star models as resources were available.  To date, our projects have included the following.

Fall 2006: Installed compact fluorescent light bulbs and two programmable thermostats for the two heat pump units.  We also replaced an old refrigerator with an Energy-Star model.

Spring 2007: The dishwasher was replaced with an energy-efficient Kenmore from Sears.

Summer 2007:  With a sunny, near south-facing roof, this house was a good candidate for solar technology.  A solar hot water system was installed in late June 2007.  The new system has two 4ftx 7ft flat panel collectors tilted at approximately 45 degrees to provide a bias towards winter efficiency.  The old 50-gallon hot water heaters were recycled, and replaced with an 80 gallon solar storage tank with an electric backup.

Fall 2007: A whole house meter was installed to monitor energy use.  In addition, a plug meter was used to test individual appliances.  An inefficient basement humidifier was replaced.

Winter 2007-2008: A blower-door test was conducted in the house to identify air leaks (house was very leaky).  Air infiltration was found in the recessed lights, around fireplaces, and around windows and doors.  Caulk and mastic were used where appropriate to seal air leaks.

Spring 2008: Gila reflective shades were installed on south-facing windows to reflect summer heat.  Thermal imaging was also used at the house to identify areas where insulation was not doing its job.

Summer 2008: We installed radiant barrier in the attic, and added insulation.  We used the results of the thermal imaging camera to improve insulation effectiveness.  A draft-stopping air pillow from Battic Door was installed in the fireplace to eliminate air leaks.

With the exception of one month, the reduction in energy use (and the associated electric bill) has been dramatic.  The following table shows electricity use in kilowatt hours before (from 2003-2006) and after (2007-2008) energy improvements were made.

Kilowatt Hour Use Per Month (Before & After Energy Improvements)

Information provided by Sustainable Future, LLC.
For most current information refer to http://SustainableFuture.biz.