(Bloomberg) -- July is set to be the hottest month on record, and over half of the US has been under excessive heat warnings and advisories this week. 

And with the climate crisis set to turn the heat up even further in the coming years, the need to keep people cool has never been more pressing, doubly so for doing it without emitting more greenhouse gases. Heat pumps have gotten a lot of the limelight, but a number of emerging climate tech startups are developing the next wave of technology that will keep us cool without frying the planet or overtaxing the grid. It’s a trifold challenge and one that industry experts agree cannot be fixed with a one-size-fits-all solution.

Air conditioners use about 6% of the US’s electricity supply, and the refrigerants required to operate ACs have a global warming potential that is 2,000 times as potent as carbon dioxide. Heat pumps — which offer more efficient, lower-carbon cooling — have been touted as a solution, gaining steam thanks to falling costs and tax credits in the Inflation Reduction Act. But the current versions on the market aren’t enough on their own to keep the grid stable, emissions down and people cool. Startups are already building the next generation of cooling technology that can help fill in the gaps.

One key way advanced cooling systems are trying to offer an upgrade over today’s heat pumps and air conditioners is by experimenting with ways to make homes’ cooling needs more responsive to power demand. With an increasingly rickety and strained grid, that’s taking on added importance. 

Carmichael Roberts, business lead of Breakthrough Energy Ventures’s (BEV) investment committee, pointed to BEV-backed Blue Frontier as an example of a startup working on doing that. 

Traditional air conditioners transfer heat from inside to outside through an evaporator that cools the home and a condenser that releases collected heat outside. A compressor moves refrigerant, a fluid that transfers the heat, between the evaporator and condenser. The Florida-based startup is designing a smart cooling and energy storage system that, in addition to other features, replaces refrigerant with a salt solution, or liquid desiccant. That liquid desiccant is kept in an energy storage tank that is currently designed to provide about four hours of cooling, allowing the roof-mounted unit to run even if there’s a blackout. 

“The utility can control your electricity consumption such that it is best for them, and the building user controls the thermostat, and they don’t have to match each other,” said chief executive officer and co-founder Daniel Betts. 

Mixing humidity with heat — a problem for many places in the eastern half of the country — adds to the challenges of staying cool. As air temperatures increase, the amount of water the air can hold also increases, making it harder for bodies to cool themselves. 

Conventional air conditioners are inefficient when it comes to humidity control, Betts said. Blue Frontier’s liquid desiccant technology can not only help its units store energy. It also pulls humidity out of the air directly, thereby cooling rooms more efficiently and reducing energy consumption by anywhere from 50% to 90%, according to lab data and field trials, he said. 

The company is currently in field trials and expects to start selling units in 2025, targeting commercial buildings initially, Betts said.  

MIMiC Systems, another advanced HVAC startup, has designed a solid-state heating and cooling system that uses solid material to transfer thermal energy, thereby requiring no moving parts like the compressors found in traditional ACs. The setup is fully modular, which means it can be more responsive to the differing temperature needs of individuals in a space. It also cuts the need for refrigerants completely, according to chief executive officer and co-founder Berardo Matalucci.

Flexibility is another part of the energy efficiency puzzle. The majority of American homes have ducted central air conditioning systems that heat and cool homes uniformly throughout the space, regardless of where people are and differences in room temperatures.

Another startup, Flair, sells a smart vent that can redirect air from one part of the house to another, effectively avoiding wasted energy and overcooling one room in order to get another to a tolerable temperature. Customers have told the company they’ve saved as much as 30% of their electricity bills by installing the system, according to chief executive officer and co-founder Daniel Myers. The company’s devices are installed in 30,000 homes.

For homes with ductless mini split systems, which make up the bulk of HVAC systems outside the US, Flair sells a smart thermostat that customers can use to control the temperature from anywhere via an app. That could allow these smart thermostat-connected HVAC units to be integrated into the grid and participate in load flexibility programs, Myers said. 

Myers called fully variable HVAC systems the company’s “North star,” both in terms of providing comfort and being responsive to the needs of the grid. They may be increasingly important as the grid strains under increasingly hot conditions. 

“At the end of the day, an average heat pump can use a substantial amount less electricity during periods of peak demand than central AC,”  Azolla Ventures general partner Amy Duffuor, said. “Smart heat pumps are a really great way to start thinking about boosting the resilience of the electric grid.” 

Azolla-backed window heat pump startup Gradient is among the companies trying to do that. Its units are internet-connected so that they can participate in a demand response program. These voluntary energy conservation programs are already being used in states like California and Texas. During critical times when extreme heat could spike energy demand, these programs help ease the load on the grid. 

All heat pump systems should be able to communicate with each other and other household appliances and understand when peak demand levels are so that they can pre-cool homes during times of surplus solar energy and smooth out peaks, said Gradient chief executive officer Vincent Romanin. 

“Buildings don’t have feelings, but people do,” he added, and smart HVAC design needs to focus on comfort as well. Keeping people cool in extreme heat is not just about lowering air temperature but taking into account all the aspects of human comfort, which include radiant temperature, air movement and humidity, he said. 

While this summer’s heat is intense, climate change will lead to even more extremes in the coming decades. Today’s heat pumps could solve some challenges to stay cool in tomorrow’s climate, but the next generation of technologies will be needed to ensure comfort while not making the climate crisis worse.

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