In the United States, residential homes and commercial buildings consume 70% of the nation’s total electricity, resulting in an annual energy bill of approximately $400 billion.
Through various energy efficiency technologies, techniques, and materials, these energy bills can be reduced by 20-50%—or more. PNNL, in concert with the Department of Energy (DOE), industry, and other national laboratories, is working to do just that.
Technologies, techniques, and materials that have been, or are being, tested include:
- Windows and window attachments
- Wall retrofits
- Indoor air quality
- Heating, ventilation, and air-conditioning
- Ductless heat pumps
- Heat pump water heaters
- Electric loads.
The PNNL Lab Homes, PNNL Power Electronics Laboratory, and field testing with partners are all critical elements that enable testing. Once complete, PNNL and its collaborators prepare written reports and recommendations to DOE and residential building partners. The results also provide valuable information to manufacturers of major appliances and home building materials.
Windows and window attachments
PNNL researchers are testing new, thin triple-pane windows that have a slim non-structural center layer of glass between two standard-thickness glass panes. Krypton gas insulates the spaces between the panes, making the end product comparable to the weight and thickness of standard double-pane windows.
High performance window attachment solutions such as exterior shades offer a large energy savings potential in the residential sector, yet they’re rarely used in the U.S. We’re working with Lawrence Berkeley National Laboratory to conduct field testing of exterior shades in two or three occupied homes with large south- and/or west-facing unshaded windows.
Research into walls involves identifying cost effective ways to retrofit residential wall assemblies that result in durable, energy efficient, and marketable strategies for deep energy retrofits. The most common practice for wall upgrades generally falls into two categories: drill and fill and bare-stud rehab.
As the name implies, drill and fill involves drilling holes into each stud bay, usually from the outside, and then typically filling each wall cavity with blown insulation. During bare-stud rehab, workers expose the wall cavities by removing drywall or lath and plaster from the interior, then fill the walls with batt, blown, or spray foam insulation and to air seal at the same time.
Indoor air quality
Indoor air quality encompasses measuring and analyzing performance of mechanical ventilation equipment in new homes and exploring how system designs and performance vary in different regions of the country.
Heating, ventilation, and air-conditioning
Researchers have shown that about 60% of heating, ventilation, and air-conditioning (HVAC) systems have installation, commissioning, and performance problems, leading to as much as a 30% increase in annual energy consumption. The efficient design and improved operation of HVAC systems in homes could lead to significant energy reduction.
We’ve conducted extensive testing of various HVAC systems in our Lab Homes, incorporating sensors and control-software to evaluate technology efficiencies.
Ductless heat pumps
In residential retrofit applications, ductless mini-split heat pumps (DHP) are often reported to have high-energy savings potential, depending on the system they are supplementing or replacing. DHPs are outdoor units (compressor, fan and coil) that provide hot or cold refrigerant through the house to various wall- or ceiling-mounted indoor units. The indoor units contain a fan that blows air over the refrigerant via a heat exchanger and hot or cold air is distributed throughout the room.
We conducted a three-phase project to help determine which control strategies would have the most energy savings impact in various climate zones around the U.S.
Heat pump water heaters
Homeowners rely on major household appliances to heat and cool their homes. Personal choice and comfort drive how much energy people use. Much of the usage, though, is determined by household technologies—many of which are less efficient than others. And these inefficient systems tend to use more energy and can add to the “stress cycle” on the power grid.
If residential building technologies can somehow adjust energy use in a way that’s transparent to the homeowner, demand on the grid can be more consistent, thereby relieving some of the cyclical stress.
In the Northwest region, we studied the demand response capability of heat pump water heaters (HPWHs) and electric resistance water heaters (ERWHs) in single- and multi-family homes. The goal: To understand if and how home technology systems work together to respond to signals from the power grid.
Miscellaneous electric loads
Miscellaneous electrical loads (MELs) represent consumed electricity that isn’t a core building function such as heating, ventilation, air conditioning, water heating, refrigeration, and lighting. Historically, DOE has focused energy efficiency initiatives on core building functions since they’ve constituted the majority of building energy consumption. However, as the energy efficiency of core loads has improved, the proliferation and energy consumption of MELs (any kind of battery being charged in the home) has increased, thereby negating a portion of core load energy savings.
Our research is focused on collecting and analyzing data on the amount of energy MELs—such as connected devices and car charging stations—consume, as well as the energy efficiency measures to limit/decrease their energy consumption.