To speed the transition to zero carbon emissions, the U.S. must focus on designing or redeveloping entire communities that are zero energy, according to Charles Kutscher, a long-time energy efficiency researcher.
Tackling building energy use at the district level provides economies of scale in heating and cooling. Used on some U.S. college and other campuses, systems with a central plant that burns natural gas to heat water, which then is circulated to the various buildings, are more efficient than dedicated systems for each building.
To achieve zero carbon emissions, the latest strategy for district systems uses an ambient temperature loop that “simultaneously and efficiently both heats and cools different buildings,” Kutscher writes. “Heat pumps at individual buildings or other points along the ambient loop add or extract heat from the loop. They can also move heat between deep geothermal wells and the circulating water.”
National research labs and other project partners are developing an open source software development kit called URBANopt that models elements of zero energy districts. These can include building efficiency/demand flexibility strategies, rooftop photovoltaic arrays, and ambient loop district thermal systems. The software can be integrated into other computer models to aid in design of zero energy communities.