Advanced Energy Perspectives

The building envelope consists of all the elements of a building that separate its interior from the exterior environment: external walls, insulation, windows, and roofing. Advanced building envelope materials can reduce building energy use and costs by lowering heating and cooling loads, which account for roughly 50% of energy consumed by a typical U.S. home and 40% in commercial buildings. Heating and cooling loads can be reduced by as much as 40% simply by using efficient building envelope technologies. Roof and attic insulation alone can reduce heating and cooling needs by 10% to 15%.

There are two types of currents that can be used when transmitting electricity: Alternating Current (AC) and Direct Current (DC). The electric grid originally developed around AC power because it was easier to manipulate and transport ef ciently over long distances compared to DC power. Technological advancements have now made high voltage DC (HVDC) lines a viable option for long distance transmission. With HVDC, converters draw AC power from the grid and convert it to DC power. The DC power flows over the transmission line, then goes through a second conversion back into AC power before it is injected into the grid. Converters at both ends allow HVDC lines to transfer power between regional grid interconnections without disruption.*

A microgrid is a network of connected electricity generation assets, controls, and loads that can operate independently from a utility grid and/or easily connect to or disconnect from a utility grid. Microgrids usually range in capacity from less than 1 MW to 40 MW, and can generally be classified as customer microgrids, utility or community microgrids, or remote microgrids. Virtual microgrids link distributed generation (DG) at multiple sites. Remote and customer-owned microgrids are well-established applications, while utility, community, and virtual microgrids are emerging alongside intelligent grid technologies. In all cases, microgrids can generate, distribute, and regulate the flow of electricity to consumers at a local level.