Green Resource – Solar Energy

Solar is green. Period. Making use of solar energy is at the heart of sustainable building. In designing a green house, solar energy comes both first and last. The goal is to create a house that consumes at least 50% less energy than one built conventionally, with a corresponding reduction in heating and cooling costs. Combining green-building techniques with active solar systems can result in a “zero energy” home, one that produces as much energy as it consumes over the course of a year.

See Chapter 13 on Solar in the Green from the Ground Up book for more details or contact us about training.

A House without Energy Bills

Building a “Zero Energy” house – one that produces as much energy as it consumes – melds a variety of green strategies.  Here are some tips and practices to consider:

Track the sun

• Calculate the amount of usable sunlight the site will get.

Preplumb for solar

• Easier to prepare a house for solar panels in the future.
• Run two 1-in. copper lines from the attic beneath a south-facing roof to the area where the water heater will be located.
• Insulate lines with the highest R-value foam insulation available.

Upgrade the Shell

• Add 1 1/2-in. resilient channel to interior studs to make thicker, better-insulated wall.
• Add 1-in. rigid foam insulation to the outside of the building.

Built Tight, Ventilate Right

• Make sure indoor moisture and indoor quality are properly managed through mechanical ventilation, such as a heat recovery ventilator or exhaust fans on programmable times.
• Install high-quality windows.
• In the crawlspace, seal vents and install a vapor retarder over exposed earth.

Install an energy use meter

• Allows homeowners to check the output of photovoltaic panels as well as track consumption.
• Displays, at a minimum, electrical output of array, battery voltage and any error messages from the inverter.
• Install in a spot where it’s easy to see.

Green from the Ground Up Best Practices

• Consider active solar systems (hot water and photovoltaic panels) once all other steps have been taken to minimize energy loads on the house.
• At a minimum, preplumb the house for solar collectors even if a system is not in the cards at the time of construction.
• Install a 1-in. metal conduit from a south-facing roof to the main electrical panel to accommodate future installation of photovoltaic panels.
• When mounting solar panels on the roof, use threaded stand-offs that are fastened into trusses or rafters rather than L-brackets fastened only to roof sheathing.They should be flashed just like a plumbing vent to reduce the risk of leaks.
• For photovoltaic panels, consider a tracking system that follows the movement of the sun, which will increase the electrical output by 25% a year.