San Diego, California
Final Report (PDF) October 2003
Another PATH Evaluation Site is now nearing completion in San Diego, California. Shea Homes, the 10th largest homebuilder in the U.S., has introduced a new product line, the High Performance Home. High Performance Homes are built to conform to the specifications of a ComfortWise™ home - meaning they are designed to expend 30% less energy on space heating and cooling than would the same footprint built to National Model Energy Code standards. These homes are equipped with such energy saving features as
thermostatic expansion valves on the HVAC system and
radiant barrier sheathing. In addition to these energy saving technologies, most of the homes will incorporate passive solar water heating and about 100 of these homes will employ
solar photovoltaics (or "PV"). The PATH program is currently providing both technical support and performance information related to household energy consumption and energy production by the solar-powered renewable energy systems.
The three High Performance Homes are equipped with roof-mounted PV systems that were mounted parallel to the sheathing - at 22.6°. The systems are comprised of 12-110 Watt DC panels and two inverters that convert the power produced to grid-quality AC electricity. PV system evaluation will cover such topics as the effect of system orientation on electricity production, system effectiveness at reducing a home's summer electric demand, comparison between simulated and actual electricity generation over the year 2002, homeowner satisfaction and perception, and recommendations on system enhancements.
High Performance Homes'
solar hot water heaters are "passive" systems that were mounted directly to the roof decking. The solar collector is essentially a rectangular shaped black box with a tempered glass top containing copper piping. Fairly unobtrusive, the collector covers a 25 ft2 area, holds 40 gallons of water, and rises just 7.5 inches above the sheathing. Located between the water delivered from the utility and the natural gas-fired hot water tank, the solar hot water system serves as a pre-heat for the hot water delivered to the home. Solar hot water heaters for two High Performance Homes were chosen for monitoring. Evaluation of the gas-fired tank and passive solar water heating system will include such topics as solar system contribution by average day hours, time of hot water use, quantity of hot water used, identification of system thermal losses, natural gas offset by the solar system, and tank standby and flue losses.
Additionally, hot water usage data of the two homes will be used to simulate the energy and economic performance of various water heating scenarios (e.g. electric or gas-fired demand water heaters combined with passive solar technology).
A final report is currently in draft form (as of April, 2003) and will be available in the coming months.
See the project profile for construction photos and status.
Content updated on 11/20/2006