How one CalNEXT-funded project shows that high efficiency dehumidification systems can save money, cut energy consumption, and make a big impact on fossil fuel emissions.
When people talk about HVAC and energy efficiency, they are most often talking about heating and air conditioning—which have both seen dramatic improvements in efficiency over the last century. While electrifying heating and cooling remains critical in the fight against climate change, dehumidification efficiency can and should become a larger part of the conversation. As one 2022 study in Joule found, global humidity loads contribute to an estimated 600 million metric tons of CO2 equivalent per year, with emissions expected to be as much as five times larger by 2050.
Dehumidification efficiency has never been more necessary. With California working to achieve carbon neutrality by 2045, one emerging technology could be key to helping the state reach that ambitious goal. A recent CalNEXT field study showed this technology—high efficiency dehumidification systems, or HEDS—can offer significant energy savings while lowering greenhouse gas emissions.
ASK Energy and AESC conducted a HEDS evaluation on behalf of the California investor-owned utilities and received funding through the CalNEXT program, California’s statewide emerging technology initiative. The final report, High Efficiency Dehumidification Field Study, looked at this new technology’s performance in a San Diego fine art museum and found something remarkable: HEDS can offer energy savings between 39 and 72 percent, and between 64 and 99 percent reductions in fossil fuel emissions. These results mirror and further validate previous findings from a study conducted by the US Department of Energy and the National Renewable Energy Laboratory.
So, what exactly is HEDS, and what makes it different than a traditional dehumidification system?
Other dehumidification systems rely on desiccant, a moisture-absorbing material, to cool and dry incoming air, or require an exhaust air stream and supply fans to precool and reheat outdoor air, which are effective but inefficient processes that lead to significant energy consumption and carbon emissions.
HEDS technology is different, as it can use up to 100 percent of the heat recovered during the HVAC cooling process to reheat and dry air. HEDS also controls airflow more efficiently. Unlike other dehumidification systems, which supply a constant flow and volume of heated or cooled air throughout a building, HEDS uses a mode called variable air volume (or VAV). VAV can adjust the volume of air being supplied to each zone in a facility, saving additional energy during times when there is less demand on the HVAC system. Â
Dehumidification is especially important in buildings where excess moisture poses increased risk to occupants and facilities, like museums. San Diego’s Timken Museum of Art is committed to protecting its gallery of 700-year-old artwork while maintaining industry-related climate standards. Because the Timken is funded by donors and offers free admission year-round, museum leadership is highly conscious of balancing environmental impact with fiscal responsibility. Â
“Having the right temperature and humidity is one of the most critical tools for the conservation of objects entrusted in our care. While museums may have different types of objects and exhibitions, the right conditions to protect artworks are standard across the industry,” said Megan Pogue, Timken executive director. “Trying to achieve these environmental benchmarks challenges every institution. Without a simple, state-of-the-art technology like HEDS, museums must rely upon expensive, energy-intensive, and often supplemental systems—as well as labor-intensive strategies—to achieve the proper temperature and humidity levels.”
The HEDS field study project team wanted to understand how well HEDS performed across seasons within an institution like the Timken. Using data taken over the course of a year at the museum, as well as data from utilities and weather stations to understand seasonal performance, the team compared the HEDS performance at the Timken with regression modeling for traditional dehumidification systems. This testing showed that the HEDS reduced overall energy consumption while maintaining the museum’s required temperature and humidity levels—even controlling those levels better than a traditional system.
Akane Karasawa of ASK Energy noted that the Timken’s HEDS offered a level of savings that nobody on the technology evaluation team had ever seen before.
“The study found HEDS energy recovery system saved significant energy and natural gas in the summer, and the HEDS HVAC optimization system enhanced and extended those electrical and fossil fuel savings throughout the year, even when dehumidification was not required,” said Karasawa. “The operational efficiency—and the reduced maintenance needs of the HEDS air handling unit—helps ensure low lifecycle costs while creating a financially viable steppingstone to reduce the costs of heat pump systems to replace chillers and boilers to fully decarbonize critical facilities.”
Along with other benefits, the HEDS reduces HVAC equipment runtime, lowers maintenance costs, and extends equipment life. It can also capture or kill 99.9 percent of airborne pathogens, thanks to ultraviolet antiviral technology originally developed for the US Department of Defense.
“The HEDS technology has proven to be a successful environmental and financial initiative for the Timken Museum of Art. The new system provided the lowest construction costs and reduced annual energy by over 70 percent and HVAC labor costs by” said Holly Martin-Bollard, Director of Operations for the Timken.
Despite these incredible benefits and its exciting potential, HEDS technology has not yet been widely adopted. The study found there are many reasons for this, most of which lie in misconceptions about HEDS, confusion surrounding energy code and regulations, and lack of general knowledge about and training on HEDS. Through incentive programs, education and training for HVAC designers and building owners, and continued focus on electrification, the project team believes these barriers can be eliminated in the coming years, giving HEDS a chance to help lead California to carbon neutrality.
To learn more about HEDS and get an in-depth look at the museum field study, you can find the full CalNEXT report here.