Building Decarbonization
The California Energy Commission’s (CEC’s) 2018 Integrated Energy Policy Report (IEPR) Update found that greenhouse gas emissions from buildings are second only to transportation. Building decarbonization encompasses a suite of technologies to lower or eliminate these emissions by making buildings more efficient and by integrating appliances and systems powered by clean energy sources.
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Grid-interactive Buildings
With proper communications and controls, advanced building technologies—including the HVAC systems, lighting, dynamic windows, occupancy sensing, and distributed generation like rooftop solar, electric vehicle charging, and battery storage—can be optimized to meet occupant needs and to support the electric grid. Grid-interactive water heaters, for example, can receive signals to turn off the electric heating elements to reduce power use when the utility system reaches peak demand and electricity costs are high, and to shift power consumption to when the system has excess capacity and costs are lower. In Willowbrook, California, a CEC-funded project features a grid-integrated community-scale solar plus storage system, sited at a low-income multifamily disadvantaged community.
Electric Heat Pumps
Electric space and water heat pumps are expected to play a major role in building decarbonization, especially in moderate climates. These technologies work by moving heat from one location to another. Air-source heat pumps collect and transfer heat from the air while geothermal or ground-coupled heat pumps collect and transfer heat from the ground. Both types of heat pumps can also work as cooling systems, transferring heat from inside to outside. Compared to traditional furnaces, air conditioners, and water heaters, heat pumps require much less energy and can significantly reduce emissions. A CEC-funded project with EPRI will develop a reversible heat pump that uses ammonia and carbon dioixde as the refrigerants. These natural refrigerants are inexpensive and have near zero global warming potential and can lower the capital and installation cost.
Non-vapor Compression HVAC
The hydrofluorocarbons (HFCs) used as refrigerants in vapor-compression heating, ventilation, and air-conditioning (HVAC) equipment, and in other applications as well, are powerful greenhouse gases with long atmospheric lifetimes. For this reason, California, and many other jurisdictions, are phasing out the use of HFCs. The development of non-vapor compression HVAC technologies that do not require HFCs is an important part of this initiative. A CEC-funded project is focusing on the scale up of a magnetic refrigeration technology that eliminates HFCs and holds promise of energy savings.
Solid-state Lighting
Solid-state lighting uses semiconductor light-emitting diodes (LEDs), organic light-emitting diodes (OLED), or polymer light-emitting diodes (PLED) as sources of illumination instead of electrical filaments, plasma (used in arc lamps such as fluorescent lamps), or gas. The technology has evolved to where LEDs are now preferred in many lighting applications. Residential LEDs—especially ENERGY STAR-rated products—use at least 75% less energy and last 25 times longer than incandescent lighting. R&D for second generation SSL will help expand the technology into more types of lighting applications and improve characteristics such light quality and controls. A CEC-funded project is supporting a new technology for ultra-thin, flexible LED lighting that could be used to produce wide-area LED luminaires in various shapes at a fraction of the cost of traditional fluorescent and LED fixtures.
Advanced Window Technologies
The energy efficiency of buildings can be improved by using highly insulating windows, window films, or electrochromic glass, also known as “smart glass,” which allows occupants to control the amount of light (and heat) that passes through a pane. Advanced window technologies such as these contribute to occupants’ comfort by alleviating temperature swings and controlling glare. Technologies to convert windows into sources of solar-generated energy constitute another area of active development. A CEC-funded project is developing a transparent coating that selectively absorbs and converts non-visible light (ultraviolet and infrared) to electricity without impeding the passage of visible light.
