The so-called ‘White Paper’ — “Reducing Home Energy Costs by Combining Solar and Energy Efficiency” — used U.S. Department of Energy software to evaluate three different ages of homes (old, typical and new) in 10 cities in the U.S. for a total of 30 different test simulations to determine what combination of energy efficiency and renewable generation makes the most sense for most homeowners.
The study showed that climate, local utility rates and home condition are the most important factors in determining the most cost effective energy savings measures. Lighting retrofits are always cost effective. Weatherization and insulation energy efficiency measures are most cost effective in old homes in cold climates, but are not cost effective in newer homes or in temperate climates.
We can’t conserve our way to energy independence; but fortunately, with affordable rooftop solar we can now generate much of the energy we need. –Barry Cinnamon, CEO, Westinghouse Solar
Basic building shell and ventilation energy efficiency measures are most cost-effective in cold climates, but have long paybacks in more temperate zones. Rooftop solar power systems have good paybacks regardless of home condition in sunny areas and in areas with either high electric rates or high solar incentives.
Solar thermal systems have good paybacks when the fuel source for hot water is electricity. Upgrades to Energy Star appliances and equipment are generally cost-effective when replacing broken or obsolete equipment, but are generally not cost effective when the existing equipment is still functional (analogous to not upgrading to a new, higher mileage car if the old one still works).
“In almost all of the U.S. housing stock built since the mid-1980s the ‘low hanging fruit’ of basic energy saving measures have already been harvested through energy efficiency regulations and rebate programs for energy efficiency measures,” said Sue Kateley, Executive Director of CALSEIA, who noted that for a typical home in the U.S., rooftop solar energy systems (electric and thermal), will generate six times more energy than can be saved with lighting, weatherization and insulation retrofits combined.
“It’s time for policymakers to reevaluate loading order priorities to ensure that the state and national policies to reduce energy consumption will be achieved in a cost effective manner,” Kateley suggested.
Barry Cinnamon, CEO of Westinghouse Solar, agreed. “The economics for rooftop solar power systems have improved dramatically since 1980,” he said. “We can’t conserve our way to energy independence; but fortunately, with affordable rooftop solar we can now generate much of the energy we need.”
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